A systematic approach to evolve aptamers with new specificities

USDA-ARS?s Scientific Manuscript database

Aptamers are single-stranded nucleic acids with high affinities and specificities for the targets against which they are selected. Both features, along with an ability to be integrated into a large variety of sensors, make possible a wide-range of aptamer applications. However, changing aptamer sp...

The Systematic Bias of Ingestible Core Temperature Sensors Requires a Correction by Linear Regression.

PubMed

Hunt, Andrew P; Bach, Aaron J E; Borg, David N; Costello, Joseph T; Stewart, Ian B

2017-01-01

An accurate measure of core body temperature is critical for monitoring individuals, groups and teams undertaking physical activity in situations of high heat stress or prolonged cold exposure. This study examined the range in systematic bias of ingestible temperature sensors compared to a certified and traceable reference thermometer. A total of 119 ingestible temperature sensors were immersed in a circulated water bath at five water temperatures (TEMP A: 35.12 ± 0.60°C, TEMP B: 37.33 ± 0.56°C, TEMP C: 39.48 ± 0.73°C, TEMP D: 41.58 ± 0.97°C, and TEMP E: 43.47 ± 1.07°C) along with a certified traceable reference thermometer. Thirteen sensors (10.9%) demonstrated a systematic bias > ±0.1°C, of which 4 (3.3%) were > ± 0.5°C. Limits of agreement (95%) indicated that systematic bias would likely fall in the range of -0.14 to 0.26°C, highlighting that it is possible for temperatures measured between sensors to differ by more than 0.4°C. The proportion of sensors with systematic bias > ±0.1°C (10.9%) confirms that ingestible temperature sensors require correction to ensure their accuracy. An individualized linear correction achieved a mean systematic bias of 0.00°C, and limits of agreement (95%) to 0.00-0.00°C, with 100% of sensors achieving ±0.1°C accuracy. Alternatively, a generalized linear function (Corrected Temperature (°C) = 1.00375 × Sensor Temperature (°C) - 0.205549), produced as the average slope and intercept of a sub-set of 51 sensors and excluding sensors with accuracy outside ±0.5°C, reduced the systematic bias to < ±0.1°C in 98.4% of the remaining sensors ( n = 64). In conclusion, these data show that using an uncalibrated ingestible temperature sensor may provide inaccurate data that still appears to be statistically, physiologically, and clinically meaningful. Correction of sensor temperature to a reference thermometer by linear function eliminates this systematic bias (individualized functions) or ensures systematic bias is within ±0.1°C in 98% of the sensors (generalized function).

Inertial Sensor Technology for Elite Swimming Performance Analysis: A Systematic Review

PubMed Central

Mooney, Robert; Corley, Gavin; Godfrey, Alan; Quinlan, Leo R; ÓLaighin, Gearóid

2015-01-01

Technical evaluation of swimming performance is an essential factor of elite athletic preparation. Novel methods of analysis, incorporating body worn inertial sensors (i.e., Microelectromechanical systems, or MEMS, accelerometers and gyroscopes), have received much attention recently from both research and commercial communities as an alternative to video-based approaches. This technology may allow for improved analysis of stroke mechanics, race performance and energy expenditure, as well as real-time feedback to the coach, potentially enabling more efficient, competitive and quantitative coaching. The aim of this paper is to provide a systematic review of the literature related to the use of inertial sensors for the technical analysis of swimming performance. This paper focuses on providing an evaluation of the accuracy of different feature detection algorithms described in the literature for the analysis of different phases of swimming, specifically starts, turns and free-swimming. The consequences associated with different sensor attachment locations are also considered for both single and multiple sensor configurations. Additional information such as this should help practitioners to select the most appropriate systems and methods for extracting the key performance related parameters that are important to them for analysing their swimmers’ performance and may serve to inform both applied and research practices. PMID:26712760

Fe3O4/γ-Fe2O3 nanoparticle multilayers deposited by the Langmuir-Blodgett technique for gas sensors application.

PubMed

Capone, S; Manera, M G; Taurino, A; Siciliano, P; Rella, R; Luby, S; Benkovicova, M; Siffalovic, P; Majkova, E

2014-02-04

Fe3O4/γ-Fe2O3 nanoparticles (NPs) based thin films were used as active layers in solid state resistive chemical sensors. NPs were synthesized by high temperature solution phase reaction. Sensing NP monolayers (ML) were deposited by Langmuir-Blodgett (LB) techniques onto chemoresistive transduction platforms. The sensing ML were UV treated to remove NP insulating capping. Sensors surface was characterized by scanning electron microscopy (SEM). Systematic gas sensing tests in controlled atmosphere were carried out toward NO2, CO, and acetone at different concentrations and working temperatures of the sensing layers. The best sensing performance results were obtained for sensors with higher NPs coverage (10 ML), mainly for NO2 gas showing interesting selectivity toward nitrogen oxides. Electrical properties and conduction mechanisms are discussed.

Light-Regulated Electrochemical Sensor Array for Efficiently Discriminating Hazardous Gases.

PubMed

Liang, Hongqiu; Zhang, Xin; Sun, Huihui; Jin, Han; Zhang, Xiaowei; Jin, Qinghui; Zou, Jie; Haick, Hossam; Jian, Jiawen

2017-10-27

Inadequate detection limit and unsatisfactory discrimination features remain the challenging issues for the widely applied electrochemical gas sensors. Quite recently, we confirmed that light-regulated electrochemical reaction significantly enhanced the electrocatalytic activity, and thereby can potentially extend the detection limit to the parts per billion (ppb) level. Nevertheless, impact of the light-regulated electrochemical reaction on response selectivity has been discussed less. Herein, we systematically report on the effect of illumination on discrimination features via design and fabrication of a light-regulated electrochemical sensor array. Upon illumination (light on), response signal to the examined gases (C 3 H 6 , NO, and CO) is selectively enhanced, resulting in the sensor array demonstrating disparate response patterns when compared with that of the sensor array operated at light off. Through processing all the response patterns derived from both light on and light off with a pattern recognition algorithm, a satisfactory discrimination feature is observed. In contrast, apparent mutual interference between NO and CO is found when the sensor array is solely operated without illumination. The impact mechanism of the illumination is studied and it is deduced that the effect of the illumination on the discriminating features can be mainly attributed to the competition of electrocatalytic activity and gas-phase reactivity. If the enhanced electrocatalytic activity (to specific gas) dominates the whole sensing progress, enhancements in the corresponding response signal would be observed upon illumination. Otherwise, illumination gives a negligible impact. Hence, the response signal to part of the examined gases is selectively enhanced by illumination. Conclusively, light-regulated electrochemical reaction would provide an efficient approach to designing future smart sensing devices.

Macro-spin modeling and experimental study of spin-orbit torque biased magnetic sensors

NASA Astrophysics Data System (ADS)

Xu, Yanjun; Yang, Yumeng; Luo, Ziyan; Xu, Baoxi; Wu, Yihong

2017-11-01

We reported a systematic study of spin-orbit torque biased magnetic sensors based on NiFe/Pt bilayers through both macro-spin modeling and experiments. The simulation results show that it is possible to achieve a linear sensor with a dynamic range of 0.1-10 Oe, power consumption of 1 μW-1mW, and sensitivity of 0.1-0.5 Ω/Oe. These characteristics can be controlled by varying the sensor dimension and current density in the Pt layer. The latter is in the range of 1 × 105-107 A/cm2. Experimental results of fabricated sensors with selected sizes agree well with the simulation results. For a Wheatstone bridge sensor comprising of four sensing elements, a sensitivity up to 0.548 Ω/Oe, linearity error below 6%, and detectivity of about 2.8 nT/√Hz were obtained. The simple structure and ultrathin thickness greatly facilitate the integration of these sensors for on-chip applications. As a proof-of-concept experiment, we demonstrate its application in detection of current flowing in an on-chip Cu wire.

Systematic methods for knowledge acquisition and expert system development

NASA Technical Reports Server (NTRS)

Belkin, Brenda L.; Stengel, Robert F.

1991-01-01

Nine cooperating rule-based systems, collectively called AUTOCREW, were designed to automate functions and decisions associated with a combat aircraft's subsystem. The organization of tasks within each system is described; performance metrics were developed to evaluate the workload of each rule base, and to assess the cooperation between the rule-bases. Each AUTOCREW subsystem is composed of several expert systems that perform specific tasks. AUTOCREW's NAVIGATOR was analyzed in detail to understand the difficulties involved in designing the system and to identify tools and methodologies that ease development. The NAVIGATOR determines optimal navigation strategies from a set of available sensors. A Navigation Sensor Management (NSM) expert system was systematically designed from Kalman filter covariance data; four ground-based, a satellite-based, and two on-board INS-aiding sensors were modeled and simulated to aid an INS. The NSM Expert was developed using the Analysis of Variance (ANOVA) and the ID3 algorithm. Navigation strategy selection is based on an RSS position error decision metric, which is computed from the covariance data. Results show that the NSM Expert predicts position error correctly between 45 and 100 percent of the time for a specified navaid configuration and aircraft trajectory. The NSM Expert adapts to new situations, and provides reasonable estimates of hybrid performance. The systematic nature of the ANOVA/ID3 method makes it broadly applicable to expert system design when experimental or simulation data is available.

Real-time sensor validation and fusion for distributed autonomous sensors

NASA Astrophysics Data System (ADS)

Yuan, Xiaojing; Li, Xiangshang; Buckles, Bill P.

2004-04-01

Multi-sensor data fusion has found widespread applications in industrial and research sectors. The purpose of real time multi-sensor data fusion is to dynamically estimate an improved system model from a set of different data sources, i.e., sensors. This paper presented a systematic and unified real time sensor validation and fusion framework (RTSVFF) based on distributed autonomous sensors. The RTSVFF is an open architecture which consists of four layers - the transaction layer, the process fusion layer, the control layer, and the planning layer. This paradigm facilitates distribution of intelligence to the sensor level and sharing of information among sensors, controllers, and other devices in the system. The openness of the architecture also provides a platform to test different sensor validation and fusion algorithms and thus facilitates the selection of near optimal algorithms for specific sensor fusion application. In the version of the model presented in this paper, confidence weighted averaging is employed to address the dynamic system state issue noted above. The state is computed using an adaptive estimator and dynamic validation curve for numeric data fusion and a robust diagnostic map for decision level qualitative fusion. The framework is then applied to automatic monitoring of a gas-turbine engine, including a performance comparison of the proposed real-time sensor fusion algorithms and a traditional numerical weighted average.

Production and detection of atomic hexadecapole at Earth's magnetic field.

PubMed

Acosta, V M; Auzinsh, M; Gawlik, W; Grisins, P; Higbie, J M; Jackson Kimball, D F; Krzemien, L; Ledbetter, M P; Pustelny, S; Rochester, S M; Yashchuk, V V; Budker, D

2008-07-21

Optical magnetometers measure magnetic fields with extremely high precision and without cryogenics. However, at geomagnetic fields, important for applications from landmine removal to archaeology, they suffer from nonlinear Zeeman splitting, leading to systematic dependence on sensor orientation. We present experimental results on a method of eliminating this systematic error, using the hexadecapole atomic polarization moment. In particular, we demonstrate selective production of the atomic hexadecapole moment at Earth's magnetic field and verify its immunity to nonlinear Zeeman splitting. This technique promises to eliminate directional errors in all-optical atomic magnetometers, potentially improving their measurement accuracy by several orders of magnitude.

Gait Partitioning Methods: A Systematic Review

PubMed Central

Taborri, Juri; Palermo, Eduardo; Rossi, Stefano; Cappa, Paolo

2016-01-01

In the last years, gait phase partitioning has come to be a challenging research topic due to its impact on several applications related to gait technologies. A variety of sensors can be used to feed algorithms for gait phase partitioning, mainly classifiable as wearable or non-wearable. Among wearable sensors, footswitches or foot pressure insoles are generally considered as the gold standard; however, to overcome some inherent limitations of the former, inertial measurement units have become popular in recent decades. Valuable results have been achieved also though electromyography, electroneurography, and ultrasonic sensors. Non-wearable sensors, such as opto-electronic systems along with force platforms, remain the most accurate system to perform gait analysis in an indoor environment. In the present paper we identify, select, and categorize the available methodologies for gait phase detection, analyzing advantages and disadvantages of each solution. Finally, we comparatively examine the obtainable gait phase granularities, the usable computational methodologies and the optimal sensor placements on the targeted body segments. PMID:26751449

Gait Partitioning Methods: A Systematic Review.

PubMed

Taborri, Juri; Palermo, Eduardo; Rossi, Stefano; Cappa, Paolo

2016-01-06

In the last years, gait phase partitioning has come to be a challenging research topic due to its impact on several applications related to gait technologies. A variety of sensors can be used to feed algorithms for gait phase partitioning, mainly classifiable as wearable or non-wearable. Among wearable sensors, footswitches or foot pressure insoles are generally considered as the gold standard; however, to overcome some inherent limitations of the former, inertial measurement units have become popular in recent decades. Valuable results have been achieved also though electromyography, electroneurography, and ultrasonic sensors. Non-wearable sensors, such as opto-electronic systems along with force platforms, remain the most accurate system to perform gait analysis in an indoor environment. In the present paper we identify, select, and categorize the available methodologies for gait phase detection, analyzing advantages and disadvantages of each solution. Finally, we comparatively examine the obtainable gait phase granularities, the usable computational methodologies and the optimal sensor placements on the targeted body segments.

Unintended Consequences of Sensor, Signal, and Imaging Informatics: New Problems and New Solutions.

PubMed

Hughes, C; Voros, S; Moreau-Gaudry, A

2016-11-10

This synopsis presents a selection for the IMIA (International Medical Informatics Association) Yearbook 2016 of excellent research in the broad field of Sensor, Signal and Imaging Informatics published in the year 2015, with a focus on Unintended consequences: new problems and new solutions. We performed a systematic initial selection and a double blind peer review process to find the best papers in this domain published in 2015, from the PubMed and Web of Science databases. The set of MesH keywords used was provided by experts. The constant advances in medical technology allow ever more relevant diagnostic and therapeutic approaches to be designed. Nevertheless, there is a need to acquire expert knowledge of these innovations in order to identify precociously new associated problems for which new solutions need to be designed and developed.

Development of a tunable diode laser sensor for measurements of gas turbine exhaust temperature

NASA Astrophysics Data System (ADS)

Liu, X.; Jeffries, J. B.; Hanson, R. K.; Hinckley, K. M.; Woodmansee, M. A.

2006-03-01

A tunable diode laser (TDL) temperature sensor is designed, constructed, tested, and demonstrated in the exhaust of an industrial gas turbine. Temperature is determined from the ratio of the measured absorbance of two water vapor overtone transitions in the near infrared where telecommunication diode lasers are available. Design rules are developed to select the optimal pair of transitions for direct absorption measurements using spectral simulations by systematically examining the absorption strength, spectral isolation, and temperature sensitivity to maximize temperature accuracy in the core flow and minimize sensitivity to water vapor in the cold boundary layer. The contribution to temperature uncertainty from the spectroscopic database is evaluated and precise line-strength data are measured for the selected transitions. Gas-temperature measurements in a heated cell are used to verify the sensor accuracy (over the temperature range of 350 to 1000 K, ΔT˜2 K for the optimal line pair and ΔT˜5 K for an alternative line pair). Field measurements of exhaust-gas temperature in an industrial gas turbine demonstrate the practical utility of TDL sensing in harsh industrial environments.

A Systematic Method of Integrating BIM and Sensor Technology for Sustainable Construction Design

NASA Astrophysics Data System (ADS)

Liu, Zhen; Deng, Zhiyu

2017-10-01

Building Information Modeling (BIM) has received lots of attention of construction field, and sensor technology was applied in construction data collection. This paper developed a method to integrate BIM and sensor technology for sustainable construction design. A brief literature review was conducted to clarify the current development of BIM and sensor technology; then a systematic method for integrating BIM and sensor technology to realize sustainable construction design was put forward; finally a brief discussion and conclusion was given.

How Magnetic Disturbance Influences the Attitude and Heading in Magnetic and Inertial Sensor-Based Orientation Estimation.

PubMed

Fan, Bingfei; Li, Qingguo; Liu, Tao

2017-12-28

With the advancements in micro-electromechanical systems (MEMS) technologies, magnetic and inertial sensors are becoming more and more accurate, lightweight, smaller in size as well as low-cost, which in turn boosts their applications in human movement analysis. However, challenges still exist in the field of sensor orientation estimation, where magnetic disturbance represents one of the obstacles limiting their practical application. The objective of this paper is to systematically analyze exactly how magnetic disturbances affects the attitude and heading estimation for a magnetic and inertial sensor. First, we reviewed four major components dealing with magnetic disturbance, namely decoupling attitude estimation from magnetic reading, gyro bias estimation, adaptive strategies of compensating magnetic disturbance and sensor fusion algorithms. We review and analyze the features of existing methods of each component. Second, to understand each component in magnetic disturbance rejection, four representative sensor fusion methods were implemented, including gradient descent algorithms, improved explicit complementary filter, dual-linear Kalman filter and extended Kalman filter. Finally, a new standardized testing procedure has been developed to objectively assess the performance of each method against magnetic disturbance. Based upon the testing results, the strength and weakness of the existing sensor fusion methods were easily examined, and suggestions were presented for selecting a proper sensor fusion algorithm or developing new sensor fusion method.

Characterizing user requirements for future land observing satellites

NASA Technical Reports Server (NTRS)

Barker, J. L.; Cressy, P. J.; Schnetzler, C. C.; Salomonson, V. V.

1981-01-01

The objective procedure was developed for identifying probable sensor and mission characteristics for an operational satellite land observing system. Requirements were systematically compiled, quantified and scored by type of use, from surveys of federal, state, local and private communities. Incremental percent increases in expected value of data were estimated for critical system improvements. Comparisons with costs permitted selection of a probable sensor system, from a set of 11 options, with the following characteristics: 30 meter spatial resolution in 5 bands and 15 meters in 1 band, spectral bands nominally at Thematic Mapper (TM) bands 1 through 6 positions, and 2 day data turn around for receipt of imagery. Improvements are suggested for both the form of questions and the procedures for analysis of future surveys in order to provide a more quantitatively precise definition of sensor and mission requirements.

Electrochemical Detection of Platinum(IV) Prodrug Satraplatin in Serum.

PubMed

Wu, Yao; Lai, Rebecca Y

2015-11-03

We report the design and fabrication of a reagentless and reusable electrochemical sensor for detection of satraplatin (SAT), a platinum(IV) prodrug. The detection strategy is based on the electrocatalytic reaction between the Pt(IV) center of SAT and surface-immobilized methylene blue. We systematically evaluated the effect of passivating diluent chain length on the overall sensor performance. Our results show that the use of a shorter diluent like 2-mercaptoethanol is more advantageous than using a longer and more passivating diluent such as 6-mercapto-1-hexanol. Independent of the use of cyclic voltammetry or chronoamperometry as the sensor interrogation technique, all three sensors, each passivated with a different alkanethiol diluent, have been demonstrated to be sensitive; the limit of detection is in the range of 1-10 μM. They are also highly specific and do not respond to Pt(II) drugs such as cisplatin and carboplatin. More importantly, they are selective enough to be employed directly in 50% serum. This sensing strategy has potential applications in clinical pharmacokinetics studies.

An investigation of the role of defect levels on the radiation response of synthetic diamond crystals when used as sensors for the detection of mammography X-rays.

PubMed

Ade, Nicholas

2017-09-01

This study evaluates the role of defects on the performances of synthetic diamond sensors on exposure to mammography X-rays. Through systematic investigations, the main cause of instability of response of examined sensors necessitating pre-irradiation was isolated and ascribed to the presence of ambient light which has the effect of emptying shallow trapping levels. The changes in response between measurements in light and dark conditions varied from 2.8 ± 1.2% to 63.0 ± 0.3%. Sensitivities between 0.4 and 6.7nCGy -1 mm -3 determined for the sensors varied with defect levels. The study indicates that differences in crystal quality due to the presence and influence of defects would cause a discrepancy in the dosimetric performances of various diamond detectors. Once a sensor plate is selected (based on the influence of defect levels) and coupled to the probe housing with the response of the diamond sensor stabilised and appropriately shielded from ambient light, daily priming is not needed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Development of a fast temperature sensor for combustion gases using a single tunable diode laser

NASA Astrophysics Data System (ADS)

Zhou, X.; Jeffries, J. B.; Hanson, R. K.

2005-09-01

The 12 best NIR water transition line pairs for temperature measurements with a single DFB laser in flames are determined by systematic analysis of the HITRAN simulation of the water spectra in the 1-2 μm spectral region. A specific line pair near 1.4 μm was targeted for non-intrusive measurements of gas temperature in combustion systems using a scanned-wavelength technique with wavelength modulation and 2f detection. This sensor uses a single diode laser (distributed-feedback), operating near 1.4 μm and is wavelength scanned over a pair of H2O absorption transitions (7154.354 cm-1 & 7153.748 cm-1) at a 2 kHz repetition rate. The wavelength is modulated (f=500 kHz) with modulation amplitude a=0.056 cm-1. Gas temperature is inferred from the ratio of the second harmonic signals of the two selected H2O transitions. The fiber-coupled-single-laser design makes the system compact, rugged, low cost and simple to assemble. As part of the sensor development effort, design rules were applied to optimize the line selection, and fundamental spectroscopic parameters of the selected transitions were determined via laboratory measurements including the temperature-dependent line strength, self-broadening coefficients, and air-broadening coefficients. The new sensor design includes considerations of hardware and software to enable fast data acquisition and analysis; a temperature readout rate of 2 kHz was demonstrated for measurements in a laboratory flame at atmospheric pressure. The combination of scanned-wavelength and wavelength-modulation minimizes interference from emission and beam steering, resulting in a robust temperature sensor that is promising for combustion control applications.

ReliefF-Based EEG Sensor Selection Methods for Emotion Recognition.

PubMed

Zhang, Jianhai; Chen, Ming; Zhao, Shaokai; Hu, Sanqing; Shi, Zhiguo; Cao, Yu

2016-09-22

Electroencephalogram (EEG) signals recorded from sensor electrodes on the scalp can directly detect the brain dynamics in response to different emotional states. Emotion recognition from EEG signals has attracted broad attention, partly due to the rapid development of wearable computing and the needs of a more immersive human-computer interface (HCI) environment. To improve the recognition performance, multi-channel EEG signals are usually used. A large set of EEG sensor channels will add to the computational complexity and cause users inconvenience. ReliefF-based channel selection methods were systematically investigated for EEG-based emotion recognition on a database for emotion analysis using physiological signals (DEAP). Three strategies were employed to select the best channels in classifying four emotional states (joy, fear, sadness and relaxation). Furthermore, support vector machine (SVM) was used as a classifier to validate the performance of the channel selection results. The experimental results showed the effectiveness of our methods and the comparison with the similar strategies, based on the F-score, was given. Strategies to evaluate a channel as a unity gave better performance in channel reduction with an acceptable loss of accuracy. In the third strategy, after adjusting channels' weights according to their contribution to the classification accuracy, the number of channels was reduced to eight with a slight loss of accuracy (58.51% ± 10.05% versus the best classification accuracy 59.13% ± 11.00% using 19 channels). In addition, the study of selecting subject-independent channels, related to emotion processing, was also implemented. The sensors, selected subject-independently from frontal, parietal lobes, have been identified to provide more discriminative information associated with emotion processing, and are distributed symmetrically over the scalp, which is consistent with the existing literature. The results will make a contribution to the realization of a practical EEG-based emotion recognition system.

Selection of a new Mycobacterium tuberculosis H37Rv aptamer and its application in the construction of a SWCNT/aptamer/Au-IDE MSPQC H37Rv sensor.

PubMed

Zhang, XiaoQing; Feng, Ye; Yao, QiongQiong; He, Fengjiao

2017-12-15

A rapid and accurate detection method for Mycobacterium tuberculosis (M. tuberculosis) is essential for effectively treating tuberculosis. However, current detection methods cannot meet these clinical requirements because the methods are slow or of low specificity. Consequently, a new highly specific ssDNA aptamer against M. tuberculosis reference strain H37Rv was selected by using the whole-cell systematic evolution of ligands by exponential enrichment technique. The selected aptamer was used to construct a fast and highly specific H37Rv sensor. The probe was produced by immobilizing thiol-modified aptamer on an Au interdigital electrode (Au-IDE) of a multichannel series piezoelectric quartz crystal (MSPQC) through Au-S bonding, and then single-walled carbon nanotubes (SWCNTs) were bonded on the aptamer by π-π stacking. SWCNTs were used as a signal indicator because of their considerable difference in conductivity compared with H37Rv. When H37Rv is present, it replaces the SWCNTs because it binds to the aptamer much more strongly than SWCNTs do. The replacement of SWCNTs by H37Rv resulted in a large change in the electrical properties, and this change was detected by the MSPQC. The proposed sensor is highly selective and can distinguish H37Rv from Mycobacterium smegmatis (M. smegmatis) and Bacillus Calmette-Guerin vaccine (BCG). The detection time was 70min and the detection limit was 100cfu/mL. Compared with conventional methods, this new SWCNT/aptamer/Au-IDE MSPQC H37Rv sensor was specific, rapid, and sensitive, and it holds great potential for the early detection of H37Rv in clinical diagnosis. Copyright © 2017 Elsevier B.V. All rights reserved.

How Magnetic Disturbance Influences the Attitude and Heading in Magnetic and Inertial Sensor-Based Orientation Estimation

PubMed Central

Li, Qingguo

2017-01-01

With the advancements in micro-electromechanical systems (MEMS) technologies, magnetic and inertial sensors are becoming more and more accurate, lightweight, smaller in size as well as low-cost, which in turn boosts their applications in human movement analysis. However, challenges still exist in the field of sensor orientation estimation, where magnetic disturbance represents one of the obstacles limiting their practical application. The objective of this paper is to systematically analyze exactly how magnetic disturbances affects the attitude and heading estimation for a magnetic and inertial sensor. First, we reviewed four major components dealing with magnetic disturbance, namely decoupling attitude estimation from magnetic reading, gyro bias estimation, adaptive strategies of compensating magnetic disturbance and sensor fusion algorithms. We review and analyze the features of existing methods of each component. Second, to understand each component in magnetic disturbance rejection, four representative sensor fusion methods were implemented, including gradient descent algorithms, improved explicit complementary filter, dual-linear Kalman filter and extended Kalman filter. Finally, a new standardized testing procedure has been developed to objectively assess the performance of each method against magnetic disturbance. Based upon the testing results, the strength and weakness of the existing sensor fusion methods were easily examined, and suggestions were presented for selecting a proper sensor fusion algorithm or developing new sensor fusion method. PMID:29283432

How Sensor, Signal, and Imaging Informatics May Impact Patient Centered Care and Care Coordination

PubMed Central

Moreau-Gaudry, A.

2015-01-01

Summary Objective This synopsis presents a selection for the IMIA (International Medical Informatics Association) Yearbook 2015 of excellent research in the broad field of Sensor, Signal, and Imaging Informatics published in the year 2014, with a focus on patient centered care coordination. Methods The two section editors performed a systematic initial selection and a double blind peer review process to select a list of candidate best papers in the domain published in 2014, from the PubMed and Web of Science databases. A set of MeSH keywords provided by experts was used. This selection was peer-reviewed by external reviewers. Results The review process highlighted articles illustrating two current trends related to care coordination and patient centered care: the enhanced capacity to predict the evolution of a disease based on patient-specific information can impact care coordination; similarly, better perception of the patient and his treatment could lead to enhanced personalized care with a potential impact on care coordination. Conclusions This review shows the multiplicity of angles from which the question of patient-centered care can be addressed, with consequences on care coordination that will need to be confirmed and demonstrated in the future. PMID:26293856

Service Oriented Architecture for Wireless Sensor Networks in Agriculture

NASA Astrophysics Data System (ADS)

Sawant, S. A.; Adinarayana, J.; Durbha, S. S.; Tripathy, A. K.; Sudharsan, D.

2012-08-01

Rapid advances in Wireless Sensor Network (WSN) for agricultural applications has provided a platform for better decision making for crop planning and management, particularly in precision agriculture aspects. Due to the ever-increasing spread of WSNs there is a need for standards, i.e. a set of specifications and encodings to bring multiple sensor networks on common platform. Distributed sensor systems when brought together can facilitate better decision making in agricultural domain. The Open Geospatial Consortium (OGC) through Sensor Web Enablement (SWE) provides guidelines for semantic and syntactic standardization of sensor networks. In this work two distributed sensing systems (Agrisens and FieldServer) were selected to implement OGC SWE standards through a Service Oriented Architecture (SOA) approach. Online interoperable data processing was developed through SWE components such as Sensor Model Language (SensorML) and Sensor Observation Service (SOS). An integrated web client was developed to visualize the sensor observations and measurements that enables the retrieval of crop water resources availability and requirements in a systematic manner for both the sensing devices. Further, the client has also the ability to operate in an interoperable manner with any other OGC standardized WSN systems. The study of WSN systems has shown that there is need to augment the operations / processing capabilities of SOS in order to understand about collected sensor data and implement the modelling services. Also, the very low cost availability of WSN systems in future, it is possible to implement the OGC standardized SWE framework for agricultural applications with open source software tools.

Skin Temperature Measurement Using Contact Thermometry: A Systematic Review of Setup Variables and Their Effects on Measured Values

PubMed Central

MacRae, Braid A.; Annaheim, Simon; Spengler, Christina M.; Rossi, René M.

2018-01-01

Background: Skin temperature (Tskin) is commonly measured using Tskin sensors affixed directly to the skin surface, although the influence of setup variables on the measured outcome requires clarification. Objectives: The two distinct objectives of this systematic review were (1) to examine measurements from contact Tskin sensors considering equilibrium temperature and temperature disturbance, sensor attachments, pressure, environmental temperature, and sensor type, and (2) to characterise the contact Tskin sensors used, conditions of use, and subsequent reporting in studies investigating sports, exercise, and other physical activity. Data sources and study selection: For the measurement comparison objective, Ovid Medline and Scopus were used (1960 to July 2016) and studies comparing contact Tskin sensor measurements in vivo or using appropriate physical models were included. For the survey of use, Ovid Medline was used (2011 to July 2016) and studies using contact temperature sensors for the measurement of human Tskin in vivo during sport, exercise, and other physical activity were included. Study appraisal and synthesis methods: For measurement comparisons, assessments of risk of bias were made according to an adapted version of the Cochrane Collaboration's risk of bias tool. Comparisons of temperature measurements were expressed, where possible, as mean difference and 95% limits of agreement (LoA). Meta-analyses were not performed due to the lack of a common reference condition. For the survey of use, extracted information was summarised in text and tabular form. Results: For measurement comparisons, 21 studies were included. Results from these studies indicated minor (<0.5°C) to practically meaningful (>0.5°C) measurement bias within the subgroups of attachment type, applied pressure, environmental conditions, and sensor type. The 95% LoA were often within 1.0°C for in vivo studies and 0.5°C for physical models. For the survey of use, 172 studies were included. Details about Tskin sensor setup were often poorly reported and, from those reporting setup information, it was evident that setups widely varied in terms of type of sensors, attachments, and locations used. Conclusions: Setup variables and conditions of use can influence the measured temperature from contact Tskin sensors and thus key setup variables need to be appropriately considered and consistently reported. PMID:29441024

Skin Temperature Measurement Using Contact Thermometry: A Systematic Review of Setup Variables and Their Effects on Measured Values.

PubMed

MacRae, Braid A; Annaheim, Simon; Spengler, Christina M; Rossi, René M

2018-01-01

Background: Skin temperature ( T skin ) is commonly measured using T skin sensors affixed directly to the skin surface, although the influence of setup variables on the measured outcome requires clarification. Objectives: The two distinct objectives of this systematic review were (1) to examine measurements from contact T skin sensors considering equilibrium temperature and temperature disturbance, sensor attachments, pressure, environmental temperature, and sensor type, and (2) to characterise the contact T skin sensors used, conditions of use, and subsequent reporting in studies investigating sports, exercise, and other physical activity. Data sources and study selection: For the measurement comparison objective, Ovid Medline and Scopus were used (1960 to July 2016) and studies comparing contact T skin sensor measurements in vivo or using appropriate physical models were included. For the survey of use, Ovid Medline was used (2011 to July 2016) and studies using contact temperature sensors for the measurement of human T skin in vivo during sport, exercise, and other physical activity were included. Study appraisal and synthesis methods: For measurement comparisons, assessments of risk of bias were made according to an adapted version of the Cochrane Collaboration's risk of bias tool. Comparisons of temperature measurements were expressed, where possible, as mean difference and 95% limits of agreement (LoA). Meta-analyses were not performed due to the lack of a common reference condition. For the survey of use, extracted information was summarised in text and tabular form. Results: For measurement comparisons, 21 studies were included. Results from these studies indicated minor (<0.5°C) to practically meaningful (>0.5°C) measurement bias within the subgroups of attachment type, applied pressure, environmental conditions, and sensor type. The 95% LoA were often within 1.0°C for in vivo studies and 0.5°C for physical models. For the survey of use, 172 studies were included. Details about T skin sensor setup were often poorly reported and, from those reporting setup information, it was evident that setups widely varied in terms of type of sensors, attachments, and locations used. Conclusions: Setup variables and conditions of use can influence the measured temperature from contact T skin sensors and thus key setup variables need to be appropriately considered and consistently reported.

Methane–oxygen electrochemical coupling in an ionic liquid: a robust sensor for simultaneous quantification†

PubMed Central

Wang, Zhe; Guo, Min; Baker, Gary A.; Stetter, Joseph R.; Lin, Lu; Mason, Andrew J.

2017-01-01

Current sensor devices for the detection of methane or natural gas emission are either expensive and have high power requirements or fail to provide a rapid response. This report describes an electrochemical methane sensor utilizing a non-volatile and conductive pyrrolidinium-based ionic liquid (IL) electrolyte and an innovative internal standard method for methane and oxygen dual-gas detection with high sensitivity, selectivity, and stability. At a platinum electrode in bis(trifluoromethylsulfonyl)imide (NTf2)-based ILs, methane is electro-oxidized to produce CO2 and water when an oxygen reduction process is included. The in situ generated CO2 arising from methane oxidation was shown to provide an excellent internal standard for quantification of the electrochemical oxygen sensor signal. The simultaneous quantification of both methane and oxygen in real time strengthens the reliability of the measurements by cross-validation of two ambient gases occurring within a single sample matrix and allows for the elimination of several types of random and systematic errors in the detection. We have also validated this IL-based methane sensor employing both conventional solid macroelectrodes and flexible microfabricated electrodes using single- and double-potential step chronoamperometry. PMID:25093213

A novel ethanol gas sensor based on TiO2/Ag0.35V2O5 branched nanoheterostructures

PubMed Central

Wang, Yuan; Liu, Lixin; Meng, Chuanmin; Zhou, Yun; Gao, Zhao; Li, Xuhai; Cao, Xiuxia; Xu, Liang; Zhu, Wenjun

2016-01-01

Much greater surface-to-volume ratio of hierarchical nanostructures renders them attract considerable interest as prototypical gas sensors. In this work, a novel resistive gas sensor based on TiO2/Ag0.35V2O5 branched nanoheterostructures is fabricated by a facile one-step synthetic process and the ethanol sensing performance of this device is characterized systematically, which shows faster response/recovery behavior, better selectivity, and higher sensitivity of about 9 times as compared to the pure TiO2 nanofibers. The enhanced sensitivity of the TiO2/Ag0.35V2O5 branched nanoheterostructures should be attributed to the extraordinary branched hierarchical structures and TiO2/Ag0.35V2O5 heterojunctions, which can eventually result in an obvious change of resistance upon ethanol exposure. This study not only indicates the gas sensing mechanism for performance enhancement of branched nanoheterostructures, but also proposes a rational approach to design nanostructure based chemical sensors with desirable performance. PMID:27615429

A novel ethanol gas sensor based on TiO2/Ag0.35V2O5 branched nanoheterostructures

NASA Astrophysics Data System (ADS)

Wang, Yuan; Liu, Lixin; Meng, Chuanmin; Zhou, Yun; Gao, Zhao; Li, Xuhai; Cao, Xiuxia; Xu, Liang; Zhu, Wenjun

2016-09-01

Much greater surface-to-volume ratio of hierarchical nanostructures renders them attract considerable interest as prototypical gas sensors. In this work, a novel resistive gas sensor based on TiO2/Ag0.35V2O5 branched nanoheterostructures is fabricated by a facile one-step synthetic process and the ethanol sensing performance of this device is characterized systematically, which shows faster response/recovery behavior, better selectivity, and higher sensitivity of about 9 times as compared to the pure TiO2 nanofibers. The enhanced sensitivity of the TiO2/Ag0.35V2O5 branched nanoheterostructures should be attributed to the extraordinary branched hierarchical structures and TiO2/Ag0.35V2O5 heterojunctions, which can eventually result in an obvious change of resistance upon ethanol exposure. This study not only indicates the gas sensing mechanism for performance enhancement of branched nanoheterostructures, but also proposes a rational approach to design nanostructure based chemical sensors with desirable performance.

Postlaunch calibration of spacecraft attitude instruments

NASA Technical Reports Server (NTRS)

Davis, W.; Hashmall, J.; Garrick, J.; Harman, R.

1993-01-01

The accuracy of both onboard and ground attitude determination can be significantly enhanced by calibrating spacecraft attitude instruments (sensors) after launch. Although attitude sensors are accurately calibrated before launch, the stresses of launch and the space environment inevitably cause changes in sensor parameters. During the mission, these parameters may continue to drift requiring repeated on-orbit calibrations. The goal of attitude sensor calibration is to reduce the systematic errors in the measurement models. There are two stages at which systematic errors may enter. The first occurs in the conversion of sensor output into an observation vector in the sensor frame. The second occurs in the transformation of the vector from the sensor frame to the spacecraft attitude reference frame. This paper presents postlaunch alignment and transfer function calibration of the attitude sensors for the Compton Gamma Ray Observatory (GRO), the Upper Atmosphere Research Satellite (UARS), and the Extreme Ultraviolet Explorer (EUVE).

Towards intrinsic MoS{sub 2} devices for high performance arsenite sensing

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

Li, Peng, E-mail: pengli@mail.tsinghua.edu.cn, E-mail: dzzhang@upc.edu.cn; Zhang, Dongzhi, E-mail: pengli@mail.tsinghua.edu.cn, E-mail: dzzhang@upc.edu.cn; Sun, Yan'e

2016-08-08

Molybdenum disulphide (MoS{sub 2}) is one of the most attractive two dimensional materials other than graphene, and the exceptional properties make it a promising candidate for bio/chemical sensing. Nevertheless, intrinsic properties and sensing performances of MoS{sub 2} are easily masked by the presence of the Schottky barrier (SB) at source/drain electrodes, and its impact on MoS{sub 2} sensors remains unclear. Here, we systematically investigated the influence of the SB on MoS{sub 2} sensors, revealing the sensing mechanism of intrinsic MoS{sub 2}. By utilizing a small work function metal, Ti, to reduce the SB, excellent electrical properties of this 2D materialmore » were yielded with 2–3 times enhanced sensitivity. We experimentally demonstrated that the sensitivity of MoS{sub 2} is superior to that of graphene. Intrinsic MoS{sub 2} was able to realize rapid detection of arsenite down to 0.1 ppb without the influence of large SB, which is two-fold lower than the World Health Organization (WHO) tolerance level and better than the detection limit of recently reported arsenite sensors. Additionally, accurately discriminating target molecules is a great challenge for sensors based on 2D materials. This work demonstrates MoS{sub 2} sensors encapsulated with ionophore film which only allows certain types of molecules to selectively permeate through it. As a result, multiplex ion detection with superb selectivity was realized. Our results show prominent advantages of intrinsic MoS{sub 2} as a sensing material.« less

The Use of Wearable Inertial Motion Sensors in Human Lower Limb Biomechanics Studies: A Systematic Review

PubMed Central

Fong, Daniel Tik-Pui; Chan, Yue-Yan

2010-01-01

Wearable motion sensors consisting of accelerometers, gyroscopes and magnetic sensors are readily available nowadays. The small size and low production costs of motion sensors make them a very good tool for human motions analysis. However, data processing and accuracy of the collected data are important issues for research purposes. In this paper, we aim to review the literature related to usage of inertial sensors in human lower limb biomechanics studies. A systematic search was done in the following search engines: ISI Web of Knowledge, Medline, SportDiscus and IEEE Xplore. Thirty nine full papers and conference abstracts with related topics were included in this review. The type of sensor involved, data collection methods, study design, validation methods and its applications were reviewed. PMID:22163542

The use of wearable inertial motion sensors in human lower limb biomechanics studies: a systematic review.

PubMed

Fong, Daniel Tik-Pui; Chan, Yue-Yan

2010-01-01

Wearable motion sensors consisting of accelerometers, gyroscopes and magnetic sensors are readily available nowadays. The small size and low production costs of motion sensors make them a very good tool for human motions analysis. However, data processing and accuracy of the collected data are important issues for research purposes. In this paper, we aim to review the literature related to usage of inertial sensors in human lower limb biomechanics studies. A systematic search was done in the following search engines: ISI Web of Knowledge, Medline, SportDiscus and IEEE Xplore. Thirty nine full papers and conference abstracts with related topics were included in this review. The type of sensor involved, data collection methods, study design, validation methods and its applications were reviewed.

Ce doped NiO nanoparticles as selective NO2 gas sensor

NASA Astrophysics Data System (ADS)

Gawali, Swati R.; Patil, Vithoba L.; Deonikar, Virendrakumar G.; Patil, Santosh S.; Patil, Deepak R.; Patil, Pramod S.; Pant, Jayashree

2018-03-01

Metal oxide gas sensors are promising portable gas detection devices because of their advantages such as low cost, easy production and compact size. The performance of such sensors is strongly dependent on material properties such as morphology, structure and doping. In the present study, we report the effect of cerium (Ce) doping on nickel oxide (NiO) nano-structured thin film sensors towards various gases. Bare NiO and Ce doped NiO nanoparticles (Ce:NiO) were synthesized by sol-gel method. To understand the effect of Ce doping in nickel oxide, various molar percentages of Ce with respect to nickel were incorporated. The structure, phase, morphology and band-gap energy of as-synthesized nanoparticles were studied by XRD, SEM, EDAX and UV-vis spectroscopy. Thin film gas sensors of all the samples were prepared and subjected to various gases such as LPG, NH3, CH3COCH3 and NO2. A systematic and comparative study reveals an enhanced gas sensing performance of Ce:NiO sensors towards NO2 gas. The maximum sensitivity for NO2 gas is around 0.719% per ppm at moderate operating temperature of 150 °C for 0.5% Ce:NiO thin film gas sensor. The enhanced gas sensing performance for Ce:NiO is attributed to the distortion of crystal lattice caused by doping of Ce into NiO.

Cross Deployment Networking and Systematic Performance Analysis of Underwater Wireless Sensor Networks.

PubMed

Wei, Zhengxian; Song, Min; Yin, Guisheng; Wang, Hongbin; Ma, Xuefei; Song, Houbing

2017-07-12

Underwater wireless sensor networks (UWSNs) have become a new hot research area. However, due to the work dynamics and harsh ocean environment, how to obtain an UWSN with the best systematic performance while deploying as few sensor nodes as possible and setting up self-adaptive networking is an urgent problem that needs to be solved. Consequently, sensor deployment, networking, and performance calculation of UWSNs are challenging issues, hence the study in this paper centers on this topic and three relevant methods and models are put forward. Firstly, the normal body-centered cubic lattice to cross body-centered cubic lattice (CBCL) has been improved, and a deployment process and topology generation method are built. Then most importantly, a cross deployment networking method (CDNM) for UWSNs suitable for the underwater environment is proposed. Furthermore, a systematic quar-performance calculation model (SQPCM) is proposed from an integrated perspective, in which the systematic performance of a UWSN includes coverage, connectivity, durability and rapid-reactivity. Besides, measurement models are established based on the relationship between systematic performance and influencing parameters. Finally, the influencing parameters are divided into three types, namely, constraint parameters, device performance and networking parameters. Based on these, a networking parameters adjustment method (NPAM) for optimized systematic performance of UWSNs has been presented. The simulation results demonstrate that the approach proposed in this paper is feasible and efficient in networking and performance calculation of UWSNs.

Cross Deployment Networking and Systematic Performance Analysis of Underwater Wireless Sensor Networks

PubMed Central

Wei, Zhengxian; Song, Min; Yin, Guisheng; Wang, Hongbin; Ma, Xuefei

2017-01-01

Underwater wireless sensor networks (UWSNs) have become a new hot research area. However, due to the work dynamics and harsh ocean environment, how to obtain an UWSN with the best systematic performance while deploying as few sensor nodes as possible and setting up self-adaptive networking is an urgent problem that needs to be solved. Consequently, sensor deployment, networking, and performance calculation of UWSNs are challenging issues, hence the study in this paper centers on this topic and three relevant methods and models are put forward. Firstly, the normal body-centered cubic lattice to cross body-centered cubic lattice (CBCL) has been improved, and a deployment process and topology generation method are built. Then most importantly, a cross deployment networking method (CDNM) for UWSNs suitable for the underwater environment is proposed. Furthermore, a systematic quar-performance calculation model (SQPCM) is proposed from an integrated perspective, in which the systematic performance of a UWSN includes coverage, connectivity, durability and rapid-reactivity. Besides, measurement models are established based on the relationship between systematic performance and influencing parameters. Finally, the influencing parameters are divided into three types, namely, constraint parameters, device performance and networking parameters. Based on these, a networking parameters adjustment method (NPAM) for optimized systematic performance of UWSNs has been presented. The simulation results demonstrate that the approach proposed in this paper is feasible and efficient in networking and performance calculation of UWSNs. PMID:28704959

Study of resonant processes in plasmonic nanostructures for sensor applications (Conference Presentation)

NASA Astrophysics Data System (ADS)

Pirunčík, Jiří; Kwiecien, Pavel; Fiala, Jan; Richter, Ivan

2017-05-01

This contribution is focused on the numerical studies of resonant processes in individual plasmonic nanostructures, with the attention particularly given to rectangular nanoparticles and concominant localized surface plasmon resonance processes. Relevant models for the description and anylysis of localized surface plasmon resonance are introduced, in particular: quasistatic approximation, Mie theory and in particular, a generalized (quasi)analytical approach for treating rectangularly shaped nanostructures. The parameters influencing resonant behavior of nanoparticles are analyzed with special interest in morphology and sensor applications. Results acquired with Lumerical FDTD Solutions software, using finite-difference time-domain simulation method, are shown and discussed. Simulations were mostly performed for selected nanostructures composed of finite rectangular nanowires with square cross-sections. Systematic analysis is made for single nanowires with varying length, parallel couple of nanowires with varying gap (cut -wires) and selected dolmen structures with varying gap between one nanowire transversely located with respect to parallel couple of nanowires (in both in-plane and -out-of-plane arrangements). The dependence of resonant peaks of cross-section spectral behavior (absorption, scattering, extinction) and their tunability via suitable structuring and morphology changes are primarily researched. These studies are then followed with an analysis of the effect of periodic arrangements. The results can be usable with respect to possible sensor applications.

Guided wave and damage detection in composite laminates using different fiber optic sensors.

PubMed

Li, Fucai; Murayama, Hideaki; Kageyama, Kazuro; Shirai, Takehiro

2009-01-01

Guided wave detection using different fiber optic sensors and their applications in damage detection for composite laminates were systematically investigated and compared in this paper. Two types of fiber optic sensors, namely fiber Bragg gratings (FBG) and Doppler effect-based fiber optic (FOD) sensors, were addressed and guided wave detection systems were constructed for both types. Guided waves generated by a piezoelectric transducer were propagated through a quasi-isotropic carbon fiber reinforced plastic (CFRP) laminate and acquired by these fiber optic sensors. Characteristics of these fiber optic sensors in ultrasonic guided wave detection were systematically compared. Results demonstrated that both the FBG and FOD sensors can be applied in guided wave and damage detection for the CFRP laminates. The signal-to-noise ratio (SNR) of guided wave signal captured by an FOD sensor is relatively high in comparison with that of the FBG sensor because of their different physical principles in ultrasonic detection. Further, the FOD sensor is sensitive to the damage-induced fundamental shear horizontal (SH(0)) guided wave that, however, cannot be detected by using the FBG sensor, because the FOD sensor is omnidirectional in ultrasound detection and, in contrast, the FBG sensor is severely direction dependent.

Optimized tuner selection for engine performance estimation

NASA Technical Reports Server (NTRS)

Simon, Donald L. (Inventor); Garg, Sanjay (Inventor)

2013-01-01

A methodology for minimizing the error in on-line Kalman filter-based aircraft engine performance estimation applications is presented. This technique specifically addresses the underdetermined estimation problem, where there are more unknown parameters than available sensor measurements. A systematic approach is applied to produce a model tuning parameter vector of appropriate dimension to enable estimation by a Kalman filter, while minimizing the estimation error in the parameters of interest. Tuning parameter selection is performed using a multi-variable iterative search routine which seeks to minimize the theoretical mean-squared estimation error. Theoretical Kalman filter estimation error bias and variance values are derived at steady-state operating conditions, and the tuner selection routine is applied to minimize these values. The new methodology yields an improvement in on-line engine performance estimation accuracy.

Whole-bacterium SELEX of DNA aptamers for rapid detection of E.coli O157:H7 using a QCM sensor.

PubMed

Yu, Xiaofan; Chen, Fang; Wang, Ronghui; Li, Yanbin

2018-01-20

The rapid detection of foodborne pathogens is critical to ensure food safety. The objective of this study is to select aptamers specifically bound to Escherichia coli O157:H7 using the whole-bacterium SELEX (Systematic Evolution of Ligands by Exponential Enrichment) and apply the selected aptamer to a QCM (quartz crystal microbalance) sensor for rapid and sensitive detection of target bacteria. A total of 19 rounds of selection against live E. coli O157:H7 and 6 rounds of counter selection against a mixture of Staphylococcus aureus, Listeria monocytogenes, and Salmonella Typhimurium, were performed. The aptamer pool from the last round was cloned and sequenced. One sequence S1 that appeared 16 times was characterized and a dissociation constant (K d ) of 10.30nM was obtained. Subsequently, a QCM aptasensor was developed for the rapid detection of E. coli O157:H7. The limit of detection (LOD) and the detection time of the aptasensor was determined to be 1.46×10 3 CFU/ml and 50min, respectively. This study demonstrated that the ssDNA aptamer selected by the whole-bacterium SELEX possessed higher sensitivity than previous work and the potential use of the constructed QCM aptasensor in rapid screening of foodborne pathogens. Copyright © 2017 Elsevier B.V. All rights reserved.

Gas-Sensing Devices Based on Zn-Doped NiO Two-Dimensional Grainy Films with Fast Response and Recovery for Ammonia Molecule Detection

NASA Astrophysics Data System (ADS)

Wang, Jian; Wei, Xiaowei; Wangyang, Peihua

2015-12-01

Zn-doped NiO two-dimensional grainy films on glass substrates are shown to be an ammonia-sensing material with excellent comprehensive performance, which could real-time detect and monitor ammonia (NH3) in the surrounding environment. The morphology and structure analysis indicated that the as-fabricated semiconductor films were composed of particles with diameters ranging from 80 to 160 nm, and each particle was composed of small crystalline grain with a narrow size about 20 nm, which was the face-centered cubic single crystal structure. X-ray diffraction peaks shifted toward lower angle, and the size of the lattice increased compared with undoped NiO, which demonstrated that zinc ions have been successfully doped into the NiO host structure. Simultaneously, we systematically investigated the gas-sensing properties of the Zn-doped NiO sensors for NH3 detection at room temperature. The sensor based on doped NiO sensing films gave four to nine times faster response and four to six times faster recovery speeds than those of sensor with undoped NiO films, which is important for the NiO sensor practical applications. Moreover, we found that the doped NiO sensors owned outstanding selectivity toward ammonia.

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

Investigating Systematic Errors of the Interstellar Flow Longitude Derived from the Pickup Ion Cutoff

NASA Astrophysics Data System (ADS)

Taut, A.; Berger, L.; Drews, C.; Bower, J.; Keilbach, D.; Lee, M. A.; Moebius, E.; Wimmer-Schweingruber, R. F.

2017-12-01

Complementary to the direct neutral particle measurements performed by e.g. IBEX, the measurement of PickUp Ions (PUIs) constitutes a diagnostic tool to investigate the local interstellar medium. PUIs are former neutral particles that have been ionized in the inner heliosphere. Subsequently, they are picked up by the solar wind and its frozen-in magnetic field. Due to this process, a characteristic Velocity Distribution Function (VDF) with a sharp cutoff evolves, which carries information about the PUI's injection speed and thus the former neutral particle velocity. The symmetry of the injection speed about the interstellar flow vector is used to derive the interstellar flow longitude from PUI measurements. Using He PUI data obtained by the PLASTIC sensor on STEREO A, we investigate how this concept may be affected by systematic errors. The PUI VDF strongly depends on the orientation of the local interplanetary magnetic field. Recently injected PUIs with speeds just below the cutoff speed typically form a highly anisotropic torus distribution in velocity space, which leads to a longitudinal transport for certain magnetic field orientation. Therefore, we investigate how the selection of magnetic field configurations in the data affects the result for the interstellar flow longitude that we derive from the PUI cutoff. Indeed, we find that the results follow a systematic trend with the filtered magnetic field angles that can lead to a shift of the result up to 5°. In turn, this means that every value for the interstellar flow longitude derived from the PUI cutoff is affected by a systematic error depending on the utilized magnetic field orientations. Here, we present our observations, discuss possible reasons for the systematic trend we discovered, and indicate selections that may minimize the systematic errors.

Software Tools to Support the Assessment of System Health

NASA Technical Reports Server (NTRS)

Melcher, Kevin J.

2013-01-01

This presentation provides an overview of three software tools that were developed by the NASA Glenn Research Center to support the assessment of system health: the Propulsion Diagnostic Method Evaluation Strategy (ProDIMES), the Systematic Sensor Selection Strategy (S4), and the Extended Testability Analysis (ETA) tool. Originally developed to support specific NASA projects in aeronautics and space, these software tools are currently available to U.S. citizens through the NASA Glenn Software Catalog. The ProDiMES software tool was developed to support a uniform comparison of propulsion gas path diagnostic methods. Methods published in the open literature are typically applied to dissimilar platforms with different levels of complexity. They often address different diagnostic problems and use inconsistent metrics for evaluating performance. As a result, it is difficult to perform a one ]to ]one comparison of the various diagnostic methods. ProDIMES solves this problem by serving as a theme problem to aid in propulsion gas path diagnostic technology development and evaluation. The overall goal is to provide a tool that will serve as an industry standard, and will truly facilitate the development and evaluation of significant Engine Health Management (EHM) capabilities. ProDiMES has been developed under a collaborative project of The Technical Cooperation Program (TTCP) based on feedback provided by individuals within the aircraft engine health management community. The S4 software tool provides a framework that supports the optimal selection of sensors for health management assessments. S4 is structured to accommodate user ]defined applications, diagnostic systems, search techniques, and system requirements/constraints. One or more sensor suites that maximize this performance while meeting other user ]defined system requirements that are presumed to exist. S4 provides a systematic approach for evaluating combinations of sensors to determine the set or sets of sensors that optimally meet the performance goals and the constraints. It identifies optimal sensor suite solutions by utilizing a merit (i.e., cost) function with one of several available optimization approaches. As part of its analysis, S4 can expose fault conditions that are difficult to diagnose due to an incomplete diagnostic philosophy and/or a lack of sensors. S4 was originally developed and applied to liquid rocket engines. It was subsequently used to study the optimized selection of sensors for a simulation ]based aircraft engine diagnostic system. The ETA Tool is a software ]based analysis tool that augments the testability analysis and reporting capabilities of a commercial ]off ]the ]shelf (COTS) package. An initial diagnostic assessment is performed by the COTS software using a user ]developed, qualitative, directed ]graph model of the system being analyzed. The ETA Tool accesses system design information captured within the model and the associated testability analysis output to create a series of six reports for various system engineering needs. These reports are highlighted in the presentation. The ETA Tool was developed by NASA to support the verification of fault management requirements early in the Launch Vehicle process. Due to their early development during the design process, the TEAMS ]based diagnostic model and the ETA Tool were able to positively influence the system design by highlighting gaps in failure detection, fault isolation, and failure recovery.

Phase-demodulation error of a fiber-optic Fabry-Perot sensor with complex reflection coefficients.

PubMed

Kilpatrick, J M; MacPherson, W N; Barton, J S; Jones, J D

2000-03-20

The influence of reflector losses attracts little discussion in standard treatments of the Fabry-Perot interferometer yet may be an important factor contributing to errors in phase-stepped demodulation of fiber optic Fabry-Perot (FFP) sensors. We describe a general transfer function for FFP sensors with complex reflection coefficients and estimate systematic phase errors that arise when the asymmetry of the reflected fringe system is neglected, as is common in the literature. The measured asymmetric response of higher-finesse metal-dielectric FFP constructions corroborates a model that predicts systematic phase errors of 0.06 rad in three-step demodulation of a low-finesse FFP sensor (R = 0.05) with internal reflector losses of 25%.

Taking Advantage of Selective Change Driven Processing for 3D Scanning

PubMed Central

Vegara, Francisco; Zuccarello, Pedro; Boluda, Jose A.; Pardo, Fernando

2013-01-01

This article deals with the application of the principles of SCD (Selective Change Driven) vision to 3D laser scanning. Two experimental sets have been implemented: one with a classical CMOS (Complementary Metal-Oxide Semiconductor) sensor, and the other one with a recently developed CMOS SCD sensor for comparative purposes, both using the technique known as Active Triangulation. An SCD sensor only delivers the pixels that have changed most, ordered by the magnitude of their change since their last readout. The 3D scanning method is based on the systematic search through the entire image to detect pixels that exceed a certain threshold, showing the SCD approach to be ideal for this application. Several experiments for both capturing strategies have been performed to try to find the limitations in high speed acquisition/processing. The classical approach is limited by the sequential array acquisition, as predicted by the Nyquist–Shannon sampling theorem, and this has been experimentally demonstrated in the case of a rotating helix. These limitations are overcome by the SCD 3D scanning prototype achieving a significantly higher performance. The aim of this article is to compare both capturing strategies in terms of performance in the time and frequency domains, so they share all the static characteristics including resolution, 3D scanning method, etc., thus yielding the same 3D reconstruction in static scenes. PMID:24084110

Design of a multisensor data fusion system for target detection

NASA Astrophysics Data System (ADS)

Thomopoulos, Stelios C.; Okello, Nickens N.; Kadar, Ivan; Lovas, Louis A.

1993-09-01

The objective of this paper is to discuss the issues that are involved in the design of a multisensor fusion system and provide a systematic analysis and synthesis methodology for the design of the fusion system. The system under consideration consists of multifrequency (similar) radar sensors. However, the fusion design must be flexible to accommodate additional dissimilar sensors such as IR, EO, ESM, and Ladar. The motivation for the system design is the proof of the fusion concept for enhancing the detectability of small targets in clutter. In the context of down-selecting the proper configuration for multisensor (similar and dissimilar, and centralized vs. distributed) data fusion, the issues of data modeling, fusion approaches, and fusion architectures need to be addressed for the particular application being considered. Although the study of different approaches may proceed in parallel, the interplay among them is crucial in selecting a fusion configuration for a given application. The natural sequence for addressing the three different issues is to begin from the data modeling, in order to determine the information content of the data. This information will dictate the appropriate fusion approach. This, in turn, will lead to a global fusion architecture. Both distributed and centralized fusion architectures are used to illustrate the design issues along with Monte-Carlo simulation performance comparison of a single sensor versus a multisensor centrally fused system.

Methods and approaches of utilizing ionic liquids as gas sensing materials

PubMed Central

Rehman, Abdul

2017-01-01

Gas monitoring is of increasing significance for a broad range of applications in the fields of environmental and civil infrastructures, climate and energy, health and safety, industry and commerce. Even though there are many gas detection devices and systems available, the increasing needs for better detection technologies that not only satisfy the high analytical standards but also meet additional device requirements (e.g., being robust to survive under field conditions, low cost, small, smart, more mobile), demand continuous efforts in developing new methods and approaches for gas detection. Ionic Liquids (ILs) have attracted a tremendous interest as potential sensing materials for the gas sensor development. Being composed entirely of ions and with a broad structural and functional diversity, i.e., bifunctional (organic/inorganic), biphasic (solid/liquid) and dual-property (solvent/electrolyte), they have the complementing attributes and the required variability to allow a systematic design process across many sensing components to enhance sensing capability especially for miniaturized sensor system implementation. The emphasis of this review is to describe molecular design and control of IL interface materials to provide selective and reproducible response and to synergistically integrate IL sensing materials with low cost and low power electrochemical, piezoelectric/QCM and optical transducers to address many gas detection challenges (e.g., sensitivity, selectivity, reproducibility, speed, stability, cost, sensor miniaturization, and robustness). We further show examples to justify the importance of understanding the mechanisms and principles of physicochemical and electrochemical reactions in ILs and then link those concepts to developing new sensing methods and approaches. By doing this, we hope to stimulate further research towards the fundamental understanding of the sensing mechanisms and new sensor system development and integration, using simple sensing designs and flexible sensor structures both in terms of scientific operation and user interface that can be miniaturized and interfaced with modern wireless monitoring technologies to achieve specifications heretofore unavailable on current markets for the next generation of gas sensor applications. PMID:29142738

Characterization Approaches to Place Invariant Sites on SI-Traceable Scales

NASA Technical Reports Server (NTRS)

Thome, Kurtis

2012-01-01

The effort to understand the Earth's climate system requires a complete integration of remote sensing imager data across time and multiple countries. Such an integration necessarily requires ensuring inter-consistency between multiple sensors to create the data sets needed to understand the climate system. Past efforts at inter-consistency have forced agreement between two sensors using sources that are viewed by both sensors at nearly the same time, and thus tend to be near polar regions over snow and ice. The current work describes a method that would provide an absolute radiometric calibration of a sensor rather than an inter-consistency of a sensor relative to another. The approach also relies on defensible error budgets that eventually provides a cross comparison of sensors without systematic errors. The basis of the technique is a model-based, SI-traceable prediction of at-sensor radiance over selected sites. The predicted radiance would be valid for arbitrary view and illumination angles and for any date of interest that is dominated by clear-sky conditions. The effort effectively works to characterize the sites as sources with known top-of-atmosphere radiance allowing accurate intercomparison of sensor data that without the need for coincident views. Data from the Advanced Spaceborne Thermal Emission and Reflection and Radiometer (ASTER), Enhanced Thematic Mapper Plus (ETM+), and Moderate Resolution Imaging Spectroradiometer (MODIS) are used to demonstrate the difficulties of cross calibration as applied to current sensors. Special attention is given to the differences caused in the cross-comparison of sensors in radiance space as opposed to reflectance space. The radiance comparisons lead to significant differences created by the specific solar model used for each sensor. The paper also proposes methods to mitigate the largest error sources in future systems. The results from these historical intercomparisons provide the basis for a set of recommendations to ensure future SI-traceable cross calibration using future missions such as CLARREO and TRUTHS. The paper describes a proposed approach that relies on model-based, SI-traceable predictions of at-sensor radiance over selected sites. The predicted radiance would be valid for arbitrary view and illumination angles and for any date of interest that is dominated by clear-sky conditions. The basis of the method is highly accurate measurements of at-sensor radiance of sufficient quality to understand the spectral and BRDF characteristics of the site and sufficient historical data to develop an understanding of temporal effects from changing surface and atmospheric conditions.

Quantitative knowledge acquisition for expert systems

NASA Technical Reports Server (NTRS)

Belkin, Brenda L.; Stengel, Robert F.

1991-01-01

A common problem in the design of expert systems is the definition of rules from data obtained in system operation or simulation. While it is relatively easy to collect data and to log the comments of human operators engaged in experiments, generalizing such information to a set of rules has not previously been a direct task. A statistical method is presented for generating rule bases from numerical data, motivated by an example based on aircraft navigation with multiple sensors. The specific objective is to design an expert system that selects a satisfactory suite of measurements from a dissimilar, redundant set, given an arbitrary navigation geometry and possible sensor failures. The systematic development is described of a Navigation Sensor Management (NSM) Expert System from Kalman Filter convariance data. The method invokes two statistical techniques: Analysis of Variance (ANOVA) and the ID3 Algorithm. The ANOVA technique indicates whether variations of problem parameters give statistically different covariance results, and the ID3 algorithms identifies the relationships between the problem parameters using probabilistic knowledge extracted from a simulation example set. Both are detailed.

Microwave-assisted synthesis and humidity sensing of nanostructured {alpha}-Fe{sub 2}O{sub 3}

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

Deshmukh, Rupali G.; Badadhe, Satish S.; Mulla, Imtiaz S.

2009-05-06

Nanocrystalline {alpha}-Fe{sub 2}O{sub 3} has been prepared on a large-scale by a facile microwave-assisted hydrothermal route from a solution of Fe(NO{sub 3}){sub 3}.9H{sub 2}O and pentaerythritol. A systematic study of the morphology, crystallinity and oxidation state of Fe using different characterization techniques, such as transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy was performed. It reveals that nanostructured {alpha}-Fe{sub 2}O{sub 3} comprises bundles of nanorods with a rhombohedral crystalline structure. The individual nanorod has 8-10 nm diameter and {approx}50 nm length. The as-prepared nanostructured {alpha}-Fe{sub 2}O{sub 3} (sensor) gives selective response towards humidity. The sensor shows high sensitivity, fastmore » linear response to change in the humidity with almost 100% reproducibility. The sensor works at room temperature and rejuvenates without heat treatment. The as-prepared nanostructured {alpha}-Fe{sub 2}O{sub 3} appears to be a promising humidity sensing material with the potential for commercialization.« less

On-board error correction improves IR earth sensor accuracy

NASA Astrophysics Data System (ADS)

Alex, T. K.; Kasturirangan, K.; Shrivastava, S. K.

1989-10-01

Infra-red earth sensors are used in satellites for attitude sensing. Their accuracy is limited by systematic and random errors. The sources of errors in a scanning infra-red earth sensor are analyzed in this paper. The systematic errors arising from seasonal variation of infra-red radiation, oblate shape of the earth, ambient temperature of sensor, changes in scan/spin rates have been analyzed. Simple relations are derived using least square curve fitting for on-board correction of these errors. Random errors arising out of noise from detector and amplifiers, instability of alignment and localized radiance anomalies are analyzed and possible correction methods are suggested. Sun and Moon interference on earth sensor performance has seriously affected a number of missions. The on-board processor detects Sun/Moon interference and corrects the errors on-board. It is possible to obtain eight times improvement in sensing accuracy, which will be comparable with ground based post facto attitude refinement.

Selective Detection of Target Volatile Organic Compounds in Contaminated Humid Air Using a Sensor Array with Principal Component Analysis

PubMed Central

Itoh, Toshio; Akamatsu, Takafumi; Tsuruta, Akihiro; Shin, Woosuck

2017-01-01

We investigated selective detection of the target volatile organic compounds (VOCs) nonanal, n-decane, and acetoin for lung cancer-related VOCs, and acetone and methyl i-butyl ketone for diabetes-related VOCs, in humid air with simulated VOC contamination (total concentration: 300 μg/m3). We used six “grain boundary-response type” sensors, including four commercially available sensors (TGS 2600, 2610, 2610, and 2620) and two Pt, Pd, and Au-loaded SnO2 sensors (Pt, Pd, Au/SnO2), and two “bulk-response type” sensors, including Zr-doped CeO2 (CeZr10), i.e., eight sensors in total. We then analyzed their sensor signals using principal component analysis (PCA). Although the six “grain boundary-response type” sensors were found to be insufficient for selective detection of the target gases in humid air, the addition of two “bulk-response type” sensors improved the selectivity, even with simulated VOC contamination. To further improve the discrimination, we selected appropriate sensors from the eight sensors based on the PCA results. The selectivity to each target gas was maintained and was not affected by contamination. PMID:28753948

Analyzing Responses of Chemical Sensor Arrays

NASA Technical Reports Server (NTRS)

Zhou, Hanying

2007-01-01

NASA is developing a third-generation electronic nose (ENose) capable of continuous monitoring of the International Space Station s cabin atmosphere for specific, harmful airborne contaminants. Previous generations of the ENose have been described in prior NASA Tech Briefs issues. Sensor selection is critical in both (prefabrication) sensor material selection and (post-fabrication) data analysis of the ENose, which detects several analytes that are difficult to detect, or that are at very low concentration ranges. Existing sensor selection approaches usually include limited statistical measures, where selectivity is more important but reliability and sensitivity are not of concern. When reliability and sensitivity can be major limiting factors in detecting target compounds reliably, the existing approach is not able to provide meaningful selection that will actually improve data analysis results. The approach and software reported here consider more statistical measures (factors) than existing approaches for a similar purpose. The result is a more balanced and robust sensor selection from a less than ideal sensor array. The software offers quick, flexible, optimal sensor selection and weighting for a variety of purposes without a time-consuming, iterative search by performing sensor calibrations to a known linear or nonlinear model, evaluating the individual sensor s statistics, scoring the individual sensor s overall performance, finding the best sensor array size to maximize class separation, finding optimal weights for the remaining sensor array, estimating limits of detection for the target compounds, evaluating fingerprint distance between group pairs, and finding the best event-detecting sensors.

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.

Distributed estimation for adaptive sensor selection in wireless sensor networks

NASA Astrophysics Data System (ADS)

Mahmoud, Magdi S.; Hassan Hamid, Matasm M.

2014-05-01

Wireless sensor networks (WSNs) are usually deployed for monitoring systems with the distributed detection and estimation of sensors. Sensor selection in WSNs is considered for target tracking. A distributed estimation scenario is considered based on the extended information filter. A cost function using the geometrical dilution of precision measure is derived for active sensor selection. A consensus-based estimation method is proposed in this paper for heterogeneous WSNs with two types of sensors. The convergence properties of the proposed estimators are analyzed under time-varying inputs. Accordingly, a new adaptive sensor selection (ASS) algorithm is presented in which the number of active sensors is adaptively determined based on the absolute local innovations vector. Simulation results show that the tracking accuracy of the ASS is comparable to that of the other algorithms.

Priority design parameters of industrialized optical fiber sensors in civil engineering

NASA Astrophysics Data System (ADS)

Wang, Huaping; Jiang, Lizhong; Xiang, Ping

2018-03-01

Considering the mechanical effects and the different paths for transferring deformation, optical fiber sensors commonly used in civil engineering have been systematically classified. Based on the strain transfer theory, the relationship between the strain transfer coefficient and allowable testing error is established. The proposed relationship is regarded as the optimal control equation to obtain the optimal value of sensors that satisfy the requirement of measurement precision. Furthermore, specific optimization design methods and priority design parameters of the classified sensors are presented. This research indicates that (1) strain transfer theory-based optimization design method is much suitable for the sensor that depends on the interfacial shear stress to transfer the deformation; (2) the priority design parameters are bonded (sensing) length, interfacial bonded strength, elastic modulus and radius of protective layer and thickness of adhesive layer; (3) the optimization design of sensors with two anchor pieces at two ends is independent of strain transfer theory as the strain transfer coefficient can be conveniently calibrated by test, and this kind of sensors has no obvious priority design parameters. Improved calibration test is put forward to enhance the accuracy of the calibration coefficient of end-expanding sensors. By considering the practical state of sensors and the testing accuracy, comprehensive and systematic analyses on optical fiber sensors are provided from the perspective of mechanical actions, which could scientifically instruct the application design and calibration test of industrialized optical fiber sensors.

Two-dimensional Layered MoS2 Biosensors Enable Highly Sensitive Detection of Biomolecules

NASA Astrophysics Data System (ADS)

Lee, Joonhyung; Dak, Piyush; Lee, Yeonsung; Park, Heekyeong; Choi, Woong; Alam, Muhammad A.; Kim, Sunkook

2014-12-01

We present a MoS2 biosensor to electrically detect prostate specific antigen (PSA) in a highly sensitive and label-free manner. Unlike previous MoS2-FET-based biosensors, the device configuration of our biosensors does not require a dielectric layer such as HfO2 due to the hydrophobicity of MoS2. Such an oxide-free operation improves sensitivity and simplifies sensor design. For a quantitative and selective detection of PSA antigen, anti-PSA antibody was immobilized on the sensor surface. Then, introduction of PSA antigen, into the anti-PSA immobilized sensor surface resulted in a lable-free immunoassary format. Measured off-state current of the device showed a significant decrease as the applied PSA concentration was increased. The minimum detectable concentration of PSA is 1 pg/mL, which is several orders of magnitude below the clinical cut-off level of ~4 ng/mL. In addition, we also provide a systematic theoretical analysis of the sensor platform - including the charge state of protein at the specific pH level, and self-consistent channel transport. Taken together, the experimental demonstration and the theoretical framework provide a comprehensive description of the performance potential of dielectric-free MoS2-based biosensor technology.

In situ combustion measurements of H2O and temperature near 2.5 µm using tunable diode laser absorption

NASA Astrophysics Data System (ADS)

Farooq, Aamir; Jeffries, Jay B.; Hanson, Ronald K.

2008-07-01

In situ combustion measurements of water vapor concentration and gas temperature were carried out with a new tunable diode laser sensor near 2.5 µm. Recent availability of room-temperature semiconductor diode lasers operating at longer wavelengths provides access to fundamental vibrational bands (ν1 and ν3) of H2O. These bands have stronger absorption line strength compared to the overtone (2ν1, 2ν3) and combination (ν1 + ν3) vibrational bands in the near-infrared region probed previously with telecommunication diode lasers. The absorption transitions of H2O vapor in the 2.5-3.0 µm region are systematically analyzed via spectral simulation, and optimal spectral line pairs are selected for combustion measurements in the temperature range of 1000-2500 K. Fundamental spectroscopic parameters (line strength, line position and line-broadening coefficients) of the selected transitions are determined via laboratory measurements in a heated cell. Absorption measurements of H2O concentration and temperature are then made in a laboratory flat-flame burner to illustrate the potential of this sensor for sensitive and accurate measurements in combustion gases with short optical path lengths.

Chemical probing of the human sirtuin 5 active site reveals its substrate acyl specificity and peptide-based inhibitors.

PubMed

Roessler, Claudia; Nowak, Theresa; Pannek, Martin; Gertz, Melanie; Nguyen, Giang T T; Scharfe, Michael; Born, Ilona; Sippl, Wolfgang; Steegborn, Clemens; Schutkowski, Mike

2014-09-26

Sirtuins are NAD(+)-dependent deacetylases acting as sensors in metabolic pathways and stress response. In mammals there are seven isoforms. The mitochondrial sirtuin 5 is a weak deacetylase but a very efficient demalonylase and desuccinylase; however, its substrate acyl specificity has not been systematically analyzed. Herein, we investigated a carbamoyl phosphate synthetase 1 derived peptide substrate and modified the lysine side chain systematically to determine the acyl specificity of Sirt5. From that point we designed six potent peptide-based inhibitors that interact with the NAD(+) binding pocket. To characterize the interaction details causing the different substrate and inhibition properties we report several X-ray crystal structures of Sirt5 complexed with these peptides. Our results reveal the Sirt5 acyl selectivity and its molecular basis and enable the design of inhibitors for Sirt5. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Filtering Methods for Error Reduction in Spacecraft Attitude Estimation Using Quaternion Star Trackers

NASA Technical Reports Server (NTRS)

Calhoun, Philip C.; Sedlak, Joseph E.; Superfin, Emil

2011-01-01

Precision attitude determination for recent and planned space missions typically includes quaternion star trackers (ST) and a three-axis inertial reference unit (IRU). Sensor selection is based on estimates of knowledge accuracy attainable from a Kalman filter (KF), which provides the optimal solution for the case of linear dynamics with measurement and process errors characterized by random Gaussian noise with white spectrum. Non-Gaussian systematic errors in quaternion STs are often quite large and have an unpredictable time-varying nature, particularly when used in non-inertial pointing applications. Two filtering methods are proposed to reduce the attitude estimation error resulting from ST systematic errors, 1) extended Kalman filter (EKF) augmented with Markov states, 2) Unscented Kalman filter (UKF) with a periodic measurement model. Realistic assessments of the attitude estimation performance gains are demonstrated with both simulation and flight telemetry data from the Lunar Reconnaissance Orbiter.

Development of a sensor for temperature and water concentration in combustion gases using a single tunable diode laser

NASA Astrophysics Data System (ADS)

Zhou, Xin; Liu, Xiang; Jeffries, Jay B.; Hanson, R. K.

2003-08-01

The water vapour spectrum in the 1-2 µm near-infrared region is systematically analysed to find the best absorption transitions for sensitive measurement of H2O concentration and temperature in combustion environments using a single tunable diode laser with typical distributed feedback single-mode scanning range (1 cm-1). The use of a single laser, even with relatively narrow tuning range, can offer distinct advantages over wavelength-multiplexing techniques. The strategy and spectroscopic criteria for selecting optimum wavelength regions and absorption line combinations are discussed. It should be stressed that no single figure of merit can be derived to simplify the selection process, and the optimum line pair should be chosen case by case. Our investigation reveals that the 1.8 µm spectral region is especially promising, and we have identified 10 of the best water line pairs in this spectral region for temperature measurements in flames. Based on these findings, a pair of H2O transitions near 1.8 µm was targeted for the design and development of an initial single-laser sensor for simultaneously measuring H2O concentration and temperature in atmospheric-pressure flames. As part of the sensor development effort, fundamental spectroscopic parameters including the line strength, line-centre frequency and lower state energies of the probed transitions were measured experimentally to improve the current databases. We conclude with demonstration results in a steady and a forced atmospheric-pressure laboratory combustor.

Incorporation of extra amino acids in peptide recognition probe to improve specificity and selectivity of an electrochemical peptide-based sensor.

PubMed

Zaitouna, Anita J; Maben, Alex J; Lai, Rebecca Y

2015-07-30

We investigated the effect of incorporating extra amino acids (AA) at the n-terminus of the thiolated and methylene blue-modified peptide probe on both specificity and selectivity of an electrochemical peptide-based (E-PB) HIV sensor. The addition of a flexible (SG)3 hexapeptide is, in particular, useful in improving sensor selectivity, whereas the addition of a highly hydrophilic (EK)3 hexapeptide has shown to be effective in enhancing sensor specificity. Overall, both E-PB sensors fabricated using peptide probes with the added AA (SG-EAA and EK-EAA) showed better specificity and selectivity, especially when compared to the sensor fabricated using a peptide probe without the extra AA (EAA). For example, the selectivity factor recorded in the 50% saliva was ∼2.5 for the EAA sensor, whereas the selectivity factor was 7.8 for both the SG-EAA and EK-EAA sensors. Other sensor properties such as the limit of detection and dynamic range were minimally affected by the addition of the six AA sequence. The limit of detection was 0.5 nM for the EAA sensor and 1 nM for both SG-EAA and EK-EAA sensors. The saturation target concentration was ∼200 nM for all three sensors. Unlike previously reported E-PB HIV sensors, the peptide probe functions as both the recognition element and antifouling passivating agent; this modification eliminates the need to include an additional antifouling diluent, which simplifies the sensor design and fabrication protocol. Copyright © 2015 Elsevier B.V. All rights reserved.

Effective Sensor Selection and Data Anomaly Detection for Condition Monitoring of Aircraft Engines

PubMed Central

Liu, Liansheng; Liu, Datong; Zhang, Yujie; Peng, Yu

2016-01-01

In a complex system, condition monitoring (CM) can collect the system working status. The condition is mainly sensed by the pre-deployed sensors in/on the system. Most existing works study how to utilize the condition information to predict the upcoming anomalies, faults, or failures. There is also some research which focuses on the faults or anomalies of the sensing element (i.e., sensor) to enhance the system reliability. However, existing approaches ignore the correlation between sensor selecting strategy and data anomaly detection, which can also improve the system reliability. To address this issue, we study a new scheme which includes sensor selection strategy and data anomaly detection by utilizing information theory and Gaussian Process Regression (GPR). The sensors that are more appropriate for the system CM are first selected. Then, mutual information is utilized to weight the correlation among different sensors. The anomaly detection is carried out by using the correlation of sensor data. The sensor data sets that are utilized to carry out the evaluation are provided by National Aeronautics and Space Administration (NASA) Ames Research Center and have been used as Prognostics and Health Management (PHM) challenge data in 2008. By comparing the two different sensor selection strategies, the effectiveness of selection method on data anomaly detection is proved. PMID:27136561

Effective Sensor Selection and Data Anomaly Detection for Condition Monitoring of Aircraft Engines.

PubMed

Liu, Liansheng; Liu, Datong; Zhang, Yujie; Peng, Yu

2016-04-29

In a complex system, condition monitoring (CM) can collect the system working status. The condition is mainly sensed by the pre-deployed sensors in/on the system. Most existing works study how to utilize the condition information to predict the upcoming anomalies, faults, or failures. There is also some research which focuses on the faults or anomalies of the sensing element (i.e., sensor) to enhance the system reliability. However, existing approaches ignore the correlation between sensor selecting strategy and data anomaly detection, which can also improve the system reliability. To address this issue, we study a new scheme which includes sensor selection strategy and data anomaly detection by utilizing information theory and Gaussian Process Regression (GPR). The sensors that are more appropriate for the system CM are first selected. Then, mutual information is utilized to weight the correlation among different sensors. The anomaly detection is carried out by using the correlation of sensor data. The sensor data sets that are utilized to carry out the evaluation are provided by National Aeronautics and Space Administration (NASA) Ames Research Center and have been used as Prognostics and Health Management (PHM) challenge data in 2008. By comparing the two different sensor selection strategies, the effectiveness of selection method on data anomaly detection is proved.

Molecular sieve sensors for selective detection at the nanogram level

DOEpatents

Bein, Thomas; Brown, Kelly D.; Frye, Gregory C.; Brinker, Charles J.

1992-01-01

The invention relates to a selective chemical sensor for selective detection of chemical entities even at the nanogram level. The invention further relates to methods of using the sensor. The sensor comprises: (a) a piezoelectric substrate capable of detecting mass changes resulting from adsorption of material thereon; and (b) a coating applied to the substrate, which selectively sorbs chemical entities of a size smaller than a preselected magnitude.

Designing of fluorescent and magnetic imprinted polymer for rapid, selective and sensitive detection of imidacloprid via activators regenerated by the electron transfer-atom transfer radical polymerization (ARGET-ATRP) technique

NASA Astrophysics Data System (ADS)

Kumar, Sunil; Karfa, Paramita; Madhuri, Rashmi; Sharma, Prashant K.

2018-05-01

In this work, we report on a dual-behavior electrochemical/optical sensor for sensitive determination of Imidacloprid by fluorescent dye (fluorescein, FL) and imprinted polymer modified europium doped superparamagnetic iron oxide nanoparticles (FL@SPIONs@MIP). The imidacloprid (IMD)-imprinted polymer was directly synthesized on the Eu-SPIONs surface via Activators regenerated by the electron transfer-atom transfer radical polymerization (ARGET-ATRP) technique. Preparation, characterization and application of the prepared FL@SPIONs@MIP were systematically investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), fluorescence spectroscopy and electrochemical techniques. The electrochemical experiments exhibited a remarkable selectivity of the prepared sensor towards IMD. Determination of IMD by the square wave stripping voltammetry method represented a wide linear range of 0.059-0.791 μg L-1 with a detection limit of 0.0125 μg L-1. In addition, the fluorescence method shows a linear range of 0.039-0.942 μg L-1 and LOD of 0.0108 μg L-1. The fluorescence property of prepared FL@SPIONs@MIP was used for rapid, on-spot but selective detection of IMD in real samples. The proposed electrode displayed excellent repeatability and long-term stability and was successfully applied for quantitative and trace level determination of IMD in several real samples.

2,4-Toluene Diisocyanate Detection in Liquid and Gas Environments through Electrochemical Oxidation in an Ionic Liquid

PubMed Central

Lin, Lu; Rehman, Abdul; Chi, Xiaowei; Zeng, Xiangqun

2016-01-01

The electrochemical oxidation of 2,4-toluene diisocyanate (2,4-TDI) in an ionic liquid (IL) has been systematically characterized to determine plausible electrochemical and chemical reaction mechanisms and to define the optimal detection methods for such a highly significant analyte. It has been found that the use of an IL as the electrolyte allows the oxidation of 2,4-TDI to occur at a less positive anodic potential with no side reactions as compared to traditional acetonitrile based electrolytes. UV-Vis, FT-IR, Cyclic Voltammetry and Electrochemical Impedance Spectroscopy (EIS) studies have revealed the unique mechanisms of dimerization of 2,4-TDI at the electrode interface by self-addition reactions, which can be utilized to improve the selectivity of detection. The study of 2,4-TDI redox chemistry further facilitates the development of a robust amperometric sensing methodology by selecting a hydrophobic IL ([C4mpy][NTf2]) and by restricting the potential window to only include the oxidation process. Thus, this innovative electrochemical sensor is capable of avoiding the two most ubiquitous interferents in ambient conditions (i.e. humidity and oxygen), thereby enhancing the sensor performance and reliability for real world applications. The method was established to detect 2,4–TDI in both liquid and gas phases. The limits of detection (LOD) values were 130.2 ppm and 0.7862 ppm, respectively, for the two phases, and are comparable to the safety standards reported by NIOSH. The as-developed 2.4-TDI amperometric sensor exhibits a sensitivity of 1.939 μA/ppm. Moreover, due to the simplicity of design and the use of an IL both as a solvent and non-volatile electrolyte, the sensor has the potential to be miniaturized for smart sensing protocols in distributed sensor applications. PMID:26763507

Sensor Selection for Aircraft Engine Performance Estimation and Gas Path Fault Diagnostics

NASA Technical Reports Server (NTRS)

Simon, Donald L.; Rinehart, Aidan W.

2015-01-01

This paper presents analytical techniques for aiding system designers in making aircraft engine health management sensor selection decisions. The presented techniques, which are based on linear estimation and probability theory, are tailored for gas turbine engine performance estimation and gas path fault diagnostics applications. They enable quantification of the performance estimation and diagnostic accuracy offered by different candidate sensor suites. For performance estimation, sensor selection metrics are presented for two types of estimators including a Kalman filter and a maximum a posteriori estimator. For each type of performance estimator, sensor selection is based on minimizing the theoretical sum of squared estimation errors in health parameters representing performance deterioration in the major rotating modules of the engine. For gas path fault diagnostics, the sensor selection metric is set up to maximize correct classification rate for a diagnostic strategy that performs fault classification by identifying the fault type that most closely matches the observed measurement signature in a weighted least squares sense. Results from the application of the sensor selection metrics to a linear engine model are presented and discussed. Given a baseline sensor suite and a candidate list of optional sensors, an exhaustive search is performed to determine the optimal sensor suites for performance estimation and fault diagnostics. For any given sensor suite, Monte Carlo simulation results are found to exhibit good agreement with theoretical predictions of estimation and diagnostic accuracies.

Sensor Selection for Aircraft Engine Performance Estimation and Gas Path Fault Diagnostics

NASA Technical Reports Server (NTRS)

Simon, Donald L.; Rinehart, Aidan W.

2016-01-01

This paper presents analytical techniques for aiding system designers in making aircraft engine health management sensor selection decisions. The presented techniques, which are based on linear estimation and probability theory, are tailored for gas turbine engine performance estimation and gas path fault diagnostics applications. They enable quantification of the performance estimation and diagnostic accuracy offered by different candidate sensor suites. For performance estimation, sensor selection metrics are presented for two types of estimators including a Kalman filter and a maximum a posteriori estimator. For each type of performance estimator, sensor selection is based on minimizing the theoretical sum of squared estimation errors in health parameters representing performance deterioration in the major rotating modules of the engine. For gas path fault diagnostics, the sensor selection metric is set up to maximize correct classification rate for a diagnostic strategy that performs fault classification by identifying the fault type that most closely matches the observed measurement signature in a weighted least squares sense. Results from the application of the sensor selection metrics to a linear engine model are presented and discussed. Given a baseline sensor suite and a candidate list of optional sensors, an exhaustive search is performed to determine the optimal sensor suites for performance estimation and fault diagnostics. For any given sensor suite, Monte Carlo simulation results are found to exhibit good agreement with theoretical predictions of estimation and diagnostic accuracies.

Simulation of an enzyme-based glucose sensor

NASA Astrophysics Data System (ADS)

Sha, Xianzheng; Jablecki, Michael; Gough, David A.

2001-09-01

An important biosensor application is the continuous monitoring blood or tissue fluid glucose concentration in people with diabetes. Our research focuses on the development of a glucose sensor based on potentiostatic oxygen electrodes and immobilized glucose oxidase for long- term application as an implant in tissues. As the sensor signal depends on many design variables, a trial-and-error approach to sensor optimization can be time-consuming. Here, the properties of an implantable glucose sensor are optimized by a systematic computational simulation approach.

Systematic Review of Real-time Remote Health Monitoring System in Triage and Priority-Based Sensor Technology: Taxonomy, Open Challenges, Motivation and Recommendations.

PubMed

Albahri, O S; Albahri, A S; Mohammed, K I; Zaidan, A A; Zaidan, B B; Hashim, M; Salman, Omar H

2018-03-22

The new and ground-breaking real-time remote monitoring in triage and priority-based sensor technology used in telemedicine have significantly bounded and dispersed communication components. To examine these technologies and provide researchers with a clear vision of this area, we must first be aware of the utilised approaches and existing limitations in this line of research. To this end, an extensive search was conducted to find articles dealing with (a) telemedicine, (b) triage, (c) priority and (d) sensor; (e) comprehensively review related applications and establish the coherent taxonomy of these articles. ScienceDirect, IEEE Xplore and Web of Science databases were checked for articles on triage and priority-based sensor technology in telemedicine. The retrieved articles were filtered according to the type of telemedicine technology explored. A total of 150 articles were selected and classified into two categories. The first category includes reviews and surveys of triage and priority-based sensor technology in telemedicine. The second category includes articles on the three-tiered architecture of telemedicine. Tier 1 represents the users. Sensors acquire the vital signs of the users and send them to Tier 2, which is the personal gateway that uses local area network protocols or wireless body area network. Medical data are sent from Tier 2 to Tier 3, which is the healthcare provider in medical institutes. Then, the motivation for using triage and priority-based sensor technology in telemedicine, the issues related to the obstruction of its application and the development and utilisation of telemedicine are examined on the basis of the findings presented in the literature.

A systematic review of novel technology for monitoring infant and newborn heart rate.

PubMed

Kevat, Ajay C; Bullen, Denise V R; Davis, Peter G; Kamlin, C Omar F

2017-05-01

Heart rate (HR) is a vital sign for assessing the need for resuscitation. We performed a systematic review of studies assessing novel methods of measuring HR in newborns and infants in the neonatal unit. Two investigators completed independent literature searches. Identified papers were independently evaluated, and relevant data were extracted and analysed. This systematic review identified seven new technologies, including camera-based photoplethysmography, reflectance pulse oximetry, laser Doppler methods, capacitive sensors, piezoelectric sensors, electromyography and a digital stethoscope. Clinicians should be aware of several of these, which may become available for clinical use in the near future. ©2017 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.

A wearable context aware system for ubiquitous healthcare.

PubMed

Kang, Dong-Oh; Lee, Hyung-Jik; Ko, Eun-Jung; Kang, Kyuchang; Lee, Jeunwoo

2006-01-01

Recent developments of information technologies are leading the advent of the era of ubiquitous healthcare, which means healthcare services at any time and at any places. The ubiquitous healthcare service needs a wearable system for more continual measurement of biological signals of a user, which gives information of the user from wearable sensors. In this paper, we propose a wearable context aware system for ubiquitous healthcare, and its systematic design process of a ubiquitous healthcare service. Some wearable sensor systems are introduced with Zigbee communication. We develop a context aware framework to send information from wearable sensors to healthcare service entities as a middleware to solve the interoperability problem between sensor makers and healthcare service providers. And, we propose a systematic process of design of ubiquitous healthcare services with the context aware framework. In order to show the feasibility of the proposed system, some application examples are given, which are applied to remote monitoring, and a self check service.

Selection of NIR H2O absorption transitions for in-cylinder measurement of temperature in IC engines

NASA Astrophysics Data System (ADS)

Zhou, Xin; Liu, Xiang; Jeffries, Jay B.; Hanson, Ronald K.

2005-12-01

The water vapour spectrum in the 1.25-1.65 µm region is systematically analysed to find the best absorption transitions for sensitive measurement of in-cylinder gas temperature over short paths in an internal combustion engine. The strategy to select the optimum wavelength regions and absorption line combinations is developed for the time-varying pressures and temperatures expected during the compression portion of an engine cycle. We have identified 14 transitions of water vapour in this spectral region as promising for this application. From these transitions, 16 potential line pairs were considered for a wavelength-modulated absorption sensor for in-cylinder gas temperature during the compression stroke. Expected performance is modelled for the intake portion of two engine cycles that produce extreme temperature and pressure variations during compression.

Optimal Multi-Type Sensor Placement for Structural Identification by Static-Load Testing

PubMed Central

Papadopoulou, Maria; Vernay, Didier; Smith, Ian F. C.

2017-01-01

Assessing ageing infrastructure is a critical challenge for civil engineers due to the difficulty in the estimation and integration of uncertainties in structural models. Field measurements are increasingly used to improve knowledge of the real behavior of a structure; this activity is called structural identification. Error-domain model falsification (EDMF) is an easy-to-use model-based structural-identification methodology which robustly accommodates systematic uncertainties originating from sources such as boundary conditions, numerical modelling and model fidelity, as well as aleatory uncertainties from sources such as measurement error and material parameter-value estimations. In most practical applications of structural identification, sensors are placed using engineering judgment and experience. However, since sensor placement is fundamental to the success of structural identification, a more rational and systematic method is justified. This study presents a measurement system design methodology to identify the best sensor locations and sensor types using information from static-load tests. More specifically, three static-load tests were studied for the sensor system design using three types of sensors for a performance evaluation of a full-scale bridge in Singapore. Several sensor placement strategies are compared using joint entropy as an information-gain metric. A modified version of the hierarchical algorithm for sensor placement is proposed to take into account mutual information between load tests. It is shown that a carefully-configured measurement strategy that includes multiple sensor types and several load tests maximizes information gain. PMID:29240684

An Observation Capability Semantic-Associated Approach to the Selection of Remote Sensing Satellite Sensors: A Case Study of Flood Observations in the Jinsha River Basin.

PubMed

Hu, Chuli; Li, Jie; Lin, Xin; Chen, Nengcheng; Yang, Chao

2018-05-21

Observation schedules depend upon the accurate understanding of a single sensor’s observation capability and the interrelated observation capability information on multiple sensors. The general ontologies for sensors and observations are abundant. However, few observation capability ontologies for satellite sensors are available, and no study has described the dynamic associations among the observation capabilities of multiple sensors used for integrated observational planning. This limitation results in a failure to realize effective sensor selection. This paper develops a sensor observation capability association (SOCA) ontology model that is resolved around the task-sensor-observation capability (TSOC) ontology pattern. The pattern is developed considering the stimulus-sensor-observation (SSO) ontology design pattern, which focuses on facilitating sensor selection for one observation task. The core aim of the SOCA ontology model is to achieve an observation capability semantic association. A prototype system called SemOCAssociation was developed, and an experiment was conducted for flood observations in the Jinsha River basin in China. The results of this experiment verified that the SOCA ontology based association method can help sensor planners intuitively and accurately make evidence-based sensor selection decisions for a given flood observation task, which facilitates efficient and effective observational planning for flood satellite sensors.

Impact of study design on development and evaluation of an activity-type classifier.

PubMed

van Hees, Vincent T; Golubic, Rajna; Ekelund, Ulf; Brage, Søren

2013-04-01

Methods to classify activity types are often evaluated with an experimental protocol involving prescribed physical activities under confined (laboratory) conditions, which may not reflect real-life conditions. The present study aims to evaluate how study design may impact on classifier performance in real life. Twenty-eight healthy participants (21-53 yr) were asked to wear nine triaxial accelerometers while performing 58 activity types selected to simulate activities in real life. For each sensor location, logistic classifiers were trained in subsets of up to 8 activities to distinguish between walking and nonwalking activities and were then evaluated in all 58 activities. Different weighting factors were used to convert the resulting confusion matrices into an estimation of the confusion matrix as would apply in the real-life setting by creating four different real-life scenarios, as well as one traditional laboratory scenario. The sensitivity of a classifier estimated with a traditional laboratory protocol is within the range of estimates derived from real-life scenarios for any body location. The specificity, however, was systematically overestimated by the traditional laboratory scenario. Walking time was systematically overestimated, except for lower back sensor data (range: 7-757%). In conclusion, classifier performance under confined conditions may not accurately reflect classifier performance in real life. Future studies that aim to evaluate activity classification methods are warranted to pay special attention to the representativeness of experimental conditions for real-life conditions.

Systematic and random variations in digital Thematic Mapper data

NASA Technical Reports Server (NTRS)

Duggin, M. J. (Principal Investigator); Sakhavat, H.

1985-01-01

Radiance recorded by any remote sensing instrument will contain noise which will consist of both systematic and random variations. Systematic variations may be due to sun-target-sensor geometry, atmospheric conditions, and the interaction of the spectral characteristics of the sensor with those of upwelling radiance. Random variations in the data may be caused by variations in the nature and in the heterogeneity of the ground cover, by variations in atmospheric transmission, and by the interaction of these variations with the sensing device. It is important to be aware of the extent of random and systematic errors in recorded radiance data across ostensibly uniform ground areas in order to assess the impact on quantative image analysis procedures for both the single date and the multidate cases. It is the intention here to examine the systematic and the random variations in digital radiance data recorded in each band by the thematic mapper over crop areas which are ostensibly uniform and which are free from visible cloud.

A highly selective and self-powered gas sensor via organic surface functionalization of p-Si/n-ZnO diodes.

PubMed

Hoffmann, Martin W G; Mayrhofer, Leonhard; Casals, Olga; Caccamo, Lorenzo; Hernandez-Ramirez, Francisco; Lilienkamp, Gerhard; Daum, Winfried; Moseler, Michael; Waag, Andreas; Shen, Hao; Prades, J Daniel

2014-12-17

Selectivity and low power consumption are major challenges in the development of sophisticated gas sensor devices. A sensor system is presented that unifies selective sensor-gas interactions and energy-harvesting properties, using defined organic-inorganic hybrid materials. Simulations of chemical-binding interactions and the consequent electronic surface modulation give more insight into the complex sensing mechanism of selective gas detection. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Wearable inertial sensors in swimming motion analysis: a systematic review.

PubMed

de Magalhaes, Fabricio Anicio; Vannozzi, Giuseppe; Gatta, Giorgio; Fantozzi, Silvia

2015-01-01

The use of contemporary technology is widely recognised as a key tool for enhancing competitive performance in swimming. Video analysis is traditionally used by coaches to acquire reliable biomechanical data about swimming performance; however, this approach requires a huge computational effort, thus introducing a delay in providing quantitative information. Inertial and magnetic sensors, including accelerometers, gyroscopes and magnetometers, have been recently introduced to assess the biomechanics of swimming performance. Research in this field has attracted a great deal of interest in the last decade due to the gradual improvement of the performance of sensors and the decreasing cost of miniaturised wearable devices. With the aim of describing the state of the art of current developments in this area, a systematic review of the existing methods was performed using the following databases: PubMed, ISI Web of Knowledge, IEEE Xplore, Google Scholar, Scopus and Science Direct. Twenty-seven articles published in indexed journals and conference proceedings, focusing on the biomechanical analysis of swimming by means of inertial sensors were reviewed. The articles were categorised according to sensor's specification, anatomical sites where the sensors were attached, experimental design and applications for the analysis of swimming performance. Results indicate that inertial sensors are reliable tools for swimming biomechanical analyses.

An Observation Capability Semantic-Associated Approach to the Selection of Remote Sensing Satellite Sensors: A Case Study of Flood Observations in the Jinsha River Basin

PubMed Central

Hu, Chuli; Li, Jie; Lin, Xin

2018-01-01

Observation schedules depend upon the accurate understanding of a single sensor’s observation capability and the interrelated observation capability information on multiple sensors. The general ontologies for sensors and observations are abundant. However, few observation capability ontologies for satellite sensors are available, and no study has described the dynamic associations among the observation capabilities of multiple sensors used for integrated observational planning. This limitation results in a failure to realize effective sensor selection. This paper develops a sensor observation capability association (SOCA) ontology model that is resolved around the task-sensor-observation capability (TSOC) ontology pattern. The pattern is developed considering the stimulus-sensor-observation (SSO) ontology design pattern, which focuses on facilitating sensor selection for one observation task. The core aim of the SOCA ontology model is to achieve an observation capability semantic association. A prototype system called SemOCAssociation was developed, and an experiment was conducted for flood observations in the Jinsha River basin in China. The results of this experiment verified that the SOCA ontology based association method can help sensor planners intuitively and accurately make evidence-based sensor selection decisions for a given flood observation task, which facilitates efficient and effective observational planning for flood satellite sensors. PMID:29883425

Horizon sensors attitude errors simulation for the Brazilian Remote Sensing Satellite

NASA Astrophysics Data System (ADS)

Vicente de Brum, Antonio Gil; Ricci, Mario Cesar

Remote sensing, meteorological and other types of satellites require an increasingly better Earth related positioning. From the past experience it is well known that the thermal horizon in the 15 micrometer band provides conditions of determining the local vertical at any time. This detection is done by horizon sensors which are accurate instruments for Earth referred attitude sensing and control whose performance is limited by systematic and random errors amounting about 0.5 deg. Using the computer programs OBLATE, SEASON, ELECTRO and MISALIGN, developed at INPE to simulate four distinct facets of conical scanning horizon sensors, attitude errors are obtained for the Brazilian Remote Sensing Satellite (the first one, SSR-1, is scheduled to fly in 1996). These errors are due to the oblate shape of the Earth, seasonal and latitudinal variations of the 15 micrometer infrared radiation, electronic processing time delay and misalignment of sensor axis. The sensor related attitude errors are thus properly quantified in this work and will, together with other systematic errors (for instance, ambient temperature variation) take part in the pre-launch analysis of the Brazilian Remote Sensing Satellite, with respect to the horizon sensor performance.

Integration of reconfigurable potentiometric electrochemical sensors into a digital microfluidic platform.

PubMed

Farzbod, Ali; Moon, Hyejin

2018-05-30

This paper presents the demonstration of on-chip fabrication of a potassium-selective sensor array enabled by electrowetting on dielectric digital microfluidics for the first time. This demonstration proves the concept that electrochemical sensors can be seamlessly integrated with sample preparation units in a digital microfluidic platform. More significantly, the successful on-chip fabrication of a sensor array indicates that sensors become reconfigurable and have longer lifetime in a digital microfluidic platform. The on-chip fabrication of ion-selective electrodes includes electroplating Ag followed by forming AgCl layer by chemical oxidation and depositing a thin layer of desired polymer-based ion selective membrane on one of the sensor electrodes. In this study, potassium ionophores work as potassium ion channels and make the membrane selective to potassium ions. This selectiveness results in the voltage difference across the membrane layer, which is correlated with potassium ion concentration. The calibration curve of the fabricated potassium-selective electrode demonstrates the slope of 58 mV/dec for potassium concentration in KCl sample solutions and shows good agreement with the ideal Nernstian response. The proposed sensor platform is an outstanding candidate for a portable home-use for continuous monitoring of ions thanks to its advantages such as easy automation of sample preparation and detection processes, elongated sensor lifetime, minimal membrane and sample consumption, and user-definable/reconfigurable sensor array. Copyright © 2018 Elsevier B.V. All rights reserved.

Fukunaga-Koontz feature transformation for statistical structural damage detection and hierarchical neuro-fuzzy damage localisation

NASA Astrophysics Data System (ADS)

Hoell, Simon; Omenzetter, Piotr

2017-07-01

Considering jointly damage sensitive features (DSFs) of signals recorded by multiple sensors, applying advanced transformations to these DSFs and assessing systematically their contribution to damage detectability and localisation can significantly enhance the performance of structural health monitoring systems. This philosophy is explored here for partial autocorrelation coefficients (PACCs) of acceleration responses. They are interrogated with the help of the linear discriminant analysis based on the Fukunaga-Koontz transformation using datasets of the healthy and selected reference damage states. Then, a simple but efficient fast forward selection procedure is applied to rank the DSF components with respect to statistical distance measures specialised for either damage detection or localisation. For the damage detection task, the optimal feature subsets are identified based on the statistical hypothesis testing. For damage localisation, a hierarchical neuro-fuzzy tool is developed that uses the DSF ranking to establish its own optimal architecture. The proposed approaches are evaluated experimentally on data from non-destructively simulated damage in a laboratory scale wind turbine blade. The results support our claim of being able to enhance damage detectability and localisation performance by transforming and optimally selecting DSFs. It is demonstrated that the optimally selected PACCs from multiple sensors or their Fukunaga-Koontz transformed versions can not only improve the detectability of damage via statistical hypothesis testing but also increase the accuracy of damage localisation when used as inputs into a hierarchical neuro-fuzzy network. Furthermore, the computational effort of employing these advanced soft computing models for damage localisation can be significantly reduced by using transformed DSFs.

Radiation area monitor device and method

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

Vencelj, Matjaz; Stowe, Ashley C.; Petrovic, Toni

A radiation area monitor device/method, utilizing: a radiation sensor having a directional radiation sensing capability; a rotation mechanism operable for selectively rotating the radiation sensor such that the directional radiation sensing capability selectively sweeps an area of interest; and a processor operable for analyzing and storing a radiation fingerprint acquired by the radiation sensor as the directional radiation sensing capability selectively sweeps the area of interest. Optionally, the radiation sensor includes a gamma and/or neutron radiation sensor. The device/method selectively operates in: a first supervised mode during which a baseline radiation fingerprint is acquired by the radiation sensor; and amore » second unsupervised mode during which a subsequent radiation fingerprint is acquired by the radiation sensor, wherein the subsequent radiation fingerprint is compared to the baseline radiation fingerprint and, if a predetermined difference threshold is exceeded, an alert is issued.« less

Is flat fielding safe for precision CCD astronomy?

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

Baumer, Michael; Davis, Christopher P.; Roodman, Aaron

The ambitious goals of precision cosmology with wide-field optical surveys such as the Dark Energy Survey (DES) and the Large Synoptic Survey Telescope (LSST) demand precision CCD astronomy as their foundation. This in turn requires an understanding of previously uncharacterized sources of systematic error in CCD sensors, many of which manifest themselves as static effective variations in pixel area. Such variation renders a critical assumption behind the traditional procedure of flat fielding—that a sensor's pixels comprise a uniform grid—invalid. In this work, we present a method to infer a curl-free model of a sensor's underlying pixel grid from flat-field images,more » incorporating the superposition of all electrostatic sensor effects—both known and unknown—present in flat-field data. We use these pixel grid models to estimate the overall impact of sensor systematics on photometry, astrometry, and PSF shape measurements in a representative sensor from the Dark Energy Camera (DECam) and a prototype LSST sensor. Applying the method to DECam data recovers known significant sensor effects for which corrections are currently being developed within DES. For an LSST prototype CCD with pixel-response non-uniformity (PRNU) of 0.4%, we find the impact of "improper" flat fielding on these observables is negligible in nominal .7'' seeing conditions. Furthermore, these errors scale linearly with the PRNU, so for future LSST production sensors, which may have larger PRNU, our method provides a way to assess whether pixel-level calibration beyond flat fielding will be required.« less

Is flat fielding safe for precision CCD astronomy?

DOE PAGES

Baumer, Michael; Davis, Christopher P.; Roodman, Aaron

2017-07-06

The ambitious goals of precision cosmology with wide-field optical surveys such as the Dark Energy Survey (DES) and the Large Synoptic Survey Telescope (LSST) demand precision CCD astronomy as their foundation. This in turn requires an understanding of previously uncharacterized sources of systematic error in CCD sensors, many of which manifest themselves as static effective variations in pixel area. Such variation renders a critical assumption behind the traditional procedure of flat fielding—that a sensor's pixels comprise a uniform grid—invalid. In this work, we present a method to infer a curl-free model of a sensor's underlying pixel grid from flat-field images,more » incorporating the superposition of all electrostatic sensor effects—both known and unknown—present in flat-field data. We use these pixel grid models to estimate the overall impact of sensor systematics on photometry, astrometry, and PSF shape measurements in a representative sensor from the Dark Energy Camera (DECam) and a prototype LSST sensor. Applying the method to DECam data recovers known significant sensor effects for which corrections are currently being developed within DES. For an LSST prototype CCD with pixel-response non-uniformity (PRNU) of 0.4%, we find the impact of "improper" flat fielding on these observables is negligible in nominal .7'' seeing conditions. Furthermore, these errors scale linearly with the PRNU, so for future LSST production sensors, which may have larger PRNU, our method provides a way to assess whether pixel-level calibration beyond flat fielding will be required.« less

Commercial Sensory Survey Radiation Testing Progress Report

NASA Technical Reports Server (NTRS)

Becker, Heidi N.; Dolphic, Michael D.; Thorbourn, Dennis O.; Alexander, James W.; Salomon, Phil M.

2008-01-01

The NASA Electronic Parts and Packaging (NEPP) Program Sensor Technology Commercial Sensor Survey task is geared toward benefiting future NASA space missions with low-cost, short-duty-cycle, visible imaging needs. Such applications could include imaging for educational outreach purposes or short surveys of spacecraft, planetary, or lunar surfaces. Under the task, inexpensive commercial grade CMOS sensors were surveyed in fiscal year 2007 (FY07) and three sensors were selected for total ionizing dose (TID) and displacement damage dose (DDD) tolerance testing. The selected sensors had to meet selection criteria chosen to support small, low-mass cameras that produce good resolution color images. These criteria are discussed in detail in [1]. This document discusses the progress of radiation testing on the Micron and OmniVision sensors selected in FY07 for radiation tolerance testing.

Time Series Analysis for Spatial Node Selection in Environment Monitoring Sensor Networks

PubMed Central

Bhandari, Siddhartha; Jurdak, Raja; Kusy, Branislav

2017-01-01

Wireless sensor networks are widely used in environmental monitoring. The number of sensor nodes to be deployed will vary depending on the desired spatio-temporal resolution. Selecting an optimal number, position and sampling rate for an array of sensor nodes in environmental monitoring is a challenging question. Most of the current solutions are either theoretical or simulation-based where the problems are tackled using random field theory, computational geometry or computer simulations, limiting their specificity to a given sensor deployment. Using an empirical dataset from a mine rehabilitation monitoring sensor network, this work proposes a data-driven approach where co-integrated time series analysis is used to select the number of sensors from a short-term deployment of a larger set of potential node positions. Analyses conducted on temperature time series show 75% of sensors are co-integrated. Using only 25% of the original nodes can generate a complete dataset within a 0.5 °C average error bound. Our data-driven approach to sensor position selection is applicable for spatiotemporal monitoring of spatially correlated environmental parameters to minimize deployment cost without compromising data resolution. PMID:29271880

High-sensitivity multifunctional spinner magnetometer using a magneto-impedance sensor

NASA Astrophysics Data System (ADS)

Kodama, Kazuto

2017-01-01

A novel spinner magnetometer was developed with a wide dynamic range from 10-10 to 10-4 Am2 and a resolution of 10-11 Am2. High sensitivity was achieved with the use of a magneto-impedance (MI) sensor, which is a compact, sensitive magnetic sensor used industrially. Its slow-spinning rate (5 Hz) and the incorporation of a unique mechanism for adjusting the spacing between the sensing unit and the spinning axis allows the measurement of fragile samples sized 10-50 mm. The sensor configuration, in which a pair of MI sensors is connected in opposite serial, along with an amplification circuit with a programmable low-pass filter, reduces the problems of external noise and sensor drift. The signal, with reference to the spinning frequency, is detected with a lock-in amplifier. The MI spinner has two selectable measurement modes: the fundamental mode (F mode) and the harmonic mode (H mode). Measurements in the F mode detect signals of the fundamental frequency (5 Hz), in the same way as conventional spinner magnetometers. In the H mode, the second (10 Hz) and the third (15 Hz) harmonic components are measured, in addition to the fundamental component. Tests in the H mode were performed using a small coil and a natural sample to simulate dipoles with various degrees of offset. The results revealed that the magnitude of the fundamental component of the offset dipole was systematically larger (by several percent) than that of the nonoffset dipole. These findings suggest that this novel MI spinner will be useful in estimating the inhomogeneity of the magnetization of a sample that can equivalently be described by an offset dipole.

Optimal Tuner Selection for Kalman Filter-Based Aircraft Engine Performance Estimation

NASA Technical Reports Server (NTRS)

Simon, Donald L.; Garg, Sanjay

2010-01-01

A linear point design methodology for minimizing the error in on-line Kalman filter-based aircraft engine performance estimation applications is presented. This technique specifically addresses the underdetermined estimation problem, where there are more unknown parameters than available sensor measurements. A systematic approach is applied to produce a model tuning parameter vector of appropriate dimension to enable estimation by a Kalman filter, while minimizing the estimation error in the parameters of interest. Tuning parameter selection is performed using a multi-variable iterative search routine which seeks to minimize the theoretical mean-squared estimation error. This paper derives theoretical Kalman filter estimation error bias and variance values at steady-state operating conditions, and presents the tuner selection routine applied to minimize these values. Results from the application of the technique to an aircraft engine simulation are presented and compared to the conventional approach of tuner selection. Experimental simulation results are found to be in agreement with theoretical predictions. The new methodology is shown to yield a significant improvement in on-line engine performance estimation accuracy

Activity recognition using dynamic multiple sensor fusion in body sensor networks.

PubMed

Gao, Lei; Bourke, Alan K; Nelson, John

2012-01-01

Multiple sensor fusion is a main research direction for activity recognition. However, there are two challenges in those systems: the energy consumption due to the wireless transmission and the classifier design because of the dynamic feature vector. This paper proposes a multi-sensor fusion framework, which consists of the sensor selection module and the hierarchical classifier. The sensor selection module adopts the convex optimization to select the sensor subset in real time. The hierarchical classifier combines the Decision Tree classifier with the Naïve Bayes classifier. The dataset collected from 8 subjects, who performed 8 scenario activities, was used to evaluate the proposed system. The results show that the proposed system can obviously reduce the energy consumption while guaranteeing the recognition accuracy.

Information Fusion for High Level Situation Assessment and Prediction

DTIC Science & Technology

2007-03-01

procedure includes deciding a sensor set that achieves the optimal trade -off between its cost and benefit, activating the identified sensors, integrating...and effective decision can be made by dynamic inference based on selecting a subset of sensors with the optimal trade -off between their cost and...first step is achieved by designing a sensor selection criterion that represents the trade -off between the sensor benefit and sensor cost. This is then

Challenges in the determination of the interstellar flow longitude from the pickup ion cutoff

NASA Astrophysics Data System (ADS)

Taut, A.; Berger, L.; Möbius, E.; Drews, C.; Heidrich-Meisner, V.; Keilbach, D.; Lee, M. A.; Wimmer-Schweingruber, R. F.

2018-03-01

Context. The interstellar flow longitude corresponds to the Sun's direction of movement relative to the local interstellar medium. Thus, it constitutes a fundamental parameter for our understanding of the heliosphere and, in particular, its interaction with its surroundings, which is currently investigated by the Interstellar Boundary EXplorer (IBEX). One possibility to derive this parameter is based on pickup ions (PUIs) that are former neutral ions that have been ionized in the inner heliosphere. The neutrals enter the heliosphere as an interstellar wind from the direction of the Sun's movement against the partially ionized interstellar medium. PUIs carry information about the spatial variation of their neutral parent population (density and flow vector field) in their velocity distribution function. From the symmetry of the longitudinal flow velocity distribution, the interstellar flow longitude can be derived. Aim. The aim of this paper is to identify and eliminate systematic errors that are connected to this approach of measuring the interstellar flow longitude; we want to minimize any systematic influences on the result of this analysis and give a reasonable estimate for the uncertainty. Methods: We use He+ data measured by the PLAsma and SupraThermal Ion Composition (PLASTIC) sensor on the Solar TErrestrial RElations Observatory Ahead (STEREO A) spacecraft. We analyze a recent approach, identify sources of systematic errors, and propose solutions to eliminate them. Furthermore, a method is introduced to estimate the error associated with this approach. Additionally, we investigate how the selection of interplanetary magnetic field angles, which is closely connected to the pickup ion velocity distribution function, affects the result for the interstellar flow longitude. Results: We find that the revised analysis used to address part of the expected systematic effects obtains significantly different results than presented in the previous study. In particular, the derived uncertainties are considerably larger. Furthermore, an unexpected systematic trend of the resulting interstellar flow longitude with the selection of interplanetary magnetic field orientation is uncovered.

Miniaturizable Ion-Selective Arrays Based on Highly Stable Polymer Membranes for Biomedical Applications

PubMed Central

Mir, Mònica; Lugo, Roberto; Tahirbegi, Islam Bogachan; Samitier, Josep

2014-01-01

Poly(vinylchloride) (PVC) is the most common polymer matrix used in the fabrication of ion-selective electrodes (ISEs). However, the surfaces of PVC-based sensors have been reported to show membrane instability. In an attempt to overcome this limitation, here we developed two alternative methods for the preparation of highly stable and robust ion-selective sensors. These platforms are based on the selective electropolymerization of poly(3,4-ethylenedioxythiophene) (PEDOT), where the sulfur atoms contained in the polymer covalently interact with the gold electrode, also permitting controlled selective attachment on a miniaturized electrode in an array format. This platform sensor was improved with the crosslinking of the membrane compounds with poly(ethyleneglycol) diglycidyl ether (PEG), thus also increasing the biocompatibility of the sensor. The resulting ISE membranes showed faster signal stabilization of the sensor response compared with that of the PVC matrix and also better reproducibility and stability, thus making these platforms highly suitable candidates for the manufacture of robust implantable sensors. PMID:24999717

Biomimetic self-templating optical structures fabricated by genetically engineered M13 bacteriophage.

PubMed

Kim, Won-Geun; Song, Hyerin; Kim, Chuntae; Moon, Jong-Sik; Kim, Kyujung; Lee, Seung-Wuk; Oh, Jin-Woo

2016-11-15

Here, we describe a highly sensitive and selective surface plasmon resonance sensor system by utilizing self-assembly of genetically engineered M13 bacteriophage. About 2700 copies of genetically expressed peptide copies give superior selectivity and sensitivity to M13 phage-based SPR sensor. Furthermore, the sensitivity of the M13 phage-based SPR sensor was enhanced due to the aligning of receptor matrix in specific direction. Incorporation of specific binding peptide (His Pro Gln: HPQ) gives M13 bacteriophage high selectivity for the streptavidin. Our M13 phage-based SPR sensor takes advantage of simplicity of self-assembly compared with relatively complex photolithography techniques or chemical conjugations. Additionally, designed structure which is composed of functionalized M13 bacteriophage can simultaneously improve the sensitivity and selectivity of SPR sensor evidently. By taking advantages of the genetic engineering and self-assembly, we propose the simple method for fabricating novel M13 phage-based SPR sensor system which has a high sensitivity and high selectivity. Copyright © 2016 Elsevier B.V. All rights reserved.

The application of remote sensing techniques to selected inter and intra urban data acquisition problems

NASA Technical Reports Server (NTRS)

Horton, F. E.

1970-01-01

The utility of remote sensing techniques to urban data acquisition problems in several distinct areas was identified. This endeavor included a comparison of remote sensing systems for urban data collection, the extraction of housing quality data from aerial photography, utilization of photographic sensors in urban transportation studies, urban change detection, space photography utilization, and an application of remote sensing techniques to the acquisition of data concerning intra-urban commercial centers. The systematic evaluation of variable extraction for urban modeling and planning at several different scales, and the model derivation for identifying and predicting economic growth and change within a regional system of cities are also studied.

Analysis and design of a capsule landing system and surface vehicle control system for Mars exploration

NASA Technical Reports Server (NTRS)

Frederick, D. K.; Lashmet, P. K.; Sandor, G. N.; Shen, C. N.; Smith, E. J.; Yerazunis, S. W.

1971-01-01

Investigation of problems related to control of a mobile planetary vehicle according to a systematic plan for the exploration of Mars has been undertaken. Problem areas receiving attention include: (1) overall systems analysis; (2) vehicle configuration and dynamics; (3) toroidal wheel design and evaluation; (4) on-board navigation systems; (5) satellite-vehicle navigation systems; (6) obstacle detection systems; (7) terrain sensing, interpretation and modeling; (8) computer simulation of terrain sensor-path selection systems; and (9) chromatographic systems design concept studies. The specific tasks which have been undertaken are defined and the progress which has been achieved during the period July 1, 1971 to December 31, 1971 is summarized.

MOF-Based Membrane Encapsulated ZnO Nanowires for Enhanced Gas Sensor Selectivity.

PubMed

Drobek, Martin; Kim, Jae-Hun; Bechelany, Mikhael; Vallicari, Cyril; Julbe, Anne; Kim, Sang Sub

2016-04-06

Gas sensors are of a great interest for applications including toxic or explosive gases detection in both in-house and industrial environments, air quality monitoring, medical diagnostics, or control of food/cosmetic properties. In the area of semiconductor metal oxides (SMOs)-based sensors, a lot of effort has been devoted to improve the sensing characteristics. In this work, we report on a general methodology for improving the selectivity of SMOx nanowires sensors, based on the coverage of ZnO nanowires with a thin ZIF-8 molecular sieve membrane. The optimized ZnO@ZIF-8-based nanocomposite sensor shows markedly selective response to H2 in comparison with the pristine ZnO nanowires sensor, while showing the negligible sensing response to C7H8 and C6H6. This original MOF-membrane encapsulation strategy applied to nanowires sensor architecture pave the way for other complex 3D architectures and various types of applications requiring either gas or ion selectivity, such as biosensors, photo(catalysts), and electrodes.

Pulse Based Time-of-Flight Range Sensing.

PubMed

Sarbolandi, Hamed; Plack, Markus; Kolb, Andreas

2018-05-23

Pulse-based Time-of-Flight (PB-ToF) cameras are an attractive alternative range imaging approach, compared to the widely commercialized Amplitude Modulated Continuous-Wave Time-of-Flight (AMCW-ToF) approach. This paper presents an in-depth evaluation of a PB-ToF camera prototype based on the Hamamatsu area sensor S11963-01CR. We evaluate different ToF-related effects, i.e., temperature drift, systematic error, depth inhomogeneity, multi-path effects, and motion artefacts. Furthermore, we evaluate the systematic error of the system in more detail, and introduce novel concepts to improve the quality of range measurements by modifying the mode of operation of the PB-ToF camera. Finally, we describe the means of measuring the gate response of the PB-ToF sensor and using this information for PB-ToF sensor simulation.

MEMS-Based Gas Sensor Using PdO-Decorated TiO2 Thin Film for Highly Sensitive and Selective H2 Detection with Low Power Consumption

NASA Astrophysics Data System (ADS)

Kwak, Seungmin; Shim, Young-Seok; Yoo, Yong Kyoung; Lee, Jin-Hyung; Kim, Inho; Kim, Jinseok; Lee, Kyu Hyoung; Lee, Jeong Hoon

2018-03-01

We report a micromachined H2 sensor that is composed of a Pt micro-heater, low-stress insulating layer (SiO2/SiNx/SiO2), Pt-interdigitated electrodes, and gas sensing materials. Three types of Pt micro-heater are designed as function of electrode width, and their thermal properties are systematically analyzed by finite element modeling FEM with infrared camera. The power consumptions when the surface temperature reached 150, 200, 250, and 300 °C are calculated to approximately 33, 48, 67 and 85 mW, respectively. The response of the PdO nanoparticles-decorated TiO2 thin films to H2 is much higher than those of other gases such as CH4 and CO at 200 °C (48 mW). Further, the response time is reduced to approximately 3 s. The enhancement of gas sensing properties is related to well-designed micro-heater and catalytic effects of PdO nanoparticles such as electronic and chemical sensitization. These results suggest that the PdO nanoparticles-decorated TiO2 thin film, namely MEMS-based H2 sensors are very promising for use in IoT application to improve the quality of human's life.

High Aspect Ratio Perforated Co₃O₄ Nanowires Derived from Cobalt-Carbonate-Hydroxide Nanowires with Enhanced Sensing Performance.

PubMed

Zhou, Tuantuan; Gao, Wanlin; Wang, Qiang; Umar, Ahmad

2018-05-01

Herein, we report the facile synthesis of high-aspect ratio perforated Co3O4 nanowires derived from cobalt-carbonate-hydroxide (Co(CO3)0.5(OH) 0.11H2O) nanowires. The Co(CO3)0.5(OH) 0.11H2O nanowires were synthesized by simple hydrothermal process at 120 °C while annealing of such nanowires at 400 °C leads the formation of perforated Co3O4 nanowires. The prepared nanowires were characterized by several techniques which confirmed the high aspect ratio and well-crystallinity for the synthesized nanowires. For application point of view, the prepared perforated Co3O4 nanowires were used as efficient electrode material to fabricate highly sensitive and selective hydrazine chemical sensor. The electrochemical impedance spectroscopy (EIS) technique was employed to confirm the successful modification of the electrode. The key parameters of chemical sensor, such as detection limit, sensitivity, and linear range, have been systematically explored. The fabricated hydrazine sensor displayed a rather low detection limit of 4.52 μM (S/N = 3), a good sensitivity of 25.70 μA · mM-1, and a wide linear range of 16.97-358.34 μM.

MEMS-Based Gas Sensor Using PdO-Decorated TiO2 Thin Film for Highly Sensitive and Selective H2 Detection with Low Power Consumption

NASA Astrophysics Data System (ADS)

Kwak, Seungmin; Shim, Young-Seok; Yoo, Yong Kyoung; Lee, Jin-Hyung; Kim, Inho; Kim, Jinseok; Lee, Kyu Hyoung; Lee, Jeong Hoon

2018-05-01

We report a micromachined H2 sensor that is composed of a Pt micro-heater, low-stress insulating layer (SiO2/SiNx/SiO2), Pt-interdigitated electrodes, and gas sensing materials. Three types of Pt micro-heater are designed as function of electrode width, and their thermal properties are systematically analyzed by finite element modeling FEM with infrared camera. The power consumptions when the surface temperature reached 150, 200, 250, and 300 °C are calculated to approximately 33, 48, 67 and 85 mW, respectively. The response of the PdO nanoparticles-decorated TiO2 thin films to H2 is much higher than those of other gases such as CH4 and CO at 200 °C (48 mW). Further, the response time is reduced to approximately 3 s. The enhancement of gas sensing properties is related to well-designed micro-heater and catalytic effects of PdO nanoparticles such as electronic and chemical sensitization. These results suggest that the PdO nanoparticles-decorated TiO2 thin film, namely MEMS-based H2 sensors are very promising for use in IoT application to improve the quality of human's life.

TiO2 Nanorods Decorated with Pd Nanoparticles for Enhanced Liquefied Petroleum Gas Sensing Performance.

PubMed

Dhawale, Dattatray S; Gujar, Tanaji P; Lokhande, Chandrakant D

2017-08-15

Development of highly sensitive and selective semiconductor-based metal oxide sensor devices to detect toxic, explosive, flammable, and pollutant gases is still a challenging research topic. In the present work, we systematically enhanced the liquefied petroleum gas (LPG) sensing performance of chemical bath deposited TiO 2 nanorods by decorating Pd nanoparticle catalyst. Surface morphology with elemental mapping, crystal structure, composition and oxidation states, and surface area measurements of pristine TiO 2 and Pd:TiO 2 nanorods was examined by high resolution transmission electron microscopy with energy-dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and nitrogen adsorption-desorption characterization techniques. LPG sensing performance of pristine TiO 2 and Pd:TiO 2 nanorods was investigated in different LPG concentration and operating temperature ranges. The LPG response of 21% for pristine TiO 2 nanorods is enhanced to 49% after Pd catalyst decoration with reasonably fast response and recovery times. Further, the sensor exhibited long-term stability, which could be due to the strong metal support (Pd:TiO 2 ) interaction and catalytic properties offered by the Pd nanoparticle catalyst. The work described herein demonstrates a general and scalable approach that provides a promising route for rational design of variety of sensor devices for LPG detection.

Harnessing the potential of the Kinect sensor for psychiatric rehabilitation for stroke survivors.

PubMed

Zhang, Melvyn W B; Ho, Roger C M

2016-03-04

Dominques et al. in their recent article described how low-cost sensors, such as Microsoft Kinect could be utilized for the measurement of various anthropometric measures. With the recent advances in sensors and sensor based technology, along with the rapid advancement in E-health, Microsoft Kinect has been increasingly recognized by researchers and bioengineers to be a low-cost sensor that could help in the collation of various measurements and various data. A recent systematic review done by Da Gama et al. (2015) have looked into the potential of Kinect in terms of motor rehabilitation. The systematic review highlighted the tremendous potential of the sensors and has clearly stated that there is a need for further studies evaluating its potential for rehabilitation. Zhang et al. (2015) in their recent article have advocated several reasons as to why biosensors are pertinent for stroke rehabilitation. Of note, recent studies done by the World Health Organization have highlighted that stroke is a growing epidemic. Aside to the utilization of smartphone based sensors for stroke rehabilitation, as proposed by Zhang et al. (2015), researchers have also investigated the use of other low cost alternatives, such as Kinect, to facilitate the rehabilitation of stroke survivors. Whilst it may seemed like that has been quite extensive evaluation of the Kinect sensor for stroke rehabilitation, one core area that bio-engineers and researchers have not looked into is that of the psychiatric and mental health issues that might at times arise following a stroke. It is thus the aim of this letter to address how such a sensor could be tapped upon for psychiatric rehabilitation amongst stroke survivors. To this end, the authors have thus conceptualized a game that could help in the cognitive remediation for stroke survivors using low cost Kinect sensors.

Evaluation of Reprocessed Suomi NPP VIIRS Sensor Data Records based on Sensitivity of Environmental Data Records Trending to Changes in Sensor Data Records

NASA Astrophysics Data System (ADS)

Huang, J.; Weng, F.; Sun, N.

2017-12-01

As the inputs to satellite Environmental Data Records (EDR) that provide continuous monitoring of Earth System changes from space, Sensor Data Records (SDR) need to meet very high standards of accuracy. SDR reprocessing, aiming for accurately accounting sensor degradation and calibration issues, is therefore very important in satellite remote sensing. Previous studies on heritage Terra MODIS in NASA Earth Observation System (EOS) indicated that SDR degradation over time, if not correctly calibrated and reprocessed, can result in false trending in several key satellite EDR observations, such as aerosol optical depth (AOD) and vegetation index (VI). Yet the sensitivity of these EDRs to the changes in the reprocessed SDRs is still not comprehensively understood or quantified. As part of the Suomi NPP SDR long term monitoring efforts, the current ongoing SDR reprocessing at NOAA NESDIS STAR provides a unique test bed for quantifying the changes of EDRs to the reprocessed SDRs, and thus improves our understanding of the potential impacts of the SDR reprocessing on our capability of critical Earth observations. For the sensitivity investigation, we selected the VIIRS aerosol algorithm, which EDR algorithm uses most of the visible to near infrared (VIS-NIR) SDR bands. Several aerosol hotspot regions over the globe are selected for conducting AOD trending analysis under several prescribed SDR reprocessing scenarios, and the changes in the spatial and temporal characterizations of AOD are linked to the changes in SDR for exploration of any potential systematic relations. Preliminary results indicated that although changes varies by regions and seasons, some EDRs can be sensitive to even slight SDR changes in certain VIS-NIR bands. The study sheds important lights on how we can use the SDR-EDR relation as an additional approach to facilitate the SDR reprocessing evaluation. Details of the finding will be reported at the presentation.

Multi-Sensor Observations of Earthquake Related Atmospheric Signals over Major Geohazard Validation Sites

NASA Technical Reports Server (NTRS)

Ouzounov, D.; Pulinets, S.; Davindenko, D.; Hattori, K.; Kafatos, M.; Taylor, P.

2012-01-01

We are conducting a scientific validation study involving multi-sensor observations in our investigation of phenomena preceding major earthquakes. Our approach is based on a systematic analysis of several atmospheric and environmental parameters, which we found, are associated with the earthquakes, namely: thermal infrared radiation, outgoing long-wavelength radiation, ionospheric electron density, and atmospheric temperature and humidity. For first time we applied this approach to selected GEOSS sites prone to earthquakes or volcanoes. This provides a new opportunity to cross validate our results with the dense networks of in-situ and space measurements. We investigated two different seismic aspects, first the sites with recent large earthquakes, viz.- Tohoku-oki (M9, 2011, Japan) and Emilia region (M5.9, 2012,N. Italy). Our retrospective analysis of satellite data has shown the presence of anomalies in the atmosphere. Second, we did a retrospective analysis to check the re-occurrence of similar anomalous behavior in atmosphere/ionosphere over three regions with distinct geological settings and high seismicity: Taiwan, Japan and Kamchatka, which include 40 major earthquakes (M>5.9) for the period of 2005-2009. We found anomalous behavior before all of these events with no false negatives; false positives were less then 10%. Our initial results suggest that multi-instrument space-borne and ground observations show a systematic appearance of atmospheric anomalies near the epicentral area that could be explained by a coupling between the observed physical parameters and earthquake preparation processes.

Suitability of E-tongue Sensors to Assess Taste-Masking of Pediatric Liquids by Different Beverages Considering Their Physico-chemical Properties.

PubMed

Immohr, Laura Isabell; Hedfeld, Claas; Lang, Artur; Pein-Hackelbusch, Miriam

2017-02-01

Manipulation of liquid oral drugs by mixing them into foodstuff is a common procedure for taste-masking of OTC pharmaceuticals when administered to children. However, the taste-masking capability of such application media is not systematically evaluated, and recommendations for suitable media are hardly published. In this study, a sensor array of commercially available and self-developed electronic tongue sensors was employed to assess the taste-masking efficiency of eight different beverages (tap water, apple juice, carrot juice, fennel tea, fruit tea, milk, cocoa, and Alete meal to drink) on the OTC pharmaceuticals Ambroxol-ratiopharm®, Cetirizin AL, and Laxoberal® by multivariate data analysis. The Euclidean distances between each pure application medium and its corresponding drug mixture were used as an indicator for the taste-masking efficiency and correlated to the physico-chemical properties of the beverages. Thus, the pH value, the viscosity, as well as the fat and sugar content of the beverages were included, whereas only the viscosity appeared to be insignificant in all cases. The sugar content as well as the fat content and pH value emerged to be a significant variable in taste-masking efficiency for some of the tested drug products. It was shown that the applied electronic tongue sensors were capable to demonstrate the impact of the physico-chemical properties of the application media on their taste-masking capacity regardless of their non-selectivity towards these characteristics.

Anion-selective interaction and colorimeter by an optical metalloreceptor based on ruthenium(II) 2,2'-biimidazole: hydrogen bonding and proton transfer.

PubMed

Cui, Ying; Mo, Hao-Jun; Chen, Jin-Can; Niu, Yan-Li; Zhong, Yong-Rui; Zheng, Kang-Cheng; Ye, Bao-Hui

2007-08-06

A new anion sensor [Ru(bpy)2(H2biim)](PF6)2 (1) (bpy = 2,2'-bipyridine and H2biim = 2,2'-biimidazole) has been developed, in which the Ru(II)-bpy moiety acts as a chromophore and the H2biim ligand as an anion receptor via hydrogen bonding. A systematic investigation shows that 1 is an eligible sensor for various anions. It donates protons for hydrogen bonding to Cl-, Br-, I-, NO3-, HSO4-, H2PO4-, and OAc- anions and further actualizes monoproton transfer to the OAc- anion, changing color from yellow to orange brown. The fluoride ion has a high affinity toward the N-H group of the H2biim ligand for proton transfer, rather than hydrogen bonding, because of the formation of the highly stable HF2- anion, resulting in stepwise deprotonation of the two N-H fragments. These processes are signaled by vivid color changes from yellow to orange brown and then to violet because of second-sphere donor-acceptor interactions between Ru(II)-H2biim and the anions. The significant color changes can be distinguished visually. The processes are not only determined by the basicity of anion but also by the strength of hydrogen bonding and the stability of the anion-receptor complexes. The design strategy and remarkable photophysical properties of sensor 1 help to extend the development of anion sensors.

Dual functional rhodium oxide nanocorals enabled sensor for both non-enzymatic glucose and solid-state pH sensing.

PubMed

Dong, Qiuchen; Huang, Yikun; Song, Donghui; Wu, Huixiang; Cao, Fei; Lei, Yu

2018-07-30

Both pH-sensitive and glucose-responsive rhodium oxide nanocorals (Rh 2 O 3 NCs) were synthesized through electrospinning followed by high-temperature calcination. The as-prepared Rh 2 O 3 NCs were systematically characterized using various advanced techniques including scanning electron microscopy, X-ray powder diffraction and Raman spectroscopy, and then employed as a dual functional nanomaterial to fabricate a dual sensor for both non-enzymatic glucose sensing and solid-state pH monitoring. The sensing performance of the Rh 2 O 3 NCs based dual sensor toward pH and glucose was evaluated using open circuit potential, cyclic voltammetry and amperometric techniques, respectively. The results show that the as-prepared Rh 2 O 3 NCs not only maintain accurate and reversible pH sensitivity of Rh 2 O 3 , but also demonstrate a good electrocatalytic activity toward glucose oxidation in alkaline medium with a sensitivity of 11.46 μA mM -1 cm -2 , a limit of detection of 3.1 μM (S/N = 3), and a reasonable selectivity against various interferents in non-enzymatic glucose detection. Its accuracy in determining glucose in human serum samples was further demonstrated. These features indicate that the as-prepared Rh 2 O 3 NCs hold great promise as a dual-functional sensing material in the development of a high-performance sensor forManjakkal both solid-state pH and non-enzymatic glucose sensing. Copyright © 2018 Elsevier B.V. All rights reserved.

Engineering a growth sensor to select intracellular antibodies in the cytosol of mammalian cells.

PubMed

Nguyen, Thuy Duong; Takasuka, Hitoshi; Kaku, Yoshihiro; Inoue, Satoshi; Nagamune, Teruyuki; Kawahara, Masahiro

2017-07-01

Intracellular antibodies (intrabodies) are expected to function as therapeutics as well as tools for elucidating in vivo function of proteins. In this study, we propose a novel intrabody selection method in the cytosol of mammalian cells by utilizing a growth signal, induced by the interaction of the target antigen and an scFv-c-kit growth sensor. Here, we challenge this method to select specific intrabodies against rabies virus nucleoprotein (RV-N) for the first time. As a result, we successfully select antigen-specific intrabodies from a naïve synthetic library using phage panning followed by our growth sensor-based intracellular selection method, demonstrating the feasibility of the method. Additionally, we succeed in improving the response of the growth sensor by re-engineering the linker region of its construction. Collectively, the described selection method utilizing a growth sensor may become a highly efficient platform for selection of functional intrabodies in the future. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Chemical multisensors with selective encapsulation of ion-selective membranes

NASA Astrophysics Data System (ADS)

Schwager, Felix J.; Bousse, Luc J.; Bowman, Lyn; Meindl, J. D.

Chemical sensors fabricated with simultaneous wafer scale encapsulation of ion selective electrode mambranes are described. The sensors are miniature ion selective electrodes in chambers located on a silicon substrate. These chambers are made by anodically bonding to the silicon a no. 7740 pyrex glass wafer in which cavities were drilled. Pores with dimensions selectable from 50 microns upwards are opened in the roofs of the chambers by drilling with a CO2 laser. Each sensor die contains four cavities which are filled under reduced pressure with liquid membrane material which is subsequently polymerized. The transducers on the cavity floor are Ag/AgCl electrodes. Interconnects between the sensor chambers on each die and bonding pads are made in the silicon substrate.

A Sensitive, Multifunctional Spinner Magnetometer Using Magneto-impedance Sensor: a Rapid and Convenient Tool for the Quantification of Inhomogeneity of Magnetization

NASA Astrophysics Data System (ADS)

Kodama, K.

2016-12-01

A new type of spinner magnetometer with wide dynamic range from 10-7 mAm2 to 10-1 mAm2 and the resolution of 10-8 mAm2 was developed. The high sensitivity was achieved by using magneto-impedance (MI) sensor, a compact, high-performance magnetic sensor used in industrial fields. The slow spinning speed (5 Hz) and the unique mechanism enabling the adjustment of the sample-sensor distance allow measurements of fragile samples in any shape and size. A differential arrangement connecting a pair of the MI sensors in opposite serial reduces external noise and temperature drift. The differential sensor output is transferred to an amplification circuit associated with a programmable low-pass filter. The signal with reference to the spinning frequency is detected with a digital lock-in amplifier. The spinner magnetometer has two selectable measurement modes, the fundamental-mode (F-mode) and the harmonic-mode (H-mode). Measurements in the F-mode detect signals oscillating at the fundamental frequency (5 Hz) as conventional spinner magnetometers do. In the H-mode, additionally, the second (10 Hz) and the third (15 Hz) harmonic components can be measured. Tests in the H-mode were performed using a small coil and changing its position to simulate an offset-dipole. The results demonstrate that the dipole moment of the fundamental component is systematically biased by both quadrupole and octupole components arising in practice from inhomogeneity of magnetization or irregularity of sample shape. This study proposes, combined with theoretical and numerical analyses, quantification of such non-dipole effects and associated errors in the determination of dipole moment of a sample, as well as their correction that may be necessary, for example, when measuring irregular-shaped samples in the proximity of the sensor.

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

PubMed Central

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

2008-01-01

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

Fabrication of taste sensor for education

NASA Astrophysics Data System (ADS)

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

2017-03-01

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

Optical filter selection for high confidence discrimination of strongly overlapping infrared chemical spectra.

PubMed

Major, Kevin J; Poutous, Menelaos K; Ewing, Kenneth J; Dunnill, Kevin F; Sanghera, Jasbinder S; Aggarwal, Ishwar D

2015-09-01

Optical filter-based chemical sensing techniques provide a new avenue to develop low-cost infrared sensors. These methods utilize multiple infrared optical filters to selectively measure different response functions for various chemicals, dependent on each chemical's infrared absorption. Rather than identifying distinct spectral features, which can then be used to determine the identity of a target chemical, optical filter-based approaches rely on measuring differences in the ensemble response between a given filter set and specific chemicals of interest. Therefore, the results of such methods are highly dependent on the original optical filter choice, which will dictate the selectivity, sensitivity, and stability of any filter-based sensing method. Recently, a method has been developed that utilizes unique detection vector operations defined by optical multifilter responses, to discriminate between volatile chemical vapors. This method, comparative-discrimination spectral detection (CDSD), is a technique which employs broadband optical filters to selectively discriminate between chemicals with highly overlapping infrared absorption spectra. CDSD has been shown to correctly distinguish between similar chemicals in the carbon-hydrogen stretch region of the infrared absorption spectra from 2800-3100 cm(-1). A key challenge to this approach is how to determine which optical filter sets should be utilized to achieve the greatest discrimination between target chemicals. Previous studies used empirical approaches to select the optical filter set; however this is insufficient to determine the optimum selectivity between strongly overlapping chemical spectra. Here we present a numerical approach to systematically study the effects of filter positioning and bandwidth on a number of three-chemical systems. We describe how both the filter properties, as well as the chemicals in each set, affect the CDSD results and subsequent discrimination. These results demonstrate the importance of choosing the proper filter set and chemicals for comparative discrimination, in order to identify the target chemical of interest in the presence of closely matched chemical interferents. These findings are an integral step in the development of experimental prototype sensors, which will utilize CDSD.

Wireless sensors and sensor networks for homeland security applications.

PubMed

Potyrailo, Radislav A; Nagraj, Nandini; Surman, Cheryl; Boudries, Hacene; Lai, Hanh; Slocik, Joseph M; Kelley-Loughnane, Nancy; Naik, Rajesh R

2012-11-01

New sensor technologies for homeland security applications must meet the key requirements of sensitivity to detect agents below risk levels, selectivity to provide minimal false-alarm rates, and response speed to operate in high throughput environments, such as airports, sea ports, and other public places. Chemical detection using existing sensor systems is facing a major challenge of selectivity. In this review, we provide a brief summary of chemical threats of homeland security importance; focus in detail on modern concepts in chemical sensing; examine the origins of the most significant unmet needs in existing chemical sensors; and, analyze opportunities, specific requirements, and challenges for wireless chemical sensors and wireless sensor networks (WSNs). We further review a new approach for selective chemical sensing that involves the combination of a sensing material that has different response mechanisms to different species of interest, with a transducer that has a multi-variable signal-transduction ability. This new selective chemical-sensing approach was realized using an attractive ubiquitous platform of battery-free passive radio-frequency identification (RFID) tags adapted for chemical sensing. We illustrate the performance of RFID sensors developed in measurements of toxic industrial materials, humidity-independent detection of toxic vapors, and detection of chemical-agent simulants, explosives, and strong oxidizers.

Sensor selection cost optimisation for tracking structurally cyclic systems: a P-order solution

NASA Astrophysics Data System (ADS)

Doostmohammadian, M.; Zarrabi, H.; Rabiee, H. R.

2017-08-01

Measurements and sensing implementations impose certain cost in sensor networks. The sensor selection cost optimisation is the problem of minimising the sensing cost of monitoring a physical (or cyber-physical) system. Consider a given set of sensors tracking states of a dynamical system for estimation purposes. For each sensor assume different costs to measure different (realisable) states. The idea is to assign sensors to measure states such that the global cost is minimised. The number and selection of sensor measurements need to ensure the observability to track the dynamic state of the system with bounded estimation error. The main question we address is how to select the state measurements to minimise the cost while satisfying the observability conditions. Relaxing the observability condition for structurally cyclic systems, the main contribution is to propose a graph theoretic approach to solve the problem in polynomial time. Note that polynomial time algorithms are suitable for large-scale systems as their running time is upper-bounded by a polynomial expression in the size of input for the algorithm. We frame the problem as a linear sum assignment with solution complexity of ?.

Ultra-Low-Power MEMS Selective Gas Sensors

NASA Technical Reports Server (NTRS)

Stetter, Joseph

2012-01-01

This innovation is a system for gas sensing that includes an ultra-low-power MEMS (microelectromechanical system) gas sensor, combined with unique electronic circuitry and a proprietary algorithm for operating the sensor. The electronics were created from scratch, and represent a novel design capable of low-power operation of the proprietary MEMS gas sensor platform. The algorithm is used to identify a specific target gas in a gas mixture, making the sensor selective to that target gas.

An Energy-Efficient Approach to Enhance Virtual Sensors Provisioning in Sensor Clouds Environments

PubMed Central

Filho, Raimir Holanda; Rabêlo, Ricardo de Andrade L.; de Carvalho, Carlos Giovanni N.; Mendes, Douglas Lopes de S.; Costa, Valney da Gama

2018-01-01

Virtual sensors provisioning is a central issue for sensors cloud middleware since it is responsible for selecting physical nodes, usually from Wireless Sensor Networks (WSN) of different owners, to handle user’s queries or applications. Recent works perform provisioning by clustering sensor nodes based on the correlation measurements and then selecting as few nodes as possible to preserve WSN energy. However, such works consider only homogeneous nodes (same set of sensors). Therefore, those works are not entirely appropriate for sensor clouds, which in most cases comprises heterogeneous sensor nodes. In this paper, we propose ACxSIMv2, an approach to enhance the provisioning task by considering heterogeneous environments. Two main algorithms form ACxSIMv2. The first one, ACASIMv1, creates multi-dimensional clusters of sensor nodes, taking into account the measurements correlations instead of the physical distance between nodes like most works on literature. Then, the second algorithm, ACOSIMv2, based on an Ant Colony Optimization system, selects an optimal set of sensors nodes from to respond user’s queries while attending all parameters and preserving the overall energy consumption. Results from initial experiments show that the approach reduces significantly the sensor cloud energy consumption compared to traditional works, providing a solution to be considered in sensor cloud scenarios. PMID:29495406

An Energy-Efficient Approach to Enhance Virtual Sensors Provisioning in Sensor Clouds Environments.

PubMed

Lemos, Marcus Vinícius de S; Filho, Raimir Holanda; Rabêlo, Ricardo de Andrade L; de Carvalho, Carlos Giovanni N; Mendes, Douglas Lopes de S; Costa, Valney da Gama

2018-02-26

Virtual sensors provisioning is a central issue for sensors cloud middleware since it is responsible for selecting physical nodes, usually from Wireless Sensor Networks (WSN) of different owners, to handle user's queries or applications. Recent works perform provisioning by clustering sensor nodes based on the correlation measurements and then selecting as few nodes as possible to preserve WSN energy. However, such works consider only homogeneous nodes (same set of sensors). Therefore, those works are not entirely appropriate for sensor clouds, which in most cases comprises heterogeneous sensor nodes. In this paper, we propose ACxSIMv2, an approach to enhance the provisioning task by considering heterogeneous environments. Two main algorithms form ACxSIMv2. The first one, ACASIMv1, creates multi-dimensional clusters of sensor nodes, taking into account the measurements correlations instead of the physical distance between nodes like most works on literature. Then, the second algorithm, ACOSIMv2, based on an Ant Colony Optimization system, selects an optimal set of sensors nodes from to respond user's queries while attending all parameters and preserving the overall energy consumption. Results from initial experiments show that the approach reduces significantly the sensor cloud energy consumption compared to traditional works, providing a solution to be considered in sensor cloud scenarios.

Assessing the quality of humidity measurements from global operational radiosonde sensors

NASA Astrophysics Data System (ADS)

Moradi, Isaac; Soden, Brian; Ferraro, Ralph; Arkin, Phillip; Vömel, Holger

2013-07-01

The quality of humidity measurements from global operational radiosonde sensors in upper, middle, and lower troposphere for the period 2000-2011 were investigated using satellite observations from three microwave water vapor channels operating at 183.31±1, 183.31±3, and 183.31±7 GHz. The radiosonde data were partitioned based on sensor type into 19 classes. The satellite brightness temperatures (Tb) were simulated using radiosonde profiles and a radiative transfer model, then the radiosonde simulated Tb's were compared with the observed Tb's from the satellites. The surface affected Tb's were excluded from the comparison due to the lack of reliable surface emissivity data at the microwave frequencies. Daytime and nighttime data were examined separately to see the possible effect of daytime radiation bias on the sonde data. The error characteristics among different radiosondes vary significantly, which largely reflects the differences in sensor type. These differences are more evident in the mid-upper troposphere than in the lower troposphere, mainly because some of the sensors stop responding to tropospheric humidity somewhere in the upper or even in the middle troposphere. In the upper troposphere, most sensors have a dry bias but Russian sensors and a few other sensors including GZZ2, VZB2, and RS80H have a wet bias. In middle troposphere, Russian sensors still have a wet bias but all other sensors have a dry bias. All sensors, including Russian sensors, have a dry bias in lower troposphere. The systematic and random errors generally decrease from upper to lower troposphere. Sensors from China, India, Russia, and the U.S. have a large random error in upper troposphere, which indicates that these sensors are not suitable for upper tropospheric studies as they fail to respond to humidity changes in the upper and even middle troposphere. Overall, Vaisala sensors perform better than other sensors throughout the troposphere exhibiting the smallest systematic and random errors. Because of the large differences between different radiosonde humidity sensors, it is important for long-term trend studies to only use data measured using a single type of sensor at any given station. If multiple sensor types are used then it is necessary to consider the bias between sensor types and its possible dependence on humidity and temperature.

Enhanced H2S Sensing Performance of a p-type Semiconducting PdO-NiO Nanoscale Heteromixture

NASA Astrophysics Data System (ADS)

Balamurugan, C.; Jeong, Y. J.; Lee, D. W.

2017-10-01

Semiconducting nanocrystalline nickel oxide (NiO) and PdO-doped NiO heteromixture (2, 5 and 10 wt%) have been synthesized via a metal-citrate complex method. The obtained materials were further characterized using TG/DTA, FT-IR, UV-vis, XRD, XPS, BET/BJH, SEM and TEM analyses to determine their structural and morphological properties. The results indicated that the spherical, uniform PdO nanoparticles were densely deposited on the NiO surface mainly in diameters of 10-15 nm. Moreover, the existence of various defect states was also analyzed with the help of photoluminescence (PL) spectroscopy. The gas response characteristics of synthesized materials were evaluated in the presence and absence of toxic gases such as hydrogen sulfide (H2S), carbon monoxide (CO), liquid petroleum gas (LPG), and ethanol (C2H5OH). The experimental results revealed that the sensitivity and selectivity of the NiO-based sensor material are dependent on the weight% of PdO loading in the NiO nanopowder. Among the investigated compound, the 5 wt% PdO-doped NiO sensor material showed excellent sensitivity and selectivity to 100 ppm H2S with a fast response/recovery characteristics of 6 s and 10 s, respectively. Furthermore, the 5 wt% PdO-doped NiO based sensor showed a linear relationship between the different concentrations of H2S gas and a significantly higher response to H2S even at the low concentration of 20 ppm (43%) at 60 °C. The dominant H2S gas sensing mechanisms in the NiO and 5 wt% PdO-doped NiO nanomaterials are systematically discussed based on the obtained characterization results.

Selective chloroform sensor using thiol functionalized reduced graphene oxide at room temperature

NASA Astrophysics Data System (ADS)

Midya, Anupam; Mukherjee, Subhrajit; Roy, Shreyasee; Santra, Sumita; Manna, Nilotpal; Ray, Samit K.

2018-02-01

This paper presents a highly selective chloroform sensor using functionalised reduced graphene oxide (RGO) as a sensing layer. Thiol group is covalently attached on the basal plan of RGO film by a simple one-step aryl diazonium chemistry to improve its selectivity. Several spectroscopic techniques like X-ray photoelectron, Raman and Fourier transform infrared spectroscopy confirm successful thiol functionalization of RGO. Finally, the fabricated chemiresistor type sensor is exposed to chloroform in the concentration range 200-800 ppm (parts per million). The sensor shows a 4.3% of response towards 800 ppm chloroform. The selectivity of the sensor is analyzed using various volatile organic compounds as well. The devices show enhanced response and faster recovery attributed to the physiosorption of chloroform onto thiol functionalized graphene making them attractive for 2D materials based sensing applications.

Bundle Block Adjustment of Airborne Three-Line Array Imagery Based on Rotation Angles

PubMed Central

Zhang, Yongjun; Zheng, Maoteng; Huang, Xu; Xiong, Jinxin

2014-01-01

In the midst of the rapid developments in electronic instruments and remote sensing technologies, airborne three-line array sensors and their applications are being widely promoted and plentiful research related to data processing and high precision geo-referencing technologies is under way. The exterior orientation parameters (EOPs), which are measured by the integrated positioning and orientation system (POS) of airborne three-line sensors, however, have inevitable systematic errors, so the level of precision of direct geo-referencing is not sufficiently accurate for surveying and mapping applications. Consequently, a few ground control points are necessary to refine the exterior orientation parameters, and this paper will discuss bundle block adjustment models based on the systematic error compensation and the orientation image, considering the principle of an image sensor and the characteristics of the integrated POS. Unlike the models available in the literature, which mainly use a quaternion to represent the rotation matrix of exterior orientation, three rotation angles are directly used in order to effectively model and eliminate the systematic errors of the POS observations. Very good experimental results have been achieved with several real datasets that verify the correctness and effectiveness of the proposed adjustment models. PMID:24811075

Bundle block adjustment of airborne three-line array imagery based on rotation angles.

PubMed

Zhang, Yongjun; Zheng, Maoteng; Huang, Xu; Xiong, Jinxin

2014-05-07

In the midst of the rapid developments in electronic instruments and remote sensing technologies, airborne three-line array sensors and their applications are being widely promoted and plentiful research related to data processing and high precision geo-referencing technologies is under way. The exterior orientation parameters (EOPs), which are measured by the integrated positioning and orientation system (POS) of airborne three-line sensors, however, have inevitable systematic errors, so the level of precision of direct geo-referencing is not sufficiently accurate for surveying and mapping applications. Consequently, a few ground control points are necessary to refine the exterior orientation parameters, and this paper will discuss bundle block adjustment models based on the systematic error compensation and the orientation image, considering the principle of an image sensor and the characteristics of the integrated POS. Unlike the models available in the literature, which mainly use a quaternion to represent the rotation matrix of exterior orientation, three rotation angles are directly used in order to effectively model and eliminate the systematic errors of the POS observations. Very good experimental results have been achieved with several real datasets that verify the correctness and effectiveness of the proposed adjustment models.

Optoelectronic Capillary Sensors in Microfluidic and Point-of-Care Instrumentation

PubMed Central

Borecki, Michał; Korwin-Pawlowski, Michael L.; Beblowska, Maria; Szmidt, Jan; Jakubowski, Andrzej

2010-01-01

This paper presents a review, based on the published literature and on the authors’ own research, of the current state of the art of fiber-optic capillary sensors and related instrumentation as well as their applications, with special emphasis on point-of-care chemical and biochemical sensors, systematizing the various types of sensors from the point of view of the principles of their construction and operation. Unlike classical fiber-optic sensors which rely on changes in light propagation inside the fiber as affected by outside conditions, optical capillary sensors rely on changes of light transmission in capillaries filled with the analyzed liquid, which opens the possibility of interesting new applications, while raising specific issues relating to the construction, materials and instrumentation of those sensors. PMID:22319325

Retrieving accurate temporal and spatial information about Taylor slug flows from non-invasive NIR photometry measurements

NASA Astrophysics Data System (ADS)

Helmers, Thorben; Thöming, Jorg; Mießner, Ulrich

2017-11-01

In this article, we introduce a novel approach to retrieve spatial- and time-resolved Taylor slug flow information from a single non-invasive photometric flow sensor. The presented approach uses disperse phase surface properties to retrieve the instantaneous velocity information from a single sensor's time-scaled signal. For this purpose, a photometric sensor system is simulated using a ray-tracing algorithm to calculate spatially resolved near-infrared transmission signals. At the signal position corresponding to the rear droplet cap, a correlation factor of the droplet's geometric properties is retrieved and used to extract the instantaneous droplet velocity from the real sensor's temporal transmission signal. Furthermore, a correlation for the rear cap geometry based on the a priori known total superficial flow velocity is developed, because the cap curvature is velocity sensitive itself. Our model for velocity derivation is validated, and measurements of a first prototype showcase the capability of the device. Long-term measurements visualize systematic fluctuations in droplet lengths, velocities, and frequencies that could otherwise, without the observation on a larger timescale, have been identified as measurement errors and not systematic phenomenas.

Application of Ionic Liquids in Amperometric Gas Sensors.

PubMed

Gębicki, Jacek; Kloskowski, Adam; Chrzanowski, Wojciech; Stepnowski, Piotr; Namiesnik, Jacek

2016-01-01

This article presents an analysis of available literature data on metrological parameters of the amperometric gas sensors containing ionic liquids as an electrolyte. Four mechanism types of signal generation in amperometric sensors with ionic liquid are described. Moreover, this article describes the influence of selected physico-chemical properties of the ionic liquids on the metrological parameters of these sensors. Some metrological parameters are also compared for amperometric sensors with GDE and SPE electrodes and with ionic liquids for selected analytes.

UV-Assisted Alcohol Sensors using Gallium Nitride Nanowires Functionalized with Zinc Oxide and Tin Dioxide Nanoparticles

NASA Astrophysics Data System (ADS)

Bajpai, Ritu

The motivation behind this work has been to address two of the most challenging issues posed to semiconductor gas sensors--- tuning the device selectivity and sensitivity to a wide variety of gases. In a chemiresistor type nanowire sensor, the sensitivity and selectivity depend on the interaction of different chemical analytes with the nanowire surface. Constrained by the surface properties of the nanowire material, most nanowire sensors can detect only specific type of analytes. In order to make a nano-sensor array for a wide range of analytes, there is a need to tune the device sensitivity and selectivity towards different chemicals. Employing the inherent advantages of nanostructure based sensing such as large surface area, miniature size, low power consumption, and nmol/mol (ppb) sensitivity, an attempt has been made to propose a device with tunable selectivity and sensitivity. The idea proposed in this work is to functionalize GaN nanowires which have relatively inactive surface properties (i.e., with no chemiresistive sensitivity to different classes of organic vapors), with analyte dependent active metal oxides. The selectivity of the sensor devices is controlled independent of the surface properties of the nanowire itself. It is the surface properties of the functionalizing metal oxides which determine the selectivity of these sensors. Further facilitated by the proposed fabrication technique, these sensors can be easily tuned to detect different gases. The prototype developed in this work is that of a UV assisted alcohol sensor using GaN nanowires functionalized with ZnO and SnO2 nanoparticles. As opposed to the widely demonstrated metal oxide based sensors assisted by elevated temperature, the operation of photoconductive semiconductor sensor devices such as those fabricated in this work, can also be assisted by UV illumination at room temperature. Temperature assisted sensing requires an integrated on-chip heater, which could impose constraints on the device fabrication process conditions. Additionally, light assisted sensing can be employed to tailor device response towards an analyte as demonstrated in this work. Therefore, there are two control knobs available for these sensor devices which are independent of the nanowire surface properties: i) sensor selectivity, regulated by the nanoparticle material selection ii) percentage response, tuned by the intensity of the incident light. Due to the small magnitude of device operating current and sensor activation at low illumination intensity (375 nW/cm2 at 365 nm wavelength has been used in this work), these sensors have low power consumption which makes them suitable for portable battery assisted operation. A fabrication recipe for freely suspended two-terminal nanowire devices has been developed. The deposition of nanoparticles was performed using the sputter deposition technique. A change in device current was observed when the device was exposed to alcohol vapors (methanol, ethanol, propanol, and butanol) at room temperature under 215 nm--400 nm UV illumination at 365 nm wavelength. The sensor reproducibly responded to a wide range of alcohol vapor concentrations, from 5000 mumol/mol (ppm) down to 200 nmol/mol (ppb) in air. Notably, the devices show low sensitivity to acetone and hexane, which allows them to selectively detect the alcohol vapors mixed with these two common volatile organic compounds (VOCs). The sensor response was not observed without UV excitation. To make a simplified quantitative and qualitative study of the sensitivity variation with variation of light intensity, the behavior of ZnO nanowire sensor devices was investigated in addition to the hybrid metal-oxide nanoparticle/GaN nanowire devices. With an increase in the light intensity, a corresponding increase in the device sensitivity was observed. In addition to the proposed sensor fabrication technique being a highly suitable candidate for making nano-sensor arrays for detection of a wide range of gases, the alcohol sensors fabricated in this work have many practical applications such as monitoring air quality, and testing the blood alcohol content (BAC) for impaired drivers.

Gating transitions in the selectivity filter region of a sodium channel are coupled to the domain IV voltage sensor.

PubMed

Capes, Deborah L; Arcisio-Miranda, Manoel; Jarecki, Brian W; French, Robert J; Chanda, Baron

2012-02-14

Voltage-dependent ion channels are crucial for generation and propagation of electrical activity in biological systems. The primary mechanism for voltage transduction in these proteins involves the movement of a voltage-sensing domain (D), which opens a gate located on the cytoplasmic side. A distinct conformational change in the selectivity filter near the extracellular side has been implicated in slow inactivation gating, which is important for spike frequency adaptation in neural circuits. However, it remains an open question whether gating transitions in the selectivity filter region are also actuated by voltage sensors. Here, we examine conformational coupling between each of the four voltage sensors and the outer pore of a eukaryotic voltage-dependent sodium channel. The voltage sensors of these sodium channels are not structurally symmetric and exhibit functional specialization. To track the conformational rearrangements of individual voltage-sensing domains, we recorded domain-specific gating pore currents. Our data show that, of the four voltage sensors, only the domain IV voltage sensor is coupled to the conformation of the selectivity filter region of the sodium channel. Trapping the outer pore in a particular conformation with a high-affinity toxin or disulphide crossbridge impedes the return of this voltage sensor to its resting conformation. Our findings directly establish that, in addition to the canonical electromechanical coupling between voltage sensor and inner pore gates of a sodium channel, gating transitions in the selectivity filter region are also coupled to the movement of a voltage sensor. Furthermore, our results also imply that the voltage sensor of domain IV is unique in this linkage and in the ability to initiate slow inactivation in sodium channels.

Head-Impact–Measurement Devices: A Systematic Review

PubMed Central

O'Connor, Kathryn L.; Rowson, Steven; Duma, Stefan M.; Broglio, Steven P.

2017-01-01

Context: With an estimated 3.8 million sport- and recreation-related concussions occurring annually, targeted prevention and diagnostic methods are needed. Biomechanical analysis of head impacts may provide quantitative information that can inform both prevention and diagnostic strategies. Objective: To assess available head-impact devices and their clinical utility. Data Sources: We performed a systematic search of the electronic database PubMed for peer-reviewed publications, using the following phrases: accelerometer and concussion, head impact telemetry, head impacts and concussion and sensor, head impacts and sensor, impact sensor and concussion, linear acceleration and concussion, rotational acceleration and concussion, and xpatch concussion. In addition to the literature review, a Google search for head impact monitor and concussion monitor yielded 15 more devices. Study Selection: Included studies were performed in vivo, used commercially available devices, and focused on sport-related concussion. Data Extraction: One author reviewed the title and abstract of each study for inclusion and exclusion criteria and then reviewed each full-text article to confirm inclusion criteria. Controversial articles were reviewed by all authors to reach consensus. Data Synthesis: In total, 61 peer-reviewed articles involving 4 head-impact devices were included. Participants in boxing, football, ice hockey, soccer, or snow sports ranged in age from 6 to 24 years; 18% (n = 11) of the studies included female athletes. The Head Impact Telemetry System was the most widely used device (n = 53). Fourteen additional commercially available devices were presented. Conclusions: Measurements collected by impact monitors provided real-time data to estimate player exposure but did not have the requisite sensitivity to concussion. Proper interpretation of previously reported head-impact kinematics across age, sport, and position may inform future research and enable staff clinicians working on the sidelines to monitor athletes. However, head-impact–monitoring systems have limited clinical utility due to error rates, designs, and low specificity in predicting concussive injury. PMID:28387553

Gold nanoparticle-sensitized quartz crystal microbalance sensor for rapid and highly selective determination of Cu(II) ions.

PubMed

Jin, Yulong; Huang, Yanyan; Liu, Guoquan; Zhao, Rui

2013-09-21

A novel quartz crystal microbalance (QCM) sensor for rapid, highly selective and sensitive detection of copper ions was developed. As a signal amplifier, gold nanoparticles (Au NPs) were self-assembled onto the surface of the sensor. A simple dip-and-dry method enabled the whole detection procedure to be accomplished within 20 min. High selectivity of the sensor towards copper ions is demonstrated by both individual and coexisting assays with interference ions. This gold nanoparticle mediated amplification allowed a detection limit down to 3.1 μM. Together with good repeatability and regeneration, the QCM sensor was also applied to the analysis of copper contamination in drinking water. This work provides a flexible method for fabricating QCM sensors for the analysis of important small molecules in environmental and biological samples.

Detecting agitation and aggression in people with dementia using sensors-A systematic review.

PubMed

Khan, Shehroz S; Ye, Bing; Taati, Babak; Mihailidis, Alex

2018-06-01

Agitation and aggression are among the most challenging symptoms of dementia. Agitated persons with dementia can harm themselves, their caregivers, or other patients in a care facility. Automatic detection of agitation would be useful to alert caregivers so that appropriate interventions can be performed. The building blocks in the automatic detection of agitation and aggression are appropriate sensing platforms and generalized predictive models. In this article, we perform a systematic review of studies that use different types of sensors to detect agitation and aggression in persons with dementia. We conclude that actigraphy shows some evidence of correlation with incidences of agitation and aggression; however, multimodal sensing has not been fully evaluated for this purpose. Based on this systematic review, we provide guidelines and recommendations for future research directions in this field. Copyright © 2018 the Alzheimer's Association. Published by Elsevier Inc. All rights reserved.

Systematic Biological Filter Design with a Desired I/O Filtering Response Based on Promoter-RBS Libraries.

PubMed

Hsu, Chih-Yuan; Pan, Zhen-Ming; Hu, Rei-Hsing; Chang, Chih-Chun; Cheng, Hsiao-Chun; Lin, Che; Chen, Bor-Sen

2015-01-01

In this study, robust biological filters with an external control to match a desired input/output (I/O) filtering response are engineered based on the well-characterized promoter-RBS libraries and a cascade gene circuit topology. In the field of synthetic biology, the biological filter system serves as a powerful detector or sensor to sense different molecular signals and produces a specific output response only if the concentration of the input molecular signal is higher or lower than a specified threshold. The proposed systematic design method of robust biological filters is summarized into three steps. Firstly, several well-characterized promoter-RBS libraries are established for biological filter design by identifying and collecting the quantitative and qualitative characteristics of their promoter-RBS components via nonlinear parameter estimation method. Then, the topology of synthetic biological filter is decomposed into three cascade gene regulatory modules, and an appropriate promoter-RBS library is selected for each module to achieve the desired I/O specification of a biological filter. Finally, based on the proposed systematic method, a robust externally tunable biological filter is engineered by searching the promoter-RBS component libraries and a control inducer concentration library to achieve the optimal reference match for the specified I/O filtering response.

DNA as Sensors and Imaging Agents for Metal Ions

PubMed Central

Xiang, Yu

2014-01-01

Increasing interests in detecting metal ions in many chemical and biomedical fields have created demands for developing sensors and imaging agents for metal ions with high sensitivity and selectivity. This review covers recent progress in DNA-based sensors and imaging agents for metal ions. Through both combinatorial selection and rational design, a number of metal ion-dependent DNAzymes and metal ion-binding DNA structures that can selectively recognize specific metal ions have been obtained. By attaching these DNA molecules with signal reporters such as fluorophores, chromophores, electrochemical tags, and Raman tags, a number of DNA-based sensors for both diamagnetic and paramagnetic metal ions have been developed for fluorescent, colorimetric, electrochemical, and surface Raman detections. These sensors are highly sensitive (with detection limit down to 11 ppt) and selective (with selectivity up to millions-fold) toward specific metal ions. In addition, through further development to simplify the operation, such as the use of “dipstick tests”, portable fluorometers, computer-readable discs, and widely available glucose meters, these sensors have been applied for on-site and real-time environmental monitoring and point-of-care medical diagnostics. The use of these sensors for in situ cellular imaging has also been reported. The generality of the combinatorial selection to obtain DNAzymes for almost any metal ion in any oxidation state, and the ease of modification of the DNA with different signal reporters make DNA an emerging and promising class of molecules for metal ion sensing and imaging in many fields of applications. PMID:24359450

A Gaussian Mixture Model-based continuous Boundary Detection for 3D sensor networks.

PubMed

Chen, Jiehui; Salim, Mariam B; Matsumoto, Mitsuji

2010-01-01

This paper proposes a high precision Gaussian Mixture Model-based novel Boundary Detection 3D (BD3D) scheme with reasonable implementation cost for 3D cases by selecting a minimum number of Boundary sensor Nodes (BNs) in continuous moving objects. It shows apparent advantages in that two classes of boundary and non-boundary sensor nodes can be efficiently classified using the model selection techniques for finite mixture models; furthermore, the set of sensor readings within each sensor node's spatial neighbors is formulated using a Gaussian Mixture Model; different from DECOMO [1] and COBOM [2], we also formatted a BN Array with an additional own sensor reading to benefit selecting Event BNs (EBNs) and non-EBNs from the observations of BNs. In particular, we propose a Thick Section Model (TSM) to solve the problem of transition between 2D and 3D. It is verified by simulations that the BD3D 2D model outperforms DECOMO and COBOM in terms of average residual energy and the number of BNs selected, while the BD3D 3D model demonstrates sound performance even for sensor networks with low densities especially when the value of the sensor transmission range (r) is larger than the value of Section Thickness (d) in TSM. We have also rigorously proved its correctness for continuous geometric domains and full robustness for sensor networks over 3D terrains.

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

NASA Astrophysics Data System (ADS)

Hauptmann, Peter R.

2006-03-01

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

Amperometric Glucose Sensors: Sources of Error and Potential Benefit of Redundancy

PubMed Central

Castle, Jessica R.; Kenneth Ward, W.

2010-01-01

Amperometric glucose sensors have advanced the care of patients with diabetes and are being studied to control insulin delivery in the research setting. However, at times, currently available sensors demonstrate suboptimal accuracy, which can result from calibration error, sensor drift, or lag. Inaccuracy can be particularly problematic in a closed-loop glycemic control system. In such a system, the use of two sensors allows selection of the more accurate sensor as the input to the controller. In our studies in subjects with type 1 diabetes, the accuracy of the better of two sensors significantly exceeded the accuracy of a single, randomly selected sensor. If an array with three or more sensors were available, it would likely allow even better accuracy with the use of voting. PMID:20167187

Support requirements for remote sensor systems on unmanned planetary missions, phase 3

NASA Technical Reports Server (NTRS)

1971-01-01

The results of a study to determine the support requirements for remote sensor systems on unmanned planetary flyby and orbiter missions are presented. Sensors and experiment groupings for selected missions are also established. Computer programs were developed to relate measurement requirements to support requirements. Support requirements were determined for sensors capable of performing required measurements at various points along the trajectories of specific selected missions.

Vibration modes interference in the MEMS resonant pressure sensor

NASA Astrophysics Data System (ADS)

Zhang, Fangfang; Li, Anlin; Bu, Zhenxiang; Wang, Lingyun; Sun, Daoheng; Du, Xiaohui; Gu, Dandan

2017-11-01

A new type of coupled balanced-mass double-ended tuning fork resonator (CBDETF) pressure sensor is fabricated and tested. However, the low accuracy of the CBDETF pressure sensor is not satisfied to us. Based on systematic analysis and tests, the coupling effect between the operational mode and interference mode is considered to be the main cause for the sensor in accuracy. To solve this problem, the stiffness of the serpentine beams is increased to pull up the resonant frequency of the interfering mode and make it separate far from the operational mode. Finally, the accuracy of the CBDETF pressure sensor is improved from + /-0.5% to less than + /-0.03% of the Full Scale (F.S.).

Synthesis and Characterization of CuO Nanodisks for High-Sensitive and Selective Ethanol Gas Sensor Applications.

PubMed

Umar, Ahmad; Lee, Jong-Heun; Kumar, Rajesh; Al-Dossary, O

2017-02-01

Herein, the fabrication and characterization of highly sensitive and selective ethanol gas sensor based on CuO nanodisks is reported. The CuO nanodisks were synthesized by facile hydrothermal process and detailed characterization revealed the well-crystallinity, high-purity and high density growth of the prepared material. To fabricate the ethanol gas sensor, the prepared nanodisks were coated on alumina substrate. The fabricated sensor exhibited high-sensitivity and the recorded gas response (resistance-ratio), response time (τ res) and recovery time (τ recov) were 6.2, 119 and 35 s, respectively for 100 ppm of C₂H₅OH at 300 °C. Further, the fabricated sensor shows high selectivity towards ethanol gas compared to H₂ and CO gases.

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

PubMed

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

2014-12-24

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

Cytosolic nucleic acid sensors and innate immune regulation.

PubMed

Ori, Daisuke; Murase, Motoya; Kawai, Taro

2017-03-04

During viral and bacterial infections, pathogen-derived cytosolic nucleic acids are recognized by the intracellular RNA sensors retinoic acid-inducible gene I and melanoma-differentiated gene 5 and intracellular DNA sensors, including cyclic-di-GMP-AMP synthase, absent in melanoma 2, interferon (IFN)-gamma inducible protein 16, polymerase III, and so on. Binding of intracellular nucleic acids to these sensors activates downstream signaling cascades, resulting in the production of type I IFNs and pro-inflammatory cytokines to induce appropriate systematic immune responses. While these sensors also recognize endogenous nucleic acids and activate immune responses, they can discriminate between self- and non-self-nucleic acids. However, dysfunction of these sensors or failure of regulatory mechanisms causes aberrant activation of immune response and autoimmune disorders. In this review, we focus on how intracellular immune sensors recognize exogenous nucleic acids and activate the innate immune system, and furthermore, how autoimmune diseases result from dysfunction of these sensors.

Material characteristics and equivalent circuit models of stacked graphene oxide for capacitive humidity sensors

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

Han, Kook In; Lee, In Gyu; Hwang, Wan Sik, E-mail: mhshin@kau.ac.kr, E-mail: whwang@kau.ac.kr

The oxidation properties of graphene oxide (GO) are systematically correlated with their chemical sensing properties. Based on an impedance analysis, the equivalent circuit models of the capacitive sensors are established, and it is demonstrated that capacitive operations are related to the degree of oxidation. This is also confirmed by X-ray diffraction and Raman analysis. Finally, highly sensitive stacked GO sensors are shown to detect humidity in capacitive mode, which can be useful in various applications requiring low power consumption.

Novel sensing technology in fall risk assessment in older adults: a systematic review.

PubMed

Sun, Ruopeng; Sosnoff, Jacob J

2018-01-16

Falls are a major health problem for older adults with significant physical and psychological consequences. A first step of successful fall prevention is to identify those at risk of falling. Recent advancement in sensing technology offers the possibility of objective, low-cost and easy-to-implement fall risk assessment. The objective of this systematic review is to assess the current state of sensing technology on providing objective fall risk assessment in older adults. A systematic review was conducted in accordance to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement (PRISMA). Twenty-two studies out of 855 articles were systematically identified and included in this review. Pertinent methodological features (sensing technique, assessment activities, outcome variables, and fall discrimination/prediction models) were extracted from each article. Four major sensing technologies (inertial sensors, video/depth camera, pressure sensing platform and laser sensing) were reported to provide accurate fall risk diagnostic in older adults. Steady state walking, static/dynamic balance, and functional mobility were used as the assessment activity. A diverse range of diagnostic accuracy across studies (47.9% - 100%) were reported, due to variation in measured kinematic/kinetic parameters and modelling techniques. A wide range of sensor technologies have been utilized in fall risk assessment in older adults. Overall, these devices have the potential to provide an accurate, inexpensive, and easy-to-implement fall risk assessment. However, the variation in measured parameters, assessment tools, sensor sites, movement tasks, and modelling techniques, precludes a firm conclusion on their ability to predict future falls. Future work is needed to determine a clinical meaningful and easy to interpret fall risk diagnosis utilizing sensing technology. Additionally, the gap between functional evaluation and user experience to technology should be addressed.

Comparison of measurement methods for capacitive tactile sensors and their implementation

NASA Astrophysics Data System (ADS)

Tarapata, Grzegorz; Sienkiewicz, Rafał

2015-09-01

This paper presents a review of ideas and implementations of measurement methods utilized for capacity measurements in tactile sensors. The paper describes technical method, charge amplification method, generation and as well integration method. Three selected methods were implemented in dedicated measurement system and utilised for capacitance measurements of ourselves made tactile sensors. The tactile sensors tested in this work were fully fabricated with the inkjet printing technology. The tests result were presented and summarised. The charge amplification method (CDC) was selected as the best method for the measurement of the tactile sensors.

Open-Filter Optical SSA Analysis Considerations

NASA Astrophysics Data System (ADS)

Lambert, J.

2016-09-01

Optical Space Situational Awareness (SSA) sensors used for space object detection and orbit refinement measurements are typically operated in an "open-filter" mode without any spectral filters to maximize sensitivity and signal-to-noise. These same optical brightness measurements are often also employed for size determination (e.g., for orbital debris), object correlation, and object status change. These functions, especially when performed using multiple sensors, are highly dependent on sensor calibration for measurement accuracy. Open-filter SSA sensors are traditionally calibrated against the cataloged visual magnitudes of solar-type stars which have similar spectral distributions as the illuminating source, the Sun. The stellar calibration is performed to a high level of accuracy, a few hundredths of a magnitude, by observing many stars over a range of elevation angles to determine sensor, telescope, and atmospheric effects. However, space objects have individual color properties which alter the reflected solar illumination producing spectral distributions which differ from those of the calibration stars. When the stellar calibrations are applied to the space object measurements, visual magnitude values are obtained which are systematically biased. These magnitudes combined with the unknown Bond albedos of the space objects result in systematically biased size determinations which will differ between sensors. Measurements of satellites of known sizes and surface materials have been analyzed to characterize these effects. The results have combined into standardized Bond albedos to correct the measured magnitudes into object sizes. However, the actual albedo values will vary between objects and represent a mean correction subject to some uncertainty. The objective of this discussion is to characterize the sensor spectral biases that are present in open-filter optical observations and examine the resulting brightness and albedo uncertainties that should accompany object size, correlation, or status change determinations, especially in the SSA analyses of individual space objects using data from multiple sensors.

Applications of artificial intelligence to space station: General purpose intelligent sensor interface

NASA Technical Reports Server (NTRS)

Mckee, James W.

1988-01-01

This final report describes the accomplishments of the General Purpose Intelligent Sensor Interface task of the Applications of Artificial Intelligence to Space Station grant for the period from October 1, 1987 through September 30, 1988. Portions of the First Biannual Report not revised will not be included but only referenced. The goal is to develop an intelligent sensor system that will simplify the design and development of expert systems using sensors of the physical phenomena as a source of data. This research will concentrate on the integration of image processing sensors and voice processing sensors with a computer designed for expert system development. The result of this research will be the design and documentation of a system in which the user will not need to be an expert in such areas as image processing algorithms, local area networks, image processor hardware selection or interfacing, television camera selection, voice recognition hardware selection, or analog signal processing. The user will be able to access data from video or voice sensors through standard LISP statements without any need to know about the sensor hardware or software.

Selective detection of vapor phase hydrogen peroxide with phthalocyanine chemiresistors.

PubMed

Bohrer, Forest I; Colesniuc, Corneliu N; Park, Jeongwon; Schuller, Ivan K; Kummel, Andrew C; Trogler, William C

2008-03-26

The use of hydrogen peroxide as a precursor to improvised explosives has made its detection a topic of critical importance. Chemiresistor arrays comprised of 50 nm thick films of metallophthalocyanines (MPcs) are redox selective vapor sensors of hydrogen peroxide. Hydrogen peroxide is shown to decrease currents in cobalt phthalocyanine sensors while it increases currents in nickel, copper, and metal-free phthalocyanine sensors; oxidation and reduction of hydrogen peroxide via catalysis at the phthalocyanine surface are consistent with the pattern of sensor responses. This represents the first example of MPc vapor sensors being oxidized and reduced by the same analyte by varying the metal center. Consequently, differential analysis by redox contrast with catalytic amplification using a small array of sensors may be used to uniquely identify peroxide vapors. Metallophthalocyanine chemiresistors represent an improvement over existing peroxide vapor detection technologies in durability and selectivity in a greatly decreased package size.

MIS-based sensors with hydrogen selectivity

DOEpatents

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

2008-03-11

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

Highly selective gas sensor arrays based on thermally reduced graphene oxide.

PubMed

Lipatov, Alexey; Varezhnikov, Alexey; Wilson, Peter; Sysoev, Victor; Kolmakov, Andrei; Sinitskii, Alexander

2013-06-21

The electrical properties of reduced graphene oxide (rGO) have been previously shown to be very sensitive to surface adsorbates, thus making rGO a very promising platform for highly sensitive gas sensors. However, poor selectivity of rGO-based gas sensors remains a major problem for their practical use. In this paper, we address the selectivity problem by employing an array of rGO-based integrated sensors instead of focusing on the performance of a single sensing element. Each rGO-based device in such an array has a unique sensor response due to the irregular structure of rGO films at different levels of organization, ranging from nanoscale to macroscale. The resulting rGO-based gas sensing system could reliably recognize analytes of nearly the same chemical nature. In our experiments rGO-based sensor arrays demonstrated a high selectivity that was sufficient to discriminate between different alcohols, such as methanol, ethanol and isopropanol, at a 100% success rate. We also discuss a possible sensing mechanism that provides the basis for analyte differentiation.

Soil pH Mapping with an On-The-Go Sensor

PubMed Central

Schirrmann, Michael; Gebbers, Robin; Kramer, Eckart; Seidel, Jan

2011-01-01

Soil pH is a key parameter for crop productivity, therefore, its spatial variation should be adequately addressed to improve precision management decisions. Recently, the Veris pH Manager™, a sensor for high-resolution mapping of soil pH at the field scale, has been made commercially available in the US. While driving over the field, soil pH is measured on-the-go directly within the soil by ion selective antimony electrodes. The aim of this study was to evaluate the Veris pH Manager™ under farming conditions in Germany. Sensor readings were compared with data obtained by standard protocols of soil pH assessment. Experiments took place under different scenarios: (a) controlled tests in the lab, (b) semicontrolled test on transects in a stop-and-go mode, and (c) tests under practical conditions in the field with the sensor working in its typical on-the-go mode. Accuracy issues, problems, options, and potential benefits of the Veris pH Manager™ were addressed. The tests demonstrated a high degree of linearity between standard laboratory values and sensor readings. Under practical conditions in the field (scenario c), the measure of fit (r2) for the regression between the on-the-go measurements and the reference data was 0.71, 0.63, and 0.84, respectively. Field-specific calibration was necessary to reduce systematic errors. Accuracy of the on-the-go maps was considerably higher compared with the pH maps obtained by following the standard protocols, and the error in calculating lime requirements was reduced by about one half. However, the system showed some weaknesses due to blockage by residual straw and weed roots. If these problems were solved, the on-the-go sensor investigated here could be an efficient alternative to standard sampling protocols as a basis for liming in Germany. PMID:22346591

Soil pH mapping with an on-the-go sensor.

PubMed

Schirrmann, Michael; Gebbers, Robin; Kramer, Eckart; Seidel, Jan

2011-01-01

Soil pH is a key parameter for crop productivity, therefore, its spatial variation should be adequately addressed to improve precision management decisions. Recently, the Veris pH Manager™, a sensor for high-resolution mapping of soil pH at the field scale, has been made commercially available in the US. While driving over the field, soil pH is measured on-the-go directly within the soil by ion selective antimony electrodes. The aim of this study was to evaluate the Veris pH Manager™ under farming conditions in Germany. Sensor readings were compared with data obtained by standard protocols of soil pH assessment. Experiments took place under different scenarios: (a) controlled tests in the lab, (b) semicontrolled test on transects in a stop-and-go mode, and (c) tests under practical conditions in the field with the sensor working in its typical on-the-go mode. Accuracy issues, problems, options, and potential benefits of the Veris pH Manager™ were addressed. The tests demonstrated a high degree of linearity between standard laboratory values and sensor readings. Under practical conditions in the field (scenario c), the measure of fit (r(2)) for the regression between the on-the-go measurements and the reference data was 0.71, 0.63, and 0.84, respectively. Field-specific calibration was necessary to reduce systematic errors. Accuracy of the on-the-go maps was considerably higher compared with the pH maps obtained by following the standard protocols, and the error in calculating lime requirements was reduced by about one half. However, the system showed some weaknesses due to blockage by residual straw and weed roots. If these problems were solved, the on-the-go sensor investigated here could be an efficient alternative to standard sampling protocols as a basis for liming in Germany.

RadMAP: The Radiological Multi-sensor Analysis Platform

NASA Astrophysics Data System (ADS)

Bandstra, Mark S.; Aucott, Timothy J.; Brubaker, Erik; Chivers, Daniel H.; Cooper, Reynold J.; Curtis, Joseph C.; Davis, John R.; Joshi, Tenzing H.; Kua, John; Meyer, Ross; Negut, Victor; Quinlan, Michael; Quiter, Brian J.; Srinivasan, Shreyas; Zakhor, Avideh; Zhang, Richard; Vetter, Kai

2016-12-01

The variability of gamma-ray and neutron background during the operation of a mobile detector system greatly limits the ability of the system to detect weak radiological and nuclear threats. The natural radiation background measured by a mobile detector system is the result of many factors, including the radioactivity of nearby materials, the geometric configuration of those materials and the system, the presence of absorbing materials, and atmospheric conditions. Background variations tend to be highly non-Poissonian, making it difficult to set robust detection thresholds using knowledge of the mean background rate alone. The Radiological Multi-sensor Analysis Platform (RadMAP) system is designed to allow the systematic study of natural radiological background variations and to serve as a development platform for emerging concepts in mobile radiation detection and imaging. To do this, RadMAP has been used to acquire extensive, systematic background measurements and correlated contextual data that can be used to test algorithms and detector modalities at low false alarm rates. By combining gamma-ray and neutron detector systems with data from contextual sensors, the system enables the fusion of data from multiple sensors into novel data products. The data are curated in a common format that allows for rapid querying across all sensors, creating detailed multi-sensor datasets that are used to study correlations between radiological and contextual data, and develop and test novel techniques in mobile detection and imaging. In this paper we will describe the instruments that comprise the RadMAP system, the effort to curate and provide access to multi-sensor data, and some initial results on the fusion of contextual and radiological data.

A Novel Sensor Selection and Power Allocation Algorithm for Multiple-Target Tracking in an LPI Radar Network

PubMed Central

She, Ji; Wang, Fei; Zhou, Jianjiang

2016-01-01

Radar networks are proven to have numerous advantages over traditional monostatic and bistatic radar. With recent developments, radar networks have become an attractive platform due to their low probability of intercept (LPI) performance for target tracking. In this paper, a joint sensor selection and power allocation algorithm for multiple-target tracking in a radar network based on LPI is proposed. It is found that this algorithm can minimize the total transmitted power of a radar network on the basis of a predetermined mutual information (MI) threshold between the target impulse response and the reflected signal. The MI is required by the radar network system to estimate target parameters, and it can be calculated predictively with the estimation of target state. The optimization problem of sensor selection and power allocation, which contains two variables, is non-convex and it can be solved by separating power allocation problem from sensor selection problem. To be specific, the optimization problem of power allocation can be solved by using the bisection method for each sensor selection scheme. Also, the optimization problem of sensor selection can be solved by a lower complexity algorithm based on the allocated powers. According to the simulation results, it can be found that the proposed algorithm can effectively reduce the total transmitted power of a radar network, which can be conducive to improving LPI performance. PMID:28009819

Sensing abilities of functionalized calix[4]arene coated QCM sensors towards volatile organic compounds in aqueous media

NASA Astrophysics Data System (ADS)

Temel, Farabi; Ozcelik, Egemen; Ture, Ayse Gul; Tabakci, Mustafa

2017-08-01

This study presents the sensing studies of QCM sensors which coated with calix[4]arene derivatives bearing different functional groups towards some selected Volatile Organic Compounds (VOCs). Initial experiments revealed that QCM sensor coated with calix-3 bearing bromopropyl functionalities was relatively more effective sensor for methylene chloride (MC) emissions than the other calix[4]arene coated QCM sensors, in aqueous media. In further experiments, this effective calix-3 coated QCM sensor were used in detailed sensing studies of selected VOCs. However, the results demonstrated that calix-3 coated QCM sensor was most useful sensor for toluene (TOL) emissions among all. Moreover, the sensing of TOLs with calix-3 coated QCM sensor was also evaluated in terms of sorption phenomena. Consequently, calix-3 coated QCM sensor was good sensor for TOL emissions, and thus it demonstrated that the coating of QCM sensor surface with calixarenes was good approach for sensing of the VOCs.

Selectivity Enhancement by Using Double-Layer MOX-Based Gas Sensors Prepared by Flame Spray Pyrolysis (FSP).

PubMed

Rebholz, Julia; Grossmann, Katharina; Pham, David; Pokhrel, Suman; Mädler, Lutz; Weimar, Udo; Barsan, Nicolae

2016-09-06

Here we present a novel concept for the selective recognition of different target gases with a multilayer semiconducting metal oxide (SMOX)-based sensor device. Direct current (DC) electrical resistance measurements were performed during exposure to CO and ethanol as single gases and mixtures of highly porous metal oxide double- and single-layer sensors obtained by flame spray pyrolysis. The results show that the calculated resistance ratios of the single- and double-layer sensors are a good indicator for the presence of specific gases in the atmosphere, and can constitute some building blocks for the development of chemical logic devices. Due to the inherent lack of selectivity of SMOX-based gas sensors, such devices could be especially relevant for domestic applications.

Selectivity Enhancement by Using Double-Layer MOX-Based Gas Sensors Prepared by Flame Spray Pyrolysis (FSP)

PubMed Central

Rebholz, Julia; Grossmann, Katharina; Pham, David; Pokhrel, Suman; Mädler, Lutz; Weimar, Udo; Barsan, Nicolae

2016-01-01

Here we present a novel concept for the selective recognition of different target gases with a multilayer semiconducting metal oxide (SMOX)-based sensor device. Direct current (DC) electrical resistance measurements were performed during exposure to CO and ethanol as single gases and mixtures of highly porous metal oxide double- and single-layer sensors obtained by flame spray pyrolysis. The results show that the calculated resistance ratios of the single- and double-layer sensors are a good indicator for the presence of specific gases in the atmosphere, and can constitute some building blocks for the development of chemical logic devices. Due to the inherent lack of selectivity of SMOX-based gas sensors, such devices could be especially relevant for domestic applications. PMID:27608028

Evaluation of light detector surface area for functional Near Infrared Spectroscopy.

PubMed

Wang, Lei; Ayaz, Hasan; Izzetoglu, Meltem; Onaral, Banu

2017-10-01

Functional Near Infrared Spectroscopy (fNIRS) is an emerging neuroimaging technique that utilizes near infrared light to detect cortical concentration changes of oxy-hemoglobin and deoxy-hemoglobin non-invasively. Using light sources and detectors over the scalp, multi-wavelength light intensities are recorded as time series and converted to concentration changes of hemoglobin via modified Beer-Lambert law. Here, we describe a potential source for systematic error in the calculation of hemoglobin changes and light intensity measurements. Previous system characterization and analysis studies looked into various fNIRS parameters such as type of light source, number and selection of wavelengths, distance between light source and detector. In this study, we have analyzed the contribution of light detector surface area to the overall outcome. Results from Monte Carlo based digital phantoms indicated that selection of detector area is a critical system parameter in minimizing the error in concentration calculations. The findings here can guide the design of future fNIRS sensors. Copyright © 2017 Elsevier Ltd. All rights reserved.

Using Bayesian Inference Framework towards Identifying Gas Species and Concentration from High Temperature Resistive Sensor Array Data

DOE PAGES

Liu, Yixin; Zhou, Kai; Lei, Yu

2015-01-01

High temperature gas sensors have been highly demanded for combustion process optimization and toxic emissions control, which usually suffer from poor selectivity. In order to solve this selectivity issue and identify unknown reducing gas species (CO, CH 4 , and CH 8 ) and concentrations, a high temperature resistive sensor array data set was built in this study based on 5 reported sensors. As each sensor showed specific responses towards different types of reducing gas with certain concentrations, based on which calibration curves were fitted, providing benchmark sensor array response database, then Bayesian inference framework was utilized to process themore » sensor array data and build a sample selection program to simultaneously identify gas species and concentration, by formulating proper likelihood between input measured sensor array response pattern of an unknown gas and each sampled sensor array response pattern in benchmark database. This algorithm shows good robustness which can accurately identify gas species and predict gas concentration with a small error of less than 10% based on limited amount of experiment data. These features indicate that Bayesian probabilistic approach is a simple and efficient way to process sensor array data, which can significantly reduce the required computational overhead and training data.« less

A novel strategy for selection of allosteric ribozymes yields RiboReporter™ sensors for caffeine and aspartame

PubMed Central

Ferguson, Alicia; Boomer, Ryan M.; Kurz, Markus; Keene, Sara C.; Diener, John L.; Keefe, Anthony D.; Wilson, Charles; Cload, Sharon T.

2004-01-01

We have utilized in vitro selection technology to develop allosteric ribozyme sensors that are specific for the small molecule analytes caffeine or aspartame. Caffeine- or aspartame-responsive ribozymes were converted into fluorescence-based RiboReporter™ sensor systems that were able to detect caffeine or aspartame in solution over a concentration range from 0.5 to 5 mM. With read-times as short as 5 min, these caffeine- or aspartame-dependent ribozymes function as highly specific and facile molecular sensors. Interestingly, successful isolation of allosteric ribozymes for the analytes described here was enabled by a novel selection strategy that incorporated elements of both modular design and activity-based selection methods typically used for generation of catalytic nucleic acids. PMID:15026535

A selective optical sensor based on [9]mercuracarborand-3, a new type of ionophore with a chloride complexing cavity

NASA Technical Reports Server (NTRS)

Badr, I. H.; Johnson, R. D.; Diaz, M.; Hawthorne, M. F.; Bachas, L. G.; Daunert, S. (Principal Investigator)

2000-01-01

A highly selective optical sensor for chloride, based on the multidentate Lewis acid ionophore [9]mercuracarborand-3, is described herein. This sensor is constructed by embedding the mercuracarborand ionophore, a suitable pH-sensitive lipophilic dye, and lipophilic cationic sites in a plasticized polymeric membrane. The multiple complementary interactions offered by the preorganized complexing cavity of [9]mercuracarborand-3 is shown to control the anion selectivity pattern of the optical film. The film exhibits a significantly enhanced selectivity for chloride over a variety of lipophilic anions such as perchlorate, nitrate, salicylate, and thiocyanate. Furthermore, the optical selectivity coefficients obtained for chloride over other biologically relevant anions are shown to meet the selectivity requirements for the determination of chloride in physiological fluids, unlike previously reported chloride optical sensors. In addition, the optical film responds to chloride reversibly over a wide dynamic range (16 microM-136 mM) with fast response and recovery times.

Flexible Transparent Electronic Gas Sensors.

PubMed

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

2016-07-01

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

Comparison of Sensor Selection Mechanisms for an ERP-Based Brain-Computer Interface

PubMed Central

Metzen, Jan H.

2013-01-01

A major barrier for a broad applicability of brain-computer interfaces (BCIs) based on electroencephalography (EEG) is the large number of EEG sensor electrodes typically used. The necessity for this results from the fact that the relevant information for the BCI is often spread over the scalp in complex patterns that differ depending on subjects and application scenarios. Recently, a number of methods have been proposed to determine an individual optimal sensor selection. These methods have, however, rarely been compared against each other or against any type of baseline. In this paper, we review several selection approaches and propose one additional selection criterion based on the evaluation of the performance of a BCI system using a reduced set of sensors. We evaluate the methods in the context of a passive BCI system that is designed to detect a P300 event-related potential and compare the performance of the methods against randomly generated sensor constellations. For a realistic estimation of the reduced system's performance we transfer sensor constellations found on one experimental session to a different session for evaluation. We identified notable (and unanticipated) differences among the methods and could demonstrate that the best method in our setup is able to reduce the required number of sensors considerably. Though our application focuses on EEG data, all presented algorithms and evaluation schemes can be transferred to any binary classification task on sensor arrays. PMID:23844021

Multiple sensor fault diagnosis for dynamic processes.

PubMed

Li, Cheng-Chih; Jeng, Jyh-Cheng

2010-10-01

Modern industrial plants are usually large scaled and contain a great amount of sensors. Sensor fault diagnosis is crucial and necessary to process safety and optimal operation. This paper proposes a systematic approach to detect, isolate and identify multiple sensor faults for multivariate dynamic systems. The current work first defines deviation vectors for sensor observations, and further defines and derives the basic sensor fault matrix (BSFM), consisting of the normalized basic fault vectors, by several different methods. By projecting a process deviation vector to the space spanned by BSFM, this research uses a vector with the resulted weights on each direction for multiple sensor fault diagnosis. This study also proposes a novel monitoring index and derives corresponding sensor fault detectability. The study also utilizes that vector to isolate and identify multiple sensor faults, and discusses the isolatability and identifiability. Simulation examples and comparison with two conventional PCA-based contribution plots are presented to demonstrate the effectiveness of the proposed methodology. Copyright © 2010 ISA. Published by Elsevier Ltd. All rights reserved.

Plasmonic Fiber Optic Refractometric Sensors: From Conventional Architectures to Recent Design Trends

PubMed Central

Klantsataya, Elizaveta; Jia, Peipei; Ebendorff-Heidepriem, Heike; Monro, Tanya M.; François, Alexandre

2016-01-01

Surface Plasmon Resonance (SPR) fiber sensor research has grown since the first demonstration over 20 year ago into a rich and diverse field with a wide range of optical fiber architectures, plasmonic coatings, and excitation and interrogation methods. Yet, the large diversity of SPR fiber sensor designs has made it difficult to understand the advantages of each approach. Here, we review SPR fiber sensor architectures, covering the latest developments from optical fiber geometries to plasmonic coatings. By developing a systematic approach to fiber-based SPR designs, we identify and discuss future research opportunities based on a performance comparison of the different approaches for sensing applications. PMID:28025532

Defect-engineered graphene chemical sensors with ultrahigh sensitivity.

PubMed

Lee, Geonyeop; Yang, Gwangseok; Cho, Ara; Han, Jeong Woo; Kim, Jihyun

2016-05-25

We report defect-engineered graphene chemical sensors with ultrahigh sensitivity (e.g., 33% improvement in NO2 sensing and 614% improvement in NH3 sensing). A conventional reactive ion etching system was used to introduce the defects in a controlled manner. The sensitivity of graphene-based chemical sensors increased with increasing defect density until the vacancy-dominant region was reached. In addition, the mechanism of gas sensing was systematically investigated via experiments and density functional theory calculations, which indicated that the vacancy defect is a major contributing factor to the enhanced sensitivity. This study revealed that defect engineering in graphene has significant potential for fabricating ultra-sensitive graphene chemical sensors.

CPAC: Energy-Efficient Data Collection through Adaptive Selection of Compression Algorithms for Sensor Networks

PubMed Central

Lee, HyungJune; Kim, HyunSeok; Chang, Ik Joon

2014-01-01

We propose a technique to optimize the energy efficiency of data collection in sensor networks by exploiting a selective data compression. To achieve such an aim, we need to make optimal decisions regarding two aspects: (1) which sensor nodes should execute compression; and (2) which compression algorithm should be used by the selected sensor nodes. We formulate this problem into binary integer programs, which provide an energy-optimal solution under the given latency constraint. Our simulation results show that the optimization algorithm significantly reduces the overall network-wide energy consumption for data collection. In the environment having a stationary sink from stationary sensor nodes, the optimized data collection shows 47% energy savings compared to the state-of-the-art collection protocol (CTP). More importantly, we demonstrate that our optimized data collection provides the best performance in an intermittent network under high interference. In such networks, we found that the selective compression for frequent packet retransmissions saves up to 55% energy compared to the best known protocol. PMID:24721763

Ultraselective Toluene-Gas Sensor: Nanosized Gold Loaded on Zinc Oxide Nanoparticles.

PubMed

Suematsu, Koichi; Watanabe, Kosuke; Tou, Akihiro; Sun, Yongjiao; Shimanoe, Kengo

2018-02-06

Selectivity is an important parameter of resistive-type gas sensors that use metal oxides. In this study, a highly selective toluene sensor is prepared using highly dispersed gold-nanoparticle-loaded zinc oxide nanoparticles (Au-ZnO NPs). Au-ZnO NPs are synthesized by coprecipitation and calcination at 400 °C with Au loadings of 0.15, 0.5, and 1.5 mol %. The Au NPs on ZnO are about 2-4 nm in size, and exist in a metallic state. Porous gas-sensing layers are fabricated by screen printing. The responses of the sensor to 200 ppm hydrogen, 200 ppm carbon monoxide, 100 ppm ethanol, 100 ppm acetaldehyde, 100 ppm acetone, and 100 ppm toluene are evaluated at 377 °C in a dry atmosphere. The sensor response of 0.15 mol % Au-ZnO NPs to toluene is about 92, whereas its sensor responses to other combustible gases are less than 7. Such selective toluene detection is probably caused by the utilization efficiency of the gas-sensing layer. Gas diffusivity into the sensing layer of Au-ZnO NPs is lowered by the catalytic oxidation of combustible gases during their diffusion through the layer. The present approach is an effective way to improve the selectivity of resistive-type gas sensors.

Development of a Kalman Filter in the Gauss-Helmert Model for Reliability Analysis in Orientation Determination with Smartphone Sensors

PubMed Central

Ettlinger, Andreas; Neuner, Hans; Burgess, Thomas

2018-01-01

The topic of indoor positioning and indoor navigation by using observations from smartphone sensors is very challenging as the determined trajectories can be subject to significant deviations compared to the route travelled in reality. Especially the calculation of the direction of movement is the critical part of pedestrian positioning approaches such as Pedestrian Dead Reckoning (“PDR”). Due to distinct systematic effects in filtered trajectories, it can be assumed that there are systematic deviations present in the observations from smartphone sensors. This article has two aims: one is to enable the estimation of partial redundancies for each observation as well as for observation groups. Partial redundancies are a measure for the reliability indicating how well systematic deviations can be detected in single observations used in PDR. The second aim is to analyze the behavior of partial redundancy by modifying the stochastic and functional model of the Kalman filter. The equations relating the observations to the orientation are condition equations, which do not exhibit the typical structure of the Gauss-Markov model (“GMM”), wherein the observations are linear and can be formulated as functions of the states. To calculate and analyze the partial redundancy of the observations from smartphone-sensors used in PDR, the system equation and the measurement equation of a Kalman filter as well as the redundancy matrix need to be derived in the Gauss-Helmert model (“GHM”). These derivations are introduced in this article and lead to a novel Kalman filter structure based on condition equations, enabling reliability assessment of each observation. PMID:29385076

Development of a Kalman Filter in the Gauss-Helmert Model for Reliability Analysis in Orientation Determination with Smartphone Sensors.

PubMed

Ettlinger, Andreas; Neuner, Hans; Burgess, Thomas

2018-01-31

The topic of indoor positioning and indoor navigation by using observations from smartphone sensors is very challenging as the determined trajectories can be subject to significant deviations compared to the route travelled in reality. Especially the calculation of the direction of movement is the critical part of pedestrian positioning approaches such as Pedestrian Dead Reckoning ("PDR"). Due to distinct systematic effects in filtered trajectories, it can be assumed that there are systematic deviations present in the observations from smartphone sensors. This article has two aims: one is to enable the estimation of partial redundancies for each observation as well as for observation groups. Partial redundancies are a measure for the reliability indicating how well systematic deviations can be detected in single observations used in PDR. The second aim is to analyze the behavior of partial redundancy by modifying the stochastic and functional model of the Kalman filter. The equations relating the observations to the orientation are condition equations, which do not exhibit the typical structure of the Gauss-Markov model ("GMM"), wherein the observations are linear and can be formulated as functions of the states. To calculate and analyze the partial redundancy of the observations from smartphone-sensors used in PDR, the system equation and the measurement equation of a Kalman filter as well as the redundancy matrix need to be derived in the Gauss-Helmert model ("GHM"). These derivations are introduced in this article and lead to a novel Kalman filter structure based on condition equations, enabling reliability assessment of each observation.

Angular and Polarization Response of Multimode Sensors with Resistive-Grid Absorbers

NASA Technical Reports Server (NTRS)

Kusaka, Akito; Wollack, Edward J.; Stevenson, Thomas R.

2014-01-01

High sensitivity receiver systems with near ideal polarization sensitivity are highly desirable for development of millimeter and sub-millimeter radio astronomy. Multimoded bolometers provide a unique solution to achieve such sensitivity, for which hundreds of single-mode sensors would otherwise be required. The primary concern in employing such multimoded sensors for polarimetery is the control of the polarization systematics. In this paper, we examine the angular- and polarization- dependent absorption pattern of a thin resistive grid or membrane, which models an absorber used for a multimoded bolometer. The result shows that a freestanding thin resistive absorber with a surface resistivity of eta/2, where eta is the impedance of free space, attains a beam pattern with equal E- and H-plane responses, leading to zero cross polarization. For a resistive-grid absorber, the condition is met when a pair of grids is positioned orthogonal to each other and both have a resistivity of eta/2. When a reflective backshort termination is employed to improve absorption efficiency, the cross-polar level can be suppressed below -30 dB if acceptance angle of the sensor is limited to < or approx. 60deg. The small cross-polar systematics have even-parity patterns and do not contaminate the measurements of odd-parity polarization patterns, for which many of recent instruments for cosmic microwave background are designed. Underlying symmetry that suppresses these cross-polar systematics is discussed in detail. The estimates and formalism provided in this paper offer key tools in the design consideration of the instruments using the multimoded polarimeters.

The search and selection for primary studies in systematic reviews published in dental journals indexed in MEDLINE was not fully reproducible.

PubMed

Faggion, Clovis Mariano; Huivin, Raquel; Aranda, Luisiana; Pandis, Nikolaos; Alarcon, Marco

2018-06-01

To evaluate whether the reporting of search strategies and the primary study selection process in dental systematic reviews is reproducible. A survey of systematic reviews published in MEDLINE-indexed dental journals from June 2015 to June 2016 was conducted. Study selection was performed independently by two authors, and the reproducibility of the selection process was assessed using a tool consisting of 12 criteria. Regression analyses were implemented to evaluate any associations between degrees of reporting (measured by the number of items positively answered) and journal impact factor (IF), presence of meta-analysis, and number of citations of the systematic review in Google Scholar. Five hundred and thirty systematic reviews were identified. Following our 12 criteria, none of the systematic reviews had complete reporting of the search strategies and selection process. Eight (1.5%) systematic reviews reported the list of excluded articles (with reasons for exclusion) after title and abstract assessment. Systematic reviews with more positive answers to the criteria were significantly associated with higher journal IF, number of citations, and inclusion of meta-analysis. Search strategies and primary study selection process in systematic reviews published in MEDLINE-indexed dental journals may not be fully reproducible. Copyright © 2018 Elsevier Inc. All rights reserved.

Methods and Systems for Configuring Sensor Acquisition Based on Pressure Steps

NASA Technical Reports Server (NTRS)

DeDonato, Mathew (Inventor)

2015-01-01

Technologies are provided for underwater measurements. A system includes an underwater vessels including: a plurality of sensors disposed thereon for measuring underwater properties; and a programmable controller configured to selectively activate the plurality of sensors based at least in part on underwater pressure. A user may program at what pressure ranges certain sensors are activated to measure selected properties, and may also program the ascent/descent rate of the underwater vessel, which is correlated with the underwater pressure.

The analysis of ion-selective field-effect transistor operation in chemical sensors

NASA Astrophysics Data System (ADS)

Hotra, Zenon; Holyaka, Roman; Hladun, Michael; Humenuk, Iryna

2003-09-01

In this paper we present the research results of influence of substrate potential in ion-selective field-effect transistors (ISFET) on output signal of chemical sensors, e.g. PH-meters. It is shown that the instability of substrate-source p-n junction bias in well-known chemical sensors, which use grounded reference electrode - ISFET gate, affect on sensor characteristics in negative way. The analytical description and research results of 'substrate effect' on ISFET characteristics are considered.

Two Dimensional Host-Guest Metal-Organic Framework Sensor with High Selectivity and Sensitivity to Picric Acid.

PubMed

Bagheri, Minoo; Masoomi, Mohammad Yaser; Morsali, Ali; Schoedel, Alexander

2016-08-24

A dye-sensitized metal-organic framework, TMU-5S, was synthesized based on introducing the laser dye Rhodamine B into the porous framework TMU-5. TMU-5S was investigated as a ratiometric fluorescent sensor for the detection of explosive nitro aromatic compounds and showed four times greater selectivity to picric acid than any state-of-the-art luminescent-based sensor. Moreover, it can selectively discriminate picric acid concentrations in the presence of other nitro aromatics and volatile organic compounds. Our findings indicate that using this sensor in two dimensions leads to a greatly reduced environmental interference response and thus creates exceptional sensitivity toward explosive molecules with a fast response.

Zeolite-based Impedimetric Gas Sensor Device in Low-cost Technology for Hydrocarbon Gas Detection

PubMed Central

Reiß, Sebastian; Hagen, Gunter; Moos, Ralf

2008-01-01

Due to increasing environmental concerns the need for inexpensive selective gas sensors is increasing. This work deals with transferring a novel zeolite-based impedimetric hydrocarbon gas sensor principle, which has been originally manufactured in a costly combination of photolithography, thin-film processes, and thick-film processes to a low-cost technology comprising only thick-film processes and one electroplating step. The sensing effect is based on a thin chromium oxide layer between the interdigital electrodes and a Pt-loaded ZSM-5 zeolite film. When hydrocarbons are present in the sensor ambient, the electrical sensor impedance increases strongly and selectively. In the present work, the chromium oxide film is electroplated on Au screen-printed interdigital electrodes and then oxidized to Cr2O3. The electrode area is covered with the screen-printed zeolite. The sensor device is self-heated utilizing a planar platinum heater on the backside. The best sensor performance is obtained at a frequency of 3 Hz at around 350 °C. The good selectivity of the original sensor setup could be confirmed, but a strong cross-sensitivity to ammonia occurs, which might prohibit its original intention for use in automotive exhausts. PMID:27873966

Bias correction for rainrate retrievals from satellite passive microwave sensors

NASA Technical Reports Server (NTRS)

Short, David A.

1990-01-01

Rainrates retrieved from past and present satellite-borne microwave sensors are affected by a fundamental remote sensing problem. Sensor fields-of-view are typically large enough to encompass substantial rainrate variability, whereas the retrieval algorithms, based on radiative transfer calculations, show a non-linear relationship between rainrate and microwave brightness temperature. Retrieved rainrates are systematically too low. A statistical model of the bias problem shows that bias correction factors depend on the probability distribution of instantaneous rainrate and on the average thickness of the rain layer.

Responsive Photonic Crystal Carbohydrate Hydrogel Sensor Materials for Selective and Sensitive Lectin Protein Detection.

PubMed

Cai, Zhongyu; Sasmal, Aniruddha; Liu, Xinyu; Asher, Sanford A

2017-10-27

Lectin proteins, such as the highly toxic lectin protein, ricin, and the immunochemically important lectin, jacalin, play significant roles in many biological functions. It is highly desirable to develop a simple but efficient method to selectively detect lectin proteins. Here we report the development of carbohydrate containing responsive hydrogel sensing materials for the selective detection of lectin proteins. The copolymerization of a vinyl linked carbohydrate monomer with acrylamide and acrylic acid forms a carbohydrate hydrogel that shows specific "multivalent" binding to lectin proteins. The resulting carbohydrate hydrogels are attached to 2-D photonic crystals (PCs) that brightly diffract visible light. This diffraction provides an optical readout that sensitively monitors the hydrogel volume. We utilize lactose, galactose, and mannose containing hydrogels to fabricate a series of 2-D PC sensors that show strong selective binding to the lectin proteins ricin, jacalin, and concanavalin A (Con A). This binding causes a carbohydrate hydrogel shrinkage which significantly shifts the diffraction wavelength. The resulting 2-D PC sensors can selectively detect the lectin proteins ricin, jacalin, and Con A. These unoptimized 2-D PC hydrogel sensors show a limit of detection (LoD) of 7.5 × 10 -8 M for ricin, a LoD of 2.3 × 10 -7 M for jacalin, and a LoD of 3.8 × 10 -8 M for Con A, respectively. This sensor fabrication approach may enable numerous sensors for the selective detection of numerous lectin proteins.

Hydrothermally grown α-MnO2 interlocked mesoporous micro-cubes of several nanocrystals as selective and sensitive nitrogen dioxide chemoresistive gas sensors

NASA Astrophysics Data System (ADS)

Shinde, Pritamkumar V.; Xia, Qi Xun; Ghule, Balaji G.; Shinde, Nanasaheb M.; Seonghee, Jeong; Kim, Kwang Ho; Mane, Rajaram S.

2018-06-01

The interesting and multifunctional properties of alpha-manganese dioxide (α-MnO2) are considered to be highly sensitive and selective to nitrogen dioxide (NO2) chemresistive gas sensors. The α-MnO2 mesoporous interlocked micro-cubes composed of several interconnected nanocrystals synthesized by a facile and low-cost hydrothermal method on soda-lime glass substrate are envisaged as selective and sensitive NO2 gas sensors. Phase-purity and surface area with pore-size distribution are initially screened. The three-dimensional α-MnO2 mesoporous-cube-based gas sensors tested for NO2 gas from room-temperature (27 °C) to 250 °C have demonstrated 33% response for 100 ppm NO2 levels at 150 °C. The response and recovery time values of the α-MnO2 sensor are found to be 26 s and recovery 91 s, respectively, with high selectivity, good sensitivity, and considerable chemical and environmental stabilities, confirming the gas sensor applications potentiality of α-MnO2 morphology which is a combination of interlocked mesoporous micro-cubes and well-connected nanocrystals.

YSZ-based sensor using Cr-Fe-based spinel-oxide electrodes for selective detection of CO.

PubMed

Anggraini, Sri Ayu; Fujio, Yuki; Ikeda, Hiroshi; Miura, Norio

2017-08-22

A selective carbon monoxide (CO) sensor was developed by the use of both of CuCrFeO 4 and CoCrFeO 4 as the sensing electrode (SE) for yttria-stabilized zirconia (YSZ)-based potentiometric sensor. The sensing-characteristic examinations of the YSZ-based sensors using each of spinel oxides as the single-SE sensor showed that CuCrFeO 4 -SE had the ability to detect CO, hydrocarbons and NO x gases, while CoCrFeO 4 -SE was sensitive to hydrocarbons and NO x gases. Thus, when both SEs were paired as a combined-SEs sensor, the resulting sensor could generate a selective response to CO at 450 °C under humid conditions. The sensor was also capable of detecting CO in the concentration range of 20-700 ppm. Its sensing mechanism that was examined via polarization-curve measurements was confirmed to be based on mixed-potential model. The CO response generated by the combined-SEs sensor was unaffected by the change of water vapor concentration in the range of 1.3-11.5 vol% H 2 O. Additionally, the sensing performance was stable during 13 days tested. Copyright © 2017 Elsevier B.V. All rights reserved.

MoO3/nano-Si heterostructure based highly sensitive and acetone selective sensor prototype: a key to non-invasive detection of diabetes.

PubMed

Dwivedi, Priyanka; Dhanekar, Saakshi; Das, Samaresh

2018-07-06

This paper presents the development of an extremely sensitive and selective acetone sensor prototype which can be used as a platform for non-invasive diabetes detection through exhaled human breath. The miniaturized sensors were produced in high yield with the use of standard microfabrication processes. The sensors were based on a heterostructure composed of MoO 3 and nano-porous silicon (NPS). Features like acetone selective, enhanced sensor response and 0.5 ppm detection limit were observed upon introduction of MoO 3 on the NPS. The sensors were found to be repeatable and stable for almost 1 year, as tested under humid conditions at room temperature. It was inferred that the interface resistance of MoO 3 and NPS played a key role in the sensing mechanism. With the use of breath analysis and lab-on-chip, medical diagnosis procedures can be simplified and provide solutions for point-of-care testing.

Sensor feature fusion for detecting buried objects

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

Clark, G.A.; Sengupta, S.K.; Sherwood, R.J.

1993-04-01

Given multiple registered images of the earth`s surface from dual-band sensors, our system fuses information from the sensors to reduce the effects of clutter and improve the ability to detect buried or surface target sites. The sensor suite currently includes two sensors (5 micron and 10 micron wavelengths) and one ground penetrating radar (GPR) of the wide-band pulsed synthetic aperture type. We use a supervised teaming pattern recognition approach to detect metal and plastic land mines buried in soil. The overall process consists of four main parts: Preprocessing, feature extraction, feature selection, and classification. These parts are used in amore » two step process to classify a subimage. Thee first step, referred to as feature selection, determines the features of sub-images which result in the greatest separability among the classes. The second step, image labeling, uses the selected features and the decisions from a pattern classifier to label the regions in the image which are likely to correspond to buried mines. We extract features from the images, and use feature selection algorithms to select only the most important features according to their contribution to correct detections. This allows us to save computational complexity and determine which of the sensors add value to the detection system. The most important features from the various sensors are fused using supervised teaming pattern classifiers (including neural networks). We present results of experiments to detect buried land mines from real data, and evaluate the usefulness of fusing feature information from multiple sensor types, including dual-band infrared and ground penetrating radar. The novelty of the work lies mostly in the combination of the algorithms and their application to the very important and currently unsolved operational problem of detecting buried land mines from an airborne standoff platform.« less

a Novel Technique for Precision Geometric Correction of Jitter Distortion for the Europa Imaging System and Other Rolling-Shutter Cameras

NASA Astrophysics Data System (ADS)

Kirk, R. L.; Shepherd, M.; Sides, S. C.

2018-04-01

We use simulated images to demonstrate a novel technique for mitigating geometric distortions caused by platform motion ("jitter") as two-dimensional image sensors are exposed and read out line by line ("rolling shutter"). The results indicate that the Europa Imaging System (EIS) on NASA's Europa Clipper can likely meet its scientific goals requiring 0.1-pixel precision. We are therefore adapting the software used to demonstrate and test rolling shutter jitter correction to become part of the standard processing pipeline for EIS. The correction method will also apply to other rolling-shutter cameras, provided they have the operational flexibility to read out selected "check lines" at chosen times during the systematic readout of the frame area.

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.

Application of zonal model on indoor air sensor network design

NASA Astrophysics Data System (ADS)

Chen, Y. Lisa; Wen, Jin

2007-04-01

Growing concerns over the safety of the indoor environment have made the use of sensors ubiquitous. Sensors that detect chemical and biological warfare agents can offer early warning of dangerous contaminants. However, current sensor system design is more informed by intuition and experience rather by systematic design. To develop a sensor system design methodology, a proper indoor airflow modeling approach is needed. Various indoor airflow modeling techniques, from complicated computational fluid dynamics approaches to simplified multi-zone approaches, exist in the literature. In this study, the effects of two airflow modeling techniques, multi-zone modeling technique and zonal modeling technique, on indoor air protection sensor system design are discussed. Common building attack scenarios, using a typical CBW agent, are simulated. Both multi-zone and zonal models are used to predict airflows and contaminant dispersion. Genetic Algorithm is then applied to optimize the sensor location and quantity. Differences in the sensor system design resulting from the two airflow models are discussed for a typical office environment and a large hall environment.

Investigating gas sensing mechanism of graphene oxide (GO) thin films through cross-selectivity to various gases

NASA Astrophysics Data System (ADS)

Kumar, Shani; Dhingra, Vishal; Garg, Amit; Chowdhuri, Arijit

2016-05-01

Worldwide researchers are actively engaged in utilizing Graphene and its related materials in gas sensing applications. A high surface-to-volume ratio that offers scope of optimization leading to enhanced sensing performance besides lower sensor operating temperatures are some advantages that graphene based sensors possess over conventional semiconducting metal oxide (SMO) sensors. Conventional SMO based gas sensors are known to suffer from problems of cross-selectivity where selectivity is understood to be a gas sensor's ability to preferentially detect one particular gas without responding to or experiencing interference from other gases present in the ambient. In the current study gas sensing mechanism of Graphene oxide (GO) thin films is investigated by repeatedly exposing the sensing configuration to various gases and its cross-selectivity response to the same is examined. In the investigation typical gas sensing response characteristics of the sensor configuration are studied in both oxidizing as well as reducing environments. The gas sensing data is acquired by means of Keithley 6487 picoammeter which is interfaced with a customized Gas Sensing Test Rig (GSTR) that provides a controlled ambient to the sensors for measurement of reproducible characteristics. GSTR further provided the option of varying the operating temperature and gas concentration for the different sensor configurations under study. XRD studies indicate formation of GO with typical crystallite size of 4.2 nm. UV-Vis investigations reveal a typical band-gap of 4.42 (eV) which is in conformity with those reported in the available literature.1,2

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.

Biomimetic virus-based colourimetric sensors.

PubMed

Oh, Jin-Woo; Chung, Woo-Jae; Heo, Kwang; Jin, Hyo-Eon; Lee, Byung Yang; Wang, Eddie; Zueger, Chris; Wong, Winnie; Meyer, Joel; Kim, Chuntae; Lee, So-Young; Kim, Won-Geun; Zemla, Marcin; Auer, Manfred; Hexemer, Alexander; Lee, Seung-Wuk

2014-01-01

Many materials in nature change colours in response to stimuli, making them attractive for use as sensor platform. However, both natural materials and their synthetic analogues lack selectivity towards specific chemicals, and introducing such selectivity remains a challenge. Here we report the self-assembly of genetically engineered viruses (M13 phage) into target-specific, colourimetric biosensors. The sensors are composed of phage-bundle nanostructures and exhibit viewing-angle independent colour, similar to collagen structures in turkey skin. On exposure to various volatile organic chemicals, the structures rapidly swell and undergo distinct colour changes. Furthermore, sensors composed of phage displaying trinitrotoluene (TNT)-binding peptide motifs identified from a phage display selectively distinguish TNT down to 300 p.p.b. over similarly structured chemicals. Our tunable, colourimetric sensors can be useful for the detection of a variety of harmful toxicants and pathogens to protect human health and national security.

Biomimetic virus-based colourimetric sensors

NASA Astrophysics Data System (ADS)

Oh, Jin-Woo; Chung, Woo-Jae; Heo, Kwang; Jin, Hyo-Eon; Lee, Byung Yang; Wang, Eddie; Zueger, Chris; Wong, Winnie; Meyer, Joel; Kim, Chuntae; Lee, So-Young; Kim, Won-Geun; Zemla, Marcin; Auer, Manfred; Hexemer, Alexander; Lee, Seung-Wuk

2014-01-01

Many materials in nature change colours in response to stimuli, making them attractive for use as sensor platform. However, both natural materials and their synthetic analogues lack selectivity towards specific chemicals, and introducing such selectivity remains a challenge. Here we report the self-assembly of genetically engineered viruses (M13 phage) into target-specific, colourimetric biosensors. The sensors are composed of phage-bundle nanostructures and exhibit viewing-angle independent colour, similar to collagen structures in turkey skin. On exposure to various volatile organic chemicals, the structures rapidly swell and undergo distinct colour changes. Furthermore, sensors composed of phage displaying trinitrotoluene (TNT)-binding peptide motifs identified from a phage display selectively distinguish TNT down to 300 p.p.b. over similarly structured chemicals. Our tunable, colourimetric sensors can be useful for the detection of a variety of harmful toxicants and pathogens to protect human health and national security.

Selectivity of the gas sensor based on the 50%In2O3-50%Ga2O3 thin film in dynamic mode of operation

NASA Astrophysics Data System (ADS)

Demin, I. E.; Kozlov, A. G.

2018-01-01

The article considers the gas sensor with the sensitive layer based on the 50%In2O3 -50%Ga2O3 thin film. The temperature and concentration dependencies of gas-induced resistance response of this sensor and the dynamical dependencies of its resistance response on the test gases in air are investigated. The test gases were ethanol, acetone, ammonia and liquefied petroleum gas. The information parameters of the sensor in the dynamical mode of operation were considered to improve its selectivity. The presented results show that the selectivity of the sensor in this mode may be improved by using the following information parameters: gas-induced resistance response in steady state, activation energy of the response and pre-exponential factor of the temperature dependence of the response time constant.

Optical Graphene Gas Sensors Based on Microfibers: A Review

PubMed Central

Wu, Yu; Yao, Baicheng; Yu, Caibin; Rao, Yunjiang

2018-01-01

Graphene has become a bridge across optoelectronics, mechanics, and bio-chemical sensing due to its unique photoelectric characteristics. Moreover, benefiting from its two-dimensional nature, this atomically thick film with full flexibility has been widely incorporated with optical waveguides such as fibers, realizing novel photonic devices including polarizers, lasers, and sensors. Among the graphene-based optical devices, sensor is one of the most important branch, especially for gas sensing, as rapid progress has been made in both sensing structures and devices in recent years. This article presents a comprehensive and systematic overview of graphene-based microfiber gas sensors regarding many aspects including sensing principles, properties, fabrication, interrogating and implementations. PMID:29565314

Miniaturized Monitors for Assessment of Exposure to Air Pollutants: A Review.

PubMed

Borghi, Francesca; Spinazzè, Andrea; Rovelli, Sabrina; Campagnolo, Davide; Del Buono, Luca; Cattaneo, Andrea; Cavallo, Domenico M

2017-08-12

Air quality has a huge impact on different aspects of life quality, and for this reason, air quality monitoring is required by national and international regulations. Technical and procedural limitations of traditional fixed-site stations for monitoring or sampling of air pollutants are also well-known. Recently, a different type of miniaturized monitors has been developed. These monitors, due to their characteristics (e.g., low cost, small size, high portability) are becoming increasingly important for individual exposure assessment, especially since this kind of instrument can provide measurements at high spatial and temporal resolution, which is a notable advantage when approaching assessment of exposure to environmental contaminants. The aim of this study is indeed to provide information regarding current knowledge regarding the use of miniaturized air pollutant sensors. A systematic review was performed to identify original articles: a literature search was carried out using an appropriate query for the search of papers across three different databases, and the papers were selected using inclusion/exclusion criteria. The reviewed articles showed that miniaturized sensors are particularly versatile and could be applied in studies with different experimental designs, helping to provide a significant enhancement to exposure assessment, even though studies regarding their performance are still sparse.

A catalytic beacon sensor for uranium with parts-per-trillion sensitivity and millionfold selectivity.

PubMed

Liu, Juewen; Brown, Andrea K; Meng, Xiangli; Cropek, Donald M; Istok, Jonathan D; Watson, David B; Lu, Yi

2007-02-13

Here, we report a catalytic beacon sensor for uranyl (UO2(2+)) based on an in vitro-selected UO2(2+)-specific DNAzyme. The sensor consists of a DNA enzyme strand with a 3' quencher and a DNA substrate with a ribonucleotide adenosine (rA) in the middle and a fluorophore and a quencher at the 5' and 3' ends, respectively. The presence of UO2(2+) causes catalytic cleavage of the DNA substrate strand at the rA position and release of the fluorophore and thus dramatic increase of fluorescence intensity. The sensor has a detection limit of 11 parts per trillion (45 pM), a dynamic range up to 400 nM, and selectivity of >1-million-fold over other metal ions. The most interfering metal ion, Th(IV), interacts with the fluorescein fluorophore, causing slightly enhanced fluorescence intensity, with an apparent dissociation constant of approximately 230 microM. This sensor rivals the most sensitive analytical instruments for uranium detection, and its application in detecting uranium in contaminated soil samples is also demonstrated. This work shows that simple, cost-effective, and portable metal sensors can be obtained with similar sensitivity and selectivity as much more expensive and sophisticated analytical instruments. Such a sensor will play an important role in environmental remediation of radionuclides such as uranium.

Computer-assisted electrochemical fabrication of a highly selective and sensitive amperometric nitrite sensor based on surface decoration of electrochemically reduced graphene oxide nanosheets with CoNi bimetallic alloy nanoparticles.

PubMed

Gholivand, Mohammad-Bagher; Jalalvand, Ali R; Goicoechea, Hector C

2014-07-01

For the first time, a novel, robust and very attractive statistical experimental design (ED) using minimum-run equireplicated resolution IV factorial design (Min-Run Res IV FD) coupled with face centered central composite design (FCCCD) and Derringer's desirability function (DF) was developed to fabricate a highly selective and sensitive amperometric nitrite sensor based on electrodeposition of CoNi bimetallic alloy nanoparticles (NPs) on electrochemically reduced graphene oxide (ERGO) nanosheets. The modifications were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), energy dispersive X-ray spectroscopic (EDS), scanning electron microscopy (SEM) techniques. The CoNi bimetallic alloy NPs were characterized using digital image processing (DIP) for particle counting (density estimation) and average diameter measurement. Under the identified optimal conditions, the novel sensor detects nitrite in concentration ranges of 0.1-30.0 μM and 30.0-330.0 μM with a limit of detection (LOD) of 0.05 μM. This sensor selectively detects nitrite even in the presence of high concentration of common ions and biological interferents therefore, we found that the sensor is highly selective. The sensor also demonstrated an excellent operational stability and good antifouling properties. The proposed sensor was used to the determination of nitrite in several foodstuff and water samples. Copyright © 2014. Published by Elsevier B.V.

Novel cell-based odorant sensor elements based on insect odorant receptors.

PubMed

Mitsuno, Hidefumi; Sakurai, Takeshi; Namiki, Shigehiro; Mitsuhashi, Hiroyuki; Kanzaki, Ryohei

2015-03-15

Development of cell-based odorant sensor elements combined not only high degree of sensitivity and selectivity but also long-term stability is crucial for their practical applications. Here we report the development of a novel cell-based odorant sensor element that sensitively and selectively detects odorants and displays increased fluorescent intensities over a long period of time. Our odorant sensor elements, based on Sf21 cell lines expressing insect odorant receptors, are sensitive to the level of several tens of parts per billion in solution, can selectively distinguish between different types of odorants based on the odorant selectivity intrinsic to the expressed receptors, and have response times of approximately 13s. Specifically, with the use of Sf21 cells and insect odorant receptors, we demonstrated that the established cell lines stably expressing insect odorant receptors are able to detect odorants with consistent responsiveness for at least 2 months, thus exceeding the short life-span normally associated with cell-based sensors. We also demonstrated the development of a compact odorant sensor chip by integrating the established insect cell lines into a microfluidic chip. The methodology we established in this study, in conjunction with the large repertoire of insect odorant receptors, will aid in the development of practical cell-based odorant sensors for various applications, including food administration and health management. Copyright © 2014 Elsevier B.V. All rights reserved.

A catalytic beacon sensor for uranium with parts-per-trillion sensitivity and millionfold selectivity

PubMed Central

Liu, Juewen; Brown, Andrea K.; Meng, Xiangli; Cropek, Donald M.; Istok, Jonathan D.; Watson, David B.; Lu, Yi

2007-01-01

Here, we report a catalytic beacon sensor for uranyl (UO22+) based on an in vitro-selected UO22+-specific DNAzyme. The sensor consists of a DNA enzyme strand with a 3′ quencher and a DNA substrate with a ribonucleotide adenosine (rA) in the middle and a fluorophore and a quencher at the 5′ and 3′ ends, respectively. The presence of UO22+ causes catalytic cleavage of the DNA substrate strand at the rA position and release of the fluorophore and thus dramatic increase of fluorescence intensity. The sensor has a detection limit of 11 parts per trillion (45 pM), a dynamic range up to 400 nM, and selectivity of >1-million-fold over other metal ions. The most interfering metal ion, Th(IV), interacts with the fluorescein fluorophore, causing slightly enhanced fluorescence intensity, with an apparent dissociation constant of ≈230 μM. This sensor rivals the most sensitive analytical instruments for uranium detection, and its application in detecting uranium in contaminated soil samples is also demonstrated. This work shows that simple, cost-effective, and portable metal sensors can be obtained with similar sensitivity and selectivity as much more expensive and sophisticated analytical instruments. Such a sensor will play an important role in environmental remediation of radionuclides such as uranium. PMID:17284609

Evaluation of Micronutrient Sensors for Food Matrices in Resource-Limited Settings: A Systematic Narrative Review.

PubMed

Waller, Anna W; Lotton, Jennifer L; Gaur, Shashank; Andrade, Jeanette M; Andrade, Juan E

2018-06-21

In resource-limited settings, mass food fortification is a common strategy to ensure the population consumes appropriate quantities of essential micronutrients. Food and government organizations in these settings, however, lack tools to monitor the quality and compliance of fortified products and their efficacy to enhance nutrient status. The World Health Organization has developed general guidelines known as ASSURED (Affordable, Sensitive, Specific, User-friendly, Rapid and Robust, Equipment-free, and Deliverable to end-users) to aid the development of useful diagnostic tools for these settings. These guidelines assume performance aspects such as sufficient accuracy, reliability, and validity. The purpose of this systematic narrative review is to examine the micronutrient sensor literature on its adherence towards the ASSURED criteria along with accuracy, reliability, and validation when developing micronutrient sensors for resource-limited settings. Keyword searches were conducted in three databases: Web of Science, PubMed, and Scopus and were based on 6-point inclusion criteria. A 16-question quality assessment tool was developed to determine the adherence towards quality and performance criteria. Of the 2,365 retrieved studies, 42 sensors were included based on inclusion/exclusion criteria. Results showed that improvements to the current sensor design are necessary, especially their affordability, user-friendliness, robustness, equipment-free, and deliverability within the ASSURED criteria, and accuracy and validity of the additional criteria to be useful in resource-limited settings. Although it requires further validation, the 16-question quality assessment tool can be used as a guide in the development of sensors for resource-limited settings. © 2018 Institute of Food Technologists®.

Semiconducting Metal Oxide Based Sensors for Selective Gas Pollutant Detection

PubMed Central

Kanan, Sofian M.; El-Kadri, Oussama M.; Abu-Yousef, Imad A.; Kanan, Marsha C.

2009-01-01

A review of some papers published in the last fifty years that focus on the semiconducting metal oxide (SMO) based sensors for the selective and sensitive detection of various environmental pollutants is presented. PMID:22408500

Mechanism for and method of biasing magnetic sensor

DOEpatents

Kautz, David R.

2007-12-04

A magnetic sensor package having a biasing mechanism involving a coil-generated, resistor-controlled magnetic field for providing a desired biasing effect. In a preferred illustrated embodiment, the package broadly comprises a substrate; a magnetic sensor element; a biasing mechanism, including a coil and a first resistance element; an amplification mechanism; a filter capacitor element; and an encapsulant. The sensor is positioned within the coil. A current applied to the coil produces a biasing magnetic field. The biasing magnetic field is controlled by selecting a resistance value for the first resistance element which achieves the desired biasing effect. The first resistance element preferably includes a plurality of selectable resistors, the selection of one or more of which sets the resistance value.

An Energy-Efficient Game-Theory-Based Spectrum Decision Scheme for Cognitive Radio Sensor Networks

PubMed Central

Salim, Shelly; Moh, Sangman

2016-01-01

A cognitive radio sensor network (CRSN) is a wireless sensor network in which sensor nodes are equipped with cognitive radio. In this paper, we propose an energy-efficient game-theory-based spectrum decision (EGSD) scheme for CRSNs to prolong the network lifetime. Note that energy efficiency is the most important design consideration in CRSNs because it determines the network lifetime. The central part of the EGSD scheme consists of two spectrum selection algorithms: random selection and game-theory-based selection. The EGSD scheme also includes a clustering algorithm, spectrum characterization with a Markov chain, and cluster member coordination. Our performance study shows that EGSD outperforms the existing popular framework in terms of network lifetime and coordination overhead. PMID:27376290

An Energy-Efficient Game-Theory-Based Spectrum Decision Scheme for Cognitive Radio Sensor Networks.

PubMed

Salim, Shelly; Moh, Sangman

2016-06-30

A cognitive radio sensor network (CRSN) is a wireless sensor network in which sensor nodes are equipped with cognitive radio. In this paper, we propose an energy-efficient game-theory-based spectrum decision (EGSD) scheme for CRSNs to prolong the network lifetime. Note that energy efficiency is the most important design consideration in CRSNs because it determines the network lifetime. The central part of the EGSD scheme consists of two spectrum selection algorithms: random selection and game-theory-based selection. The EGSD scheme also includes a clustering algorithm, spectrum characterization with a Markov chain, and cluster member coordination. Our performance study shows that EGSD outperforms the existing popular framework in terms of network lifetime and coordination overhead.

Selection of DNA aptamers against Human Cardiac Troponin I for colorimetric sensor based dot blot application.

PubMed

Dorraj, Ghamar Soltan; Rassaee, Mohammad Javad; Latifi, Ali Mohammad; Pishgoo, Bahram; Tavallaei, Mahmood

2015-08-20

Troponin T and I are ideal markers which are highly sensitive and specific for myocardial injury and have shown better efficacy than earlier markers. Since aptamers are ssDNA or RNA that bind to a wide variety of target molecules, the purpose of this research was to select an aptamer from a 79bp single-stranded DNA (ssDNA) random library that was used to bind the Human Cardiac Troponin I from a synthetic nucleic acids library by systematic evolution of ligands exponential enrichment (Selex) based on several selection and amplification steps. Human Cardiac Troponin I protein was coated onto the surface of streptavidin magnetic beads to extract specific aptamer from a large and diverse random ssDNA initial oligonucleotide library. As a result, several aptamers were selected and further examined for binding affinity and specificity. Finally TnIApt 23 showed beast affinity in nanomolar range (2.69nM) toward the target protein. A simple and rapid colorimetric detection assay for Human Cardiac Troponin I using the novel and specific aptamer-AuNPs conjugates based on dot blot assay was developed. The detection limit for this protein using aptamer-AuNPs-based assay was found to be 5ng/ml. Copyright © 2015 Elsevier B.V. All rights reserved.

Near-IR Two-Photon Fluorescent Sensor for K(+) Imaging in Live Cells.

PubMed

Sui, Binglin; Yue, Xiling; Kim, Bosung; Belfield, Kevin D

2015-08-19

A new two-photon excited fluorescent K(+) sensor is reported. The sensor comprises three moieties, a highly selective K(+) chelator as the K(+) recognition unit, a boron-dipyrromethene (BODIPY) derivative modified with phenylethynyl groups as the fluorophore, and two polyethylene glycol chains to afford water solubility. The sensor displays very high selectivity (>52-fold) in detecting K(+) over other physiological metal cations. Upon binding K(+), the sensor switches from nonfluorescent to highly fluorescent, emitting red to near-IR (NIR) fluorescence. The sensor exhibited a good two-photon absorption cross section, 500 GM at 940 nm. Moreover, it is not sensitive to pH in the physiological pH range. Time-dependent cell imaging studies via both one- and two-photon fluorescence microscopy demonstrate that the sensor is suitable for dynamic K(+) sensing in living cells.

Towards outperforming conventional sensor arrays with fabricated individual photonic vapour sensors inspired by Morpho butterflies

PubMed Central

Potyrailo, Radislav A.; Bonam, Ravi K.; Hartley, John G.; Starkey, Timothy A.; Vukusic, Peter; Vasudev, Milana; Bunning, Timothy; Naik, Rajesh R.; Tang, Zhexiong; Palacios, Manuel A.; Larsen, Michael; Le Tarte, Laurie A.; Grande, James C.; Zhong, Sheng; Deng, Tao

2015-01-01

Combining vapour sensors into arrays is an accepted compromise to mitigate poor selectivity of conventional sensors. Here we show individual nanofabricated sensors that not only selectively detect separate vapours in pristine conditions but also quantify these vapours in mixtures, and when blended with a variable moisture background. Our sensor design is inspired by the iridescent nanostructure and gradient surface chemistry of Morpho butterflies and involves physical and chemical design criteria. The physical design involves optical interference and diffraction on the fabricated periodic nanostructures and uses optical loss in the nanostructure to enhance the spectral diversity of reflectance. The chemical design uses spatially controlled nanostructure functionalization. Thus, while quantitation of analytes in the presence of variable backgrounds is challenging for most sensor arrays, we achieve this goal using individual multivariable sensors. These colorimetric sensors can be tuned for numerous vapour sensing scenarios in confined areas or as individual nodes for distributed monitoring. PMID:26324320

Disbonding effects on elastic wave generation and reception by bonded piezoelectric sensor systems

NASA Astrophysics Data System (ADS)

Blackshire, James L.; Martin, Steven A.; Na, Jeong K.

2007-04-01

Durable integrated sensor systems are needed for long-term health monitoring evaluations of aerospace systems. For legacy aircraft the primary means of implementing a sensor system will be through surface mounting or bonding of the sensors to the structure. Previous work has shown that the performance of surface-bonded piezo sensors can degrade due to environmental effects such as vibrations, temperature fluctuations, and substrate flexure motions. This performance degradation included sensor cracking, disbonding, and general loss of efficiency over time. In this research effort, the bonding state of a piezo sensor system was systematically studied to understand and improve the long-term durability and survivability of the sensor system. Analytic and computational models were developed and used to understand elastic wave generation and reception performance for various states of sensor disbond. Experimental studies were also conducted using scanning laser vibrometry, pitch-catch ultrasound, and pulse-echo ultrasound methods to understand elastic wave propagation effects in thin plate materials. Significant performance loss was observed for increasing levels of sensor disbond as well as characteristic frequency signatures which may be useful in understanding sensor performance levels for future structural health monitoring systems.

Enhancing the Discrimination Ability of a Gas Sensor Array Based on a Novel Feature Selection and Fusion Framework.

PubMed

Deng, Changjian; Lv, Kun; Shi, Debo; Yang, Bo; Yu, Song; He, Zhiyi; Yan, Jia

2018-06-12

In this paper, a novel feature selection and fusion framework is proposed to enhance the discrimination ability of gas sensor arrays for odor identification. Firstly, we put forward an efficient feature selection method based on the separability and the dissimilarity to determine the feature selection order for each type of feature when increasing the dimension of selected feature subsets. Secondly, the K-nearest neighbor (KNN) classifier is applied to determine the dimensions of the optimal feature subsets for different types of features. Finally, in the process of establishing features fusion, we come up with a classification dominance feature fusion strategy which conducts an effective basic feature. Experimental results on two datasets show that the recognition rates of Database I and Database II achieve 97.5% and 80.11%, respectively, when k = 1 for KNN classifier and the distance metric is correlation distance (COR), which demonstrates the superiority of the proposed feature selection and fusion framework in representing signal features. The novel feature selection method proposed in this paper can effectively select feature subsets that are conducive to the classification, while the feature fusion framework can fuse various features which describe the different characteristics of sensor signals, for enhancing the discrimination ability of gas sensors and, to a certain extent, suppressing drift effect.

A Systematic Approach for Model-Based Aircraft Engine Performance Estimation

NASA Technical Reports Server (NTRS)

Simon, Donald L.; Garg, Sanjay

2010-01-01

A requirement for effective aircraft engine performance estimation is the ability to account for engine degradation, generally described in terms of unmeasurable health parameters such as efficiencies and flow capacities related to each major engine module. This paper presents a linear point design methodology for minimizing the degradation-induced error in model-based aircraft engine performance estimation applications. The technique specifically focuses on the underdetermined estimation problem, where there are more unknown health parameters than available sensor measurements. A condition for Kalman filter-based estimation is that the number of health parameters estimated cannot exceed the number of sensed measurements. In this paper, the estimated health parameter vector will be replaced by a reduced order tuner vector whose dimension is equivalent to the sensed measurement vector. The reduced order tuner vector is systematically selected to minimize the theoretical mean squared estimation error of a maximum a posteriori estimator formulation. This paper derives theoretical estimation errors at steady-state operating conditions, and presents the tuner selection routine applied to minimize these values. Results from the application of the technique to an aircraft engine simulation are presented and compared to the estimation accuracy achieved through conventional maximum a posteriori and Kalman filter estimation approaches. Maximum a posteriori estimation results demonstrate that reduced order tuning parameter vectors can be found that approximate the accuracy of estimating all health parameters directly. Kalman filter estimation results based on the same reduced order tuning parameter vectors demonstrate that significantly improved estimation accuracy can be achieved over the conventional approach of selecting a subset of health parameters to serve as the tuner vector. However, additional development is necessary to fully extend the methodology to Kalman filter-based estimation applications.

ZnO-carbon nanofibers for stable, high response, and selective H2S sensors.

PubMed

Zhang, Jitao; Zhu, Zijian; Chen, Changmiao; Chen, Zhi; Cai, Mengqiu; Qu, Baihua; Wang, Taihong; Zhang, Ming

2018-07-06

Hydrogen sulfide (H 2 S), as a typical atmospheric pollutant, is neurotoxic and flammable even at a very low concentration. In this study, we design stable H 2 S sensors based on ZnO-carbon nanofibers. Nanofibers with 30.34 wt% carbon are prepared by a facial electrospinning route followed by an annealing treatment. The resulting H 2 S sensors show excellent selectivity and response compared to the pure ZnO nanofiber H 2 S sensors, particularly the response in the range of 102-50 ppm of H 2 S. Besides, they exhibited a nearly constant response of approximately 40-20 ppm of H 2 S over 60 days. The superior performance of these H 2 S sensors can be attributed to the protection of carbon, which ensures the high stability of ZnO, and oxygen vacancies that improve the response and selectivity of H 2 S. The good performance of ZnO-carbon H 2 S sensors suggests that composites with oxygen vacancies prepared by a facial electrospinning route may provide a new research strategy in the field of gas sensors, photocatalysts, and semiconductor devices.

Multivariable passive RFID vapor sensors: roll-to-roll fabrication on a flexible substrate.

PubMed

Potyrailo, Radislav A; Burns, Andrew; Surman, Cheryl; Lee, D J; McGinniss, Edward

2012-06-21

We demonstrate roll-to-roll (R2R) fabrication of highly selective, battery-free radio frequency identification (RFID) sensors on a flexible polyethylene terephthalate (PET) polymeric substrate. Selectivity of our developed RFID sensors is provided by measurements of their resonance impedance spectra, followed by the multivariate analysis of spectral features, and correlation of these spectral features to the concentrations of vapors of interest. The multivariate analysis of spectral features also provides the ability for the rejection of ambient interferences. As a demonstration of our R2R fabrication process, we employed polyetherurethane (PEUT) as a "classic" sensing material, extruded this sensing material as 25, 75, and 125-μm thick films, and thermally laminated the films onto RFID inlays, rapidly producing approximately 5000 vapor sensors. We further tested these RFID vapor sensors for their response selectivity toward several model vapors such as toluene, acetone, and ethanol as well as water vapor as an abundant interferent. Our RFID sensing concept features 16-bit resolution provided by the sensor reader, granting a highly desired independence from costly proprietary RFID memory chips with a low-resolution analog input. Future steps are being planned for field-testing of these sensors in numerous conditions.

Sensing in the collaborative Internet of Things.

PubMed

Borges Neto, João B; Silva, Thiago H; Assunção, Renato Martins; Mini, Raquel A F; Loureiro, Antonio A F

2015-03-19

We are entering a new era of computing technology, the era of Internet of Things (IoT). An important element for this popularization is the large use of off-the-shelf sensors. Most of those sensors will be deployed by different owners, generally common users, creating what we call the Collaborative IoT. This collaborative IoT helps to increase considerably the amount and availability of collected data for different purposes, creating new interesting opportunities, but also several challenges. For example, it is very challenging to search for and select a desired sensor or a group of sensors when there is no description about the provided sensed data or when it is imprecise. Given that, in this work we characterize the properties of the sensed data in the Internet of Things, mainly the sensed data contributed by several sources, including sensors from common users. We conclude that, in order to safely use data available in the IoT, we need a filtering process to increase the data reliability. In this direction, we propose a new simple and powerful approach that helps to select reliable sensors. We tested our method for different types of sensed data, and the results reveal the effectiveness in the correct selection of sensor data.

Isatinphenylsemicarbazones as efficient colorimetric sensors for fluoride and acetate anions - anions induce tautomerism.

PubMed

Jakusová, Klaudia; Donovalová, Jana; Cigáň, Marek; Gáplovský, Martin; Garaj, Vladimír; Gáplovský, Anton

2014-04-05

The anion induced tautomerism of isatin-3-4-phenyl(semicarbazone) derivatives is studied herein. The interaction of F(-), AcO(-), H2PO4(-), Br(-) or HSO4(-) anions with E and Z isomers of isatin-3-4-phenyl(semicarbazone) and N-methylisatin-3-4-phenyl(semicarbazone) as sensors influences the tautomeric equilibrium of these sensors in the liquid phase. This tautomeric equilibrium is affected by (1) the inter- and intra-molecular interactions' modulation of isatinphenylsemicarbazone molecules due to the anion induced change in the solvation shell of receptor molecules and (2) the sensor-anion interaction with the urea hydrogens. The acid-base properties of anions and the difference in sensor structure influence the equilibrium ratio of the individual tautomeric forms. Here, the tautomeric equilibrium changes were indicated by "naked-eye" experiment, UV-VIS spectral and (1)H NMR titration, resulting in confirmation that appropriate selection of experimental conditions leads to a high degree of sensor selectivity for some investigated anions. Sensors' E and Z isomers differ in sensitivity, selectivity and sensing mechanism. Detection of F(-) or CH3COO(-) anions at high weakly basic anions' excess is possible. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis of molecularly imprinted dye-silica nanocomposites with high selectivity and sensitivity: Fluorescent imprinted sensor for rapid and efficient detection of τ-fluvalinate in vodka.

PubMed

Wang, Yunyun; Wang, Jixiang; Cheng, Rujia; Sun, Lin; Dai, Xiaohui; Yan, Yongsheng

2018-04-01

An imprinted fluorescent sensor was fabricated based on SiO 2 nanoparticles encapsulated with a molecularly imprinted polymer containing allyl fluorescein. High fluorine cypermethirin as template molecules, methyl methacrylate as functional monomer, and allyl fluorescein as optical materials synthesized a core-shell fluorescent molecular imprinted sensor, which showed a high and rapid sensitivity and selectivity for the detection of τ-fluvalinate. The sensor presented appreciable sensitivity with a limit of 13.251 nM, rapid detection that reached to equilibrium within 3 min, great linear relationship in the relevant concentration range from 0 to 150 nM, and excellent selectivity over structural analogues. In addition, the fluorescent sensor demonstrated desirable regeneration ability (eight cycling operations). The molecularly imprinted polymers ensured specificity, while the fluorescent dyes provided the stabile sensitivity. Finally, an effective application of the sensor was implemented by the detection of τ-fluvalinate in real samples from vodka. The molecularly imprinted fluorescent sensor showed a promising potential in environmental monitoring and food safety. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Strontium (II)-Selective Potentiometric Sensor Based on Ester Derivative of 4-tert-butylcalix(8)arene in PVC Matrix

PubMed Central

Jain, Ajay K.; Gupta, Vinod K.; Raisoni, Jitendra R.

2004-01-01

Membranes of 4-tert-butylcalix(8)arene-octaacetic acid octaethyl ester (I) as an electroactive material, sodium tetraphenyl borate (NaTPB) as an anion excluder, and tri-n-butyl phosphate (TBP) as a solvent mediator in poly(vinyl chloride) (PVC) matrix have been tried for a strontium-selective sensor. The best performance was exhibited by the membrane having a composition 5:100:150:2 (I: PVC: TBP: NaTPB (w/w)). This sensor exhibits a good potentiometric response to Sr2+ over a wide concentration range (3.2 × 10 –5 –1.0 × 10 –1 M) with a Nernstian slope (30 mV/ decade). The response time of the sensor is 10 s and it has been used for a period of four months without any drift in potentials. The selectivity coefficient values are in the order of 0.01 for mono-, bi-, and trivalent cations which indicate a good selectivity for Sr2+ over a large number of cations. The useful pH range for the sensor was found to be 3-10 and it works well in mixtures with non-aqueous content up to 25 % (v/v). The sensor has been used as an indicator electrode in the potentiometric titration of Sr2+ against EDTA.

Optimal Tuner Selection for Kalman-Filter-Based Aircraft Engine Performance Estimation

NASA Technical Reports Server (NTRS)

Simon, Donald L.; Garg, Sanjay

2011-01-01

An emerging approach in the field of aircraft engine controls and system health management is the inclusion of real-time, onboard models for the inflight estimation of engine performance variations. This technology, typically based on Kalman-filter concepts, enables the estimation of unmeasured engine performance parameters that can be directly utilized by controls, prognostics, and health-management applications. A challenge that complicates this practice is the fact that an aircraft engine s performance is affected by its level of degradation, generally described in terms of unmeasurable health parameters such as efficiencies and flow capacities related to each major engine module. Through Kalman-filter-based estimation techniques, the level of engine performance degradation can be estimated, given that there are at least as many sensors as health parameters to be estimated. However, in an aircraft engine, the number of sensors available is typically less than the number of health parameters, presenting an under-determined estimation problem. A common approach to address this shortcoming is to estimate a subset of the health parameters, referred to as model tuning parameters. The problem/objective is to optimally select the model tuning parameters to minimize Kalman-filterbased estimation error. A tuner selection technique has been developed that specifically addresses the under-determined estimation problem, where there are more unknown parameters than available sensor measurements. A systematic approach is applied to produce a model tuning parameter vector of appropriate dimension to enable estimation by a Kalman filter, while minimizing the estimation error in the parameters of interest. Tuning parameter selection is performed using a multi-variable iterative search routine that seeks to minimize the theoretical mean-squared estimation error of the Kalman filter. This approach can significantly reduce the error in onboard aircraft engine parameter estimation applications such as model-based diagnostic, controls, and life usage calculations. The advantage of the innovation is the significant reduction in estimation errors that it can provide relative to the conventional approach of selecting a subset of health parameters to serve as the model tuning parameter vector. Because this technique needs only to be performed during the system design process, it places no additional computation burden on the onboard Kalman filter implementation. The technique has been developed for aircraft engine onboard estimation applications, as this application typically presents an under-determined estimation problem. However, this generic technique could be applied to other industries using gas turbine engine technology.

Structural Modifications and Photophysical Studies of Fluorescent Conjugated Polymers for Solid State Sensor Development

NASA Astrophysics Data System (ADS)

Chen, Anting

Fluorescent conjugated polymers (FCPs) represent an exciting area of research in chemosensors and biosensors. Previously, the polymer tmeda-PPETE, N,N,N'-trimethylethylenediamino (tmeda) receptors on a poly[2,5-thiophenediyl-1,2-ethynediyl-1,4-phenylenediyl-1,2-ethynediyl] (PPETE) backbone, showed significant quenching when copper(II) was added. Tmeda-PPETE polymer preloaded with copper(II) was found to be a fluorescent "turn-on" sensor for iron cations. Additional investigation of this metallopolymer revealed a selective sensory system toward carbonate and phosphorus anions through a competitive binding of copper(II) between the polymer tmeda-PPETE and the anions. Fluorescent turn-on response under systematically varied pH was affected by the equilibrium shift of the ionization of polyprotic ions. A sterically hindered pentiptycene group was introduced to the PPETE polymer backbone aiming to reduce aggregation and self-quenching in the solid state. A new FCP, tmeda-PPpETE (poly[(pentiptycene ethynylene)-alt-(thienylene ethynylene)] with tmeda receptors, has been designed and synthesized via Sonogashira cross-coupling reaction. Absorption and emission spectra of tmeda-PPpETE showed blue shifting from tmeda-PPETE, suggesting increased rigidity of polymer backbone. Tmeda-PPpETE showed a high selectivity towards copper(II) with improved sensitivity compared to tmeda-PPETE. The fluorescent quenching response is over 120-fold at emission maximum, and the detection limit is 1.04 ppb, significantly lower than the EPA action level of 1.3 ppm for copper(II). A small turn-off fluorescent response of tmeda-PPpETE was also observed upon addition of iron cations. To further investigate the interaction between pentiptycene containing polymers and iron cations, tmpda-PPpETE containing N,N,N'-trimethylpropylenediamino (tmpda) receptors was designed and synthesized. The absorption and emission spectra for tmpda-PPpETE were analogous to those of tmeda-PPpETE, with a higher quantum yield for tmpda-PPpETE. The cation selectivity test in solution showed selective fluorescent quenching for iron cations. Investigation of the polymer-iron interaction showed that two binding mechanisms were involved. This is the first report of pentiptycene-derived polymer participating in a metal complex formation. By using 1,3,5-triethynylbenzene as the linker group, a network of PPETE polymer backbone loaded with tmeda receptors was designed and synthesized. This transformed the linear FCP, tmeda-PPETE into a network polymer. Two derivatives of this polymer were also successfully synthesized. The metal cation selectivity test showed similar fluorescent response as tmeda-PPETE, which revealed the potential in developing solid state sensors.

Afocal optical flow sensor for reducing vertical height sensitivity in indoor robot localization and navigation.

PubMed

Yi, Dong-Hoon; Lee, Tae-Jae; Cho, Dong-Il Dan

2015-05-13

This paper introduces a novel afocal optical flow sensor (OFS) system for odometry estimation in indoor robotic navigation. The OFS used in computer optical mouse has been adopted for mobile robots because it is not affected by wheel slippage. Vertical height variance is thought to be a dominant factor in systematic error when estimating moving distances in mobile robots driving on uneven surfaces. We propose an approach to mitigate this error by using an afocal (infinite effective focal length) system. We conducted experiments in a linear guide on carpet and three other materials with varying sensor heights from 30 to 50 mm and a moving distance of 80 cm. The same experiments were repeated 10 times. For the proposed afocal OFS module, a 1 mm change in sensor height induces a 0.1% systematic error; for comparison, the error for a conventional fixed-focal-length OFS module is 14.7%. Finally, the proposed afocal OFS module was installed on a mobile robot and tested 10 times on a carpet for distances of 1 m. The average distance estimation error and standard deviation are 0.02% and 17.6%, respectively, whereas those for a conventional OFS module are 4.09% and 25.7%, respectively.

The Cramér-Rao Bounds and Sensor Selection for Nonlinear Systems with Uncertain Observations.

PubMed

Wang, Zhiguo; Shen, Xiaojing; Wang, Ping; Zhu, Yunmin

2018-04-05

This paper considers the problems of the posterior Cramér-Rao bound and sensor selection for multi-sensor nonlinear systems with uncertain observations. In order to effectively overcome the difficulties caused by uncertainty, we investigate two methods to derive the posterior Cramér-Rao bound. The first method is based on the recursive formula of the Cramér-Rao bound and the Gaussian mixture model. Nevertheless, it needs to compute a complex integral based on the joint probability density function of the sensor measurements and the target state. The computation burden of this method is relatively high, especially in large sensor networks. Inspired by the idea of the expectation maximization algorithm, the second method is to introduce some 0-1 latent variables to deal with the Gaussian mixture model. Since the regular condition of the posterior Cramér-Rao bound is unsatisfied for the discrete uncertain system, we use some continuous variables to approximate the discrete latent variables. Then, a new Cramér-Rao bound can be achieved by a limiting process of the Cramér-Rao bound of the continuous system. It avoids the complex integral, which can reduce the computation burden. Based on the new posterior Cramér-Rao bound, the optimal solution of the sensor selection problem can be derived analytically. Thus, it can be used to deal with the sensor selection of a large-scale sensor networks. Two typical numerical examples verify the effectiveness of the proposed methods.

Sulfadiazine-selective determination in aquaculture environment: selective potentiometric transduction by neutral or charged ionophores.

PubMed

Almeida, S A A; Heitor, A M; Montenegro, M C B S M; Sales, M G F

2011-09-15

Solid-contact sensors for the selective screening of sulfadiazine (SDZ) in aquaculture waters are reported. Sensor surfaces were made from PVC membranes doped with tetraphenylporphyrin-manganese(III) chloride, α-cyclodextrin, β-cyclodextrin, or γ-cyclodextrin ionophores that were dispersed in plasticizer. Some membranes also presented a positive or a negatively charged additive. Phorphyrin-based sensors relied on a charged carrier mechanism. They exhibited a near-Nernstian response with slopes of 52 mV decade(-1) and detection limits of 3.91×10(-5) mol L(-1). The addition of cationic lipophilic compounds to the membrane originated Nernstian behaviours, with slopes ranging 59.7-62.0 mV decade(-1) and wider linear ranges. Cyclodextrin-based sensors acted as neutral carriers. In general, sensors with positively charged additives showed an improved potentiometric performance when compared to those without additive. Some SDZ selective membranes displayed higher slopes and extended linear concentration ranges with an increasing amount of additive (always <100% ionophore). The sensors were independent from the pH of test solutions within 2-7. The sensors displayed fast response, always <15s. In general, a good discriminating ability was found in real sample environment. The sensors were successfully applied to the fast screening of SDZ in real waters samples from aquaculture fish farms. The method offered the advantages of simplicity, accuracy, and automation feasibility. The sensing membrane may contribute to the development of small devices allowing in locus measurements of sulfadiazine or parent-drugs. Copyright © 2011 Elsevier B.V. All rights reserved.

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

Battery-free radio frequency identification (RFID) sensors for food quality and safety

PubMed Central

Potyrailo, Radislav A.; Nagraj, Nandini; Tang, Zhexiong; Mondello, Frank J.; Surman, Cheryl; Morris, William

2012-01-01

The market demands for new sensors for food quality and safety stimulate the development of new sensing technologies that can provide an unobtrusive sensor form factor, battery-free operation, and minimal sensor cost. Intelligent labeling of food products to indicate and report their freshness and other conditions is one of important possible applications of such new sensors. We have applied passive (battery-free) radio frequency identification (RFID) sensors for highly sensitive and selective detection of food freshness and bacterial growth. In these sensors, the electric field generated in the RFID sensor antenna extends out from the plane of the RFID sensor and is affected by the ambient environment providing the opportunity for sensing. This environment may be in the form of a food sample within the electric field of the sensing region or a sensing film deposited onto the sensor antenna. Examples of applications include monitoring of freshness of milk, freshness of fish, and bacterial growth in a solution. Unlike other food freshness monitoring approaches that require a thin film battery for operation of an RFID sensor and fabrication of custom-made sensors, our developed passive RFID sensing approach combines advantages of both battery-free and cost-effective sensor design and offers response selectivity that is impossible to achieve with other individual sensors. PMID:22881825

Battery-free radio frequency identification (RFID) sensors for food quality and safety.

PubMed

Potyrailo, Radislav A; Nagraj, Nandini; Tang, Zhexiong; Mondello, Frank J; Surman, Cheryl; Morris, William

2012-09-05

Market demands for new sensors for food quality and safety stimulate the development of new sensing technologies that can provide an unobtrusive sensor form, battery-free operation, and minimal sensor cost. Intelligent labeling of food products to indicate and report their freshness and other conditions is one important possible application of such new sensors. This study applied passive (battery-free) radio frequency identification (RFID) sensors for the highly sensitive and selective detection of food freshness and bacterial growth. In these sensors, the electric field generated in the RFID sensor antenna extends from the plane of the RFID sensor and is affected by the ambient environment, providing the opportunity for sensing. This environment may be in the form of a food sample within the electric field of the sensing region or a sensing film deposited onto the sensor antenna. Examples of applications include monitoring of milk freshness, fish freshness, and bacterial growth in a solution. Unlike other food freshness monitoring approaches that require a thin film battery for operation of an RFID sensor and fabrication of custom-made sensors, the passive RFID sensing approach developed here combines the advantages of both battery-free and cost-effective sensor design and offers response selectivity that is impossible to achieve with other individual sensors.

Batch-processed semiconductor gas sensor array for the selective detection of NOx in automotive exhaust gas

NASA Astrophysics Data System (ADS)

Jang, Hani; Kim, Minki; Kim, Yongjun

2016-12-01

This paper reports on a semiconductor gas sensor array to detect nitrogen oxides (NOx) in automotive exhaust gas. The proposed semiconductor gas sensor array consisted of one common electrode and three individual electrodes to minimize the size of the sensor array, and three sensing layers [TiO2 + SnO2 (15 wt%), SnO2, and Ga2O3] were deposited using screen printing. In addition, sensing materials were sintered under the same conditions in order to take advantage of batch processing. The sensing properties of the proposed sensor array were verified by experimental measurements, and the selectivity improved by using pattern recognition.

Sensor placement in nuclear reactors based on the generalized empirical interpolation method

NASA Astrophysics Data System (ADS)

Argaud, J.-P.; Bouriquet, B.; de Caso, F.; Gong, H.; Maday, Y.; Mula, O.

2018-06-01

In this paper, we apply the so-called generalized empirical interpolation method (GEIM) to address the problem of sensor placement in nuclear reactors. This task is challenging due to the accumulation of a number of difficulties like the complexity of the underlying physics and the constraints in the admissible sensor locations and their number. As a result, the placement, still today, strongly relies on the know-how and experience of engineers from different areas of expertise. The present methodology contributes to making this process become more systematic and, in turn, simplify and accelerate the procedure.

Integrated embedded frequency selective surface sensors for structural health monitoring.

DOT National Transportation Integrated Search

2014-08-01

The objective of this project is to design an embedded sensor element capable of characterizing mechanical properties including shear strain. This element will be designed using a Frequency Selective Surface (FSS) approach, and will be intended for i...

Influence of time and length size feature selections for human activity sequences recognition.

PubMed

Fang, Hongqing; Chen, Long; Srinivasan, Raghavendiran

2014-01-01

In this paper, Viterbi algorithm based on a hidden Markov model is applied to recognize activity sequences from observed sensors events. Alternative features selections of time feature values of sensors events and activity length size feature values are tested, respectively, and then the results of activity sequences recognition performances of Viterbi algorithm are evaluated. The results show that the selection of larger time feature values of sensor events and/or smaller activity length size feature values will generate relatively better results on the activity sequences recognition performances. © 2013 ISA Published by ISA All rights reserved.

A DMAP Program for the Selection of Accelerometer Locations in MSC/NASTRAN

NASA Technical Reports Server (NTRS)

Peck, Jeff; Torres, Isaias

2004-01-01

A new program for selecting sensor locations has been written in the DMAP (Direct Matrix Abstraction Program) language of MSC/NASTRAN. The program implements the method of Effective Independence for selecting sensor locations, and is executed within a single NASTRAN analysis as a "rigid format alter" to the normal modes solution sequence (SOL 103). The user of the program is able to choose among various analysis options using Case Control and Bulk Data entries. Algorithms tailored for the placement of both uni-axial and tri- axial accelerometers are available, as well as several options for including the model s mass distribution into the calculations. Target modes for the Effective Independence analysis are selected from the MSC/NASTRAN ASET modes calculated by the "SOL 103" solution sequence. The initial candidate sensor set is also under user control, and is selected from the ASET degrees of freedom. Analysis results are printed to the MSCINASTRAN output file (*.f06), and may include the current candidate sensors set, and their associated Effective Independence distribution, at user specified iteration intervals. At the conclusion of the analysis, the model is reduced to the final sensor set, and frequencies and orthogonality checks are printed. Example results are given for a pre-test analysis of NASA s five-segment solid rocket booster modal test.

A novel, highly sensitive, selective, reversible and turn-on chemi-sensor based on Schiff base for rapid detection of Cu(II)

NASA Astrophysics Data System (ADS)

Saleh, Sayed M.; Ali, Reham; Ali, Ibrahim A. I.

2017-08-01

In this work, a novel optical fluoro-chemisensor was designed and synthesized for copper (II) ions detection. The sensor film is created by embedded N,N-Bis(2-hydroxo-5-bromobenzyl)ethylenediamine in poly vinyl chloride (PVC) film in presence of dioctyl phthalate (DOP) as plasticizer. The receptor Schiff base reveals "off-on" mode with high selectivity, significant sensitivity to Cu(II) ions. The selectivity of optical sensor for Cu(II) ions is the result of chelation enhanced fluorescence (CHEF). The optimal conditions of pH and response time at which higher efficiency of sensor film is performed was found to be 6.8 and 2.48 min. The possible interference of other metal ions in solution was examined in presence of different types of metal ions. This film shows high selectivity and ultra-sensitivity with low detection limit LOD (1.1 × 10- 8 M). Thus, these considerable properties make it viable to monitor copper metal ions within very low concentration range (0-15 × 10- 6 M Cu(II)) and highly selective even in the presence of different types of metal ions. The sensor reversibility was achieved by utilizing EDTA solution with concentration of 0.1 M solution.

A highly selective and picomolar level photoelectrochemical sensor for PCB 101 detection in environmental water samples.

PubMed

Shi, Huijie; Zhao, Jinzhi; Wang, Yingling; Zhao, Guohua

2016-07-15

A highly selective and sensitive photoelectrochemical (PEC) sensor was fabricated for fast and convenient detection of PCB 101 in environmental water samples with a low detection limit of 1.0×10(-14)molL(-1) based on single crystalline TiO2 nanorods (NRs). By integration with molecular imprinting (MI) technique, the PEC sensor's selectivity towards PCB 101 was significantly improved, so that the interference caused by 100-fold excess of PCB 126 and PCB 77 which had similar structure with PCB 101 was below 37%, not to mention other coexisted pollutants. This high selectivity could be attributed to the high-quality expression of the molecular imprinting sites on the rigid and smooth surface of single crystalline TiO2 NRs on which PCB 101 could be selectively and preferentially adsorbed. The oriented and multiple halogen bonds formed between PCB 101 and the molecular imprinting sites played a critical role in improving the recognition ability of the PEC sensor. Meanwhile, the one dimensional nanorods structure of TiO2 was beneficial for the efficient separation of photogenerated electrons and holes, leading to enhanced photocurrent response and further improving the sensitivity of the PEC sensor. Copyright © 2016 Elsevier B.V. All rights reserved.

Molecular imprinting ratiometric fluorescence sensor for highly selective and sensitive detection of phycocyanin.

PubMed

Wang, Xiaoyan; Yu, Jialuo; Kang, Qi; Shen, Dazhong; Li, Jinhua; Chen, Lingxin

2016-03-15

A facile strategy was developed to prepare molecular imprinting ratiometric fluorescence sensor for highly selective and sensitive detection of phycocyanin (PC) based on fluorescence resonance energy transfer (FRET), via a sol-gel polymerization process using nitrobenzoxadiazole (NBD) as fluorescent signal source. The ratio of two fluorescence peak emission intensities of NBD and PC was utilized to determine the concentration of PC, which could effectively reduce the background interference and fluctuation of diverse conditions. As a result, this sensor obtained high sensitivity with a low detection limit of 0.14 nM within 6 min, and excellent recognition specificity for PC over its analogues with a high imprinting factor of 9.1. Furthermore, the sensor attained high recoveries in the range of 93.8-110.2% at three spiking levels of PC, with precisions below 4.7% in seawater and lake water samples. The developed sensor strategy demonstrated simplicity, reliability, rapidity, high selectivity and high sensitivity, proving to be a feasible way to develop high efficient fluorescence sensors and thus potentially applicable for ultratrace analysis of complicated matrices. Copyright © 2015 Elsevier B.V. All rights reserved.

Highly Sensitive and Selective Hydrogen Gas Sensor Using the Mesoporous SnO₂ Modified Layers.

PubMed

Xue, Niuzi; Zhang, Qinyi; Zhang, Shunping; Zong, Pan; Yang, Feng

2017-10-14

It is important to improve the sensitivities and selectivities of metal oxide semiconductor (MOS) gas sensors when they are used to monitor the state of hydrogen in aerospace industry and electronic field. In this paper, the ordered mesoporous SnO₂ (m-SnO₂) powders were prepared by sol-gel method, and the morphology and structure were characterized by X-ray diffraction analysis (XRD), transmission electron microscope (TEM) and Brunauer-Emmett-Teller (BET). The gas sensors were fabricated using m-SnO₂ as the modified layers on the surface of commercial SnO₂ (c-SnO₂) by screen printing technology, and tested for gas sensing towards ethanol, benzene and hydrogen with operating temperatures ranging from 200 °C to 400 °C. Higher sensitivity was achieved by using the modified m-SnO₂ layers on the c-SnO₂ gas sensor, and it was found that the S(c/m2) sensor exhibited the highest response (Ra/Rg = 22.2) to 1000 ppm hydrogen at 400 °C. In this paper, the mechanism of the sensitivity and selectivity improvement of the gas sensors is also discussed.

Potentiometric sensors for the selective determination of sulbutiamine.

PubMed

Ahmed, M A; Elbeshlawy, M M

1999-11-01

Five novel polyvinyl chloride (PVC) matrix membrane sensors for the selective determination of sulbutiamine (SBA) cation are described. These sensors are based on molybdate, tetraphenylborate, reineckate, phosphotun gestate and phosphomolybdate, as possible ion-pairing agents. These sensors display rapid near-Nernstian stable response over a relatively wide concentration range 1x10(-2)-1x10(-6) M of sulbutiamine, with calibration slopes 28 32.6 mV decade(-1) over a reasonable pH range 2-6. The proposed sensors proved to have a good selectivity for SBA over some inorganic and organic cations. The five potentiometric sensors were applied successfully in the determination of SBA in a pharmaceutical preparation (arcalion-200) using both direct potentiometry and potentiometric titration. Direct potentiometric determination of microgram quantities of SBA gave average recoveries of 99.4 and 99.3 with mean standard deviation of 0.7 and 0.3 for pure SBA and arcalion-200 formulation respectively. Potentiometric titration of milligram quantities of SBA gave average recoveries of 99.3 and 98.7% with mean standard deviation of 0.7 and 1.2 for pure SBA and arcalion-200 formulation, respectively.

Tattoo-based potentiometric ion-selective sensors for epidermal pH monitoring.

PubMed

Bandodkar, Amay J; Hung, Vinci W S; Jia, Wenzhao; Valdés-Ramírez, Gabriela; Windmiller, Joshua R; Martinez, Alexandra G; Ramírez, Julian; Chan, Garrett; Kerman, Kagan; Wang, Joseph

2013-01-07

This article presents the fabrication and characterization of novel tattoo-based solid-contact ion-selective electrodes (ISEs) for non-invasive potentiometric monitoring of epidermal pH levels. The new fabrication approach combines commercially available temporary transfer tattoo paper with conventional screen printing and solid-contact polymer ISE methodologies. The resulting tattoo-based potentiometric sensors exhibit rapid and sensitive response to a wide range of pH changes with no carry-over effects. Furthermore, the tattoo ISE sensors endure repetitive mechanical deformation, which is a key requirement of wearable and epidermal sensors. The flexible and conformal nature of the tattoo sensors enable them to be mounted on nearly any exposed skin surface for real-time pH monitoring of the human perspiration, as illustrated from the response during a strenuous physical activity. The resulting tattoo-based ISE sensors offer considerable promise as wearable potentiometric sensors suitable for diverse applications.

High-Sensitivity and Low-Power Flexible Schottky Hydrogen Sensor Based on Silicon Nanomembrane.

PubMed

Cho, Minkyu; Yun, Jeonghoon; Kwon, Donguk; Kim, Kyuyoung; Park, Inkyu

2018-04-18

High-performance and low-power flexible Schottky diode-based hydrogen sensor was developed. The sensor was fabricated by releasing Si nanomembrane (SiNM) and transferring onto a plastic substrate. After the transfer, palladium (Pd) and aluminum (Al) were selectively deposited as a sensing material and an electrode, respectively. The top-down fabrication process of flexible Pd/SiNM diode H 2 sensor is facile compared to other existing bottom-up fabricated flexible gas sensors while showing excellent H 2 sensitivity (Δ I/ I 0 > 700-0.5% H 2 concentrations) and fast response time (τ 10-90 = 22 s) at room temperature. In addition, selectivity, humidity, and mechanical tests verify that the sensor has excellent reliability and robustness under various environments. The operating power consumption of the sensor is only in the nanowatt range, which indicates its potential applications in low-power portable and wearable electronics.

Understanding selective molecular recognition in integrated carbon nanotube-polymer sensors by simulating physical analyte binding on carbon nanotube-polymer scaffolds.

PubMed

Lin, Shangchao; Zhang, Jingqing; Strano, Michael S; Blankschtein, Daniel

2014-08-28

Macromolecular scaffolds made of polymer-wrapped single-walled carbon nanotubes (SWCNTs) have been explored recently (Zhang et al., Nature Nanotechnology, 2013) as a new class of molecular-recognition motifs. However, selective analyte recognition is still challenging and lacks the underlying fundamental understanding needed for its practical implementation in biological sensors. In this report, we combine coarse-grained molecular dynamics (CGMD) simulations, physical adsorption/binding theories, and photoluminescence (PL) experiments to provide molecular insight into the selectivity of such sensors towards a large set of biologically important analytes. We find that the physical binding affinities of the analytes on a bare SWCNT partially correlate with their distribution coefficients in a bulk water/octanol system, suggesting that the analyte hydrophobicity plays a key role in determining the binding affinities of the analytes considered, along with the various specific interactions between the analytes and the polymer anchor groups. Two distinct categories of analytes are identified to demonstrate a complex picture for the correlation between optical sensor signals and the simulated binding affinities. Specifically, a good correlation was found between the sensor signals and the physical binding affinities of the three hormones (estradiol, melatonin, and thyroxine), the neurotransmitter (dopamine), and the vitamin (riboflavin) to the SWCNT-polymer scaffold. The four amino acids (aspartate, glycine, histidine, and tryptophan) and the two monosaccharides (fructose and glucose) considered were identified as blank analytes which are unable to induce sensor signals. The results indicate great success of our physical adsorption-based model in explaining the ranking in sensor selectivities. The combined framework presented here can be used to screen and select polymers that can potentially be used for creating synthetic molecular recognition motifs.

Peptide–Nanowire Hybrid Materials for Selective Sensing of Small Molecules

PubMed Central

McAlpine, Michael C.; Agnew, Heather D.; Rohde, Rosemary D.; Blanco, Mario; Ahmad, Habib; Stuparu, Andreea D.; Goddard, William A.

2013-01-01

The development of a miniaturized sensing platform for the selective detection of chemical odorants could stimulate exciting scientific and technological opportunities. Oligopeptides are robust substrates for the selective recognition of a variety of chemical and biological species. Likewise, semiconducting nanowires are extremely sensitive gas sensors. Here we explore the possibilities and chemistries of linking peptides to silicon nanowire sensors for the selective detection of small molecules. The silica surface of the nanowires is passivated with peptides using amide coupling chemistry. The peptide/nanowire sensors can be designed, through the peptide sequence, to exhibit orthogonal responses to acetic acid and ammonia vapors, and can detect traces of these gases from “chemically camouflaged” mixtures. Through both theory and experiment, we find that this sensing selectivity arises from both acid/base reactivity and from molecular structure. These results provide a model platform for what can be achieved in terms of selective and sensitive “electronic noses.” PMID:18576642

Perimeter intrusion detection and assessment system

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

Eaton, M.J.; Jacobs, J.; McGovern, D.E.

1977-11-01

To obtain an effective perimeter intrusion detection system requires careful sensor selection, procurement, and installation. The selection process involves a thorough understanding of the unique site features and how these features affect the performance of each type of sensor. It is necessary to develop procurement specifications to establish acceptable sensor performance limits. Careful explanation and inspection of critical installation dimensions is required during on-site construction. The implementation of these activities at a particular site is discussed.

Advanced Standoff Interdiction Weapon and Sensor System. Volume 1

DTIC Science & Technology

1972-06-15

interdiction system to counter enemy infiltration along the water - ways and roads of Southeast Asia. The sensors were selected to give the helicopter a...was con- ceived as an interdiction system to counter enemy infiltration along the water - ways ard roads of Southeast Asia. The sensors were selected...controller enabled him to fly the helicopter to intercept the moving target. Mount camera film was exposed while the target was being fracked by the

Environmental Technology Verification Report for Instrumentation Northwest, Inc., Aquistar® TempHion Smart Sensor and Datalogger Nitrate-specific Ion-selective Electrode for Groundwater Remediation Monitoring

EPA Science Inventory

Environmental Technology Verification Report for Instrumentation Northwest, Inc., Aquistar® TempHion Smart Sensor and Datalogger Nitrate-specific Ion-selective Electrode for Groundwater Remediation Monitoring

Common-Path Interferometric Wavefront Sensing for Space Telescopes

NASA Technical Reports Server (NTRS)

Wallace, James Kent

2011-01-01

This paper presents an optical configuration for a common-path phase-shifting interferometric wavefront sensor.1 2 This sensor has a host of attractive features which make it well suited for space-based adaptive optics. First, it is strictly reflective and therefore operates broadband, second it is common mode and therefore does not suffer from systematic errors (like vibration) that are typical in other interferometers, third it is a phase-shifting interferometer and therefore benefits from both the sensitivity of interferometric sensors as well as the noise rejection afforded by synchronous detection. Unlike the Shack-Hartman wavefront sensor, it has nearly uniform sensitivity to all pupil modes. Optical configuration, theory and simulations for such a system will be discussed along with predicted performance.

Development of a drone equipped with optimized sensors for nuclear and radiological risk characterization

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

Boudergui, K.; Carrel, F.; Domenech, T.

2011-07-01

The MOBISIC project, funded by the Systematic Paris-Region cluster, is being developed in the context of local crisis (attack bombing in urban environment, in confined space such as an underground train tunnel etc.) or specific event securing (soccer world cup, political meeting etc.). It consists in conceiving, developing and experimenting a mobile, modular ('plug and play') and multi-sensors securing system. In this project, CEA LIST has suggested different solutions for nuclear risks detection and identification. It results in embedding a CZT sensor and a gamma camera in an indoor drone. This article first presents the different modifications carried out onmore » the UAV and different sensors, and focuses then on the experimental performances. (authors)« less

Fabrication and Performance of All-Solid-State Chloride Sensors in Synthetic Concrete Pore Solutions

PubMed Central

Gao, Xiaojian; Zhang, Jian; Yang, Yingzi; Deng, Hongwei

2010-01-01

One type of all-solid-state chloride sensor was fabricated using a MnO2 electrode and a Ag/AgCl electrode. The potentiometric response of the sensor to chloride in synthetic concrete pore solutions was systematically studied, and the polarization performance was also evaluated. The results show a good linear relationship between the potential reading of the sensor and the logarithm of chloride activity (concentration ranges from 0.05 to 5.0 M), and the potential value remains stable with increasing immersion time. The existence of K+, Ca2+, Na+ and SO42− ions have little influence on the potentiometric response of the sensor to chloride, but the pH has a significant influence on the potential value of the sensor at low chloride concentration. The potential reading of the sensor increases linearly with the solution temperature over the range from 5 to 45 °C. Meanwhile, an excellent polarization behavior is proven by galvanostatic and potentiodynamic tests. All of the results reveal that the developed sensor has a great potential for monitoring chloride ions in concrete environments. PMID:22163467

Fabrication and performance of all-solid-state chloride sensors in synthetic concrete pore solutions.

PubMed

Gao, Xiaojian; Zhang, Jian; Yang, Yingzi; Deng, Hongwei

2010-01-01

One type of all-solid-state chloride sensor was fabricated using a MnO(2) electrode and a Ag/AgCl electrode. The potentiometric response of the sensor to chloride in synthetic concrete pore solutions was systematically studied, and the polarization performance was also evaluated. The results show a good linear relationship between the potential reading of the sensor and the logarithm of chloride activity (concentration ranges from 0.05 to 5.0 M), and the potential value remains stable with increasing immersion time. The existence of K(+), Ca(2+), Na(+) and SO(4) (2-) ions have little influence on the potentiometric response of the sensor to chloride, but the pH has a significant influence on the potential value of the sensor at low chloride concentration. The potential reading of the sensor increases linearly with the solution temperature over the range from 5 to 45 °C. Meanwhile, an excellent polarization behavior is proven by galvanostatic and potentiodynamic tests. All of the results reveal that the developed sensor has a great potential for monitoring chloride ions in concrete environments.

Low-Temperature Photochemically Activated Amorphous Indium-Gallium-Zinc Oxide for Highly Stable Room-Temperature Gas Sensors.

PubMed

Jaisutti, Rawat; Kim, Jaeyoung; Park, Sung Kyu; Kim, Yong-Hoon

2016-08-10

We report on highly stable amorphous indium-gallium-zinc oxide (IGZO) gas sensors for ultraviolet (UV)-activated room-temperature detection of volatile organic compounds (VOCs). The IGZO sensors fabricated by a low-temperature photochemical activation process and exhibiting two orders higher photocurrent compared to conventional zinc oxide sensors, allowed high gas sensitivity against various VOCs even at room temperature. From a systematic analysis, it was found that by increasing the UV intensity, the gas sensitivity, response time, and recovery behavior of an IGZO sensor were strongly enhanced. In particular, under an UV intensity of 30 mW cm(-2), the IGZO sensor exhibited gas sensitivity, response time and recovery time of 37%, 37 and 53 s, respectively, against 750 ppm concentration of acetone gas. Moreover, the IGZO gas sensor had an excellent long-term stability showing around 6% variation in gas sensitivity over 70 days. These results strongly support a conclusion that a low-temperature solution-processed amorphous IGZO film can serve as a good candidate for room-temperature VOCs sensors for emerging wearable electronics.

Intrusion recognition for optic fiber vibration sensor based on the selective attention mechanism

NASA Astrophysics Data System (ADS)

Xu, Haiyan; Xie, Yingjuan; Li, Min; Zhang, Zhuo; Zhang, Xuewu

2017-11-01

Distributed fiber-optic vibration sensors receive extensive investigation and play a significant role in the sensor panorama. A fiber optic perimeter detection system based on all-fiber interferometric sensor is proposed, through the back-end analysis, processing and intelligent identification, which can distinguish effects of different intrusion activities. In this paper, an intrusion recognition based on the auditory selective attention mechanism is proposed. Firstly, considering the time-frequency of vibration, the spectrogram is calculated. Secondly, imitating the selective attention mechanism, the color, direction and brightness map of the spectrogram is computed. Based on these maps, the feature matrix is formed after normalization. The system could recognize the intrusion activities occurred along the perimeter sensors. Experiment results show that the proposed method for the perimeter is able to differentiate intrusion signals from ambient noises. What's more, the recognition rate of the system is improved while deduced the false alarm rate, the approach is proved by large practical experiment and project.

Polymeric Optical Sensors for Selective and Sensitive Nitrite Detection Using Cobalt(III) Corrole and Rh(III) Porphyrin as Ionophores

PubMed Central

Yang, Si; Wo, Yaqi; Meyerhoff, Mark E.

2014-01-01

Cobalt(III) 5, 10, 15-tris(4-tert-butylphenyl) corrole with a triphenylphosphine axial ligand and rhodium(III) 5,10,15,20-tetra(p-tert-butylphenyl)porphyrin are incorporated into plasticized poly(vinyl chloride) films to fabricate nitrite-selective bulk optodes via absorbance measurements. The resulting films yield sensitive, fast and fully reversible response toward nitrite with significantly enhanced nitrite selectivity over other anions including lipophilic anions such as thiocyanate and perchlorate. The selectivity patterns differ greatly from the Hofmeister series based on anion lipophilicity and are consistent with selectivity obtained with potentiometric sensors based on the same ionophores. The optical nitrite sensors are shown to be useful for detecting rates of emission of nitric oxide (NO) from NO releasing polymers containing S-nitroso-N-acetyl-penicillamine. PMID:25150700

A highly sensitive hydrogen sensor with gas selectivity using a PMMA membrane-coated Pd nanoparticle/single-layer graphene hybrid.

PubMed

Hong, Juree; Lee, Sanggeun; Seo, Jungmok; Pyo, Soonjae; Kim, Jongbaeg; Lee, Taeyoon

2015-02-18

A polymer membrane-coated palladium (Pd) nanoparticle (NP)/single-layer graphene (SLG) hybrid sensor was fabricated for highly sensitive hydrogen gas (H2) sensing with gas selectivity. Pd NPs were deposited on SLG via the galvanic displacement reaction between graphene-buffered copper (Cu) and Pd ion. During the galvanic displacement reaction, graphene was used as a buffer layer, which transports electrons from Cu for Pd to nucleate on the SLG surface. The deposited Pd NPs on the SLG surface were well-distributed with high uniformity and low defects. The Pd NP/SLG hybrid was then coated with polymer membrane layer for the selective filtration of H2. Because of the selective H2 filtration effect of the polymer membrane layer, the sensor had no responses to methane, carbon monoxide, or nitrogen dioxide gas. On the contrary, the PMMA/Pd NP/SLG hybrid sensor exhibited a good response to exposure to 2% H2: on average, 66.37% response within 1.81 min and recovery within 5.52 min. In addition, reliable and repeatable sensing behaviors were obtained when the sensor was exposed to different H2 concentrations ranging from 0.025 to 2%.

A Quantitative Evaluation of Drive Pattern Selection for Optimizing EIT-Based Stretchable Sensors

PubMed Central

Nefti-Meziani, Samia; Carbonaro, Nicola

2017-01-01

Electrical Impedance Tomography (EIT) is a medical imaging technique that has been recently used to realize stretchable pressure sensors. In this method, voltage measurements are taken at electrodes placed at the boundary of the sensor and are used to reconstruct an image of the applied touch pressure points. The drawback with EIT-based sensors, however, is their low spatial resolution due to the ill-posed nature of the EIT reconstruction. In this paper, we show our performance evaluation of different EIT drive patterns, specifically strategies for electrode selection when performing current injection and voltage measurements. We compare voltage data with Signal-to-Noise Ratio (SNR) and Boundary Voltage Changes (BVC), and study image quality with Size Error (SE), Position Error (PE) and Ringing (RNG) parameters, in the case of one-point and two-point simultaneous contact locations. The study shows that, in order to improve the performance of EIT based sensors, the electrode selection strategies should dynamically change correspondingly to the location of the input stimuli. In fact, the selection of one drive pattern over another can improve the target size detection and position accuracy up to 4.7% and 18%, respectively. PMID:28858252

A Quantitative Evaluation of Drive Pattern Selection for Optimizing EIT-Based Stretchable Sensors.

PubMed

Russo, Stefania; Nefti-Meziani, Samia; Carbonaro, Nicola; Tognetti, Alessandro

2017-08-31

Electrical Impedance Tomography (EIT) is a medical imaging technique that has been recently used to realize stretchable pressure sensors. In this method, voltage measurements are taken at electrodes placed at the boundary of the sensor and are used to reconstruct an image of the applied touch pressure points. The drawback with EIT-based sensors, however, is their low spatial resolution due to the ill-posed nature of the EIT reconstruction. In this paper, we show our performance evaluation of different EIT drive patterns, specifically strategies for electrode selection when performing current injection and voltage measurements. We compare voltage data with Signal-to-Noise Ratio (SNR) and Boundary Voltage Changes (BVC), and study image quality with Size Error (SE), Position Error (PE) and Ringing (RNG) parameters, in the case of one-point and two-point simultaneous contact locations. The study shows that, in order to improve the performance of EIT based sensors, the electrode selection strategies should dynamically change correspondingly to the location of the input stimuli. In fact, the selection of one drive pattern over another can improve the target size detection and position accuracy up to 4.7% and 18%, respectively.

A selective iodide ion sensor electrode based on functionalized ZnO nanotubes.

PubMed

Ibupoto, Zafar Hussain; Khun, Kimleang; Willander, Magnus

2013-02-04

In this research work, ZnO nanotubes were fabricated on a gold coated glass substrate through chemical etching by the aqueous chemical growth method. For the first time a nanostructure-based iodide ion selective electrode was developed. The ZnO nanotubes were functionalized with miconazole ion exchanger and the electromotive force (EMF) was measured by the potentiometric method. The iodide ion sensor exhibited a linear response over a wide range of concentrations (1 × 10-6 to 1 × 10-1 M) and excellent sensitivity of -62 ± 1 mV/decade. The detection limit of the proposed sensor was found to be 5 × 10-7 M. The effects of pH, temperature, additive, plasticizer and stabilizer on the potential response of iodide ion selective electrode were also studied. The proposed iodide ion sensor demonstrated a fast response time of less than 5 s and high selectivity against common organic and the inorganic anions. All the obtained results revealed that the iodide ion sensor based on functionalized ZnO nanotubes may be used for the detection of iodide ion in environmental water samples, pharmaceutical products and other real samples.

A Selective Iodide Ion Sensor Electrode Based on Functionalized ZnO Nanotubes

PubMed Central

Ibupoto, Zafar Hussain; Khun, Kimleang; Willander, Magnus

2013-01-01

In this research work, ZnO nanotubes were fabricated on a gold coated glass substrate through chemical etching by the aqueous chemical growth method. For the first time a nanostructure-based iodide ion selective electrode was developed. The ZnO nanotubes were functionalized with miconazole ion exchanger and the electromotive force (EMF) was measured by the potentiometric method. The iodide ion sensor exhibited a linear response over a wide range of concentrations (1 × 10−6 to 1 × 10−1 M) and excellent sensitivity of −62 ± 1 mV/decade. The detection limit of the proposed sensor was found to be 5 × 10−7 M. The effects of pH, temperature, additive, plasticizer and stabilizer on the potential response of iodide ion selective electrode were also studied. The proposed iodide ion sensor demonstrated a fast response time of less than 5 s and high selectivity against common organic and the inorganic anions. All the obtained results revealed that the iodide ion sensor based on functionalized ZnO nanotubes may be used for the detection of iodide ion in environmental water samples, pharmaceutical products and other real samples. PMID:23385412

Potentiometric chemical sensors for the detection of paralytic shellfish toxins.

PubMed

Ferreira, Nádia S; Cruz, Marco G N; Gomes, Maria Teresa S R; Rudnitskaya, Alisa

2018-05-01

Potentiometric chemical sensors for the detection of paralytic shellfish toxins have been developed. Four toxins typically encountered in Portuguese waters, namely saxitoxin, decarbamoyl saxitoxin, gonyautoxin GTX5 and C1&C2, were selected for the study. A series of miniaturized sensors with solid inner contact and plasticized polyvinylchloride membranes containing ionophores, nine compositions in total, were prepared and their characteristics evaluated. Sensors displayed cross-sensitivity to four studied toxins, i.e. response to several toxins together with low selectivity. High selectivity towards paralytic shellfish toxins was observed in the presence of inorganic cations with selectivity coefficients ranging from 0.04 to 0.001 for Na + and K + and 3.6*10 -4 to 3.4*10 -5 for Ca 2+ . Detection limits were in the range from 0.25 to 0.9 μmolL -1 for saxitoxin and decarbamoyl saxitoxin, and from 0.08 to 1.8 μmolL -1 for GTX5 and C1&C2, which allows toxin detection at the concentration levels corresponding to the legal limits. Characteristics of the developed sensors allow their use in the electronic tongue multisensor system for simultaneous quantification of paralytic shellfish toxins. Copyright © 2018 Elsevier B.V. All rights reserved.

Rhodamine spirolactam sensors operated by sulfur-cooperated metal complexation

NASA Astrophysics Data System (ADS)

Heo, Gisuk; Lee, Dahye; Kim, Chi Gwan; Do, Jung Yun

2018-01-01

New rhodamine Schiff base sensors were developed to improve selective sensing by introducing sulfide, ester, and dithiocarbonate groups, as well as using ketones coupled to rhodamine-hydrazine. Metal sensing proceeded through the 1:1 complexation of the metal ion for most sensors in the presence of Cu2 + and Hg2 +. A sensor carrying a dithiocarbonate group responded selectively to Hg2 + showing a strong colorimetric change and intense fluorescence. The association constants of the sensors were determined from a linear plot performed at micro-molar concentrations to afford values in the range of 104. Sensing was interrupted at the initial time of Hg2 + exposure due to the isomerization of imine and preferential metal bonding of two dithiocarbonate groups regardless of the main structure of rhodamine. The sensors exhibited the reversible and reproducible performance for Hg2 + sensing.

Poly(3,6-diamino-9-ethylcarbazole) based molecularly imprinted polymer sensor for ultra-sensitive and selective detection of 17-β-estradiol in biological fluids.

PubMed

Liu, Weilu; Li, Haifeng; Yu, Shangmin; Zhang, Jiaxing; Zheng, Weihua; Niu, Liting; Li, Gengen

2018-05-01

In this work, we reported the synthesis of 3, 6-diamino-9-ethylcarbazole and its application as a new monomer for preparation of molecularly imprinted polymer (MIP) electrochemical sensor. The as prepared MIP sensor exhibited ultrahigh sensitivity and selectivity for the detection of 17-β-estradiol in attomolar levels (1 × 10 -18 molL -1 ). The sensor works by detecting the change of the interfacial impedance that is derived from recognition of 17-β-estradiol on the MIP layer. The MIP sensor based on 3, 6-diamino-9-ethylcarbazole monomer revealed better performance than that of unmodified carbazole monomer. The monomer/template ratio, electropolymerization scanning cycles, and the incubation pH values were optimised in order to obtain the best detection efficiency. Under the optimised condition, the MIP sensor exhibits a wide linear range from 1aM to 10μM (1 × 10 -18 ̶ 1 × 10 -5 molL -1 ). A low detection limit of 0.36aM (3.6 × 10 -19 molL -1 ) and a good selectivity towards structurally similar compounds were obtained. The proposed MIP sensor also exhibits long-term stability and applicability in human serum samples. These advantages enabled this MIP sensor to be a promising alternative of electrochemical sensor and may be extended to detection of other endogenous compounds. Copyright © 2018 Elsevier B.V. All rights reserved.

A 100-Year Review: Identification and genetic selection of economically important traits in dairy cattle.

PubMed

Miglior, Filippo; Fleming, Allison; Malchiodi, Francesca; Brito, Luiz F; Martin, Pauline; Baes, Christine F

2017-12-01

Over the past 100 yr, the range of traits considered for genetic selection in dairy cattle populations has progressed to meet the demands of both industry and society. At the turn of the 20th century, dairy farmers were interested in increasing milk production; however, a systematic strategy for selection was not available. Organized milk performance recording took shape, followed quickly by conformation scoring. Methodological advances in both genetic theory and statistics around the middle of the century, together with technological innovations in computing, paved the way for powerful multitrait analyses. As more sophisticated analytical techniques for traits were developed and incorporated into selection programs, production began to increase rapidly, and the wheels of genetic progress began to turn. By the end of the century, the focus of selection had moved away from being purely production oriented toward a more balanced breeding goal. This shift occurred partly due to increasing health and fertility issues and partly due to societal pressure and welfare concerns. Traits encompassing longevity, fertility, calving, health, and workability have now been integrated into selection indices. Current research focuses on fitness, health, welfare, milk quality, and environmental sustainability, underlying the concentrated emphasis on a more comprehensive breeding goal. In the future, on-farm sensors, data loggers, precision measurement techniques, and other technological aids will provide even more data for use in selection, and the difficulty will lie not in measuring phenotypes but rather in choosing which traits to select for. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Procedures for the Systematic Evaluation of Remote Sensor Performance and Quantitative Mission Planning

DTIC Science & Technology

1976-08-01

bare soil and grass areas, Vicksburg, Mississippi . ....... .. 101 25 Schematic of typical thermal IR scanner system . . . . 103 26 Sensor spatial...following categories: a. Soils b. Vegetation S. Topography d. Bedrock It is the knowledge of these characteristics and their distribution within the...necessary to know the changes in soil , vegetation, topography, and bedrock characteristics as a function of time as well as their spa- tial distribution at

Flow-driven triboelectric generator for directly powering a wireless sensor node.

PubMed

Wang, Shuhua; Mu, Xiaojing; Yang, Ya; Sun, Chengliang; Gu, Alex Yuandong; Wang, Zhong Lin

2015-01-14

A triboelectric generator (TEG) for scavenging flow-driven mechanical -energy to directly power a wireless sensor node is demonstrated for the first time. The output performances of TEGs with different dimensions are systematically investigated, indicating that a largest output power of about 3.7 mW for one TEG can be achieved under an external load of 3 MΩ. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of Mathematical Models in Support of AFGL Atmospheric Studies.

DTIC Science & Technology

1980-05-15

can systematically design a sensor and predict its sensitivity, false alarm rate and detection probability. When one considers a mosaic staring sensor...data base to improve the Air Force’s ability to specify and predict geomagnetic activity. This information is very useful in the studying of propagation...storms or proton showers which cause these disturbances cannot be predicted without a knowledge of the solar activity which causes them. During periods

Lateral position detection and control for friction stir systems

DOEpatents

Fleming, Paul; Lammlein, David; Cook, George E.; Wilkes, Don Mitchell; Strauss, Alvin M.; Delapp, David; Hartman, Daniel A.

2010-12-14

A friction stir system for processing at least a first workpiece includes a spindle actuator coupled to a rotary tool comprising a rotating member for contacting and processing the first workpiece. A detection system is provided for obtaining information related to a lateral alignment of the rotating member. The detection system comprises at least one sensor for measuring a force experienced by the rotary tool or a parameter related to the force experienced by the rotary tool during processing, wherein the sensor provides sensor signals. A signal processing system is coupled to receive and analyze the sensor signals and determine a lateral alignment of the rotating member relative to a selected lateral position, a selected path, or a direction to decrease a lateral distance relative to the selected lateral position or selected path. In one embodiment, the friction stir system can be embodied as a closed loop tracking system, such as a robot-based tracked friction stir welding (FSW) or friction stir processing (FSP) system.

Selective and reversible ammonia gas detection with nanoporous film functionalized silicon photonic micro-ring resonator.

PubMed

Yebo, Nebiyu A; Sree, Sreeprasanth Pulinthanathu; Levrau, Elisabeth; Detavernier, Christophe; Hens, Zeger; Martens, Johan A; Baets, Roel

2012-05-21

Portable, low cost and real-time gas sensors have a considerable potential in various biomedical and industrial applications. For such applications, nano-photonic gas sensors based on standard silicon fabrication technology offer attractive opportunities. Deposition of high surface area nano-porous coatings on silicon photonic sensors is a means to achieve selective, highly sensitive and multiplexed gas detection on an optical chip. Here we demonstrate selective and reversible ammonia gas detection with functionalized silicon-on-insulator optical micro-ring resonators. The micro-ring resonators are coated with acidic nano-porous aluminosilicate films for specific ammonia sensing, which results in a reversible response to NH(3)with selectivity relative to CO(2). The ammonia detection limit is estimated at about 5 ppm. The detectors reach a steady response to NH(3) within 30 and return to their base level within 60 to 90 seconds. The work opens perspectives on development of nano-photonic sensors for real-time, non-invasive, low cost and light weight biomedical and industrial sensing applications.

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.

Methanol, ethanol and hydrogen sensing using metal oxide and metal (TiO(2)-Pt) composite nanoclusters on GaN nanowires: a new route towards tailoring the selectivity of nanowire/nanocluster chemical sensors.

PubMed

Aluri, Geetha S; Motayed, Abhishek; Davydov, Albert V; Oleshko, Vladimir P; Bertness, Kris A; Sanford, Norman A; Mulpuri, Rao V

2012-05-04

We demonstrate a new method for tailoring the selectivity of chemical sensors using semiconductor nanowires (NWs) decorated with metal and metal oxide multicomponent nanoclusters (NCs). Here we present the change of selectivity of titanium dioxide (TiO(2)) nanocluster-coated gallium nitride (GaN) nanowire sensor devices on the addition of platinum (Pt) nanoclusters. The hybrid sensor devices were developed by fabricating two-terminal devices using individual GaN NWs followed by the deposition of TiO(2) and/or Pt nanoclusters (NCs) using the sputtering technique. This paper present the sensing characteristics of GaN/(TiO(2)-Pt) nanowire-nanocluster (NWNC) hybrids and GaN/(Pt) NWNC hybrids, and compare their selectivity with that of the previously reported GaN/TiO(2) sensors. The GaN/TiO(2) NWNC hybrids showed remarkable selectivity to benzene and related aromatic compounds, with no measurable response for other analytes. Addition of Pt NCs to GaN/TiO(2) sensors dramatically altered their sensing behavior, making them sensitive only to methanol, ethanol and hydrogen, but not to any other chemicals we tested. The GaN/(TiO(2)-Pt) hybrids were able to detect ethanol and methanol concentrations as low as 100 nmol mol(-1) (ppb) in air in approximately 100 s, and hydrogen concentrations from 1 µmol mol(-1) (ppm) to 1% in nitrogen in less than 60 s. However, GaN/Pt NWNC hybrids showed limited sensitivity only towards hydrogen and not towards any alcohols. All these hybrid sensors worked at room temperature and are photomodulated, i.e. they responded to analytes only in the presence of ultraviolet (UV) light. We propose a qualitative explanation based on the heat of adsorption, ionization energy and solvent polarity to explain the observed selectivity of the different hybrids. These results are significant from the standpoint of applications requiring room-temperature hydrogen sensing and sensitive alcohol monitoring. These results demonstrate the tremendous potential for tailoring the selectivity of the hybrid nanosensors for a multitude of environmental and industrial sensing applications.

Spatial tuning of a RF frequency selective surface through origami

NASA Astrophysics Data System (ADS)

Fuchi, Kazuko; Buskohl, Philip R.; Bazzan, Giorgio; Durstock, Michael F.; Joo, James J.; Reich, Gregory W.; Vaia, Richard A.

2016-05-01

Origami devices have the ability to spatially reconfigure between 2D and 3D states through folding motions. The precise mapping of origami presents a novel method to spatially tune radio frequency (RF) devices, including adaptive antennas, sensors, reflectors, and frequency selective surfaces (FSSs). While conventional RF FSSs are designed based upon a planar distribution of conductive elements, this leaves the large design space of the out of plane dimension underutilized. We investigated this design regime through the computational study of four FSS origami tessellations with conductive dipoles. The dipole patterns showed increased resonance shift with decreased separation distances, with the separation in the direction orthogonal to the dipole orientations having a more significant effect. The coupling mechanisms between dipole neighbours were evaluated by comparing surface charge densities, which revealed the gain and loss of coupling as the dipoles moved in and out of alignment via folding. Collectively, these results provide a basis of origami FSS designs for experimental study and motivates the development of computational tools to systematically predict optimal fold patterns for targeted frequency response and directionality.

Ion sensors based on novel fiber organic electrochemical transistors for lead ion detection.

PubMed

Wang, Yuedan; Zhou, Zhou; Qing, Xing; Zhong, Weibing; Liu, Qiongzhen; Wang, Wenwen; Li, Mufang; Liu, Ke; Wang, Dong

2016-08-01

Fiber organic electrochemical transistors (FECTs) based on polypyrrole and nanofibers have been prepared for the first time. FECTs exhibited excellent electrical performances, on/off ratios up to 10(4) and low applied voltages below 2 V. The ion sensitivity behavior of the fiber organic electrochemical transistors was investigated. It exhibited that the transfer curve of FECTs shifted to lower gate voltage with increasing cations concentration, the sensitivity reached to 446 μA/dec in the 10(-5)-10(-2) M Pb(2+) concentration range. The ion selective properties of the FECTs have also been systematically studied for the detection of potassium, calcium, aluminum, and lead ions. The devices with different cations showed great difference in response curves. It was suitable for selectively monitoring Pb(2+) with respect to other cations. The results indicated FECTs were very effective for electrochemical sensing of lead ion, which opened a promising perspective for wearable electronics in healthcare and biological application. Graphical Abstract The schematic diagram of fiber organic electrochemical transistors based on polypyrrole and nanofibers for ion sensing.

Linear Covariance Analysis for a Lunar Lander

NASA Technical Reports Server (NTRS)

Jang, Jiann-Woei; Bhatt, Sagar; Fritz, Matthew; Woffinden, David; May, Darryl; Braden, Ellen; Hannan, Michael

2017-01-01

A next-generation lunar lander Guidance, Navigation, and Control (GNC) system, which includes a state-of-the-art optical sensor suite, is proposed in a concept design cycle. The design goal is to allow the lander to softly land within the prescribed landing precision. The achievement of this precision landing requirement depends on proper selection of the sensor suite. In this paper, a robust sensor selection procedure is demonstrated using a Linear Covariance (LinCov) analysis tool developed by Draper.

Fabrication of highly sensitive and selective H₂ gas sensor based on SnO₂ thin film sensitized with microsized Pd islands.

PubMed

Nguyen, Van Toan; Nguyen, Viet Chien; Nguyen, Van Duy; Hoang, Si Hong; Hugo, Nguyen; Nguyen, Duc Hoa; Nguyen, Van Hieu

2016-01-15

Ultrasensitive and selective hydrogen gas sensor is vital component in safe use of hydrogen that requires a detection and alarm of leakage. Herein, we fabricated a H2 sensing devices by adopting a simple design of planar-type structure sensor in which the heater, electrode, and sensing layer were patterned on the front side of a silicon wafer. The SnO2 thin film-based sensors that were sensitized with microsized Pd islands were fabricated at a wafer-scale by using a sputtering system combined with micro-electronic techniques. The thicknesses of SnO2 thin film and microsized Pd islands were optimized to maximize the sensing performance of the devices. The optimized sensor could be used for monitoring hydrogen gas at low concentrations of 25-250 ppm, with a linear dependence to H2 concentration and a fast response and recovery time. The sensor also showed excellent selectivity for monitoring H2 among other gases, such as CO, NH3, and LPG, and satisfactory characteristics for ensuring safety in handling hydrogen. The hydrogen sensing characteristics of the sensors sensitized with Pt and Au islands were also studied to clarify the sensing mechanisms. Copyright © 2015 Elsevier B.V. All rights reserved.

Sensing in the Collaborative Internet of Things

PubMed Central

Borges Neto, João B.; Silva, Thiago H.; Assunção, Renato Martins; Mini, Raquel A. F.; Loureiro, Antonio A. F.

2015-01-01

We are entering a new era of computing technology, the era of Internet of Things (IoT). An important element for this popularization is the large use of off-the-shelf sensors. Most of those sensors will be deployed by different owners, generally common users, creating what we call the Collaborative IoT. This collaborative IoT helps to increase considerably the amount and availability of collected data for different purposes, creating new interesting opportunities, but also several challenges. For example, it is very challenging to search for and select a desired sensor or a group of sensors when there is no description about the provided sensed data or when it is imprecise. Given that, in this work we characterize the properties of the sensed data in the Internet of Things, mainly the sensed data contributed by several sources, including sensors from common users. We conclude that, in order to safely use data available in the IoT, we need a filtering process to increase the data reliability. In this direction, we propose a new simple and powerful approach that helps to select reliable sensors. We tested our method for different types of sensed data, and the results reveal the effectiveness in the correct selection of sensor data. PMID:25808766

A Simple Small Size and Low Cost Sensor Based on Surface Plasmon Resonance for Selective Detection of Fe(III)

PubMed Central

Cennamo, Nunzio; Alberti, Giancarla; Pesavento, Maria; D'Agostino, Girolamo; Quattrini, Federico; Biesuz, Raffaela; Zeni, Luigi

2014-01-01

A simple, small size, and low cost sensor based on a Deferoxamine Self Assembled Monolayer (DFO-SAM) and Surface Plasmon Resonance (SPR) transduction, in connection with a Plastic Optical Fiber (POF), has been developed for the selective detection of Fe(III). DFO-SAM sensors based on appropriate electrochemical techniques can be frequently found in the scientific literature. In this work, we present the first example of a DFO-SAM sensor based on SPR in an optical fiber. The SPR sensing platform was realized by removing the cladding of a plastic optical fiber along half the circumference, spin coating a buffer of Microposit S1813 photoresist on the exposed core, and finally sputtering a thin gold film. The hydroxamate siderophore deferoxamine (DFO), having high binding affinity for Fe(III), is then used in its immobilized form, as self-assembled monolayer on the gold layer surface of the POF sensor. The results showed that the DFO-SAM-POF-sensor was able to sense the formation of the Fe(III)/DFO complex in the range of concentrations between 1 μm and 50 μm with a linearity range from 0 to 30 μm of Fe(III). The selectivity of the sensor was also proved by interference tests. PMID:24608007

A simple small size and low cost sensor based on surface plasmon resonance for selective detection of Fe(III).

PubMed

Cennamo, Nunzio; Alberti, Giancarla; Pesavento, Maria; D'Agostino, Girolamo; Quattrini, Federico; Biesuz, Raffaela; Zeni, Luigi

2014-03-07

A simple, small size, and low cost sensor based on a Deferoxamine Self Assembled Monolayer (DFO-SAM) and Surface Plasmon Resonance (SPR) transduction, in connection with a Plastic Optical Fiber (POF), has been developed for the selective detection of Fe(III). DFO-SAM sensors based on appropriate electrochemical techniques can be frequently found in the scientific literature. In this work, we present the first example of a DFO-SAM sensor based on SPR in an optical fiber. The SPR sensing platform was realized by removing the cladding of a plastic optical fiber along half the circumference, spin coating a buffer of Microposit S1813 photoresist on the exposed core, and finally sputtering a thin gold film. The hydroxamate siderophore deferoxamine (DFO), having high binding affinity for Fe(III), is then used in its immobilized form, as self-assembled monolayer on the gold layer surface of the POF sensor. The results showed that the DFO-SAM-POF-sensor was able to sense the formation of the Fe(III)/DFO complex in the range of concentrations between 1 μm and 50 μm with a linearity range from 0 to 30 μm of Fe(III). The selectivity of the sensor was also proved by interference tests.

Cooperative Robots to Observe Moving Targets: Review.

PubMed

Khan, Asif; Rinner, Bernhard; Cavallaro, Andrea

2018-01-01

The deployment of multiple robots for achieving a common goal helps to improve the performance, efficiency, and/or robustness in a variety of tasks. In particular, the observation of moving targets is an important multirobot application that still exhibits numerous open challenges, including the effective coordination of the robots. This paper reviews control techniques for cooperative mobile robots monitoring multiple targets. The simultaneous movement of robots and targets makes this problem particularly interesting, and our review systematically addresses this cooperative multirobot problem for the first time. We classify and critically discuss the control techniques: cooperative multirobot observation of multiple moving targets, cooperative search, acquisition, and track, cooperative tracking, and multirobot pursuit evasion. We also identify the five major elements that characterize this problem, namely, the coordination method, the environment, the target, the robot and its sensor(s). These elements are used to systematically analyze the control techniques. The majority of the studied work is based on simulation and laboratory studies, which may not accurately reflect real-world operational conditions. Importantly, while our systematic analysis is focused on multitarget observation, our proposed classification is useful also for related multirobot applications.

Enhanced and selective ammonia sensing of reduced graphene oxide based chemo resistive sensor at room temperature

NASA Astrophysics Data System (ADS)

Kumar, Ramesh; Kaur, Amarjeet

2016-05-01

The reduced graphene oxide thin films were fabricated by using the spin coating method. The reduced graphene oxide samples were characterised by Raman studies to obtain corresponding D and G bands at 1360 and 1590 cm-1 respectively. Fourier transform infra-red (FTIR) spectra consists of peak corresponds to sp2 hybridisation of carbon atoms at 1560 cm-1. The reduced graphene oxide based chemoresistive sensor exhibited a p-type semiconductor behaviour in ambient conditions and showed good sensitivity to different concentration of ammonia from 25 ppm to 500 ppm and excellent selectivity at room temperature. The sensor displays selectivity to several hazardous vapours such as methanol, ethanol, acetone and hydrazine hydrate. The sensor demonstrated a sensitivity of 9.8 at 25 ppm concentration of ammonia with response time of 163 seconds.

Highly sensitive and selective liquid crystal optical sensor for detection of ammonia.

PubMed

Niu, Xiaofang; Zhong, Yuanbo; Chen, Rui; Wang, Fei; Luo, Dan

2017-06-12

Ammonia detection technologies are very important in environment monitoring. However, most existing technologies are complex and expensive, which limit the useful range of real-time application. Here, we propose a highly sensitive and selective optical sensor for detection of ammonia (NH 3 ) based on liquid crystals (LCs). This optical sensor is realized through the competitive binding between ammonia and liquid crystals on chitosan-Cu 2+ that decorated on glass substrate. We achieve a broad detection range of ammonia from 50 ppm to 1250 ppm, with a low detection limit of 16.6 ppm. This sensor is low-cost, simple, fast, and highly sensitive and selective for detection of ammonia. The proposal LC sensing method can be a sensitive detection platform for other molecule monitors such as proteins, DNAs and other heavy metal ions by modifying sensing molecules.

System and method for controlling ammonia levels in a selective catalytic reduction catalyst using a nitrogen oxide sensor

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

None

A system according to the principles of the present disclosure includes an air/fuel ratio determination module and an emission level determination module. The air/fuel ratio determination module determines an air/fuel ratio based on input from an air/fuel ratio sensor positioned downstream from a three-way catalyst that is positioned upstream from a selective catalytic reduction (SCR) catalyst. The emission level determination module selects one of a predetermined value and an input based on the air/fuel ratio. The input is received from a nitrogen oxide sensor positioned downstream from the three-way catalyst. The emission level determination module determines an ammonia level basedmore » on the one of the predetermined value and the input received from the nitrogen oxide sensor.« less

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.

Applying Sensor-Based Technology to Improve Construction Safety Management.

PubMed

Zhang, Mingyuan; Cao, Tianzhuo; Zhao, Xuefeng

2017-08-11

Construction sites are dynamic and complicated systems. The movement and interaction of people, goods and energy make construction safety management extremely difficult. Due to the ever-increasing amount of information, traditional construction safety management has operated under difficult circumstances. As an effective way to collect, identify and process information, sensor-based technology is deemed to provide new generation of methods for advancing construction safety management. It makes the real-time construction safety management with high efficiency and accuracy a reality and provides a solid foundation for facilitating its modernization, and informatization. Nowadays, various sensor-based technologies have been adopted for construction safety management, including locating sensor-based technology, vision-based sensing and wireless sensor networks. This paper provides a systematic and comprehensive review of previous studies in this field to acknowledge useful findings, identify the research gaps and point out future research directions.

Applying Sensor-Based Technology to Improve Construction Safety Management

PubMed Central

Zhang, Mingyuan; Cao, Tianzhuo; Zhao, Xuefeng

2017-01-01

Construction sites are dynamic and complicated systems. The movement and interaction of people, goods and energy make construction safety management extremely difficult. Due to the ever-increasing amount of information, traditional construction safety management has operated under difficult circumstances. As an effective way to collect, identify and process information, sensor-based technology is deemed to provide new generation of methods for advancing construction safety management. It makes the real-time construction safety management with high efficiency and accuracy a reality and provides a solid foundation for facilitating its modernization, and informatization. Nowadays, various sensor-based technologies have been adopted for construction safety management, including locating sensor-based technology, vision-based sensing and wireless sensor networks. This paper provides a systematic and comprehensive review of previous studies in this field to acknowledge useful findings, identify the research gaps and point out future research directions. PMID:28800061

Higher-order mode photonic crystal based nanofluidic sensor

NASA Astrophysics Data System (ADS)

Peng, Wang; Chen, Youping; Ai, Wu

2017-01-01

A higher-order photonic crystal (PC) based nanofluidic sensor, which worked at 532 nm, was designed and demonstrated. A systematical and detailed method for sculpturing a PC sensor for a given peak wavelength value (PWV) and specified materials was illuminated. It was the first time that the higher order mode was used to design PC based nanofluidic sensor, and the refractive index (RI) sensitivity of this sensor had been verified with FDTD simulation software from Lumerical. The enhanced electrical field of higher order mode structure was mostly confined in the channel area, where the enhance field is wholly interacting with the analytes in the channels. The comparison of RI sensitivity between fundamental mode and higher order mode shows the RI variation of higher order mode is 124.5 nm/RIU which is much larger than the fundamental mode. The proposed PC based nanofluidic structure pioneering a novel style for future optofluidic design.

A predictive model for biomimetic plate type broadband frequency sensor

NASA Astrophysics Data System (ADS)

Ahmed, Riaz U.; Banerjee, Sourav

2016-04-01

In this work, predictive model for a bio-inspired broadband frequency sensor is developed. Broadband frequency sensing is essential in many domains of science and technology. One great example of such sensor is human cochlea, where it senses a frequency band of 20 Hz to 20 KHz. Developing broadband sensor adopting the physics of human cochlea has found tremendous interest in recent years. Although few experimental studies have been reported, a true predictive model to design such sensors is missing. A predictive model is utmost necessary for accurate design of selective broadband sensors that are capable of sensing very selective band of frequencies. Hence, in this study, we proposed a novel predictive model for the cochlea-inspired broadband sensor, aiming to select the frequency band and model parameters predictively. Tapered plate geometry is considered mimicking the real shape of the basilar membrane in the human cochlea. The predictive model is intended to develop flexible enough that can be employed in a wide variety of scientific domains. To do that, the predictive model is developed in such a way that, it can not only handle homogeneous but also any functionally graded model parameters. Additionally, the predictive model is capable of managing various types of boundary conditions. It has been found that, using the homogeneous model parameters, it is possible to sense a specific frequency band from a specific portion (B) of the model length (L). It is also possible to alter the attributes of `B' using functionally graded model parameters, which confirms the predictive frequency selection ability of the developed model.

Polymer-carbon black composite sensors in an electronic nose for air-quality monitoring

NASA Technical Reports Server (NTRS)

Ryan, M. A.; Shevade, A. V.; Zhou, H.; Homer, M. L.

2004-01-01

An electronic nose that uses an array of 32 polymer-carbon black composite sensors has been developed, trained, and tested. By selecting a variety of chemical functionalities in the polymers used to make sensors, it is possible to construct an array capable of identifying and quantifying a broad range of target compounds, such as alcohols and aromatics, and distinguishing isomers and enantiomers (mirror-image isomers). A model of the interaction between target molecules and the polymer-carbon black composite sensors is under development to aid in selecting the array members and to enable identification of compounds with responses not stored in the analysis library.

Polyaniline nanowires-gold nanoparticles hybrid network based chemiresistive hydrogen sulfide sensor

NASA Astrophysics Data System (ADS)

Shirsat, Mahendra D.; Bangar, Mangesh A.; Deshusses, Marc A.; Myung, Nosang V.; Mulchandani, Ashok

2009-02-01

We report a sensitive, selective, and fast responding room temperature chemiresistive sensor for hydrogen sulfide detection and quantification using polyaniline nanowires-gold nanoparticles hybrid network. The sensor was fabricated by facile electrochemical technique. Initially, polyaniline nanowires with a diameter of 250-320 nm bridging the gap between a pair of microfabricated gold electrodes were synthesized using templateless electrochemical polymerization using a two step galvanostatic technique. Polyaniline nanowires were then electrochemically functionalized with gold nanoparticles using cyclic voltammetry technique. These chemiresistive sensors show an excellent limit of detection (0.1 ppb), wide dynamic range (0.1-100 ppb), and very good selectivity and reproducibility.

Synthesis of a novel BODIPY library and its application in the discovery of a fructose sensor.

PubMed

Zhai, Duanting; Lee, Sung-Chan; Vendrell, Marc; Leong, Lai Peng; Chang, Young-Tae

2012-02-13

We prepared a new library of 160 compounds by conjugation of a BODIPY core to a collection of aldehydes. This library was screened against 52 biologically relevant analytes and we identified one fluorescent sensor of fructose (Fructose Orange). Fructose Orange showed a 24-fold fluorescence increase upon recognition of fructose and an outstanding selectivity among 24 different saccharides. NMR studies confirmed that five different binding interactions were formed between the sensor and fructose. Furthermore, Fructose Orange was applied to the quantification of fructose in soft drinks, being the most selective fluorescent sensor for fructose reported to date.

Recent advances in magnesium assessment: From single selective sensors to multisensory approach.

PubMed

Lvova, Larisa; Gonçalves, Carla Guanais; Di Natale, Corrado; Legin, Andrey; Kirsanov, Dmitry; Paolesse, Roberto

2018-03-01

The development of efficient analytical procedures for the selective detection of magnesium is an important analytical task, since this element is one of the most abundant metals in cells and plays an essential role in a plenty of cellular processes. Magnesium misbalance has been related to several pathologies and diseases both in plants and animals, as far as in humans, but the number of suitable methods for magnesium detection especially in life sample and biological environments is scarce. Chemical sensors, due to their high reliability, simplicity of handling and instrumentation, fast and real-time in situ and on site analysis are promising candidates for magnesium analysis and represent an attractive alternative to the standard instrumental methods. Here the recent achievements in the development of chemical sensors for magnesium ions detection over the last decade are reviewed. The working principles and the main types of sensors applied are described. Focus is placed on the optical sensors and multisensory systems applications for magnesium assessment in different media. Further, a critical outlook on the employment of multisensory approach in comparison to single selective sensors application in biological samples is presented. Copyright © 2017 Elsevier B.V. All rights reserved.

Potential transducers based man-tailored biomimetic sensors for selective recognition of dextromethorphan as an antitussive drug.

PubMed

El-Naby, Eman H; Kamel, Ayman H

2015-09-01

A biomimetic potentiometric sensor for specific recognition of dextromethorphan (DXM), a drug classified according to the Drug Enforcement Administration (DEA) as a "drug of concern", is designed and characterized. A molecularly imprinted polymer (MIP), with special molecular recognition properties of DXM, was prepared by thermal polymerization in which DXM acted as template molecule, methacrylic acid (MAA) and acrylonitrile (AN) acted as functional monomers in the presence of ethylene glycol dimethacrylate (EGDMA) as crosslinker. The sensors showed a high selectivity and a sensitive response to the template in aqueous system. Electrochemical evaluation of these sensors revealed near-Nernstian response with slopes of 49.6±0.5 and 53.4±0.5 mV decade(-1) with a detection limit of 1.9×10(-6), and 1.0×10(-6) mol L(-1) DXM with MIP/MAA and MIP/AN membrane based sensors, respectively. Significantly improved accuracy, precision, response time, stability, selectivity and sensitivity were offered by these simple and cost-effective potentiometric sensors compared with other standard techniques. The method has the requisite accuracy, sensitivity and precision to assay DXM in pharmaceutical products. Copyright © 2015 Elsevier B.V. All rights reserved.

Highly Sensitive and Selective Hydrogen Gas Sensor Using the Mesoporous SnO2 Modified Layers

PubMed Central

Xue, Niuzi; Zhang, Qinyi; Zhang, Shunping; Zong, Pan; Yang, Feng

2017-01-01

It is important to improve the sensitivities and selectivities of metal oxide semiconductor (MOS) gas sensors when they are used to monitor the state of hydrogen in aerospace industry and electronic field. In this paper, the ordered mesoporous SnO2 (m-SnO2) powders were prepared by sol-gel method, and the morphology and structure were characterized by X-ray diffraction analysis (XRD), transmission electron microscope (TEM) and Brunauer–Emmett–Teller (BET). The gas sensors were fabricated using m-SnO2 as the modified layers on the surface of commercial SnO2 (c-SnO2) by screen printing technology, and tested for gas sensing towards ethanol, benzene and hydrogen with operating temperatures ranging from 200 °C to 400 °C. Higher sensitivity was achieved by using the modified m-SnO2 layers on the c-SnO2 gas sensor, and it was found that the S(c/m2) sensor exhibited the highest response (Ra/Rg = 22.2) to 1000 ppm hydrogen at 400 °C. In this paper, the mechanism of the sensitivity and selectivity improvement of the gas sensors is also discussed. PMID:29036898

Plenoptic camera wavefront sensing with extended sources

NASA Astrophysics Data System (ADS)

Jiang, Pengzhi; Xu, Jieping; Liang, Yonghui; Mao, Hongjun

2016-09-01

The wavefront sensor is used in adaptive optics to detect the atmospheric distortion, which feeds back to the deformable mirror to compensate for this distortion. Different from the Shack-Hartmann sensor that has been widely used with point sources, the plenoptic camera wavefront sensor has been proposed as an alternative wavefront sensor adequate for extended objects in recent years. In this paper, the plenoptic camera wavefront sensing with extended sources is discussed systematically. Simulations are performed to investigate the wavefront measurement error and the closed-loop performance of the plenoptic sensor. The results show that there are an optimal lenslet size and an optimal number of pixels to make the best performance. The RMS of the resulting corrected wavefront in closed-loop adaptive optics system is less than 108 nm (0.2λ) when D/r0 ≤ 10 and the magnitude M ≤ 5. Our investigation indicates that the plenoptic sensor is efficient to operate on extended sources in the closed-loop adaptive optics system.

Embedded Triboelectric Active Sensors for Real-Time Pneumatic Monitoring.

PubMed

Fu, Xian Peng; Bu, Tian Zhao; Xi, Feng Ben; Cheng, Ting Hai; Zhang, Chi; Wang, Zhong Lin

2017-09-20

Pneumatic monitoring sensors have great demands for power supply in cylinder systems. Here, we present an embedded sliding triboelectric nanogenerator (TENG) in air cylinder as active sensors for position and velocity monitoring. The embedded TENG is composed of a circular poly(tetrafluoroethylene) polymer and a triangular copper electrode. The working mechanism as triboelectric active sensors and electric output performance are systematically investigated. By integrating into the pneumatic system, the embedded triboelectric active sensors have been used for real-time air pressure/flow monitoring and energy storage. Air pressures are measured from 0.04 to 0.12 MPa at a step of 0.02 MPa with a sensitivity of 49.235 V/MPa, as well as airflow from 50 to 250 L/min at a step of 50 L/min with a sensitivity of 0.002 μA·min/L. This work has first demonstrated triboelectric active sensors for pneumatic monitoring and may promote the development of TENG in intelligent pneumatic system.

Miniaturized force/torque sensor for in vivo measurements of tissue characteristics.

PubMed

Hessinger, M; Pilic, T; Werthschutzky, R; Pott, P P

2016-08-01

This paper presents the development of a surgical instrument to measure interaction forces/torques with organic tissue during operation. The focus is on the design progress of the sensor element, consisting of a spoke wheel deformation element with a diameter of 12 mm and eight inhomogeneous doped piezoresistive silicon strain gauges on an integrated full-bridge assembly with an edge length of 500 μm. The silicon chips are contacted to flex-circuits via flip chip and bonded on the substrate with a single component adhesive. A signal processing board with an 18 bit serial A/D converter is integrated into the sensor. The design concept of the handheld surgical sensor device consists of an instrument coupling, the six-axis sensor, a wireless communication interface and battery. The nominal force of the sensing element is 10 N and the nominal torque is 1 N-m in all spatial directions. A first characterization of the force sensor results in a maximal systematic error of 4.92 % and random error of 1.13 %.

Highly sensitive MoTe2 chemical sensor with fast recovery rate through gate biasing

NASA Astrophysics Data System (ADS)

Feng, Zhihong; Xie, Yuan; Chen, Jiancui; Yu, Yuanyuan; Zheng, Shijun; Zhang, Rui; Li, Quanning; Chen, Xuejiao; Sun, Chongling; Zhang, Hao; Pang, Wei; Liu, Jing; Zhang, Daihua

2017-06-01

The unique properties of two dimensional (2D) materials make them promising candidates for chemical and biological sensing applications. However, most 2D nanomaterial sensors suffer very long recovery time due to slow molecular desorption at room temperature. Here, we report a highly sensitive molybdenum ditelluride (MoTe2) gas sensor for NO2 and NH3 detection with greatly enhanced recovery rate. The effects of gate bias on sensing performance have been systematically studied. It is found that the recovery kinetics can be effectively adjusted by biasing the sensor to different gate voltages. Under the optimum biasing potential, the MoTe2 sensor can achieve more than 90% recovery after each sensing cycle well within 10 min at room temperature. The results demonstrate the potential of MoTe2 as a promising candidate for high-performance chemical sensors. The idea of exploiting gate bias to adjust molecular desorption kinetics can be readily applied to much wider sensing platforms based on 2D nanomaterials.

Performance Evaluation of Wearable Sensor Systems: A Case Study in Moderate-Scale Deployment in Hospital Environment.

PubMed

Sun, Wen; Ge, Yu; Zhang, Zhiqiang; Wong, Wai-Choong

2015-09-25

A wearable sensor system enables continuous and remote health monitoring and is widely considered as the next generation of healthcare technology. The performance, the packet error rate (PER) in particular, of a wearable sensor system may deteriorate due to a number of factors, particularly the interference from the other wearable sensor systems in the vicinity. We systematically evaluate the performance of the wearable sensor system in terms of PER in the presence of such interference in this paper. The factors that affect the performance of the wearable sensor system, such as density, traffic load, and transmission power in a realistic moderate-scale deployment case in hospital are all considered. Simulation results show that with 20% duty cycle, only 68.5% of data transmission can achieve the targeted reliability requirement (PER is less than 0.05) even in the off-peak period in hospital. We then suggest some interference mitigation schemes based on the performance evaluation results in the case study.

Flush Mounting Of Thin-Film Sensors

NASA Technical Reports Server (NTRS)

Moore, Thomas C., Sr.

1992-01-01

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

Remote sensing in hydrology: A survey of applications with selected bibliography and abstracts

NASA Technical Reports Server (NTRS)

Sers, S. W. (Compiler)

1971-01-01

Remote infrared sensing as a water exploration technique is demonstrated. Various applications are described, demonstrating that infrared sensors can locate aquifers, geothermal water, water trapped by faults, springs and water in desert regions. The potentiality of airborne IR sensors as a water prospecting tool is considered. Also included is a selected bibliography with abstracts concentrating on those publications which will better acquaint the hydrologist with investigations using thermal remote sensors as applied to water exploration.

A core-substituted naphthalene diimide fluoride sensor.

PubMed

Bhosale, Sheshanath V; Bhosale, Sidhanath V; Kalyankar, Mohan B; Langford, Steven J

2009-12-03

The synthesis and characterization of a highly fluorescent core-substituted naphthalene diimide sensor (varphi = 0.34) bearing a bis-sulfonamide group is described. The compound shows a unique selectivity and reactivity for the fluoride ion over other anions in CHCl(3) by a two-stage deprotonation process leading to a colorimetric response. In DMSO solution, the sensor is shown to be highly selective for fluoride (K(a) approximately 10(6) M(-1)) over other anions with more pronounced changes in absorption characteristics.

Frequency Selective Surface for Structural Health Monitoring

NASA Astrophysics Data System (ADS)

Norlyana Azemi, Saidatul; Mustaffa, Farzana Hazira Wan; Faizal Jamlos, Mohd; Abdullah Al-Hadi, Azremi; Soh, Ping Jack

2018-03-01

Structural health monitoring (SHM) technologies have attained attention to monitor civil structures. SHM sensor systems have been used in various civil structures such as bridges, buildings, tunnels and so on. However the previous sensor for SHM is wired and encounter with problem to cover large areas. Therefore, wireless sensor was introduced for SHM to reduce network connecting problem. Wireless sensors for Structural Health monitoring are new technology and have many advantages to overcome the drawback of conventional and wired sensor. This project proposed passive wireless SHM sensor using frequency selective surface (FSS) as an alternative to conventional sensors. The electromagnetic wave characteristic of FSS will change by geometrical changes of FSS due to mechanical strain or structural failure. The changes feature is used as a sensing function without any connecting wires. Two type of design which are circular ring and square loop along with the transmission and reflection characteristics of SHM using FSS were discussed in this project. A simulation process has shown that incident angle characteristics can be use as a data for SHM application.

Geographically distributed environmental sensor system

DOEpatents

French, Patrick; Veatch, Brad; O'Connor, Mike

2006-10-03

The present invention is directed to a sensor network that includes a number of sensor units and a base unit. The base station operates in a network discovery mode (in which network topology information is collected) in a data polling mode (in which sensed information is collected from selected sensory units). Each of the sensor units can include a number of features, including an anemometer, a rain gauge, a compass, a GPS receiver, a barometric pressure sensor, an air temperature sensor, a humidity sensor, a level, and a radiant temperature sensor.

The application of machine learning in multi sensor data fusion for activity recognition in mobile device space

NASA Astrophysics Data System (ADS)

Marhoubi, Asmaa H.; Saravi, Sara; Edirisinghe, Eran A.

2015-05-01

The present generation of mobile handheld devices comes equipped with a large number of sensors. The key sensors include the Ambient Light Sensor, Proximity Sensor, Gyroscope, Compass and the Accelerometer. Many mobile applications are driven based on the readings obtained from either one or two of these sensors. However the presence of multiple-sensors will enable the determination of more detailed activities that are carried out by the user of a mobile device, thus enabling smarter mobile applications to be developed that responds more appropriately to user behavior and device usage. In the proposed research we use recent advances in machine learning to fuse together the data obtained from all key sensors of a mobile device. We investigate the possible use of single and ensemble classifier based approaches to identify a mobile device's behavior in the space it is present. Feature selection algorithms are used to remove non-discriminant features that often lead to poor classifier performance. As the sensor readings are noisy and include a significant proportion of missing values and outliers, we use machine learning based approaches to clean the raw data obtained from the sensors, before use. Based on selected practical case studies, we demonstrate the ability to accurately recognize device behavior based on multi-sensor data fusion.

High-Performance Sensors Based on Resistance Fluctuations of Single-Layer-Graphene Transistors.

PubMed

Amin, Kazi Rafsanjani; Bid, Aveek

2015-09-09

One of the most interesting predicted applications of graphene-monolayer-based devices is as high-quality sensors. In this article, we show, through systematic experiments, a chemical vapor sensor based on the measurement of low-frequency resistance fluctuations of single-layer-graphene field-effect-transistor devices. The sensor has extremely high sensitivity, very high specificity, high fidelity, and fast response times. The performance of the device using this scheme of measurement (which uses resistance fluctuations as the detection parameter) is more than 2 orders of magnitude better than a detection scheme in which changes in the average value of the resistance is monitored. We propose a number-density-fluctuation-based model to explain the superior characteristics of a noise-measurement-based detection scheme presented in this article.

Bis-ureidoquinoline as a selective fluoride anion sensor through hydrogen-bond interactions.

PubMed

Jo, Yunhee; Chidalla, Nagesh; Cho, Dong-Gyu

2014-10-03

Bis-ureidoquinoline shows a characteristic UV-vis absorbance and turn-on fluorescence changes in the presence of the fluoride anion. Such selective changes probably originate from the hydrogen-bond interactions, as shown by the (1)H NMR titration and DFT calculations. Bis-ureidoquinoline can be used as a fluoride-selective sensor for the detection of fluoride anions under illumination from a laboratory hand-held UV lamp.

Search and selection methodology of systematic reviews in orthodontics (2000-2004).

PubMed

Flores-Mir, Carlos; Major, Michael P; Major, Paul W

2006-08-01

More systematic reviews related to orthodontic topics are published each year, although little has been done to evaluate their search and selection methodologies. Systematic reviews related to orthodontics published between January 1, 2000, and December 31, 2004, were searched for their use of multiple electronic databases and secondary searches. The search and selection methods of identified systematic reviews were evaluated against the Cochrane Handbook's guidelines. Sixteen orthodontic systematic reviews were identified in this period. The percentage of reviews documenting and using each criterion of article searching has changed over the last 5 years, with no recognizable directional trend. On average, most systematic reviews documented their electronic search terms (88%) and inclusion-exclusion criteria (100%), and used secondary searching (75%). Many still failed to search more than MEDLINE (56%), failed to document the database names and search dates (37%), failed to document the search strategy (62%), did not use several reviewers for selecting studies (75%), and did not include all languages (81%). The methodology of systematic reviews in orthodontics is still limited, with key methodological components frequently absent or not appropriately described.

Graphene-oxide-coated interferometric optical microfiber ethanol vapor sensor.

PubMed

Zhang, Jingle; Fu, Haiwei; Ding, Jijun; Zhang, Min; Zhu, Yi

2017-11-01

A graphene-oxide-coated interferometric microfiber-sensor-based polarization-maintaining optical fiber is proposed for highly sensitive detecting for ethanol vapor concentration at room temperature in this paper. The strong sensing capability of the sensor to detect the concentration of ethanol vapor is demonstrated, taking advantage of the evanescent field enhancement and gas absorption of a graphene-oxide-coated microfiber. The transmission spectrum of the sensor varies with concentrations of ethanol vapor, and the redshift of the transmission spectrum has been analyzed for the concentration range from 0 to 80 ppm with sensitivity as high as 0.138 nm/ppm. The coated graphene oxide layer induces the evanescent field enhancement and gas selective adsorption, which improves sensitivity and selectivity of the microfiber gas sensor for ethanol vapor detection.

Advanced Taste Sensors Based on Artificial Lipids with Global Selectivity to Basic Taste Qualities and High Correlation to Sensory Scores

PubMed Central

Kobayashi, Yoshikazu; Habara, Masaaki; Ikezazki, Hidekazu; Chen, Ronggang; Naito, Yoshinobu; Toko, Kiyoshi

2010-01-01

Effective R&D and strict quality control of a broad range of foods, beverages, and pharmaceutical products require objective taste evaluation. Advanced taste sensors using artificial-lipid membranes have been developed based on concepts of global selectivity and high correlation with human sensory score. These sensors respond similarly to similar basic tastes, which they quantify with high correlations to sensory score. Using these unique properties, these sensors can quantify the basic tastes of saltiness, sourness, bitterness, umami, astringency and richness without multivariate analysis or artificial neural networks. This review describes all aspects of these taste sensors based on artificial lipid, ranging from the response principle and optimal design methods to applications in the food, beverage, and pharmaceutical markets. PMID:22319306

Highly sensitive and selective detection of Al(III) ions in aqueous buffered solution with fluorescent peptide-based sensor.

PubMed

In, Byunggyu; Hwang, Gi Won; Lee, Keun-Hyeung

2016-09-15

A fluorescent sensor based on a tripeptide (SerGluGlu) with a dansyl fluorophore detected selectively Al(III) among 16 metal ions in aqueous buffered solutions without any organic cosolvent. The peptide-based sensor showed a highly sensitive turn on response to aluminium ion with high binding affinity (1.84×10(4)M(-1)) in aqueous buffered solutions. The detection limit (230nM, 5.98ppb) of the peptide-based sensor was much lower than the maximum allowable level (7.41μM) of aluminium ions in drinking water demanded by EPA. The binding mode of the peptide sensor with aluminium ions was characterized using ESI mass spectrometry, NMR titration, and pH titration experiments. Copyright © 2016 Elsevier Ltd. All rights reserved.

Planar Zeolite Film-Based Potentiometric Gas Sensors Manufactured by a Combined Thick-Film and Electroplating Technique

PubMed Central

Marr, Isabella; Reiß, Sebastian; Hagen, Gunter; Moos, Ralf

2011-01-01

Zeolites are promising materials in the field of gas sensors. In this technology-oriented paper, a planar setup for potentiometric hydrocarbon and hydrogen gas sensors using zeolites as ionic sodium conductors is presented, in which the Pt-loaded Na-ZSM-5 zeolite is applied using a thick-film technique between two interdigitated gold electrodes and one of them is selectively covered for the first time by an electroplated chromium oxide film. The influence of the sensor temperature, the type of hydrocarbons, the zeolite film thickness, and the chromium oxide film thickness is investigated. The influence of the zeolite on the sensor response is briefly discussed in the light of studies dealing with zeolites as selectivity-enhancing cover layers. PMID:22164042

Chalcogenide fiber-optic SPR chemical sensor with MoS2 monolayer, polymer clad, and polythiophene layer in NIR using selective ray launching

NASA Astrophysics Data System (ADS)

Sharma, Anuj K.; Kaur, Baljinder

2018-07-01

Surface plasmon resonance (SPR) based chalcogenide fiber-optic sensor with polymer clad and MoS2 monolayer is simulated and analyzed in near infrared (NIR) for detection of mixture of alcohols (ethanol and methanol) dissolved in water solution. The proposed fiber optic sensor is analyzed under angular interrogation method, which is based on selective ray (on-axis) launching of monochromatic light into the fiber core at varying angle followed by measuring the loss of power (in dB) after passing through the SPR probe region. The performance of the sensor is analyzed in terms of its figure of merit (FOM). The sensor's specificity towards alcohols along with considerably larger FOM is achieved by utilizing a polythiophene (PT) layer. The results indicate that longer NIR wavelength (λ) provides superior sensing performance. The sensor's performance is better for larger volume fraction of methanol in the water solution. The proposed fiber optic SPR sensor has the capability of providing much greater FOM compared with the previously-reported SPR sensors.

10 CFR Appendix U to Subpart B of... - Uniform Test Method for Measuring the Energy Consumption of Ceiling Fans

Code of Federal Regulations, 2010 CFR

2010-01-01

... performing the airflow test, measure ceiling fan power using a RMS sensor capable of measuring power with an accuracy of ±1 %. Prior to using the sensor and sensor software it has selected, the test laboratory shall verify performance of the sensor and sensor software. Measure power input at a point that includes all...

Investigation of thiol derivatized gold nanoparticle sensors for gas analysis

NASA Astrophysics Data System (ADS)

Stephens, Jared S.

Analysis of volatile organic compounds (VOCs) in air and exhaled breath by sensor array is a very useful testing technique. It can provide non-invasive, fast, inexpensive testing for many diseases. Breath analysis has been very successful in identifying cancer and other diseases by using a chemiresistor sensor or array with gold nanoparticles to detect biomarkers. Acetone is a biomarker for diabetes and having a portable testing device could help to monitor diabetic and therapeutic progress. An advantage to this testing method is it is conducted at room temperature instead of 200 degrees Celsius. 3. The objective of this research is to determine the effect of thiol derivatized gold nanoparticles based on sensor(s) detection of VOCs. The VOCs to be tested are acetone, ethanol, and a mixture of acetone and ethanol. Each chip is tested under all three VOCs and three concentration levels (0.1, 1, and 5.0 ppm). VOC samples are used to test the sensors' ability to detect and differentiate VOCs. Sensors (also referred to as a chip) are prepared using several types of thiol derivatized gold nanoparticles. The factors are: thiol compound and molar volume loading of the thiol in synthesis. The average resistance results are used to determine the VOC selectivity of the sensors tested. The results show a trend of increasing resistance as VOC concentration is increased relative to dry air; which is used as baseline for VOCs. Several sensors show a high selectivity to one or more VOCs. Overall the 57 micromoles of 4-methoxy-toluenethiol sensor shows the strongest selectivity for VOCs tested. 3. Gerfen, Kurt. 2012. Detection of Acetone in Air Using Silver Ion Exchanged ZSM-5 and Zinc Oxide Sensing Films. Master of Science thesis, University of Louisville.

A molecular rotor based ratiometric sensor for basic amino acids

NASA Astrophysics Data System (ADS)

Pettiwala, Aafrin M.; Singh, Prabhat K.

2018-01-01

The inevitable importance of basic amino acids, arginine and lysine, in human health and metabolism demands construction of efficient sensor systems for them. However, there are only limited reports on the 'ratiometric' detection of basic amino acids which is further restricted by the use of chemically complex sensor molecules, which impedes their prospect for practical applications. Herein, we report a ratiometric sensor system build on simple mechanism of disassociation of novel emissive Thioflavin-T H-aggregates from heparin surface, when subjected to interaction with basic amino acids. The strong and selective electrostatic and hydrogen bonding interaction of basic amino acids with heparin leads to large alteration in photophysical attributes of heparin bound Thioflavin-T, which forms a highly sensitive sensor platform for detection of basic amino acids in aqueous solution. These selective interactions between basic amino acids and heparin allow our sensor system to discriminate arginine and lysine from other amino acids. This unique mechanism of dissociation of Thioflavin-T aggregates from heparin surface provides ratiometric response on both fluorimetric and colorimetric outputs for detection of arginine and lysine, and thus it holds a significant advantage over other developed sensor systems which are restricted to single wavelength detection. Apart from the sensitivity and selectivity, our system also provides the advantage of simplicity, dual mode of sensing, and more importantly, it employs an inexpensive commercially available probe molecule, which is a significant advantage over other developed sensor systems that uses tedious synthesis protocol for the employed probe in the detection scheme, an impediment for practical applications. Additionally, our sensor system also shows response in complex biological media of serum samples.

Operational calibration and validation of landsat data continuity mission (LDCM) sensors using the image assessment system (IAS)

USGS Publications Warehouse

Micijevic, Esad; Morfitt, Ron

2010-01-01

Systematic characterization and calibration of the Landsat sensors and the assessment of image data quality are performed using the Image Assessment System (IAS). The IAS was first introduced as an element of the Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM+) ground segment and recently extended to Landsat 4 (L4) and 5 (L5) Thematic Mappers (TM) and Multispectral Sensors (MSS) on-board the Landsat 1-5 satellites. In preparation for the Landsat Data Continuity Mission (LDCM), the IAS was developed for the Earth Observer 1 (EO-1) Advanced Land Imager (ALI) with a capability to assess pushbroom sensors. This paper describes the LDCM version of the IAS and how it relates to unique calibration and validation attributes of its on-board imaging sensors. The LDCM IAS system will have to handle a significantly larger number of detectors and the associated database than the previous IAS versions. An additional challenge is that the LDCM IAS must handle data from two sensors, as the LDCM products will combine the Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) spectral bands.

Multi-Layer Approach for the Detection of Selective Forwarding Attacks

PubMed Central

Alajmi, Naser; Elleithy, Khaled

2015-01-01

Security breaches are a major threat in wireless sensor networks (WSNs). WSNs are increasingly used due to their broad range of important applications in both military and civilian domains. WSNs are prone to several types of security attacks. Sensor nodes have limited capacities and are often deployed in dangerous locations; therefore, they are vulnerable to different types of attacks, including wormhole, sinkhole, and selective forwarding attacks. Security attacks are classified as data traffic and routing attacks. These security attacks could affect the most significant applications of WSNs, namely, military surveillance, traffic monitoring, and healthcare. Therefore, there are different approaches to detecting security attacks on the network layer in WSNs. Reliability, energy efficiency, and scalability are strong constraints on sensor nodes that affect the security of WSNs. Because sensor nodes have limited capabilities in most of these areas, selective forwarding attacks cannot be easily detected in networks. In this paper, we propose an approach to selective forwarding detection (SFD). The approach has three layers: MAC pool IDs, rule-based processing, and anomaly detection. It maintains the safety of data transmission between a source node and base station while detecting selective forwarding attacks. Furthermore, the approach is reliable, energy efficient, and scalable. PMID:26610499

Bionanomaterials and Bioinspired Nanostructures for Selective Vapor Sensing

NASA Astrophysics Data System (ADS)

Potyrailo, Radislav; Naik, Rajesh R.

2013-07-01

At present, monitoring of air at the workplace, in urban environments, and on battlefields; exhaled air from medical patients; air in packaged food containers; and so forth can be accomplished with different types of analytical instruments. Vapor sensors have their niche in these measurements when an unobtrusive, low-power, and cost-sensitive technical solution is required. Unfortunately, existing vapor sensors often degrade their vapor-quantitation accuracy in the presence of high levels of interferences and cannot quantitate several components in complex gas mixtures. Thus, new sensing approaches with improved sensor selectivity are required. This technological task can be accomplished by the careful design of sensing materials with new performance properties and by coupling these materials with the suitable physical transducers. This review is focused on the assessment of the capabilities of bionanomaterials and bioinspired nanostructures for selective vapor sensing. We demonstrate that these sensing materials can operate with diverse transducers based on electrical, mechanical, and optical readout principles and can provide vapor-response selectivity previously unattainable by using other sensing materials. This ability for selective vapor sensing provides opportunities to significantly impact the major directions in development and application scenarios of vapor sensors.

Multi-Layer Approach for the Detection of Selective Forwarding Attacks.

PubMed

Alajmi, Naser; Elleithy, Khaled

2015-11-19

Security breaches are a major threat in wireless sensor networks (WSNs). WSNs are increasingly used due to their broad range of important applications in both military and civilian domains. WSNs are prone to several types of security attacks. Sensor nodes have limited capacities and are often deployed in dangerous locations; therefore, they are vulnerable to different types of attacks, including wormhole, sinkhole, and selective forwarding attacks. Security attacks are classified as data traffic and routing attacks. These security attacks could affect the most significant applications of WSNs, namely, military surveillance, traffic monitoring, and healthcare. Therefore, there are different approaches to detecting security attacks on the network layer in WSNs. Reliability, energy efficiency, and scalability are strong constraints on sensor nodes that affect the security of WSNs. Because sensor nodes have limited capabilities in most of these areas, selective forwarding attacks cannot be easily detected in networks. In this paper, we propose an approach to selective forwarding detection (SFD). The approach has three layers: MAC pool IDs, rule-based processing, and anomaly detection. It maintains the safety of data transmission between a source node and base station while detecting selective forwarding attacks. Furthermore, the approach is reliable, energy efficient, and scalable.

A New Thiosemicarbazone-Based Fluorescence "Turn-on" Sensor for Zn(2+) Recognition with a Large Stokes Shift and its Application in Live Cell Imaging.

PubMed

Tang, Lijun; Huang, Zhenlong; Zheng, Zhuxuan; Zhong, Keli; Bian, Yanjiang

2016-09-01

Selective fluorescence turn on Zn(2+) sensor with long-wavelength emission and a large Stokes shift is highly desirable in Zn(2+) sensing area. We reported herein the synthesis and Zn(2+) recognition properties of a new thiosemicarbazone-based fluorescent sensor L. L displays high selectivity and sensitivity toward Zn(2+) over other metal ions in DMSO-H2O (1:1, v/v, HEPES 10 mM, pH = 7.4) solution with a long-wavelength emission at 572 nm and a large Stokes shift of 222 nm. Confocal fluorescence microscopy experiments demonstrate that L is cell-permeable and capable of monitoring intracellular Zn(2+). Graphical Abstract We report a new thiosemicarbazone-based fluorescent sensor (L) for selective recognition of Zn(2+) with a long wavelength emission and a large Stokes shift.

Enhanced and selective ammonia sensing of reduced graphene oxide based chemo resistive sensor at room temperature

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

Kumar, Ramesh, E-mail: rameshphysicsdu@gmail.com; Kaur, Amarjeet, E-mail: amarkaur@physics.du.ac.in

The reduced graphene oxide thin films were fabricated by using the spin coating method. The reduced graphene oxide samples were characterised by Raman studies to obtain corresponding D and G bands at 1360 and 1590 cm{sup −1} respectively. Fourier transform infra-red (FTIR) spectra consists of peak corresponds to sp{sup 2} hybridisation of carbon atoms at 1560 cm{sup −1}. The reduced graphene oxide based chemoresistive sensor exhibited a p-type semiconductor behaviour in ambient conditions and showed good sensitivity to different concentration of ammonia from 25 ppm to 500 ppm and excellent selectivity at room temperature. The sensor displays selectivity to several hazardous vapours such asmore » methanol, ethanol, acetone and hydrazine hydrate. The sensor demonstrated a sensitivity of 9.8 at 25 ppm concentration of ammonia with response time of 163 seconds.« less

Application of oxybutynin selective sensors for monitoring the dissolution profile and assay of pharmaceutical dosage forms.

PubMed

El Hamshary, Marwa S; Salem, Omar H; El Nashar, Rasha M

2010-01-01

Two ion-selective sensors of the plastic membrane type were prepared for the determination of oxybutynin hydrochloride (OxCl). They depend on the incorporation of the ion-associates with phosphotungestic acid or phosphomolybdic acid in a PVC matrix. A comparative study is made between their performance characteristics in batch and FIA conditions. The sensors have nearly the same usable concentration, temperature and pH range. They have a wide range of selectivity and can be applied for the determination of the relevant drug with nearly the same precision and accuracy in vitro. Dissolution testing was applied using the sensors; this offers a simple, rapid, cheap way out of sophisticated and high cost instruments used in the pharmacopeial method using HPLC. The investigated drug was determined in its pure and pharmaceutical preparations. The results were accurate and precise, as indicated by the recovery values and coefficients of variation.

A Support Vector Learning-Based Particle Filter Scheme for Target Localization in Communication-Constrained Underwater Acoustic Sensor Networks

PubMed Central

Zhang, Chenglin; Yan, Lei; Han, Song; Guan, Xinping

2017-01-01

Target localization, which aims to estimate the location of an unknown target, is one of the key issues in applications of underwater acoustic sensor networks (UASNs). However, the constrained property of an underwater environment, such as restricted communication capacity of sensor nodes and sensing noises, makes target localization a challenging problem. This paper relies on fractional sensor nodes to formulate a support vector learning-based particle filter algorithm for the localization problem in communication-constrained underwater acoustic sensor networks. A node-selection strategy is exploited to pick fractional sensor nodes with short-distance pattern to participate in the sensing process at each time frame. Subsequently, we propose a least-square support vector regression (LSSVR)-based observation function, through which an iterative regression strategy is used to deal with the distorted data caused by sensing noises, to improve the observation accuracy. At the same time, we integrate the observation to formulate the likelihood function, which effectively update the weights of particles. Thus, the particle effectiveness is enhanced to avoid “particle degeneracy” problem and improve localization accuracy. In order to validate the performance of the proposed localization algorithm, two different noise scenarios are investigated. The simulation results show that the proposed localization algorithm can efficiently improve the localization accuracy. In addition, the node-selection strategy can effectively select the subset of sensor nodes to improve the communication efficiency of the sensor network. PMID:29267252

Nonlinear estimation for arrays of chemical sensors

NASA Astrophysics Data System (ADS)

Yosinski, Jason; Paffenroth, Randy

2010-04-01

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

Spectroelectrochemistry as a Strategy for Improving Selectivity of Sensors for Security and Defense Applications

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

Heineman, William R.; Seliskar, Carl J.; Morris, Laura K.

2012-12-19

Spectroelectrochemistry provides improved selectivity for sensors by electrochemically modulating the optical signal associated with the analyte. The sensor consists of an optically transparent electrode (OTE) coated with a film that preconcentrates the target analyte. The OTE functions as an optical waveguide for attenuated total reflectance (ATR) spectroscopy, which detects the analyte by absorption. Alternatively, the OTE can serve as the excitation light for fluorescence detection, which is generally more sensitive than absorption. The analyte partitions into the film, undergoes an electrochemical redox reaction at the OTE surface, and absorbs or emits light in its oxidized or reduced state. The changemore » in the optical response associated with electrochemical oxidation or reduction at the OTE is used to quantify the analyte. Absorption sensors for metal ion complexes such as [Fe(CN)6]4- and [Ru(bpy)3]2+ and fluorescence sensors for [Ru(bpy)3]2+ and the polycyclic aromatic hydrocarbon 1-hydroxypyrene have been developed. The sensor concept has been extended to binding assays for a protein using avidin–biotin and 17β-estradiol–anti-estradiol antibodies. The sensor has been demonstrated to measure metal complexes in complex samples such as nuclear waste and natural water. This sensor has qualities needed for security and defense applications that require a high level of selectivity and good detection limits for target analytes in complex samples. Quickly monitoring and designating intent of a nuclear program by measuring the Ru/Tc fission product ratio is such an application.« less

A Support Vector Learning-Based Particle Filter Scheme for Target Localization in Communication-Constrained Underwater Acoustic Sensor Networks.

PubMed

Li, Xinbin; Zhang, Chenglin; Yan, Lei; Han, Song; Guan, Xinping

2017-12-21

Target localization, which aims to estimate the location of an unknown target, is one of the key issues in applications of underwater acoustic sensor networks (UASNs). However, the constrained property of an underwater environment, such as restricted communication capacity of sensor nodes and sensing noises, makes target localization a challenging problem. This paper relies on fractional sensor nodes to formulate a support vector learning-based particle filter algorithm for the localization problem in communication-constrained underwater acoustic sensor networks. A node-selection strategy is exploited to pick fractional sensor nodes with short-distance pattern to participate in the sensing process at each time frame. Subsequently, we propose a least-square support vector regression (LSSVR)-based observation function, through which an iterative regression strategy is used to deal with the distorted data caused by sensing noises, to improve the observation accuracy. At the same time, we integrate the observation to formulate the likelihood function, which effectively update the weights of particles. Thus, the particle effectiveness is enhanced to avoid "particle degeneracy" problem and improve localization accuracy. In order to validate the performance of the proposed localization algorithm, two different noise scenarios are investigated. The simulation results show that the proposed localization algorithm can efficiently improve the localization accuracy. In addition, the node-selection strategy can effectively select the subset of sensor nodes to improve the communication efficiency of the sensor network.

Application of an Optimal Tuner Selection Approach for On-Board Self-Tuning Engine Models

NASA Technical Reports Server (NTRS)

Simon, Donald L.; Armstrong, Jeffrey B.; Garg, Sanjay

2012-01-01

An enhanced design methodology for minimizing the error in on-line Kalman filter-based aircraft engine performance estimation applications is presented in this paper. It specific-ally addresses the under-determined estimation problem, in which there are more unknown parameters than available sensor measurements. This work builds upon an existing technique for systematically selecting a model tuning parameter vector of appropriate dimension to enable estimation by a Kalman filter, while minimizing the estimation error in the parameters of interest. While the existing technique was optimized for open-loop engine operation at a fixed design point, in this paper an alternative formulation is presented that enables the technique to be optimized for an engine operating under closed-loop control throughout the flight envelope. The theoretical Kalman filter mean squared estimation error at a steady-state closed-loop operating point is derived, and the tuner selection approach applied to minimize this error is discussed. A technique for constructing a globally optimal tuning parameter vector, which enables full-envelope application of the technology, is also presented, along with design steps for adjusting the dynamic response of the Kalman filter state estimates. Results from the application of the technique to linear and nonlinear aircraft engine simulations are presented and compared to the conventional approach of tuner selection. The new methodology is shown to yield a significant improvement in on-line Kalman filter estimation accuracy.

Gondola-shaped tetra-rhenium metallacycles modified evanescent wave infrared chemical sensors for selective determination of volatile organic compounds.

PubMed

Huang, Genin Gary; Lee, Chung-Jay; Tsai, Bo-Chan; Yang, Jyisy; Sathiyendiran, Malaichamy; Lu, Kuang-Lieh

2011-07-15

Water-stable and cavity-contained rhenium metallacycles were synthesized, and their ability to selectively interact with volatile organic compounds (VOCs) systematically studied using attenuated total reflection infrared (ATR-IR) spectroscopy. Integrating the unique properties of rhenium metallacycles into optical sensing technologies significantly improves selectivity in detecting aromatic compounds. To explore the interaction of rhenium metallacycles with VOCs, the surface of ATR sensing elements was modified with the synthesized rhenium metallacycles and used to detect VOCs. The results indicate that rhenium metallacycles have crown ether-like recognition sites, which can selectively interact with aromatic compounds, especially those bearing polar functional groups. The IR absorption bands of rhenium metallacycles shift significantly upon adsorption of aromatic VOCs, revealing a strong interaction between the tetra-rhenium metallacycles and guest aromatic compounds. Optimizing the thickness of the metallacycles coated on the surface of the sensing element led to rapid response in detection. The dynamic range of response was generally up to 30 mg/L with detection limits ca. 30 μg/L. Further studies of the effect of interferences indicate that recovery can be higher than 95% for most of the compounds tested. The results on the flow-cell device indicated that the performances were similar to a static detection system but the detection of VOCs can be largely simplified. Copyright © 2011 Elsevier B.V. All rights reserved.

Analytical network process based optimum cluster head selection in wireless sensor network.

PubMed

Farman, Haleem; Javed, Huma; Jan, Bilal; Ahmad, Jamil; Ali, Shaukat; Khalil, Falak Naz; Khan, Murad

2017-01-01

Wireless Sensor Networks (WSNs) are becoming ubiquitous in everyday life due to their applications in weather forecasting, surveillance, implantable sensors for health monitoring and other plethora of applications. WSN is equipped with hundreds and thousands of small sensor nodes. As the size of a sensor node decreases, critical issues such as limited energy, computation time and limited memory become even more highlighted. In such a case, network lifetime mainly depends on efficient use of available resources. Organizing nearby nodes into clusters make it convenient to efficiently manage each cluster as well as the overall network. In this paper, we extend our previous work of grid-based hybrid network deployment approach, in which merge and split technique has been proposed to construct network topology. Constructing topology through our proposed technique, in this paper we have used analytical network process (ANP) model for cluster head selection in WSN. Five distinct parameters: distance from nodes (DistNode), residual energy level (REL), distance from centroid (DistCent), number of times the node has been selected as cluster head (TCH) and merged node (MN) are considered for CH selection. The problem of CH selection based on these parameters is tackled as a multi criteria decision system, for which ANP method is used for optimum cluster head selection. Main contribution of this work is to check the applicability of ANP model for cluster head selection in WSN. In addition, sensitivity analysis is carried out to check the stability of alternatives (available candidate nodes) and their ranking for different scenarios. The simulation results show that the proposed method outperforms existing energy efficient clustering protocols in terms of optimum CH selection and minimizing CH reselection process that results in extending overall network lifetime. This paper analyzes that ANP method used for CH selection with better understanding of the dependencies of different components involved in the evaluation process.

Analytical network process based optimum cluster head selection in wireless sensor network

PubMed Central

Javed, Huma; Jan, Bilal; Ahmad, Jamil; Ali, Shaukat; Khalil, Falak Naz; Khan, Murad

2017-01-01

Wireless Sensor Networks (WSNs) are becoming ubiquitous in everyday life due to their applications in weather forecasting, surveillance, implantable sensors for health monitoring and other plethora of applications. WSN is equipped with hundreds and thousands of small sensor nodes. As the size of a sensor node decreases, critical issues such as limited energy, computation time and limited memory become even more highlighted. In such a case, network lifetime mainly depends on efficient use of available resources. Organizing nearby nodes into clusters make it convenient to efficiently manage each cluster as well as the overall network. In this paper, we extend our previous work of grid-based hybrid network deployment approach, in which merge and split technique has been proposed to construct network topology. Constructing topology through our proposed technique, in this paper we have used analytical network process (ANP) model for cluster head selection in WSN. Five distinct parameters: distance from nodes (DistNode), residual energy level (REL), distance from centroid (DistCent), number of times the node has been selected as cluster head (TCH) and merged node (MN) are considered for CH selection. The problem of CH selection based on these parameters is tackled as a multi criteria decision system, for which ANP method is used for optimum cluster head selection. Main contribution of this work is to check the applicability of ANP model for cluster head selection in WSN. In addition, sensitivity analysis is carried out to check the stability of alternatives (available candidate nodes) and their ranking for different scenarios. The simulation results show that the proposed method outperforms existing energy efficient clustering protocols in terms of optimum CH selection and minimizing CH reselection process that results in extending overall network lifetime. This paper analyzes that ANP method used for CH selection with better understanding of the dependencies of different components involved in the evaluation process. PMID:28719616

Evaluation of accelerometer based multi-sensor versus single-sensor activity recognition systems.

PubMed

Gao, Lei; Bourke, A K; Nelson, John

2014-06-01

Physical activity has a positive impact on people's well-being and it had been shown to decrease the occurrence of chronic diseases in the older adult population. To date, a substantial amount of research studies exist, which focus on activity recognition using inertial sensors. Many of these studies adopt a single sensor approach and focus on proposing novel features combined with complex classifiers to improve the overall recognition accuracy. In addition, the implementation of the advanced feature extraction algorithms and the complex classifiers exceed the computing ability of most current wearable sensor platforms. This paper proposes a method to adopt multiple sensors on distributed body locations to overcome this problem. The objective of the proposed system is to achieve higher recognition accuracy with "light-weight" signal processing algorithms, which run on a distributed computing based sensor system comprised of computationally efficient nodes. For analysing and evaluating the multi-sensor system, eight subjects were recruited to perform eight normal scripted activities in different life scenarios, each repeated three times. Thus a total of 192 activities were recorded resulting in 864 separate annotated activity states. The methods for designing such a multi-sensor system required consideration of the following: signal pre-processing algorithms, sampling rate, feature selection and classifier selection. Each has been investigated and the most appropriate approach is selected to achieve a trade-off between recognition accuracy and computing execution time. A comparison of six different systems, which employ single or multiple sensors, is presented. The experimental results illustrate that the proposed multi-sensor system can achieve an overall recognition accuracy of 96.4% by adopting the mean and variance features, using the Decision Tree classifier. The results demonstrate that elaborate classifiers and feature sets are not required to achieve high recognition accuracies on a multi-sensor system. Copyright © 2014 IPEM. Published by Elsevier Ltd. All rights reserved.

Microcontact imprinted surface plasmon resonance sensor for myoglobin detection.

PubMed

Osman, Bilgen; Uzun, Lokman; Beşirli, Necati; Denizli, Adil

2013-10-01

In this study, we prepared surface plasmon resonance (SPR) sensor using the molecular imprinting technique for myoglobin detection in human serum. For this purpose, we synthesized myoglobin imprinted poly(hydroxyethyl methacrylate-N-methacryloyl-l-tryptophan methyl ester) [poly(HEMA-MATrp)] nanofilm on the surface of SPR sensor. We also synthesized non-imprinted poly(HEMA-MATrp) nanofilm without myoglobin for the control experiments. The SPR sensor was characterized with contact angle measurements, atomic force microscopy, X-ray photoelectron spectroscopy, and ellipsometry. We investigated the effectiveness of the sensor using the SPR system. We evaluated the ability of SPR sensor to sense myoglobin with myoglobin solutions (pH7.4, phosphate buffer) in different concentration range and in the serum taken from a patient with acute myocardial infarction. We found that the Langmuir adsorption model was the most suitable for the sensor system. The detection limit was 87.6 ng/mL. In order to show the selectivity of the SPR sensor, we investigated the competitive detection of myoglobin, lysozyme, cytochrome c and bovine serum albumin. The results showed that the SPR sensor has high selectivity and sensitivity for myoglobin. Copyright © 2013. Published by Elsevier B.V.

Optimizing Cluster Heads for Energy Efficiency in Large-Scale Heterogeneous Wireless Sensor Networks

DOE PAGES

Gu, Yi; Wu, Qishi; Rao, Nageswara S. V.

2010-01-01

Many complex sensor network applications require deploying a large number of inexpensive and small sensors in a vast geographical region to achieve quality through quantity. Hierarchical clustering is generally considered as an efficient and scalable way to facilitate the management and operation of such large-scale networks and minimize the total energy consumption for prolonged lifetime. Judicious selection of cluster heads for data integration and communication is critical to the success of applications based on hierarchical sensor networks organized as layered clusters. We investigate the problem of selecting sensor nodes in a predeployed sensor network to be the cluster heads tomore » minimize the total energy needed for data gathering. We rigorously derive an analytical formula to optimize the number of cluster heads in sensor networks under uniform node distribution, and propose a Distance-based Crowdedness Clustering algorithm to determine the cluster heads in sensor networks under general node distribution. The results from an extensive set of experiments on a large number of simulated sensor networks illustrate the performance superiority of the proposed solution over the clustering schemes based on k -means algorithm.« less

A Formal Approach to the Selection by Minimum Error and Pattern Method for Sensor Data Loss Reduction in Unstable Wireless Sensor Network Communications

PubMed Central

Kim, Changhwa; Shin, DongHyun

2017-01-01

There are wireless networks in which typically communications are unsafe. Most terrestrial wireless sensor networks belong to this category of networks. Another example of an unsafe communication network is an underwater acoustic sensor network (UWASN). In UWASNs in particular, communication failures occur frequently and the failure durations can range from seconds up to a few hours, days, or even weeks. These communication failures can cause data losses significant enough to seriously damage human life or property, depending on their application areas. In this paper, we propose a framework to reduce sensor data loss during communication failures and we present a formal approach to the Selection by Minimum Error and Pattern (SMEP) method that plays the most important role for the reduction in sensor data loss under the proposed framework. The SMEP method is compared with other methods to validate its effectiveness through experiments using real-field sensor data sets. Moreover, based on our experimental results and performance comparisons, the SMEP method has been validated to be better than others in terms of the average sensor data value error rate caused by sensor data loss. PMID:28498312

A Formal Approach to the Selection by Minimum Error and Pattern Method for Sensor Data Loss Reduction in Unstable Wireless Sensor Network Communications.

PubMed

Kim, Changhwa; Shin, DongHyun

2017-05-12

There are wireless networks in which typically communications are unsafe. Most terrestrial wireless sensor networks belong to this category of networks. Another example of an unsafe communication network is an underwater acoustic sensor network (UWASN). In UWASNs in particular, communication failures occur frequently and the failure durations can range from seconds up to a few hours, days, or even weeks. These communication failures can cause data losses significant enough to seriously damage human life or property, depending on their application areas. In this paper, we propose a framework to reduce sensor data loss during communication failures and we present a formal approach to the Selection by Minimum Error and Pattern (SMEP) method that plays the most important role for the reduction in sensor data loss under the proposed framework. The SMEP method is compared with other methods to validate its effectiveness through experiments using real-field sensor data sets. Moreover, based on our experimental results and performance comparisons, the SMEP method has been validated to be better than others in terms of the average sensor data value error rate caused by sensor data loss.

Conducting electrospun fibres with polyanionic grafts as highly selective, label-free, electrochemical biosensor with a low detection limit for non-Hodgkin lymphoma gene.

PubMed

Kerr-Phillips, Thomas E; Aydemir, Nihan; Chan, Eddie Wai Chi; Barker, David; Malmström, Jenny; Plesse, Cedric; Travas-Sejdic, Jadranka

2018-02-15

A highly selective, label-free sensor for the non-Hodgkin lymphoma gene, with an aM detection limit, utilizing electrochemical impedance spectroscopy (EIS) is presented. The sensor consists of a conducting electrospun fibre mat, surface-grafted with poly(acrylic acid) (PAA) brushes and a conducting polymer sensing element with covalently attached oligonucleotide probes. The sensor was fabricated from electrospun NBR rubber, embedded with poly(3,4-ethylenedioxythiophene) (PEDOT), followed by grafting poly(acrylic acid) brushes and then electrochemically polymerizing a conducting polymer monomer with ssDNA probe sequence pre-attached. The resulting non-Hodgkin lymphoma gene sensor showed a detection limit of 1aM (1 × 10 -18 mol/L), more than 400 folds lower compared to a thin-film analogue. The sensor presented extraordinary selectivity, with only 1%, 2.7% and 4.6% of the signal recorded for the fully non-complimentary, T-A and G-C base mismatch oligonucleotide sequences, respectively. We suggest that such greatly enhanced selectivity is due to the presence of negatively charged carboxylic acid moieties from PAA grafts that electrostatically repel the non-complementary and mismatch DNA sequences, overcoming the non-specific binding. Copyright © 2017 Elsevier B.V. All rights reserved.

A new molecularly imprinted polymer (MIP)-based electrochemical sensor for monitoring 2,4,6-trinitrotoluene (TNT) in natural waters and soil samples.

PubMed

Alizadeh, Taher; Zare, Mashaalah; Ganjali, Mohamad Reza; Norouzi, Parviz; Tavana, Babak

2010-01-15

A high selective voltammetric sensor for 2,4,6-trinitrotoluene (TNT) was introduced. TNT selective MIP and non-imprinted polymer (NIP) were synthesized and then used for carbon paste (CP) electrode preparation. The MIP, incorporated in the carbon paste electrode, functioned as selectively recognition element and pre-concentrator agent for TNT determination. The prepared electrode was used for TNT measurement by the three steps procedure, including analyte extraction in the electrode, electrode washing and electrochemical measurement of TNT. The MIP-CP electrode showed very high recognition ability in comparison to NIP-CP. It was shown that electrode washing after TNT extraction led to enhanced selectivity. The response of square wave voltammetry for TNT determination by proposed electrode was higher than that of differential pulse voltammetry. Some parameters affecting sensor response were optimized and then a calibration curve plotted. A dynamic linear range of 5x10(-9) to 1x10(-6) mol l(-1) was obtained. The detection limit of the sensor was calculated equal to 1.5x10(-9) mol l(-1). This sensor was used successfully for TNT determination in different water and soil samples. Copyright 2009 Elsevier B.V. All rights reserved.

Highly Selective and Sensitive Self-Powered Glucose Sensor Based on Capacitor Circuit.

PubMed

Slaughter, Gymama; Kulkarni, Tanmay

2017-05-03

Enzymatic glucose biosensors are being developed to incorporate nanoscale materials with the biological recognition elements to assist in the rapid and sensitive detection of glucose. Here we present a highly sensitive and selective glucose sensor based on capacitor circuit that is capable of selectively sensing glucose while simultaneously powering a small microelectronic device. Multi-walled carbon nanotubes (MWCNTs) is chemically modified with pyrroloquinoline quinone glucose dehydrogenase (PQQ-GDH) and bilirubin oxidase (BOD) at anode and cathode, respectively, in the biofuel cell arrangement. The input voltage (as low as 0.25 V) from the biofuel cell is converted to a stepped-up power and charged to the capacitor to the voltage of 1.8 V. The frequency of the charge/discharge cycle of the capacitor corresponded to the oxidation of glucose. The biofuel cell structure-based glucose sensor synergizes the advantages of both the glucose biosensor and biofuel cell. In addition, this glucose sensor favored a very high selectivity towards glucose in the presence of competing and non-competing analytes. It exhibited unprecedented sensitivity of 37.66 Hz/mM.cm 2 and a linear range of 1 to 20 mM. This innovative self-powered glucose sensor opens new doors for implementation of biofuel cells and capacitor circuits for medical diagnosis and powering therapeutic devices.

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

NASA Astrophysics Data System (ADS)

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

2018-05-01

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

A uniform energy consumption algorithm for wireless sensor and actuator networks based on dynamic polling point selection.

PubMed

Li, Shuo; Peng, Jun; Liu, Weirong; Zhu, Zhengfa; Lin, Kuo-Chi

2013-12-19

Recent research has indicated that using the mobility of the actuator in wireless sensor and actuator networks (WSANs) to achieve mobile data collection can greatly increase the sensor network lifetime. However, mobile data collection may result in unacceptable collection delays in the network if the path of the actuator is too long. Because real-time network applications require meeting data collection delay constraints, planning the path of the actuator is a very important issue to balance the prolongation of the network lifetime and the reduction of the data collection delay. In this paper, a multi-hop routing mobile data collection algorithm is proposed based on dynamic polling point selection with delay constraints to address this issue. The algorithm can actively update the selection of the actuator's polling points according to the sensor nodes' residual energies and their locations while also considering the collection delay constraint. It also dynamically constructs the multi-hop routing trees rooted by these polling points to balance the sensor node energy consumption and the extension of the network lifetime. The effectiveness of the algorithm is validated by simulation.

Accelerator Vacuum Protection System

NASA Astrophysics Data System (ADS)

Barua, Pradip; Kothari, Ashok; Archunan, M.; Joshi, Rajan

2012-11-01

A new and elaborate automatic vacuum protection system using fast acting valve has been installed to avoid accidental venting of accelerator from experimental chamber side. To cover all the beam lines and to reduce the system cost, it has been installed at a common point from where all the seven beam lines originate. The signals are obtained by placing fast response pressure sensing gauges (HV SENSOR) near all the experimental stations. The closing time of the fast valve is 10 milli-second. The fast closing system protects only one vacuum line at a time. At IUAC, we have seven beam lines so one sensor was placed in each of the beam lines near experimental chamber and a multiplexer was incorporated into the fast closing system. At the time of experiment, the sensor of the active beam line is selected through the multiplexer and the Fast closing valve is interlocked with the selected sensor. As soon as the pressure sensor senses the pressure rise beyond a selected pressure, the signal is transferred and the fast valve closes within 10 to 12 millisecond.

Supramolecular fabrication of multilevel graphene-based gas sensors with high NO2 sensibility.

PubMed

Chen, Zhuo; Umar, Ahmad; Wang, Shiwei; Wang, Yao; Tian, Tong; Shang, Ying; Fan, Yuzun; Qi, Qi; Xu, Dongmei; Jiang, Lei

2015-06-14

This study reports the supramolecular assembly of a silver nanoparticle-naphthalene-1-sulphonic acid-reduced graphene oxide composite (Ag-NA-rGO) and its utilization to fabricate a highly sensitive and selective gas sensor. The prepared supramolecular assembly acted not only as a non-covalent functionalization platform (π-π interaction) but was also an excellent scaffold to fabricate a highly sensitive and selective low concentration NO2 gas sensor. The prepared composites were characterized using several techniques, which revealed that the graphene sheets were dispersed as ultrathin monolayers with a uniform distribution of silver nanoparticles. The fabricated multilevel structure exhibited an excellent sensing performance, i.e. 2.8 times better, towards 10 ppm NO2 compared to the NA-rGO and rGO based sensors. Apart from its high sensitivity, superior reversibility and selectivity, the prepared supramolecular assembly exhibited an outstanding linear response over the large concentration range from 1 ppm to 10 ppm. The obtained results demonstrate that the prepared supramolecular assembly holds great potential in the fabrication of efficient and effective low-concentration NO2 gas sensors for practical applications.

The improvement of gas-sensing properties of SnO2/zeolite-assembled composite

NASA Astrophysics Data System (ADS)

Sun, Yanhui; Wang, Jing; Li, Xiaogan; Du, Haiying; Huang, Qingpan

2018-05-01

SnO2-impregnated zeolite composites were used as gas-sensing materials to improve the sensitivity and selectivity of the metal oxide-based resistive-type gas sensors. Nanocrystalline MFI type zeolite (ZSM-5) was prepared by hydrothermal synthesis. Highly dispersive SnO2 nanoparticles were then successfully assembled on the surface of the ZSM-5 nanoparticles by using the impregnation methods. The SnO2 nanoparticles are nearly spherical with the particle size of 10 nm. An enhanced formaldehyde sensing of as-synthesized SnO2-ZSM-5-based sensor was observed whereas a suppression on the sensor response to other volatile organic vapors (VOCs) such as acetone, ethanol, and methanol was noticed. The possible reasons for this contrary observation were proposed to be related to the amount of the produced water vapor during the sensing reactions assisted by the ZSM-5 nanoparticles. This provides a possible new strategy to improve the selectivity of the gas sensors. The effect of the humidity on the sensor response to formaldehyde was investigated and it was found the higher humidity would decrease the sensor response. A coating layer of the ZSM-5 nanoparticles on top of the SnO2-ZSM-5-sensing film was thus applied to further improve the sensitivity and selectivity of the sensor through the strong adsorption ability to polar gases and the "filtering effect" by the pores of ZSM-5.

Highly selective room temperature NO2 gas sensor based on rGO-ZnO composite

NASA Astrophysics Data System (ADS)

Jyoti, Kanaujiya, Neha; Varma, G. D.

2018-05-01

Blending metal oxide nanoparticles with graphene or its derivatives can greatly enhance gas sensing characteristics. In the present work, ZnO nanoparticles have been synthesized via reflux method. Thin films of reduced graphene oxide (rGO) and composite of rGO-ZnO have been fabricated by drop casting method for gas sensing application. The samples have been characterized by X-ray diffraction (XRD) and Field-emission scanning electron microscope (FESEM) for the structural and morphological studies respectively. Sensing measurements have been carried out for the composite film of rGO-ZnO for different concentrations of NO2 ranging from 4 to 100 ppm. Effect of increasing temperature on the sensing performance has also been studied and the rGO-ZnO composite sensor shows maximum percentage response at room temperature. The limit of detection (LOD) for rGO-ZnO composite sensor is 4ppm and it exhibits a high response of 48.4% for 40 ppm NO2 at room temperature. To check the selectivity of the composite sensor, sensor film has been exposed to 40 ppm different gases like CO, NH3, H2S and Cl2 at room temperature and the sensor respond negligibly to these gases. The present work suggests that rGO-ZnO composite material can be a better candidate for fabrication of highly selective room temperature NO2 gas sensor.

Systematic Treatment Selection (STS): A Review and Future Directions

ERIC Educational Resources Information Center

Nguyen, Tam T.; Bertoni, Matteo; Charvat, Mylea; Gheytanchi, Anahita; Beutler, Larry E.

2007-01-01

Systematic Treatment Selection (STS) is a form of technical eclectism that develops and plans treatments using empirically founded principles of psychotherapy. It is a model that provides systematic guidelines for the utilization of different psychotherapeutic strategies based on patient qualities and problem characteristics. Historically, it…

An Electrochemical NO2 Sensor Based on Ionic Liquid: Influence of the Morphology of the Polymer Electrolyte on Sensor Sensitivity

PubMed Central

Kuberský, Petr; Altšmíd, Jakub; Hamáček, Aleš; Nešpůrek, Stanislav; Zmeškal, Oldřich

2015-01-01

A systematic study was carried out to investigate the effect of ionic liquid in solid polymer electrolyte (SPE) and its layer morphology on the characteristics of an electrochemical amperometric nitrogen dioxide sensor. Five different ionic liquids were immobilized into a solid polymer electrolyte and key sensor parameters (sensitivity, response/recovery times, hysteresis and limit of detection) were characterized. The study revealed that the sensor based on 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][N(Tf)2]) showed the best sensitivity, fast response/recovery times, and low sensor response hysteresis. The working electrode, deposited from water-based carbon nanotube ink, was prepared by aerosol-jet printing technology. It was observed that the thermal treatment and crystallinity of poly(vinylidene fluoride) (PVDF) in the solid polymer electrolyte influenced the sensitivity. Picture analysis of the morphology of the SPE layer based on [EMIM][N(Tf)2] ionic liquid treated under different conditions suggests that the sensor sensitivity strongly depends on the fractal dimension of PVDF spherical objects in SPE. Their deformation, e.g., due to crowding, leads to a decrease in sensor sensitivity. PMID:26569248

Establishing imaging sensor specifications for digital still cameras

NASA Astrophysics Data System (ADS)

Kriss, Michael A.

2007-02-01

Digital Still Cameras, DSCs, have now displaced conventional still cameras in most markets. The heart of a DSC is thought to be the imaging sensor, be it Full Frame CCD, and Interline CCD, a CMOS sensor or the newer Foveon buried photodiode sensors. There is a strong tendency by consumers to consider only the number of mega-pixels in a camera and not to consider the overall performance of the imaging system, including sharpness, artifact control, noise, color reproduction, exposure latitude and dynamic range. This paper will provide a systematic method to characterize the physical requirements of an imaging sensor and supporting system components based on the desired usage. The analysis is based on two software programs that determine the "sharpness", potential for artifacts, sensor "photographic speed", dynamic range and exposure latitude based on the physical nature of the imaging optics, sensor characteristics (including size of pixels, sensor architecture, noise characteristics, surface states that cause dark current, quantum efficiency, effective MTF, and the intrinsic full well capacity in terms of electrons per square centimeter). Examples will be given for consumer, pro-consumer, and professional camera systems. Where possible, these results will be compared to imaging system currently on the market.

A Systematic Review of Wearable Patient Monitoring Systems - Current Challenges and Opportunities for Clinical Adoption.

PubMed

Baig, Mirza Mansoor; GholamHosseini, Hamid; Moqeem, Aasia A; Mirza, Farhaan; Lindén, Maria

2017-07-01

The aim of this review is to investigate barriers and challenges of wearable patient monitoring (WPM) solutions adopted by clinicians in acute, as well as in community, care settings. Currently, healthcare providers are coping with ever-growing healthcare challenges including an ageing population, chronic diseases, the cost of hospitalization, and the risk of medical errors. WPM systems are a potential solution for addressing some of these challenges by enabling advanced sensors, wearable technology, and secure and effective communication platforms between the clinicians and patients. A total of 791 articles were screened and 20 were selected for this review. The most common publication venue was conference proceedings (13, 54%). This review only considered recent studies published between 2015 and 2017. The identified studies involved chronic conditions (6, 30%), rehabilitation (7, 35%), cardiovascular diseases (4, 20%), falls (2, 10%) and mental health (1, 5%). Most studies focussed on the system aspects of WPM solutions including advanced sensors, wireless data collection, communication platform and clinical usability based on a specific area or disease. The current studies are progressing with localized sensor-software integration to solve a specific use-case/health area using non-scalable and 'silo' solutions. There is further work required regarding interoperability and clinical acceptance challenges. The advancement of wearable technology and possibilities of using machine learning and artificial intelligence in healthcare is a concept that has been investigated by many studies. We believe future patient monitoring and medical treatments will build upon efficient and affordable solutions of wearable technology.

Analysis of Public Datasets for Wearable Fall Detection Systems.

PubMed

Casilari, Eduardo; Santoyo-Ramón, José-Antonio; Cano-García, José-Manuel

2017-06-27

Due to the boom of wireless handheld devices such as smartwatches and smartphones, wearable Fall Detection Systems (FDSs) have become a major focus of attention among the research community during the last years. The effectiveness of a wearable FDS must be contrasted against a wide variety of measurements obtained from inertial sensors during the occurrence of falls and Activities of Daily Living (ADLs). In this regard, the access to public databases constitutes the basis for an open and systematic assessment of fall detection techniques. This paper reviews and appraises twelve existing available data repositories containing measurements of ADLs and emulated falls envisaged for the evaluation of fall detection algorithms in wearable FDSs. The analysis of the found datasets is performed in a comprehensive way, taking into account the multiple factors involved in the definition of the testbeds deployed for the generation of the mobility samples. The study of the traces brings to light the lack of a common experimental benchmarking procedure and, consequently, the large heterogeneity of the datasets from a number of perspectives (length and number of samples, typology of the emulated falls and ADLs, characteristics of the test subjects, features and positions of the sensors, etc.). Concerning this, the statistical analysis of the samples reveals the impact of the sensor range on the reliability of the traces. In addition, the study evidences the importance of the selection of the ADLs and the need of categorizing the ADLs depending on the intensity of the movements in order to evaluate the capability of a certain detection algorithm to discriminate falls from ADLs.

Analysis of Public Datasets for Wearable Fall Detection Systems

PubMed Central

Santoyo-Ramón, José-Antonio; Cano-García, José-Manuel

2017-01-01

Due to the boom of wireless handheld devices such as smartwatches and smartphones, wearable Fall Detection Systems (FDSs) have become a major focus of attention among the research community during the last years. The effectiveness of a wearable FDS must be contrasted against a wide variety of measurements obtained from inertial sensors during the occurrence of falls and Activities of Daily Living (ADLs). In this regard, the access to public databases constitutes the basis for an open and systematic assessment of fall detection techniques. This paper reviews and appraises twelve existing available data repositories containing measurements of ADLs and emulated falls envisaged for the evaluation of fall detection algorithms in wearable FDSs. The analysis of the found datasets is performed in a comprehensive way, taking into account the multiple factors involved in the definition of the testbeds deployed for the generation of the mobility samples. The study of the traces brings to light the lack of a common experimental benchmarking procedure and, consequently, the large heterogeneity of the datasets from a number of perspectives (length and number of samples, typology of the emulated falls and ADLs, characteristics of the test subjects, features and positions of the sensors, etc.). Concerning this, the statistical analysis of the samples reveals the impact of the sensor range on the reliability of the traces. In addition, the study evidences the importance of the selection of the ADLs and the need of categorizing the ADLs depending on the intensity of the movements in order to evaluate the capability of a certain detection algorithm to discriminate falls from ADLs. PMID:28653991

Low Cost Sensors-Current Capabilities and Gaps

EPA Science Inventory

1. Present the findings from the a recent technology review of gas and particulate phase sensors 2. Focus on the lower-cost sensors 3. Discuss current capabilities, estimated range of measurement, selectivity, deployment platforms, response time, and expected range of acceptabl...

FaptaSyme: A Strategy for Converting a Monomer/Oligomer-Nonselective Aptameric Sensor into an Oligomer-Selective One.

PubMed

Evangelista, Baggio A; Kim, Yoon-Seong; Kolpashchikov, Dmitry M

2018-04-26

Aptameric sensors can bind molecular targets and produce output signals, a phenomenon that is used in bioassays. In some cases, it is important to distinguish between monomeric and oligomeric forms of a target. Here, we propose a strategy to convert a monomer/oligomer-nonselective sensor into an oligomer-selective sensor. We designed an aptazyme that produced a high fluorescent output in the presence of oligomeric α-synuclein (a molecular marker of Parkinson's disease) but not its monomeric form. The strategy is potentially useful in the design of point-of-care tests for the diagnosis of neurodegenerative diseases. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fiber optic vibration sensor

DOEpatents

Dooley, Joseph B.; Muhs, Jeffrey D.; Tobin, Kenneth W.

1995-01-01

A fiber optic vibration sensor utilizes two single mode optical fibers supported by a housing with one optical fiber fixedly secured to the housing and providing a reference signal and the other optical fiber having a free span length subject to vibrational displacement thereof with respect to the housing and the first optical fiber for providing a signal indicative of a measurement of any perturbation of the sensor. Damping or tailoring of the sensor to be responsive to selected levels of perturbation is provided by altering the diameter of optical fibers or by immersing at least a portion of the free span length of the vibration sensing optical fiber into a liquid of a selected viscosity.

Fiber optic vibration sensor

DOEpatents

Dooley, J.B.; Muhs, J.D.; Tobin, K.W.

1995-01-10

A fiber optic vibration sensor utilizes two single mode optical fibers supported by a housing with one optical fiber fixedly secured to the housing and providing a reference signal and the other optical fiber having a free span length subject to vibrational displacement thereof with respect to the housing and the first optical fiber for providing a signal indicative of a measurement of any perturbation of the sensor. Damping or tailoring of the sensor to be responsive to selected levels of perturbation is provided by altering the diameter of optical fibers or by immersing at least a portion of the free span length of the vibration sensing optical fiber into a liquid of a selected viscosity. 2 figures.

Sensor selection and chemo-sensory optimization: toward an adaptable chemo-sensory system.

PubMed

Vergara, Alexander; Llobet, Eduard

2011-01-01

Over the past two decades, despite the tremendous research on chemical sensors and machine olfaction to develop micro-sensory systems that will accomplish the growing existent needs in personal health (implantable sensors), environment monitoring (widely distributed sensor networks), and security/threat detection (chemo/bio warfare agents), simple, low-cost molecular sensing platforms capable of long-term autonomous operation remain beyond the current state-of-the-art of chemical sensing. A fundamental issue within this context is that most of the chemical sensors depend on interactions between the targeted species and the surfaces functionalized with receptors that bind the target species selectively, and that these binding events are coupled with transduction processes that begin to change when they are exposed to the messy world of real samples. With the advent of fundamental breakthroughs at the intersection of materials science, micro- and nano-technology, and signal processing, hybrid chemo-sensory systems have incorporated tunable, optimizable operating parameters, through which changes in the response characteristics can be modeled and compensated as the environmental conditions or application needs change. The objective of this article, in this context, is to bring together the key advances at the device, data processing, and system levels that enable chemo-sensory systems to "adapt" in response to their environments. Accordingly, in this review we will feature the research effort made by selected experts on chemical sensing and information theory, whose work has been devoted to develop strategies that provide tunability and adaptability to single sensor devices or sensory array systems. Particularly, we consider sensor-array selection, modulation of internal sensing parameters, and active sensing. The article ends with some conclusions drawn from the results presented and a visionary look toward the future in terms of how the field may evolve.

Sensor Selection and Chemo-Sensory Optimization: Toward an Adaptable Chemo-Sensory System

PubMed Central

Vergara, Alexander; Llobet, Eduard

2011-01-01

Over the past two decades, despite the tremendous research on chemical sensors and machine olfaction to develop micro-sensory systems that will accomplish the growing existent needs in personal health (implantable sensors), environment monitoring (widely distributed sensor networks), and security/threat detection (chemo/bio warfare agents), simple, low-cost molecular sensing platforms capable of long-term autonomous operation remain beyond the current state-of-the-art of chemical sensing. A fundamental issue within this context is that most of the chemical sensors depend on interactions between the targeted species and the surfaces functionalized with receptors that bind the target species selectively, and that these binding events are coupled with transduction processes that begin to change when they are exposed to the messy world of real samples. With the advent of fundamental breakthroughs at the intersection of materials science, micro- and nano-technology, and signal processing, hybrid chemo-sensory systems have incorporated tunable, optimizable operating parameters, through which changes in the response characteristics can be modeled and compensated as the environmental conditions or application needs change. The objective of this article, in this context, is to bring together the key advances at the device, data processing, and system levels that enable chemo-sensory systems to “adapt” in response to their environments. Accordingly, in this review we will feature the research effort made by selected experts on chemical sensing and information theory, whose work has been devoted to develop strategies that provide tunability and adaptability to single sensor devices or sensory array systems. Particularly, we consider sensor-array selection, modulation of internal sensing parameters, and active sensing. The article ends with some conclusions drawn from the results presented and a visionary look toward the future in terms of how the field may evolve. PMID:22319492

SSC Geopositional Assessment of the Advanced Wide Field Sensor

NASA Technical Reports Server (NTRS)

Ross, Kenton

2006-01-01

The geopositional accuracy of the standard geocorrected product from the Advanced Wide Field Sensor (AWiFS) was evaluated using digital orthophoto quarter quadrangles and other reference sources of similar accuracy. Images were analyzed from summer 2004 through spring 2005. Forty to fifty check points were collected manually per scene and analyzed to determine overall circular error, estimates of horizontal bias, and other systematic errors. Measured errors were somewhat higher than the specifications for the data, but they were consistent with the analysis of the distributing vendor.

Thirty-fifth anniversary of the optical affinity sensor for glucose: a personal retrospective.

PubMed

Schultz, Jerome S

2015-01-01

Since 1962 when Clark introduced the enzyme electrode, research has been intense for a robust implantable glucose sensor. An alternative "optical affinity sensor" was introduced by Jerome Schultz in 1979. The evolution of this sensor technology into a new methodology is reviewed. The approach integrates a variety of disparate concepts: the selectivity of immunoassays-selectivity for glucose was obtained with concanavalin A, detection sensitivity was obtained with fluorescence (FITC-Dextran), and miniaturization was achieved by the use of an optical fiber readout system. Refinements of Schultz's optical affinity sensor approach over the past 35 years have led to a number of configurations that show great promise to meet the needs of a successful implantable continuous monitoring device for diabetics, some of which are currently being tested clinically. © 2014 Diabetes Technology Society.

Electrochemical Impedance Sensors for Monitoring Trace Amounts of NO3 in Selected Growing Media.

PubMed

Ghaffari, Seyed Alireza; Caron, William-O; Loubier, Mathilde; Normandeau, Charles-O; Viens, Jeff; Lamhamedi, Mohammed S; Gosselin, Benoit; Messaddeq, Younes

2015-07-21

With the advent of smart cities and big data, precision agriculture allows the feeding of sensor data into online databases for continuous crop monitoring, production optimization, and data storage. This paper describes a low-cost, compact, and scalable nitrate sensor based on electrochemical impedance spectroscopy for monitoring trace amounts of NO3- in selected growing media. The nitrate sensor can be integrated to conventional microelectronics to perform online nitrate sensing continuously over a wide concentration range from 0.1 ppm to 100 ppm, with a response time of about 1 min, and feed data into a database for storage and analysis. The paper describes the structural design, the Nyquist impedance response, the measurement sensitivity and accuracy, and the field testing of the nitrate sensor performed within tree nursery settings under ISO/IEC 17025 certifications.

Electrochemical Impedance Sensors for Monitoring Trace Amounts of NO3 in Selected Growing Media

PubMed Central

Ghaffari, Seyed Alireza; Caron, William-O.; Loubier, Mathilde; Normandeau, Charles-O.; Viens, Jeff; Lamhamedi, Mohammed S.; Gosselin, Benoit; Messaddeq, Younes

2015-01-01

With the advent of smart cities and big data, precision agriculture allows the feeding of sensor data into online databases for continuous crop monitoring, production optimization, and data storage. This paper describes a low-cost, compact, and scalable nitrate sensor based on electrochemical impedance spectroscopy for monitoring trace amounts of NO3− in selected growing media. The nitrate sensor can be integrated to conventional microelectronics to perform online nitrate sensing continuously over a wide concentration range from 0.1 ppm to 100 ppm, with a response time of about 1 min, and feed data into a database for storage and analysis. The paper describes the structural design, the Nyquist impedance response, the measurement sensitivity and accuracy, and the field testing of the nitrate sensor performed within tree nursery settings under ISO/IEC 17025 certifications. PMID:26197322

A novel reaction-based colorimetric and ratiometric fluorescent sensor for cyanide anion with a large emission shift and high selectivity.

PubMed

Wang, Shaodan; Fei, Xiaoliang; Guo, Jing; Yang, Qingbiao; Li, Yaoxian; Song, Yan

2016-01-01

A hybrid carbazole-hemicyanine dye (Cac) has been developed as a novel colorimetric and ratiometric fluorescent sensor for cyanide detection. Upon treatment with cyanide, Cac displayed a remarkable fluorescence ratiometric response, with the emission wavelength displaying a very large emission shift (214 nm). The detection of cyanide was performed via the nucleophilic addition of cyanide anion to the indolium group of the sensor, which resulted in the blocking of the intramolecular charge transfer (ICT) process in the sensor, inducing a ratiometric fluorescence change and simultaneously an obvious color change. Furthermore, competitive anions did not showed any significant changes both in color and emission intensity ratio (I381/I595), indicating the high selectivity of the sensor to CN(-). Copyright © 2015 Elsevier B.V. All rights reserved.

Potentiometric sensors using cotton yarns, carbon nanotubes and polymeric membranes.

PubMed

Guinovart, Tomàs; Parrilla, Marc; Crespo, Gastón A; Rius, F Xavier; Andrade, Francisco J

2013-09-21

A simple and generalized approach to build electrochemical sensors for wearable devices is presented. Commercial cotton yarns are first turned into electrical conductors through a simple dyeing process using a carbon nanotube ink. These conductive yarns are then partially coated with a suitable polymeric membrane to build ion-selective electrodes. Potentiometric measurements using these yarn-potentiometric sensors are demonstrated. Examples of yarns that can sense pH, K(+) and NH4(+) are presented. In all cases, these sensing yarns show limits of detection and linear ranges that are similar to those obtained with lab-made solid-state ion-selective electrodes. Through the immobilization of these sensors in a band-aid, it is shown that this approach could be easily implemented in a wearable device. Factors affecting the performance of the sensors and future potential applications are discussed.

Radiation sensors based on the generation of mobile protons in organic dielectrics.

PubMed

Kapetanakis, Eleftherios; Douvas, Antonios M; Argitis, Panagiotis; Normand, Pascal

2013-06-26

A sensing scheme based on mobile protons generated by radiation, including ionizing radiation (IonR), in organic gate dielectrics is investigated for the development of metal-insulator-semiconductor (MIS)-type dosimeters. Application of an electric field to the gate dielectric moves the protons and thereby alters the flat band voltage (VFB) of the MIS device. The shift in the VFB is proportional to the IonR-generated protons and, therefore, to the IonR total dose. Triphenylsulfonium nonaflate (TPSNF) photoacid generator (PAG)-containing poly(methyl methacrylate) (PMMA) polymeric films was selected as radiation-sensitive gate dielectrics. The effects of UV (249 nm) and gamma (Co-60) irradiations on the high-frequency capacitance versus the gate voltage (C-VG) curves of the MIS devices were investigated for different total dose values. Systematic improvements in sensitivity can be accomplished by increasing the concentration of the TPSNF molecules embedded in the polymeric matrix.

Performance characterization of material identification systems

NASA Astrophysics Data System (ADS)

Brown, Christopher D.; Green, Robert L.

2006-10-01

In recent years a number of analytical devices have been proposed and marketed specifically to enable field-based material identification. Technologies reliant on mass, near- and mid-infrared, and Raman spectroscopies are available today, and other platforms are imminent. These systems tend to perform material recognition based on an on-board library of material signatures. While figures of merit for traditional quantitative analytical sensors are broadly established (e.g., SNR, selectivity, sensitivity, limit of detection/decision), measures of performance for material identification systems have not been systematically discussed. In this paper we present an approach to performance characterization similar in spirit to ROC curves, but including elements of precision-recall curves and specialized for the intended-use of material identification systems. Important experimental considerations are discussed, including study design, sources of bias, uncertainty estimation, and cross-validation and the approach as a whole is illustrated using a commercially available handheld Raman material identification system.

Ultrasensitive and Selective Organic FET-type Nonenzymatic Dopamine Sensor Based on Platinum Nanoparticles-Decorated Reduced Graphene Oxide.

PubMed

Oh, Jungkyun; Lee, Jun Seop; Jun, Jaemoon; Kim, Sung Gun; Jang, Jyongsik

2017-11-15

Dopamine (DA), a catecholamine hormone, is an important neurotransmitter that controls renal and cardiovascular organizations and regulates physiological activities. Abnormal concentrations of DA cause unfavorable neuronal illnesses such as Parkinson's disease, schizophrenia, and attention deficit hyperactivity disorder/attention deficit disorder. However, the DA concentration is exceedingly low in patients and difficult to detect with existing biosensors. In this study, we developed an organic field-effect-transistor-type (OFET) nonenzyme biosensor using platinum nanoparticle-decorated reduced graphene oxide (Pt_rGO) for ultrasensitive and selective DA detection. The Pt_rGOs were fabricated by reducing GO aqueous solution-containing Pt precursors (PtCl 4 ) with a chemical reducing agent. The Pt_rGOs were immobilized on a graphene substrate by π-π interactions and a conducting-polymer source-drain electrode was patterned on the substrate to form the DA sensor. The resulting OFET sensor showed a high sensitivity to remarkably low DA concentrations (100 × 10 -18 M) and selectivity among interfering molecules. Good stability was expected for the OFET sensor because it was fabricated without an enzymatic receptor, and π-π conjugation is a part of the immobilization process. Furthermore, the OFET sensors are flexible and offer the possibility of wide application as wearable and portable sensors.

Estimation of end point foot clearance points from inertial sensor data.

PubMed

Santhiranayagam, Braveena K; Lai, Daniel T H; Begg, Rezaul K; Palaniswami, Marimuthu

2011-01-01

Foot clearance parameters provide useful insight into tripping risks during walking. This paper proposes a technique for the estimate of key foot clearance parameters using inertial sensor (accelerometers and gyroscopes) data. Fifteen features were extracted from raw inertial sensor measurements, and a regression model was used to estimate two key foot clearance parameters: First maximum vertical clearance (m x 1) after toe-off and the Minimum Toe Clearance (MTC) of the swing foot. Comparisons are made against measurements obtained using an optoelectronic motion capture system (Optotrak), at 4 different walking speeds. General Regression Neural Networks (GRNN) were used to estimate the desired parameters from the sensor features. Eight subjects foot clearance data were examined and a Leave-one-subject-out (LOSO) method was used to select the best model. The best average Root Mean Square Errors (RMSE) across all subjects obtained using all sensor features at the maximum speed for m x 1 was 5.32 mm and for MTC was 4.04 mm. Further application of a hill-climbing feature selection technique resulted in 0.54-21.93% improvement in RMSE and required fewer input features. The results demonstrated that using raw inertial sensor data with regression models and feature selection could accurately estimate key foot clearance parameters.

A highly selective electrochemical sensor based on molecularly imprinted polypyrrole-modified gold electrode for the determination of glyphosate in cucumber and tap water.

PubMed

Zhang, Chao; She, Yongxin; Li, Tengfei; Zhao, Fengnian; Jin, Maojun; Guo, Yirong; Zheng, Lufei; Wang, Shanshan; Jin, Fen; Shao, Hua; Liu, Haijin; Wang, Jing

2017-12-01

An electrochemical sensor based on molecularly imprinted polypyrrole (MIPPy) was developed for selective and sensitive detection of the herbicide glyphosate (Gly) in cucumber and tap water samples. The sensor was prepared via synthesis of molecularly imprinted polymers on a gold electrode in the presence of Gly as the template molecule and pyrrole as the functional monomer by cyclic voltammetry (CV). The sensor preparation conditions including the ratio of template to functional monomers, number of CV cycles in the electropolymerization process, the method of template removal, incubation time, and pH were optimized. Under the optimal experimental conditions, the DPV peak currents of hexacyanoferrate/hexacyanoferrite changed linearly with Gly concentration in the range from 5 to 800 ng mL -1 , with a detection limit of 0.27 ng mL -1 (S/N = 3). The sensor was used to detect the concentration of Gly in cucumber and tap water samples, with recoveries ranging from 72.70 to 98.96%. The proposed sensor showed excellent selectivity, good stability and reversibility, and could detect the Gly in real samples rapidly and sensitively. Graphical abstract Schematic illustration of the experimental procedure to detect Gly using the MIPPy electrode.

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

DOEpatents

Allendorf, Mark D; Robinson, Alex L

2014-12-09

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

Model-Based Method for Sensor Validation

NASA Technical Reports Server (NTRS)

Vatan, Farrokh

2012-01-01

Fault detection, diagnosis, and prognosis are essential tasks in the operation of autonomous spacecraft, instruments, and in situ platforms. One of NASA s key mission requirements is robust state estimation. Sensing, using a wide range of sensors and sensor fusion approaches, plays a central role in robust state estimation, and there is a need to diagnose sensor failure as well as component failure. Sensor validation can be considered to be part of the larger effort of improving reliability and safety. The standard methods for solving the sensor validation problem are based on probabilistic analysis of the system, from which the method based on Bayesian networks is most popular. Therefore, these methods can only predict the most probable faulty sensors, which are subject to the initial probabilities defined for the failures. The method developed in this work is based on a model-based approach and provides the faulty sensors (if any), which can be logically inferred from the model of the system and the sensor readings (observations). The method is also more suitable for the systems when it is hard, or even impossible, to find the probability functions of the system. The method starts by a new mathematical description of the problem and develops a very efficient and systematic algorithm for its solution. The method builds on the concepts of analytical redundant relations (ARRs).

A molecular rotor based ratiometric sensor for basic amino acids.

PubMed

Pettiwala, Aafrin M; Singh, Prabhat K

2018-01-05

The inevitable importance of basic amino acids, arginine and lysine, in human health and metabolism demands construction of efficient sensor systems for them. However, there are only limited reports on the 'ratiometric' detection of basic amino acids which is further restricted by the use of chemically complex sensor molecules, which impedes their prospect for practical applications. Herein, we report a ratiometric sensor system build on simple mechanism of disassociation of novel emissive Thioflavin-T H-aggregates from heparin surface, when subjected to interaction with basic amino acids. The strong and selective electrostatic and hydrogen bonding interaction of basic amino acids with heparin leads to large alteration in photophysical attributes of heparin bound Thioflavin-T, which forms a highly sensitive sensor platform for detection of basic amino acids in aqueous solution. These selective interactions between basic amino acids and heparin allow our sensor system to discriminate arginine and lysine from other amino acids. This unique mechanism of dissociation of Thioflavin-T aggregates from heparin surface provides ratiometric response on both fluorimetric and colorimetric outputs for detection of arginine and lysine, and thus it holds a significant advantage over other developed sensor systems which are restricted to single wavelength detection. Apart from the sensitivity and selectivity, our system also provides the advantage of simplicity, dual mode of sensing, and more importantly, it employs an inexpensive commercially available probe molecule, which is a significant advantage over other developed sensor systems that uses tedious synthesis protocol for the employed probe in the detection scheme, an impediment for practical applications. Additionally, our sensor system also shows response in complex biological media of serum samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Dynamic Modeling Accuracy Dependence on Errors in Sensor Measurements, Mass Properties, and Aircraft Geometry

NASA Technical Reports Server (NTRS)

Grauer, Jared A.; Morelli, Eugene A.

2013-01-01

A nonlinear simulation of the NASA Generic Transport Model was used to investigate the effects of errors in sensor measurements, mass properties, and aircraft geometry on the accuracy of dynamic models identified from flight data. Measurements from a typical system identification maneuver were systematically and progressively deteriorated and then used to estimate stability and control derivatives within a Monte Carlo analysis. Based on the results, recommendations were provided for maximum allowable errors in sensor measurements, mass properties, and aircraft geometry to achieve desired levels of dynamic modeling accuracy. Results using other flight conditions, parameter estimation methods, and a full-scale F-16 nonlinear aircraft simulation were compared with these recommendations.

Fiber optical sensors for aircraft applications

NASA Astrophysics Data System (ADS)

Pechstedt, Ralf D.

2014-09-01

In this paper selected fiber optical point sensors that are of potential interest for deployment in aircraft are discussed. The operating principles together with recent measurement results are described. Examples include a high-temperature combined pressure and temperature sensor for engine health, hydraulics and landing gear monitoring, an ultra-high sensitive pressure sensor for oil, pneumatic and fluid aero systems applications and a combined acceleration and temperature sensor for condition monitoring of rotating components.

Feature Selection for Chemical Sensor Arrays Using Mutual Information

PubMed Central

Wang, X. Rosalind; Lizier, Joseph T.; Nowotny, Thomas; Berna, Amalia Z.; Prokopenko, Mikhail; Trowell, Stephen C.

2014-01-01

We address the problem of feature selection for classifying a diverse set of chemicals using an array of metal oxide sensors. Our aim is to evaluate a filter approach to feature selection with reference to previous work, which used a wrapper approach on the same data set, and established best features and upper bounds on classification performance. We selected feature sets that exhibit the maximal mutual information with the identity of the chemicals. The selected features closely match those found to perform well in the previous study using a wrapper approach to conduct an exhaustive search of all permitted feature combinations. By comparing the classification performance of support vector machines (using features selected by mutual information) with the performance observed in the previous study, we found that while our approach does not always give the maximum possible classification performance, it always selects features that achieve classification performance approaching the optimum obtained by exhaustive search. We performed further classification using the selected feature set with some common classifiers and found that, for the selected features, Bayesian Networks gave the best performance. Finally, we compared the observed classification performances with the performance of classifiers using randomly selected features. We found that the selected features consistently outperformed randomly selected features for all tested classifiers. The mutual information filter approach is therefore a computationally efficient method for selecting near optimal features for chemical sensor arrays. PMID:24595058

Selection of a battery of rapid toxicity sensors for drinking water evaluation.

PubMed

van der Schalie, William H; James, Ryan R; Gargan, Thomas P

2006-07-15

Comprehensive identification of chemical contaminants in Army field water supplies can be a lengthy process, but rapid analytical methods suitable for field use are limited. A complementary approach is to directly measure toxicity instead of individual chemical constituents. Ten toxicity sensors utilizing enzymes, bacteria, or vertebrate cells were tested to determine the minimum number of sensors that could rapidly identify toxicity in water samples containing one of 12 industrial chemicals. The ideal sensor would respond at a concentration just exceeding the Military Exposure Guideline (MEG) level for the chemical (an estimated threshold for adverse effects) but below the human lethal concentration. Chemical solutions were provided to testing laboratories as blind samples. No sensors responded to deionized water blanks, and only one sensor responded to a hard water blank. No single toxicity sensor responded to more than six chemicals in the desired response range, and one chemical (nicotine) was not detected by any sensor with the desired sensitivity. A combination of three sensors (Microtox, the Electric Cell Substrate Impedance Sensing (ECIS) test, and the Hepatocyte low density lipoprotein (LDL) uptake test) responded appropriately to nine of twelve chemicals. Adding a fourth sensor (neuronal microelectrode array) to the test battery allowed detection of two additional chemicals (aldicarb and methamidophos), but the neuronal microelectrode array was overly sensitive to paraquat. Evaluating sensor performance using a standard set of chemicals and a desired sensitivity range provides a basis both for selecting among available toxicity sensors and for evaluating emerging sensor technologies. Recommendations for future toxicity sensor evaluations are discussed.

Imprinted propyl gallate electrochemical sensor based on graphene/single walled carbon nanotubes/sol-gel film.

PubMed

Xu, Guilin; Chi, Yu; Li, Lu; Liu, Shouhua; Kan, Xianwen

2015-06-15

A novel imprinted sol-gel electrochemical sensor for the determination of propyl gallate (PG) was developed based on a composite of graphene and single walled carbon nanotubes (GR-SWCNTs). It was fabricated by stepwise modifying GR-SWCNTs and molecularly imprinted polymers and stored in 0.10 mol L(-1) phosphate buffer solution pH 6.0, which endowed the sensor good sensitivity and selective recognition towards template molecules. The morphology and specific adsorption capacity of the sensor was characterized by scanning electron microscope and electrochemical methods, respectively. Under the optimized conditions, a linear range of the sensor to PG was 8.0 × 10(-8)-2.6 × 10(-3)mo lL(-1) with a limit of detection of 5.0 × 10(-8)mol L(-1) (S/N=3). The sensor exhibited specificity and selectivity towards template molecules as well as excellent reproducibility, regeneration and stability. Furthermore, the sensor could be applied to determine PG in edible oils, instant noodles and cookies with satisfactory results. Copyright © 2015 Elsevier Ltd. All rights reserved.

Sensitive and selective detection of Cu(II) ion: A new effective 1,8-naphthalimide-based fluorescence 'turn off' sensor.

PubMed

Huang, Guozhen; Li, Chuang; Han, Xintong; Aderinto, Stephen Opeyemi; Shen, Kesheng; Mao, Shanshan; Wu, Huilu

2018-06-01

The present study reports the development of a new 1,8-naphthalimide-based fluorescent sensor V for monitoring Cu(II) ions. The sensor exhibited pH independence over a wide pH range 2.52-9.58, and indicated its possible use for monitoring Cu(II) ions in a competitive pH medium. The sensor also showed high selectivity and sensitivity towards the Cu(II) ions over other competitive metal ions in DMSO-HEPES buffer (v/v, 1:1; pH 7.4) with a fluorescence 'turn off' mode of 79.79% observed. A Job plot indicated the formation of a 1:1 binding mode of the sensor with Cu(II) ions. The association constant and detection limit were 1.14 × 10 6  M -1 and 4.67 × 10 -8 M, respectively. The fluorescence spectrum of the sensor was quenched due to the powerful paramagnetic nature of the Cu(II) ions. Potential application of this sensor was also demonstrated when determining Cu(II) ion levels in two different water samples. Copyright © 2018 John Wiley & Sons, Ltd.

Novel Platform Development Using an Assembly of Carbon Nanotube, Nanogold and Immobilized RNA Capture Element Towards Rapid, Selective Sensing of Bacteria

DTIC Science & Technology

2012-06-12

Doped Polyaniline/Carbon Nanotube Composite for Sensitive and Selective Detection of the Neurotransmitter Dopamine . Anal. Chem. 2007, 79, 2583–2587...biosensor with aptamers as bio-recognition element. Sensors 2010, 10, 5859–5871. Sensors 2012, 12 8144 14. Hernandez, F.J.; Ozalp, V.C. Graphene

In vitro selection and amplification protocols for isolation of aptameric sensors for small molecules

PubMed Central

Yang, Kyung-Ae; Pei, Renjun; Stojanovic, Milan N.

2016-01-01

We recently optimized a procedure that directly yields aptameric sensors for small molecules in so-called structure-switching format. The protocol has a high success rate, short time, and is sufficiently simple to be readily implemented in a non-specialist laboratory. We provide a stepwise guide to this selection protocol. PMID:27155227

Two-photon fluorescent sensor for K+ imaging in live cells (Conference Presentation)

NASA Astrophysics Data System (ADS)

Sui, Binglin; Yue, Xiling; Kim, Bosung; Belfield, Kevin D.

2016-03-01

It is difficult to overstate the physiological importance of potassium for life as its indispensable roles in a variety of biological processes are widely known. As a result, efficient methods for determining physiological levels of potassium are of paramount importance. Despite this, relatively few K+ fluorescence sensors have been reported, with only one being commercially available. A new two-photon excited fluorescent K+ sensor is reported. The sensor is comprised of three moieties, a highly selective K+ chelator as the K+ recognition unit, a boron-dipyrromethene (BODIPY) derivative modified with phenylethynyl groups as the fluorophore, and two polyethylene glycol chains to afford water solubility. The sensor displays very high selectivity (<52-fold) in detecting K+ over other physiological metal cations. Upon binding K+, the sensor switches from non-fluorescent to highly fluorescent, emitting red to near-IR (NIR) fluorescence. The sensor exhibited a good two-photon absorption cross section, 500 GM at 940 nm. Moreover, it is not sensitive to pH in the physiological pH range. Time-dependent cell imaging studies via both one- and two-photon fluorescence microscopy demonstrate that the sensor is suitable for dynamic K+ sensing in living cells.

Switch on or switch off: an optical DNA sensor based on poly(p-phenylenevinylene) grafted magnetic beads.

PubMed

Srinivas, Anupama R Gulur; Peng, Hui; Barker, David; Travas-Sejdic, Jadranka

2012-05-15

There has been an enormous demand for commercial label-free DNA sensors in a diverse range of fields including pre-emptive medicine, diagnostics, environmental monitoring, and food industry. Addressing the need for sensitive, selective and facile DNA sensors, we demonstrate a novel switch on/off sensor design that utilizes sandwich hybridization between photoluminescent anionic conjugated polyelectrolyte (CPE) bound captureprobe coated onto magnetic beads, target and the signaling probe. The hybridization-readout in our sensor was monitored by either fluorescence resonance energy transfer (FRET, switch-on) or superquenching (switch-off) depending on the type of signaling probe used. Moreover recent designs that utilize beads for sensing DNA have been limited towards using electrostatic interactions or intercalation of dyes to observe FRET. To our knowledge this is the first report of a switch on/off sensor utilizing either FRET or superquenching thus providing flexibility for future development of such rapid, facile and sensitive DNA sensors. The FRET-based sensor was investigated by optimizing the reaction parameters and selectivity. A low detection limit of 240 fmol in 2 mL of SSC buffer was achieved. Copyright © 2012 Elsevier B.V. All rights reserved.

Voltage Sensor Inactivation in Potassium Channels

PubMed Central

Bähring, Robert; Barghaan, Jan; Westermeier, Regina; Wollberg, Jessica

2012-01-01

In voltage-gated potassium (Kv) channels membrane depolarization causes movement of a voltage sensor domain. This conformational change of the protein is transmitted to the pore domain and eventually leads to pore opening. However, the voltage sensor domain may interact with two distinct gates in the pore domain: the activation gate (A-gate), involving the cytoplasmic S6 bundle crossing, and the pore gate (P-gate), located externally in the selectivity filter. How the voltage sensor moves and how tightly it interacts with these two gates on its way to adopt a relaxed conformation when the membrane is depolarized may critically determine the mode of Kv channel inactivation. In certain Kv channels, voltage sensor movement leads to a tight interaction with the P-gate, which may cause conformational changes that render the selectivity filter non-conductive (“P/C-type inactivation”). Other Kv channels may preferably undergo inactivation from pre-open closed-states during voltage sensor movement, because the voltage sensor temporarily uncouples from the A-gate. For this behavior, known as “preferential” closed-state inactivation, we introduce the term “A/C-type inactivation”. Mechanistically, P/C- and A/C-type inactivation represent two forms of “voltage sensor inactivation.” PMID:22654758

Temperature-Centric Evaluation of Sensor Transients

NASA Astrophysics Data System (ADS)

Ayhan, Tuba; Muezzinoglu, Kerem; Vergara, Alexander; Yalcin, Mustak

2011-09-01

Controllable sensing conditions provide the means for diversifying sensor response and achieving better selectivity. Modulating the sensing layer temperature of metal-oxide sensors is a popular method for multiplexing the limited number of sensing elements that can be employed in a practical array. Time limitations in many applications, however, cannot tolerate an ad-hoc, one-size-fits-all modulation pattern. When the response pattern is itself non-stationary, as in the transient phase, a temperature program also becomes infeasible. We consider the problem of determining and tuning into a fixed optimum temperature in a sensor array. For this purpose, we present an empirical analysis of the temperature's role on the performance of a metal-oxide gas sensor array in the identification of odorants along the response transient. We show that the optimal temperature in this sense depends heavily on the selection of (i) the set of candidate analytes, (ii) the time-window of the analysis, (iii) the feature extracted from the sensor response, and (iv) the computational identification method used.

Universal sensor based on the spectroscopy of glow discharge for the detection of traces of atoms or molecules in air

NASA Astrophysics Data System (ADS)

Atutov, S. N.; Galeyev, A. E.; Plekhanov, A. I.; Yakovlev, A. V.

2018-03-01

A sensitive and versatile sensor for the detection of traces of atoms or molecules in air based on the emission spectroscopy of glow discharge in air has been developed and studied. The advantages of this sensor compared to other well-known methods are that it renders the use of ultrahigh vacuum or cryogenic temperatures superfluous. The sensor is insensitive to the presence of water vapor (for example, in exhaled air) because of the absence of strong water lines in the visible spectral range. It has a high spectral selectivity limited only by Doppler broadening of the emission lines. The high selectivity of the sensor combined with a wide spectral range allows the detection of many toxic impurities, which can be present in air. Moreover, the spectral range used covers almost all biomarkers in exhaled air, making the proposed sensor extremely interesting for medical applications. To our knowledge, the proposed method is the first based on a glow discharge in air.

Evaluation of sensitivity and selectivity of piezoresistive cantilever-array sensors

NASA Astrophysics Data System (ADS)

Yoshikawa, Genki; Lang, Hans-Peter; Staufer, Urs; Vettiger, Peter; Sakurai, Toshio; Gerber, Christoph

2008-03-01

Microfabricated cantilever-array sensors have attracted much attention in recent years due to their real-time detection of low concentration of molecules. Since the piezoresistive cantilever-array sensors do not require a bulky and expensive optical read-out system, they possess many advantages compared with optical read-out cantilever-array sensors. They can be miniaturized and integrated into a match-box sized device. In this study, we present the piezoresistive cantilever-array sensor system and evaluate its sensitivity and selectivity using various vapors of molecules, including alkane molecules with different chain length from 5 (n-pentane) to 12 (n-dodecane). Piezoresistive cantilevers were coated with different polymers (PVP, PAAM, PEI, and PVA) using an inkjet spotter. Each cantilever has a reference cantilever, constituting a Wheatstone-bridge. Each vapor was mixed with a constant nitrogen gas flow and introduced into the measurement chamber. According to the principle component analysis of data obtained, each molecule can be clearly distinguished from others. We also confirmed that this piezoresistive cantilever-array sensor system has sub-ppm sensitivity.

Robust Operation of Tendon-Driven Robot Fingers Using Force and Position-Based Control Laws

NASA Technical Reports Server (NTRS)

Hargrave, Brian (Inventor); Abdallah, Muhammad E (Inventor); Reiland, Matthew J (Inventor); Diftler, Myron A (Inventor); Strawser, Philip A (Inventor); Platt, Jr., Robert J. (Inventor); Ihrke, Chris A. (Inventor)

2013-01-01

A robotic system includes a tendon-driven finger and a control system. The system controls the finger via a force-based control law when a tension sensor is available, and via a position-based control law when a sensor is not available. Multiple tendons may each have a corresponding sensor. The system selectively injects a compliance value into the position-based control law when only some sensors are available. A control system includes a host machine and a non-transitory computer-readable medium having a control process, which is executed by the host machine to control the finger via the force- or position-based control law. A method for controlling the finger includes determining the availability of a tension sensor(s), and selectively controlling the finger, using the control system, via the force or position-based control law. The position control law allows the control system to resist disturbances while nominally maintaining the initial state of internal tendon tensions.

Improvement of Toluene Selectivity via the Application of an Ethanol Oxidizing Catalytic Cell Upstream of a YSZ-Based Sensor for Air Monitoring Applications

PubMed Central

Sato, Tomoaki; Breedon, Michael; Miura, Norio

2012-01-01

The sensing characteristics of a yttria-stabilized zirconia (YSZ)-based sensor utilizing a NiO sensing-electrode (SE) towards toluene (C7H8) and interfering gases (C3H6, H2, CO, NO2 and C2H5OH) were evaluated with a view to selective C7H8 monitoring in indoor atmospheres. The fabricated YSZ-based sensor showed preferential responses toward 480 ppb C2H5OH, rather than the target 50 ppb C7H8 at an operational temperature of 450 °C under humid conditions (RH ≃ 32%). To overcome this limitation, the catalytic activity of Cr2O3, SnO2, Fe2O3 and NiO powders were evaluated for their selective ethanol oxidation ability. Among these oxides, SnO2 was found to selectively oxidize C2H5OH, thus improving C7H8 selectivity. An inline pre-catalytic cell loaded with SnO2 powder was installed upstream of the YSZ-based sensor utilizing NiO-SE, which enabled the following excellent abilities by selectively catalyzing common interfering gases; sensitive ppb level detection of C7H8 lower than the established Japanese Guideline value; low interferences from 50 ppb C3H6, 500 ppb H2, 100 ppb CO, 40 ppb NO2, as well as 480 ppb C2H5OH. These operational characteristics are all indicative that the developed sensor may be suitable for real-time C7H8 concentration monitoring in indoor environments. PMID:22666053

A virus resonance light scattering sensor based on mussel-inspired molecularly imprinted polymers for high sensitive and high selective detection of Hepatitis A Virus.

PubMed

Yang, Bin; Gong, Hang; Chen, Chunyan; Chen, Xiaoming; Cai, Changqun

2017-01-15

We described a novel resonance light scattering (RLS) sensor for the specific recognition of trace quantities of Hepatitis A Virus (HAV); the sensor was based on a mussel-inspired hepatitis molecularly imprinted polymer. As a recognition element, polydopamine (PDA)-coated totivirus-imprinted polymer was introduced on the surface of SiO 2 nanoparticles (virus-imprinted SiO 2 @PDA NPs) using an efficient one-step synthesis method. The target virus was selectively captured by the imprinted polymer films, thereby increasing the RLS intensity. A simple fluorescence spectrophotometer was employed to measure the changes in the intensity. The enhanced RLS intensity (∆I RLS ) was proportional to the concentration of HAV in the range of 0.04-6.0nmol∙L -1 , with a low limit of detection of 8.6pmol∙L -1 . The selectivity study confirmed that the resultant HAV-imprinted SiO 2 @PDA NPs possessed high selectivity for HAV. The sensor was successfully applied for the direct detection of additional HAV from a 20,000-fold dilution of human serum. The proposed strategy is simple, eco-friendly, highly selective, and sensitive. Copyright © 2016 Elsevier B.V. All rights reserved.

A highly sensitive and selective fluorescent sensor for detection of sulfide anion based on the steric hindrance effect

NASA Astrophysics Data System (ADS)

Chen, Guanfan; Tang, Mengzhuo; Fu, Xiufang; Cheng, Fenmin; Zou, Xianghua; Wang, Jingpei; Zeng, Rongjin

2018-01-01

Sulfide anions are not only generated as a byproduct from industrial processes but also as a crucial kind of element in biological systems. Therefore, fluorescent probes for detecting sulfide anion with sensitive and selective characters are highly popular. In this study, we report a highly sensitive and selective fluorescent sensor M1 for detection of sulfide anion based on the steric hindrance effect, where the recognition unit, dinitrobenzenesulfonate ester group is linked to aromatic ortho-position in the porphyrin, and correspondingly the fluorescence of fluorescein is efficiently quenched. Compared with the sensors with recognition unit linked to the other aromatic positions, the fluorescent sensor M1 has a lower fluorescence background. Furthermore, the corresponding fluorescence responses (F/F0) of M1 for mercapto amino-acid GSH, Hcy and Cys, were all far lower than the relative fluorescence ratio F/F0 values for S2-. It means that M1 is sensitive and selective to detection of S2-, and has an anti-disturbance ability to the biologically-relevant thiols, GSH, Hcy and Cys, and has the prospect of application in the exact detection of sulfide anions in living organisms. This approach offers some useful insights for realizing sensitive and selective fluorescent turn-on sensing in the detection assays for other analytes.

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.

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.

Optical multi-species gas monitoring sensor and system

NASA Technical Reports Server (NTRS)

Korman, Valentin (Inventor); Polzin, Kurt A. (Inventor)

2012-01-01

The system includes at least one light source generating light energy having a corresponding wavelength. The system's sensor is based on an optical interferometer that receives light energy from each light source. The interferometer includes a free-space optical path disposed in an environment of interest. The system's sensor includes an optical device disposed in the optical path that causes light energy of a first selected wavelength to continue traversing the optical path whereas light energy of at least one second selected wavelength is directed away from the optical path. The interferometer generates an interference between the light energy of the first selected wavelength so-traversing the optical path with the light energy at the corresponding wavelength incident on the optical interferometer. A first optical detector detects the interference. At least one second detector detects the light energy at the at least one second selected wavelength directed away from the optical path.

Theoretical and experimental analysis of analyte transport in a fiber-optic, protein C immuno-biosensor.

PubMed

Tang, Liang; Kwon, Hyun J; Kang, Kyung A

2004-12-30

Protein C (PC) is an important anticoagulant in human blood plasma, and early diagnosis of PC deficiency is critical for preventing dangerous thromboembolic complications. A fiber-optic PC immuno-biosensor has been under development in our research group for real-time PC-deficiency diagnosis. The sensor has demonstrated a good sensitivity and specificity for quantifying PC in buffered solutions. However, for plasma samples, with a limited sample reaction time, the sensor produced only 30% of the signal intensity of PC in buffer. The high plasma viscosity (1.9 cP) was speculated as the major reason for signal intensity reduction. In this investigation, the sensing performance of the fiber-optic PC biosensor is systematically characterized in terms of physical and chemical properties of the sample media. Theoretical and experimental analyses indicate that the reduced diffusion rate of PC molecules in viscous samples caused the sensing system to be more mass-transfer-limited. Convective flow of sample/reagent solutions during immunoreactions can increase the rate of the analyte mass transport from the bulk solution to the sensor surface, with reaction kinetics changing from mass-transfer-limited to reaction-limited as flow velocity increases. It was shown that PC sensor performance was significantly improved for plasma samples with convection. The effect of the flow velocity and incubation times for samples and reagents on the sensor performance was also systematically analyzed to optimize the assay protocol for PC sensing. Currently, a 6-cm-long immuno-biosensor is capable of quantifying PC in plasma (1 mL) in the heterozygous PC deficiency range (0.5 to 2.5 microg/mL) within 5 minutes, at an average signal-to-noise ratio of 50. 2004 Wiley Periodicals, Inc.

COMPARISON OF RANDOM AND SYSTEMATIC SITE SELECTION FOR ASSESSING ATTAINMENT OF AQUATIC LIFE USES IN SEGMENTS OF THE OHIO RIVER

EPA Science Inventory

This report is a description of field work and data analysis results comparing a design comparable to systematic site selection with one based on random selection of sites. The report is expected to validate the use of random site selection in the bioassessment program for the O...

Cross-Selectivity Enhancement of Poly(vinylidene fluoride-hexafluoropropylene)-Based Sensor Arrays for Detecting Acetone and Ethanol.

PubMed

Daneshkhah, Ali; Shrestha, Sudhir; Siegel, Amanda; Varahramyan, Kody; Agarwal, Mangilal

2017-03-15

Two methods for cross-selectivity enhancement of porous poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP)/carbon black (CB) composite-based resistive sensors are provided. The sensors are tested with acetone and ethanol in the presence of humid air. Cross-selectivity is enhanced using two different methods to modify the basic response of the PVDF-HFP/CB sensing platform. In method I, the adsorption properties of PVDF-HFP/CB are altered by adding a polyethylene oxide (PEO) layer or by treating with infrared (IR). In method II, the effects of the interaction of acetone and ethanol are enhanced by adding diethylene carbonate (DEC) or PEO dispersed in DEC (PEO/DEC) to the film. The results suggest the approaches used in method I alter the composite ability to adsorb acetone and ethanol, while in method II, they alter the transduction characteristics of the composite. Using these approaches, sensor relative response to acetone was increased by 89% compared with the PVDF-HFP/CB untreated film, whereas sensor relative response to ethanol could be decreased by 57% or increased by 197%. Not only do these results demonstrate facile methods for increasing sensitivity of PVDF-HFP/CB film, used in parallel they demonstrate a roadmap for enhancing system cross-selectivity that can be applied to separate units on an array. Fabrication methods, experimental procedures and results are presented and discussed.

Cross-Selectivity Enhancement of Poly(vinylidene fluoride-hexafluoropropylene)-Based Sensor Arrays for Detecting Acetone and Ethanol

PubMed Central

Daneshkhah, Ali; Shrestha, Sudhir; Siegel, Amanda; Varahramyan, Kody; Agarwal, Mangilal

2017-01-01

Two methods for cross-selectivity enhancement of porous poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP)/carbon black (CB) composite-based resistive sensors are provided. The sensors are tested with acetone and ethanol in the presence of humid air. Cross-selectivity is enhanced using two different methods to modify the basic response of the PVDF-HFP/CB sensing platform. In method I, the adsorption properties of PVDF-HFP/CB are altered by adding a polyethylene oxide (PEO) layer or by treating with infrared (IR). In method II, the effects of the interaction of acetone and ethanol are enhanced by adding diethylene carbonate (DEC) or PEO dispersed in DEC (PEO/DEC) to the film. The results suggest the approaches used in method I alter the composite ability to adsorb acetone and ethanol, while in method II, they alter the transduction characteristics of the composite. Using these approaches, sensor relative response to acetone was increased by 89% compared with the PVDF-HFP/CB untreated film, whereas sensor relative response to ethanol could be decreased by 57% or increased by 197%. Not only do these results demonstrate facile methods for increasing sensitivity of PVDF-HFP/CB film, used in parallel they demonstrate a roadmap for enhancing system cross-selectivity that can be applied to separate units on an array. Fabrication methods, experimental procedures and results are presented and discussed. PMID:28294961

Evaluation of realistic layouts for next generation on-scalp MEG: spatial information density maps.

PubMed

Riaz, Bushra; Pfeiffer, Christoph; Schneiderman, Justin F

2017-08-01

While commercial magnetoencephalography (MEG) systems are the functional neuroimaging state-of-the-art in terms of spatio-temporal resolution, MEG sensors have not changed significantly since the 1990s. Interest in newer sensors that operate at less extreme temperatures, e.g., high critical temperature (high-T c ) SQUIDs, optically-pumped magnetometers, etc., is growing because they enable significant reductions in head-to-sensor standoff (on-scalp MEG). Various metrics quantify the advantages of on-scalp MEG, but a single straightforward one is lacking. Previous works have furthermore been limited to arbitrary and/or unrealistic sensor layouts. We introduce spatial information density (SID) maps for quantitative and qualitative evaluations of sensor arrays. SID-maps present the spatial distribution of information a sensor array extracts from a source space while accounting for relevant source and sensor parameters. We use it in a systematic comparison of three practical on-scalp MEG sensor array layouts (based on high-T c SQUIDs) and the standard Elekta Neuromag TRIUX magnetometer array. Results strengthen the case for on-scalp and specifically high-T c SQUID-based MEG while providing a path for the practical design of future MEG systems. SID-maps are furthermore general to arbitrary magnetic sensor technologies and source spaces and can thus be used for design and evaluation of sensor arrays for magnetocardiography, magnetic particle imaging, etc.

Improved Sensor Fault Detection, Isolation, and Mitigation Using Multiple Observers Approach

PubMed Central

Wang, Zheng; Anand, D. M.; Moyne, J.; Tilbury, D. M.

2017-01-01

Traditional Fault Detection and Isolation (FDI) methods analyze a residual signal to detect and isolate sensor faults. The residual signal is the difference between the sensor measurements and the estimated outputs of the system based on an observer. The traditional residual-based FDI methods, however, have some limitations. First, they require that the observer has reached its steady state. In addition, residual-based methods may not detect some sensor faults, such as faults on critical sensors that result in an unobservable system. Furthermore, the system may be in jeopardy if actions required for mitigating the impact of the faulty sensors are not taken before the faulty sensors are identified. The contribution of this paper is to propose three new methods to address these limitations. Faults that occur during the observers' transient state can be detected by analyzing the convergence rate of the estimation error. Open-loop observers, which do not rely on sensor information, are used to detect faults on critical sensors. By switching among different observers, we can potentially mitigate the impact of the faulty sensor during the FDI process. These three methods are systematically integrated with a previously developed residual-based method to provide an improved FDI and mitigation capability framework. The overall approach is validated mathematically, and the effectiveness of the overall approach is demonstrated through simulation on a 5-state suspension system. PMID:28924303

A simple ratiometric fluorescent sensor for fructose based on complexation of 10-hydroxybenzo[h]quinoline with boronic acid

NASA Astrophysics Data System (ADS)

Li, Huihui; Yang, Cailing; Zhu, Xinyue; Zhang, Haixia

2017-06-01

A simple ratiometric fluorescent sensor for fructose was presented. It consisted of 10-hydroxybenzo[h]quinoline (HBQ) which showed emission at 572 nm and 3-pyridylboronic acid (PDBA) whose complex with HBQ gave emission at 500 nm. The reaction of fructose with PDBA inhibited the complexation of HBQ with PDBA, resulting in the change of dual-emission intensity ratio. The sensor well quantified fructose in the range of 0.015-2.5 mM with detection limit of 0.005 mM. Besides, this sensor exhibited excellent selectivity and was successfully applied to fructose detection in food. This work provides a simple ratiometric sensing platform for sensitive and selective detection of fructose.

PWM Switching Frequency Effects on Eddy Current Sensors for Magnetically Suspended Flywheel Systems

NASA Technical Reports Server (NTRS)

Jansen, Ralph; Lebron, Ramon; Dever, Timothy P.; Birchenough, Arthur G.

2003-01-01

A flywheel magnetic bearing (MB) pulse width modulated power amplifier (PWM) configuration is selected to minimize noise generated by the PWMs in the flywheel position sensor system. Two types of noise are addressed: beat frequency noise caused by variations in PWM switching frequencies, and demodulation noise caused by demodulation of high order harmonics of the switching voltage into the MB control band. Beat frequency noise is eliminated by synchronizing the PWM switch frequencies, and demodulation noise is minimized by selection of a switching frequency which does not have harmonics at the carrier frequency of the sensor. The recommended MB PWM system has five synchronized PWMs switching at a non-integer harmonic of the sensor carrier.

Aptamer-based impedimetric sensor for bacterial typing.

PubMed

Labib, Mahmoud; Zamay, Anna S; Kolovskaya, Olga S; Reshetneva, Irina T; Zamay, Galina S; Kibbee, Richard J; Sattar, Syed A; Zamay, Tatiana N; Berezovski, Maxim V

2012-10-02

The development of an aptamer-based impedimetric sensor for typing of bacteria (AIST-B) is presented. Highly specific DNA aptamers to Salmonella enteritidis were selected via Cell-SELEX technique. Twelve rounds of selection were performed; each comprises a positive selection step against S. enteritidis and a negative selection step against a mixture of related pathogens, including Salmonella typhimurium, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Citrobacter freundii, to ensure the species-specificity of the selected aptamers. After sequencing of the pool showing the highest binding affinity to S. enteritidis, a DNA sequence of high affinity to the bacteria was integrated into an impedimetric sensor via self-assembly onto a gold nanoparticles-modified screen-printed carbon electrode (GNPs-SPCE). Remarkably, this aptasensor is highly selective and can successfully detect S. enteritidis down to 600 CFU mL(-1) (equivalent to 18 CFU in 30 μL assay volume) in 10 min and distinguish it from other Salmonella species, including S. typhimurium and S. choleraesuis. This report is envisaged to open a new venue for the aptamer-based typing of a variety of microorganisms using a rapid, economic, and label-free electrochemical platform.

The Systematics of Strong Lens Modeling Quantified: The Effects of Constraint Selection and Redshift Information on Magnification, Mass, and Multiple Image Predictability

NASA Astrophysics Data System (ADS)

Johnson, Traci L.; Sharon, Keren

2016-11-01

Until now, systematic errors in strong gravitational lens modeling have been acknowledged but have never been fully quantified. Here, we launch an investigation into the systematics induced by constraint selection. We model the simulated cluster Ares 362 times using random selections of image systems with and without spectroscopic redshifts and quantify the systematics using several diagnostics: image predictability, accuracy of model-predicted redshifts, enclosed mass, and magnification. We find that for models with >15 image systems, the image plane rms does not decrease significantly when more systems are added; however, the rms values quoted in the literature may be misleading as to the ability of a model to predict new multiple images. The mass is well constrained near the Einstein radius in all cases, and systematic error drops to <2% for models using >10 image systems. Magnification errors are smallest along the straight portions of the critical curve, and the value of the magnification is systematically lower near curved portions. For >15 systems, the systematic error on magnification is ∼2%. We report no trend in magnification error with the fraction of spectroscopic image systems when selecting constraints at random; however, when using the same selection of constraints, increasing this fraction up to ∼0.5 will increase model accuracy. The results suggest that the selection of constraints, rather than quantity alone, determines the accuracy of the magnification. We note that spectroscopic follow-up of at least a few image systems is crucial because models without any spectroscopic redshifts are inaccurate across all of our diagnostics.

Influence of Mn concentration on magnetic topological insulator Mn xBi 2−xTe 3 thin-film Hall-effect sensor

DOE PAGES

Ni, Y.; Zhang, Z.; Nlebedim, I. C.; ...

2015-06-11

Hall-effect (HE) sensors based on high-quality Mn-doped Bi 2Te 3 topological insulator (TI) thin films have been systematically studied in this paper. Improvement of Hall sensitivity is found after doping the magnetic element Mn into Bi 2Te 3. The sensors with low Mn concentrations, Mn xBi 2-xTe 3, x = 0.01 and 0.08 show the linear behavior of Hall resistance with sensitivity about 5 Ω/T. And their Hall sensitivity shows weak dependence on temperature. For sensors with high Mn concentration (x = 0.23), the Hall resistance with respect to magnetic field shows a hysteretic behavior. Moreover, its sensitivity shows almostmore » eight times as high as that of the HE sensors with low Mn concentration. The highest sensitivity can reach 43 Ω/T at very low magnetic field. This increase of Hall sensitivity is caused by the occurrence of anomalous HE (AHE) after ferromagnetic phase transition. Our work indicates that the magnetic-element-doped TIs with AHE are good candidates for HE sensors.« less

Autonomous sensor manager agents (ASMA)

NASA Astrophysics Data System (ADS)

Osadciw, Lisa A.

2004-04-01

Autonomous sensor manager agents are presented as an algorithm to perform sensor management within a multisensor fusion network. The design of the hybrid ant system/particle swarm agents is described in detail with some insight into their performance. Although the algorithm is designed for the general sensor management problem, a simulation example involving 2 radar systems is presented. Algorithmic parameters are determined by the size of the region covered by the sensor network, the number of sensors, and the number of parameters to be selected. With straight forward modifications, this algorithm can be adapted for most sensor management problems.

Designing of MIP based QCM sensor having thymine recognition sites based on biomimicking DNA approach.

PubMed

Diltemiz, S Emir; Hür, D; Ersöz, A; Denizli, A; Say, R

2009-11-15

Quartz crystal microbalance (QCM) sensors coated with molecular imprinted polymers (MIP) have been developed for the determination of thymine. In this method, methacryloylamidoadenine (MA-Ade) have used as a new monomer and thymine template for inspiration of DNA nucleobases interaction. The thymine can be simultaneously hydrogen binding to MA-Ade and fit into the shape-selective cavities. Thus, the interaction between nucleobases has an effect on the binding ability of the QCM sensors. The binding affinity of the thymine imprinted sensors has investigated by using the Langmuir isotherm. The thymine imprinted QCM electrodes have shown homogeneous binding sites for thymine (K(a): 1.0 x 10(5)M(-1)) while heterogeneous binding sites for uracil. On the other hand, recognition selectivity of the QCM sensor based on thymine imprinted polymer toward to uracil, ssDNA and ssRNA has been reported in this work.

Method and apparatus for assessing weld quality

DOEpatents

Smartt, Herschel B.; Kenney, Kevin L.; Johnson, John A.; Carlson, Nancy M.; Clark, Denis E.; Taylor, Paul L.; Reutzel, Edward W.

2001-01-01

Apparatus for determining a quality of a weld produced by a welding device according to the present invention includes a sensor operatively associated with the welding device. The sensor is responsive to at least one welding process parameter during a welding process and produces a welding process parameter signal that relates to the at least one welding process parameter. A computer connected to the sensor is responsive to the welding process parameter signal produced by the sensor. A user interface operatively associated with the computer allows a user to select a desired welding process. The computer processes the welding process parameter signal produced by the sensor in accordance with one of a constant voltage algorithm, a short duration weld algorithm or a pulsed current analysis module depending on the desired welding process selected by the user. The computer produces output data indicative of the quality of the weld.

Portable Nanoparticle-Based Sensors for Food Safety Assessment

PubMed Central

Bülbül, Gonca; Hayat, Akhtar; Andreescu, Silvana

2015-01-01

The use of nanotechnology-derived products in the development of sensors and analytical measurement methodologies has increased significantly over the past decade. Nano-based sensing approaches include the use of nanoparticles (NPs) and nanostructures to enhance sensitivity and selectivity, design new detection schemes, improve sample preparation and increase portability. This review summarizes recent advancements in the design and development of NP-based sensors for assessing food safety. The most common types of NPs used to fabricate sensors for detection of food contaminants are discussed. Selected examples of NP-based detection schemes with colorimetric and electrochemical detection are provided with focus on sensors for the detection of chemical and biological contaminants including pesticides, heavy metals, bacterial pathogens and natural toxins. Current trends in the development of low-cost portable NP-based technology for rapid assessment of food safety as well as challenges for practical implementation and future research directions are discussed. PMID:26690169

Self-assembly of nitrogen-doped carbon nanoparticles: a new ratiometric UV-vis optical sensor for the highly sensitive and selective detection of Hg(2+) in aqueous solution.

PubMed

Ruan, Yudi; Wu, Lie; Jiang, Xiue

2016-05-23

Water-soluble nitrogen-doped carbon nanoparticles (N-CNPs) prepared by the one-step hydrothermal treatment of uric acid were found to show ratiometric changes in their UV-vis spectra due to Hg(2+)-mediated self-assembly. For the first time, such a property was developed into a UV-vis optical sensor for detecting Hg(2+) in aqueous solutions with high sensitively and selectively (detection limit = 1.4 nM). More importantly, this novel sensor exhibits a higher linear sensitivity over a wider concentration range compared with the fluorescence sensor based on the same N-CNPs. This work opens an exciting new avenue to explore the use of carbon nanoparticles in constructing UV-vis optical sensors for the detection of metal ions and the use of carbon nanoparticles as a new building block to self-assemble into superlattices.

Selective vancomycin detection using optical fibre long period gratings functionalised with molecularly imprinted polymer nanoparticles.

PubMed

Korposh, Sergiy; Chianella, Iva; Guerreiro, Antonio; Caygill, Sarah; Piletsky, Sergey; James, Stephen W; Tatam, Ralph P

2014-05-07

An optical fibre long period grating (LPG) sensor modified with molecularly imprinted polymer nanoparticles (nanoMIPs) for the specific detection of antibiotics is presented. The operation of the sensor is based on the measurement of changes in refractive index induced by the interaction of nanoMIPs deposited onto the cladding of the LPG with free vancomycin (VA). The binding of nanoMIPs to vancomycin was characterised by a binding constant of 4.3 ± 0.1 × 10(-8) M. The lowest concentration of analyte measured by the fibre sensor was 10 nM. In addition, the sensor exhibited selectivity, as much smaller responses were obtained for high concentrations (∼700 μM) of other commonly prescribed antibiotics such as amoxicillin, bleomycin and gentamicin. In addition, the response of the sensor was characterised in a complex matrix, porcine plasma, spiked with 10 μM of VA.

Selective vancomycin detection using optical fibre long period gratings functionalised with molecularly imprinted polymer nanoparticles

PubMed Central

Korposh, Sergiy; Chianella, Iva; Guerreiro, Antonio; Caygill, Sarah; Piletsky, Sergey; James, Stephen W.; Tatam, Ralph P.

2015-01-01

An optical fibre long period grating (LPG) sensor modified with molecularly imprinted polymer nanoparticles (nanoMIPs) for the specific detection of antibiotics is presented. The operation of the sensor is based on the measurement of changes in refractive index induced by the interaction of nanoMIPs deposited onto the cladding of the LPG with free vancomycin (VA). The binding of nanoMIPs to vancomycin was characterised by a binding constant of 4.3±0.1×10−8 M. The lowest concentration of analyte measured by the fibre sensor was 10 nM. In addition, the sensor exhibited selectivity, as much smaller responses were obtained for high concentrations (~ 700 μM) of other commonly prescribed antibiotics such as amoxicillin, bleomycin and gentamicin. In addition, the response of the sensor was characterised in a complex matrix, porcine plasma, spiked with 10 μM of VA. PMID:24634909

Photo-crosslinkable polymers for fabrication of photonic multilayer sensors

NASA Astrophysics Data System (ADS)

Chiappelli, Maria; Hayward, Ryan C.

2013-03-01

We have used photo-crosslinkable polymers to fabricate photonic multilayer sensors. Benzophenone is utilized as a covalently incorporated pendent photo-crosslinker, providing a convenient means of fabricating multilayer films by sequential spin-coating and crosslinking processes. Colorimetric temperature sensors were designed from thermally-responsive, low-refractive index poly(N-isopropylacrylamide) (PNIPAM) and high-refractive index poly(para-methyl styrene) (P pMS). Copolymer chemistries and layer thicknesses were selected to provide robust multilayer sensors which show color changes across nearly the full visible spectrum due to changes in temperature of the hydrated film stack. We have characterized the uniformity and interfacial broadening within the multilayers, the kinetics of swelling and de-swelling, and the reversibility over multiple hydration/dehydration cycles. We also describe how the approach can be extended to alternative sensor designs through the ability to tailor each layer independently, as well as to additional stimuli by selecting alternative copolymer chemistries.

Fluorescent tris-imidazolium sensors for picric acid explosive.

PubMed

Roy, Bijan; Bar, Arun Kumar; Gole, Bappaditya; Mukherjee, Partha Sarathi

2013-02-01

Two new anthracene-functionalized fluorescent tris-imidazolium salts have been synthesized, characterized, and proven to be selective sensors for picric acid, which is a common constituent of many powerful explosives. Theoretical studies revealed an unusual ground-state electron transfer from picrate anion to the sensor molecules.

Study of a QCM dimethyl methylphosphonate sensor based on a ZnO-modified nanowire-structured manganese dioxide film.

PubMed

Pei, Zhifu; Ma, Xingfa; Ding, Pengfei; Zhang, Wuming; Luo, Zhiyuan; Li, Guang

2010-01-01

Sensitive, selective and fast detection of chemical warfare agents is necessary for anti-terrorism purposes. In our search for functional materials sensitive to dimethyl methylphosphonate (DMMP), a simulant of sarin and other toxic organophosphorus compounds, we found that zinc oxide (ZnO) modification potentially enhances the absorption of DMMP on a manganese dioxide (MnO(2)) surface. The adsorption behavior of DMMP was evaluated through the detection of tiny organophosphonate compounds with quartz crystal microbalance (QCM) sensors coated with ZnO-modified MnO(2) nanofibers and pure MnO(2) nanofibers. Experimental results indicated that the QCM sensor coated with ZnO-modified nanostructured MnO(2) film exhibited much higher sensitivity and better selectivity in comparison with the one coated with pure MnO(2) nanofiber film. Therefore, the DMMP sensor developed with this composite nanostructured material should possess excellent selectivity and reasonable sensitivity towards the tiny gaseous DMMP species.

Highly selective dopamine electrochemical sensor based on electrochemically pretreated graphite and nafion composite modified screen printed carbon electrode.

PubMed

Ku, Shuhao; Palanisamy, Selvakumar; Chen, Shen-Ming

2013-12-01

Herein, we report a highly selective dopamine electrochemical sensor based on electrochemically pretreated graphite/nafion composite modified screen printed carbon (SPC) electrode. Electrochemically activated graphite/nafion composite was prepared by using a simple electrochemical method. Scanning electron microscope (SEM) used to characterize the surface morphology of the fabricated composite electrode. The SEM result clearly indicates that the graphitic basal planes were totally disturbed and leads to the formation of graphite nanosheets. The composite modified electrode showed an enhanced electrocatalytic activity toward the oxidation of DA when compared with either electrochemical pretreated graphite or nafion SPC electrodes. The fabricated composite electrode exhibits a good electrocatalytic oxidation toward DA in the linear response range from 0.5 to 70 μM with the detection limit of 0.023 μM. The proposed sensor also exhibits very good selectivity and stability, with the appreciable sensitivity. In addition, the proposed sensor showed satisfactory recovery results toward the commercial pharmaceutical DA samples. Copyright © 2013 Elsevier Inc. All rights reserved.

Nanostructured TiO2-based gas sensors with enhanced sensitivity to reducing gases

PubMed Central

Kusior, Anna; Trenczek-Zajac, Anita

2016-01-01

2D TiO2 thin films and 3D flower-like TiO2-based nanostructures, also decorated with SnO2, were prepared by chemical and thermal oxidation of Ti substrates, respectively. The crystal structure, morphology and gas sensing properties of the TiO2-based sensing materials were investigated. 2D TiO2 thin films crystallized mainly in the form of rutile, while the flower-like 3D nanostructures as anatase. The sensor based on the 2D TiO2 showed the best performance for H2 detection, while the flower-like 3D nanostructures exhibited enhanced selectivity to CO(CH3)2 after sensitization by SnO2 nanoparticles. The sensor response time was of the order of several seconds. Their fast response, high sensitivity to selected gas species, improved selectivity and stability suggest that the SnO2-decorated flower-like 3D nanostructures are a promising material for application as an acetone sensor. PMID:28144521

An Orthogonal and pH-Tunable Sensor-Selector for Muconic Acid Biosynthesis in Yeast.

PubMed

Snoek, Tim; Romero-Suarez, David; Zhang, Jie; Ambri, Francesca; Skjoedt, Mette L; Sudarsan, Suresh; Jensen, Michael K; Keasling, Jay D

2018-04-20

Microbes offer enormous potential for production of industrially relevant chemicals and therapeutics, yet the rapid identification of high-producing microbes from large genetic libraries is a major bottleneck in modern cell factory development. Here, we develop and apply a synthetic selection system in Saccharomyces cerevisiae that couples the concentration of muconic acid, a plastic precursor, to cell fitness by using the prokaryotic transcriptional regulator BenM driving an antibiotic resistance gene. We show that the sensor-selector does not affect production nor fitness, and find that tuning pH of the cultivation medium limits the rise of nonproducing cheaters. We apply the sensor-selector to selectively enrich for best-producing variants out of a large library of muconic acid production strains, and identify an isolate that produces more than 2 g/L muconic acid in a bioreactor. We expect that this sensor-selector can aid the development of other synthetic selection systems based on allosteric transcription factors.

Study of a QCM Dimethyl Methylphosphonate Sensor Based on a ZnO-Modified Nanowire-Structured Manganese Dioxide Film

PubMed Central

Pei, Zhifu; Ma, Xingfa; Ding, Pengfei; Zhang, Wuming; Luo, Zhiyuan; Li, Guang

2010-01-01

Sensitive, selective and fast detection of chemical warfare agents is necessary for anti-terrorism purposes. In our search for functional materials sensitive to dimethyl methylphosphonate (DMMP), a simulant of sarin and other toxic organophosphorus compounds, we found that zinc oxide (ZnO) modification potentially enhances the absorption of DMMP on a manganese dioxide (MnO2) surface. The adsorption behavior of DMMP was evaluated through the detection of tiny organophosphonate compounds with quartz crystal microbalance (QCM) sensors coated with ZnO-modified MnO2 nanofibers and pure MnO2 nanofibers. Experimental results indicated that the QCM sensor coated with ZnO-modified nanostructured MnO2 film exhibited much higher sensitivity and better selectivity in comparison with the one coated with pure MnO2 nanofiber film. Therefore, the DMMP sensor developed with this composite nanostructured material should possess excellent selectivity and reasonable sensitivity towards the tiny gaseous DMMP species. PMID:22163653

New potentiometric sensor based on molecularly imprinted nanoparticles for cocaine detection.

PubMed

Smolinska-Kempisty, K; Ahmad, O Sheej; Guerreiro, A; Karim, K; Piletska, E; Piletsky, S

2017-10-15

Here we present a potentiometric sensor for cocaine detection based on molecularly imprinted polymer nanoparticles (nanoMIPs) produced by the solid-phase imprinting method. The composition of polymers with high affinity for cocaine was optimised using molecular modelling. Four compositions were selected and polymers prepared using two protocols: chemical polymerisation in water and UV-initiated polymerisation in organic solvent. All synthesised nanoparticles had very good affinity to cocaine with dissociation constants between 0.6nM and 5.3nM. Imprinted polymers produced in organic solvent using acrylamide as a functional monomer demonstrated the highest yield and affinity, and so were selected for further sensor development. For this, nanoparticles were incorporated within a PVC matrix which was then used to prepare an ion-selective membrane integrated with a potentiometric transducer. It was demonstrated that the sensor was able to quantify cocaine in blood serum samples in the range of concentrations between 1nM and 1mM. Copyright © 2017 Elsevier B.V. All rights reserved.

Mesoporous structured MIPs@CDs fluorescence sensor for highly sensitive detection of TNT.

PubMed

Xu, Shoufang; Lu, Hongzhi

2016-11-15

A facile strategy was developed to prepare mesoporous structured molecularly imprinted polymers capped carbon dots (M-MIPs@CDs) fluorescence sensor for highly sensitive and selective determination of TNT. The strategy using amino-CDs directly as "functional monomer" for imprinting simplify the imprinting process and provide well recognition sites accessibility. The as-prepared M-MIPs@CDs sensor, using periodic mesoporous silica as imprinting matrix, and amino-CDs directly as "functional monomer", exhibited excellent selectivity and sensitivity toward TNT with detection limit of 17nM. The recycling process was sustainable for 10 times without obvious efficiency decrease. The feasibility of the developed method in real samples was successfully evaluated through the analysis of TNT in soil and water samples with satisfactory recoveries of 88.6-95.7%. The method proposed in this work was proved to be a convenient and practical way to prepare high sensitive and selective fluorescence MIPs@CDs sensors. Copyright © 2016 Elsevier B.V. All rights reserved.

Imaging sensor constellation for tomographic chemical cloud mapping.

PubMed

Cosofret, Bogdan R; Konno, Daisei; Faghfouri, Aram; Kindle, Harry S; Gittins, Christopher M; Finson, Michael L; Janov, Tracy E; Levreault, Mark J; Miyashiro, Rex K; Marinelli, William J

2009-04-01

A sensor constellation capable of determining the location and detailed concentration distribution of chemical warfare agent simulant clouds has been developed and demonstrated on government test ranges. The constellation is based on the use of standoff passive multispectral infrared imaging sensors to make column density measurements through the chemical cloud from two or more locations around its periphery. A computed tomography inversion method is employed to produce a 3D concentration profile of the cloud from the 2D line density measurements. We discuss the theoretical basis of the approach and present results of recent field experiments where controlled releases of chemical warfare agent simulants were simultaneously viewed by three chemical imaging sensors. Systematic investigations of the algorithm using synthetic data indicate that for complex functions, 3D reconstruction errors are less than 20% even in the case of a limited three-sensor measurement network. Field data results demonstrate the capability of the constellation to determine 3D concentration profiles that account for ~?86%? of the total known mass of material released.

Occupant detection using support vector machines with a polynomial kernel function

NASA Astrophysics Data System (ADS)

Destefanis, Eduardo A.; Kienzle, Eberhard; Canali, Luis R.

2000-10-01

The use of air bags in the presence of bad passenger and baby seat positions in car seats can injure or kill these individuals in case of an accident when this device is inflated. A proposed solution is the use of range sensors to detect passenger and baby seat risky positions. Such sensors allow the Airbag inflation to be controlled. This work is concerned with the application of different classification schemes to a real world problem and the optimization of a sensor as a function of the classification performance. The sensor is constructed using a new technology which is called Photo-Mixer-Device (PMD). A systematic analysis of the occupant detection problem was made using real and virtual environments. The challenge is to find the best sensor geometry and to adapt a classification scheme under the current technological constraints. Passenger head position detection is also a desirable issue. A couple of classifiers have been used into a simple configuration to reach this goal. Experiences and results are described.

Bias due to selective inclusion and reporting of outcomes and analyses in systematic reviews of randomised trials of healthcare interventions.

PubMed

Page, Matthew J; McKenzie, Joanne E; Kirkham, Jamie; Dwan, Kerry; Kramer, Sharon; Green, Sally; Forbes, Andrew

2014-10-01

Systematic reviews may be compromised by selective inclusion and reporting of outcomes and analyses. Selective inclusion occurs when there are multiple effect estimates in a trial report that could be included in a particular meta-analysis (e.g. from multiple measurement scales and time points) and the choice of effect estimate to include in the meta-analysis is based on the results (e.g. statistical significance, magnitude or direction of effect). Selective reporting occurs when the reporting of a subset of outcomes and analyses in the systematic review is based on the results (e.g. a protocol-defined outcome is omitted from the published systematic review). To summarise the characteristics and synthesise the results of empirical studies that have investigated the prevalence of selective inclusion or reporting in systematic reviews of randomised controlled trials (RCTs), investigated the factors (e.g. statistical significance or direction of effect) associated with the prevalence and quantified the bias. We searched the Cochrane Methodology Register (to July 2012), Ovid MEDLINE, Ovid EMBASE, Ovid PsycINFO and ISI Web of Science (each up to May 2013), and the US Agency for Healthcare Research and Quality (AHRQ) Effective Healthcare Program's Scientific Resource Center (SRC) Methods Library (to June 2013). We also searched the abstract books of the 2011 and 2012 Cochrane Colloquia and the article alerts for methodological work in research synthesis published from 2009 to 2011 and compiled in Research Synthesis Methods. We included both published and unpublished empirical studies that investigated the prevalence and factors associated with selective inclusion or reporting, or both, in systematic reviews of RCTs of healthcare interventions. We included empirical studies assessing any type of selective inclusion or reporting, such as investigations of how frequently RCT outcome data is selectively included in systematic reviews based on the results, outcomes and analyses are discrepant between protocol and published review or non-significant outcomes are partially reported in the full text or summary within systematic reviews. Two review authors independently selected empirical studies for inclusion, extracted the data and performed a risk of bias assessment. A third review author resolved any disagreements about inclusion or exclusion of empirical studies, data extraction and risk of bias. We contacted authors of included studies for additional unpublished data. Primary outcomes included overall prevalence of selective inclusion or reporting, association between selective inclusion or reporting and the statistical significance of the effect estimate, and association between selective inclusion or reporting and the direction of the effect estimate. We combined prevalence estimates and risk ratios (RRs) using a random-effects meta-analysis model. Seven studies met the inclusion criteria. No studies had investigated selective inclusion of results in systematic reviews, or discrepancies in outcomes and analyses between systematic review registry entries and published systematic reviews. Based on a meta-analysis of four studies (including 485 Cochrane Reviews), 38% (95% confidence interval (CI) 23% to 54%) of systematic reviews added, omitted, upgraded or downgraded at least one outcome between the protocol and published systematic review. The association between statistical significance and discrepant outcome reporting between protocol and published systematic review was uncertain. The meta-analytic estimate suggested an increased risk of adding or upgrading (i.e. changing a secondary outcome to primary) when the outcome was statistically significant, although the 95% CI included no association and a decreased risk as plausible estimates (RR 1.43, 95% CI 0.71 to 2.85; two studies, n = 552 meta-analyses). Also, the meta-analytic estimate suggested an increased risk of downgrading (i.e. changing a primary outcome to secondary) when the outcome was statistically significant, although the 95% CI included no association and a decreased risk as plausible estimates (RR 1.26, 95% CI 0.60 to 2.62; two studies, n = 484 meta-analyses). None of the included studies had investigated whether the association between statistical significance and adding, upgrading or downgrading of outcomes was modified by the type of comparison, direction of effect or type of outcome; or whether there is an association between direction of the effect estimate and discrepant outcome reporting.Several secondary outcomes were reported in the included studies. Two studies found that reasons for discrepant outcome reporting were infrequently reported in published systematic reviews (6% in one study and 22% in the other). One study (including 62 Cochrane Reviews) found that 32% (95% CI 21% to 45%) of systematic reviews did not report all primary outcomes in the abstract. Another study (including 64 Cochrane and 118 non-Cochrane reviews) found that statistically significant primary outcomes were more likely to be completely reported in the systematic review abstract than non-significant primary outcomes (RR 2.66, 95% CI 1.81 to 3.90). None of the studies included systematic reviews published after 2009 when reporting standards for systematic reviews (Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) Statement, and Methodological Expectations of Cochrane Intervention Reviews (MECIR)) were disseminated, so the results might not be generalisable to more recent systematic reviews. Discrepant outcome reporting between the protocol and published systematic review is fairly common, although the association between statistical significance and discrepant outcome reporting is uncertain. Complete reporting of outcomes in systematic review abstracts is associated with statistical significance of the results for those outcomes. Systematic review outcomes and analysis plans should be specified prior to seeing the results of included studies to minimise post-hoc decisions that may be based on the observed results. Modifications that occur once the review has commenced, along with their justification, should be clearly reported. Effect estimates and CIs should be reported for all systematic review outcomes regardless of the results. The lack of research on selective inclusion of results in systematic reviews needs to be addressed and studies that avoid the methodological weaknesses of existing research are also needed.

"Reactive" optical sensor for Hg2+ and its application in environmental aqueous media and biological systems.

PubMed

Chen, Zhi; Chen, Jiayun; Pan, Dong; Li, Hongwei; Yao, Yunhui; Lyu, Zu; Yang, Liting; Ma, Li-Jun

2017-03-01

A new rhodamine B-based "reactive" optical sensor (1) for Hg 2+ was synthesized. Sensor 1 shows a unique colorimetric and fluorescent "turn-on" selectivity to Hg 2+ over 14 other metal ions with a hypersensitivity (detection limits are 27.6 nM (5.5 ppb) and 6.9 nM (1.4 ppb), respectively) in neutral buffer solution. To test its applicability in the environment, sensor 1 was applied to quantify and visualize low levels of Hg 2+ in tap water and river water samples. The results indicate sensor 1 is a highly sensitive fluorescent sensor for Hg 2+ with a detection limit of 1.7 ppb in tap water and river water. Moreover, sensor 1 is a convenient visualizing sensor for low levels of Hg 2+ (0.1 ppm) in water environment (from colorless to light pink). In addition, sensor 1 shows good potential as a fluorescent visualizing sensor for Hg 2+ in fetal bovine serum and living 293T cells. The results indicate that sensor 1 shows good potential as a highly sensitive sensor for the detection of Hg 2+ in environmental and biological samples. Graphical Abstract A new rhodamine B-based "reactive" optical sensor (1) for Hg 2+ was synthesized. 1 shows a unique colorimetric and fluorescent "turn-on" selectivity to Hg 2+ over 14 other metal ions with a hypersensitivity in water environment. And it is a convenient visualizing probe for low levels of Hg 2+ in environment aqueous media, fetal bovine serum and living 293T cells.

Development of a conformable electronic skin based on silver nanowires and PDMS

NASA Astrophysics Data System (ADS)

Wang, Haopeng

2017-06-01

This paper presented the designed and tested a flexible and stretchable pressure sensor array that could be used to cover 3D surface to measure contact pressure. The sensor array is laminated into a thin film with 1 mm in thickness and can easily be stretched without losing its functionality. The fabricated sensor array contained 8×8 sensing elements, each could measure the pressure up to 180 kPa. An improved sandwich structure is used to build the sensor array. The upper and lower layers were PDMS thin films embedded with conductor strips formed by PDMS-based silver nanowires (AgNWs) networks covered with nano-scale thin metal film. The middle layer was formed a porous PDMS film inserted with circular conductive rubber. The sensor array could detect the contact pressure within 30% stretching rate. In this paper, the performance of the pressure sensor array was systematically studied. With the corresponding scanning power-supply circuit and data acquisition system, it is demonstrated that the system can successfully capture the tactile images induced by objects of different shapes. Such sensor system could be applied on complex surfaces in robots or medical devices for contact pressure detection and feedback.

Benchmarking for On-Scalp MEG Sensors.

PubMed

Xie, Minshu; Schneiderman, Justin F; Chukharkin, Maxim L; Kalabukhov, Alexei; Riaz, Bushra; Lundqvist, Daniel; Whitmarsh, Stephen; Hamalainen, Matti; Jousmaki, Veikko; Oostenveld, Robert; Winkler, Dag

2017-06-01

We present a benchmarking protocol for quantitatively comparing emerging on-scalp magnetoencephalography (MEG) sensor technologies to their counterparts in state-of-the-art MEG systems. As a means of validation, we compare a high-critical-temperature superconducting quantum interference device (high T c SQUID) with the low- T c SQUIDs of an Elekta Neuromag TRIUX system in MEG recordings of auditory and somatosensory evoked fields (SEFs) on one human subject. We measure the expected signal gain for the auditory-evoked fields (deeper sources) and notice some unfamiliar features in the on-scalp sensor-based recordings of SEFs (shallower sources). The experimental results serve as a proof of principle for the benchmarking protocol. This approach is straightforward, general to various on-scalp MEG sensors, and convenient to use on human subjects. The unexpected features in the SEFs suggest on-scalp MEG sensors may reveal information about neuromagnetic sources that is otherwise difficult to extract from state-of-the-art MEG recordings. As the first systematically established on-scalp MEG benchmarking protocol, magnetic sensor developers can employ this method to prove the utility of their technology in MEG recordings. Further exploration of the SEFs with on-scalp MEG sensors may reveal unique information about their sources.

Approaches that use software to support the prevention of pressure ulcer: A systematic review.

PubMed

Marchione, F G; Araújo, L M Q; Araújo, L V

2015-10-01

The incidence and costs for pressure ulcer (PU) treatment remain high even though preventive methods are applied. Approaches that use software to support the prevention of PU are presented in the literature to make it more effective. Identify the state of art of the approaches that use software to support the prevention of PUs. A systematic literature review was performed to analyze approaches that use software to support the prevention of PU. ACM, IEEE, PubMed, Scopus, CINAHL and Embase databases have been searched with a predetermined search string to identify primary studies. We selected the ones that met the established inclusion criteria. Thirty-six articles met the inclusion criteria. To support prevention, most approaches monitor the patient to provide information about exposure to pressure, temperature level, humidity level and estimated body position in bed providing risk factor intensity charts and intensity maps. The main method to perform patient's monitoring is using sensors installed on the mattress, but recently, alternative methods have been proposed such as electronic sensors and tactile sensory coils. Part of the approaches performs automated management of the risk factors using ventilation tubes and mattresses with porous cells to decrease body's temperature and movable cells to automatically redistribute the pressure over the body. Matters as cost of the approach, patient comfort and hygiene of the monitoring equipment is only briefly discussed in the selected articles. No experiments have been conducted to evidence the approached may reduce PU incidence. Currently, approaches that use software to support the prevention of PU provide relevant information to health professionals such as risk factor intensity charts and intensity maps. Some of them can even automatically manage risk factors in a limited way. Yet, the approaches are based on risk factor monitoring methods that require patient's contact with the monitoring equipment. Therefore, some matters need to be considered such as patient's comfort and the hygiene or replacement of the equipment due to the risk of infection. With the emergence of new alternative methods of monitoring, new technologies that do not require contact could be explored by new researches. Randomized Control Trials could also be conducted to verify which approaches are really effective to reduce PU incidence. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Using URIs to effectively transmit sensor data and metadata

NASA Astrophysics Data System (ADS)

Kokkinaki, Alexandra; Buck, Justin; Darroch, Louise; Gardner, Thomas

2017-04-01

Autonomous ocean observation is massively increasing the number of sensors in the ocean. Accordingly, the continuing increase in datasets produced, makes selecting sensors that are fit for purpose a growing challenge. Decision making on selecting quality sensor data, is based on the sensor's metadata, i.e. manufacturer specifications, history of calibrations etc. The Open Geospatial Consortium (OGC) has developed the Sensor Web Enablement (SWE) standards to facilitate integration and interoperability of sensor data and metadata. The World Wide Web Consortium (W3C) Semantic Web technologies enable machine comprehensibility promoting sophisticated linking and processing of data published on the web. Linking the sensor's data and metadata according to the above-mentioned standards can yield practical difficulties, because of internal hardware bandwidth restrictions and a requirement to constrain data transmission costs. Our approach addresses these practical difficulties by uniquely identifying sensor and platform models and instances through URIs, which resolve via content negotiation to either OGC's sensor meta language, sensorML or W3C's Linked Data. Data transmitted by a sensor incorporate the sensor's unique URI to refer to its metadata. Sensor and platform model URIs and descriptions are created and hosted by the British Oceanographic Data Centre (BODC) linked systems service. The sensor owner creates the sensor and platform instance URIs prior and during sensor deployment, through an updatable web form, the Sensor Instance Form (SIF). SIF enables model and instance URI association but also platform and sensor linking. The use of URIs, which are dynamically generated through the SIF, offers both practical and economical benefits to the implementation of SWE and Linked Data standards in near real time systems. Data can be linked to metadata dynamically in-situ while saving on the costs associated to the transmission of long metadata descriptions. The transmission of short URIs also enables the implementation of standards on systems where it is impractical, such as legacy hardware.

Sensor Data Quality and Angular Rate Down-Selection Algorithms on SLS EM-1

NASA Technical Reports Server (NTRS)

Park, Thomas; Oliver, Emerson; Smith, Austin

2018-01-01

The NASA Space Launch System Block 1 launch vehicle is equipped with an Inertial Navigation System (INS) and multiple Rate Gyro Assemblies (RGA) that are used in the Guidance, Navigation, and Control (GN&C) algorithms. The INS provides the inertial position, velocity, and attitude of the vehicle along with both angular rate and specific force measurements. Additionally, multiple sets of co-located rate gyros supply angular rate data. The collection of angular rate data, taken along the launch vehicle, is used to separate out vehicle motion from flexible body dynamics. Since the system architecture uses redundant sensors, the capability was developed to evaluate the health (or validity) of the independent measurements. A suite of Sensor Data Quality (SDQ) algorithms is responsible for assessing the angular rate data from the redundant sensors. When failures are detected, SDQ will take the appropriate action and disqualify or remove faulted sensors from forward processing. Additionally, the SDQ algorithms contain logic for down-selecting the angular rate data used by the GN&C software from the set of healthy measurements. This paper provides an overview of the algorithms used for both fault-detection and measurement down selection.

Rapid and selective detection of acetone using hierarchical ZnO gas sensor for hazardous odor markers application.

PubMed

Jia, Qianqian; Ji, Huiming; Zhang, Ying; Chen, Yalu; Sun, Xiaohong; Jin, Zhengguo

2014-07-15

Hierarchical nanostructured ZnO dandelion-like spheres were synthesized via solvothermal reaction at 200°C for 4h. The products were pure hexagonal ZnO with large exposure of (002) polar facet. Side-heating gas sensor based on hierarchical ZnO spheres was prepared to evaluate the acetone gas sensing properties. The detection limit to acetone for the ZnO sensor is 0.25ppm. The response (Ra/Rg) toward 100ppm acetone was 33 operated at 230°C and the response time was as short as 3s. The sensor exhibited remarkable acetone selectivity with negligible response toward other hazardous gases and water vapor. The high proportion of electron depletion region and oxygen vacancies contributed to high gas response sensitivity. The hollow and porous structure of dandelion-like ZnO spheres facilitated the diffusion of gas molecules, leading to a rapid response speed. The largely exposed (002) polar facets could adsorb acetone gas molecules easily and efficiently, resulting in a rapid response speed and good selectivity of hierarchical ZnO spheres gas sensor at low operating temperature. Copyright © 2014 Elsevier B.V. All rights reserved.

Multiocular image sensor with on-chip beam-splitter and inner meta-micro-lens for single-main-lens stereo camera.

PubMed

Koyama, Shinzo; Onozawa, Kazutoshi; Tanaka, Keisuke; Saito, Shigeru; Kourkouss, Sahim Mohamed; Kato, Yoshihisa

2016-08-08

We developed multiocular 1/3-inch 2.75-μm-pixel-size 2.1M- pixel image sensors by co-design of both on-chip beam-splitter and 100-nm-width 800-nm-depth patterned inner meta-micro-lens for single-main-lens stereo camera systems. A camera with the multiocular image sensor can capture horizontally one-dimensional light filed by both the on-chip beam-splitter horizontally dividing ray according to incident angle, and the inner meta-micro-lens collecting the divided ray into pixel with small optical loss. Cross-talks between adjacent light field images of a fabricated binocular image sensor and of a quad-ocular image sensor are as low as 6% and 7% respectively. With the selection of two images from one-dimensional light filed images, a selective baseline for stereo vision is realized to view close objects with single-main-lens. In addition, by adding multiple light field images with different ratios, baseline distance can be tuned within an aperture of a main lens. We suggest the electrically selective or tunable baseline stereo vision to reduce 3D fatigue of viewers.

A Uniform Energy Consumption Algorithm for Wireless Sensor and Actuator Networks Based on Dynamic Polling Point Selection

PubMed Central

Li, Shuo; Peng, Jun; Liu, Weirong; Zhu, Zhengfa; Lin, Kuo-Chi

2014-01-01

Recent research has indicated that using the mobility of the actuator in wireless sensor and actuator networks (WSANs) to achieve mobile data collection can greatly increase the sensor network lifetime. However, mobile data collection may result in unacceptable collection delays in the network if the path of the actuator is too long. Because real-time network applications require meeting data collection delay constraints, planning the path of the actuator is a very important issue to balance the prolongation of the network lifetime and the reduction of the data collection delay. In this paper, a multi-hop routing mobile data collection algorithm is proposed based on dynamic polling point selection with delay constraints to address this issue. The algorithm can actively update the selection of the actuator's polling points according to the sensor nodes' residual energies and their locations while also considering the collection delay constraint. It also dynamically constructs the multi-hop routing trees rooted by these polling points to balance the sensor node energy consumption and the extension of the network lifetime. The effectiveness of the algorithm is validated by simulation. PMID:24451455

Theoretical studies of structure and selectivity of 5-methyl-4-(2-thiazolylazo) resorcinol as a sensor for metal ions: DFT calculation

NASA Astrophysics Data System (ADS)

Thaomola, Sukhontip; Sompech, Supachai

2018-05-01

The global minimum optimized structures of the free sensor 5-methyl-4-(2-thiazolylazo) resorcinol (5-Me-TAR) and 5-Me-TAR-Cu2+ complexes in the gas phase have been investigated by using Density Functional Theory (DFT) with the def2-TZVP basis set. To compare the selectivity of 5-Me-TAR for metal ions, the binding energy of 5-Me-TAR with various metal ions (Na+, K+, Mg2+, Ca2+, Ba2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Pd2+, Cd2+ and Hg2+) were calculated at the same level as the theory. Binding energy values of most transition metal ions are lower than alkaline earth metal ions and alkali metal ions, respectively. The 5-Me-TAR sensor shows the highest selectivity with the Cu2+ ion. Moreover, Dependent Density Functional Theory (TDDFT) results confirm that the 5-Me-TAR-Cu2+ complex is stabilized by the sensor to metal charge transfer process. The computational studies suggested that the 5-Me-TAR is suitable for Cu2+ ion detection sensor development.

A novel sensor for monitoring of iron(III) ions based on porphyrins.

PubMed

Vlascici, Dana; Fagadar-Cosma, Eugenia; Popa, Iuliana; Chiriac, Vlad; Gil-Agusti, Mayte

2012-01-01

Three A(3)B porphyrins with mixed carboxy-, phenoxy-, pyridyl-, and dimethoxy-substituent functionalization on the meso-phenyl groups were obtained by multicomponent synthesis, fully characterized and used as ionophores for preparing PVC-based membrane sensors selective to iron(III). The membranes have an ionophore:PVC:plasticizer composition ratio of 1:33:66. Sodium tetraphenylborate was used as additive (20 mol% relative to ionophore). The performance characteristics (linear concentration range, slope and selectivity) of the sensors were investigated. The best results were obtained for the membrane based on 5-(4-carboxyphenyl)-10,15,20-tris(4-phenoxyphenyl)-porphyrin plasticized with bis(2-ethylhexyl)sebacate, in a linear range from 1 × 10(-7)-1 × 10(-1) M with a slope of 21.6 mV/decade. The electrode showed high selectivity with respect to alkaline and heavy metal ions and a response time of 20 s. The influence of pH on the sensor response was studied. The sensor was used for a period of six weeks and the utility has been tested for the quantitative determination of Fe(III) in recovered solutions from spent lithium ion batteries and for the quantitative determination of Fe(III) in tap water samples.

Vapor sensors using porous silicon-based optical interferometers

NASA Astrophysics Data System (ADS)

Gao, Ting

The ability to detect or monitor various gases is important for many applications. Smaller, more portable, lower power, and less expensive gas sensors are needed. Porous silicon (PS) has attracted attention for use in such devices due to its unique optical and electronic properties and its large surface area. This thesis describes the preparation and characteristics of vapor sensors using thin PS Fabry-Perot films. The average refractive index of the PS layer increases when the PS film is exposed to analyte vapors, causing the optical fringes to shift to longer wavelengths. Two methods for monitoring the shifts in these optical fringes are explored in this thesis. The first technique measures the reflection spectrum using a white light source, and the second measures the intensity of reflected light using a low-power red diode laser source. The latter method offers a simple, low-cost and reliable transduction mechanism for vapor sensing. A vapor sensor with a detection limit of 250 ppb and a wide dynamic range (five orders of magnitude) is demonstrated. The effect of the PS film thickness and porosity on sensitivity are systematically studied. A model based on the Bruggeman approximation and capillary condensation is proposed to explain this sensing behavior. Two approaches to improve the sensitivity of the PS sensors are explored. In the first, porous Si is chemically modified and the investigation shows that the sensing response varies with different surface properties. In a second study, thin polymer layers are coated on the porous Si substrate to selectively filter solvent vapors. This bi-layer approach is also applied to porous Si layers that have luminescent quantum structures. These latter structures sense adsorbates based on quenching of luminescence from the quantum-confined silicon nanostructures. In the course of this thesis, an anomalous response of ozone-oxidized PS films to water vapor was discovered. The effect was studied by optical interferometry, isotope studies, and in-situ Fourier transform infrared spectroscopy. It is concluded that in some porous Si films, water forms a strongly hydrogen bonded network that results in compression of the porous Si layer.

Combined Ozone Retrieval From METOP Sensors Using META-Training Of Deep Neural Networks

NASA Astrophysics Data System (ADS)

Felder, Martin; Sehnke, Frank; Kaifel, Anton

2013-12-01

The newest installment of our well-proven Neural Net- work Ozone Retrieval System (NNORSY) combines the METOP sensors GOME-2 and IASI with cloud information from AVHRR. Through the use of advanced meta- learning techniques like automatic feature selection and automatic architecture search applied to a set of deep neural networks, having at least two or three hidden layers, we have been able to avoid many technical issues normally encountered during the construction of such a joint retrieval system. This has been made possible by harnessing the processing power of modern consumer graphics cards with high performance graphic processors (GPU), which decreases training times by about two orders of magnitude. The system was trained on data from 2009 and 2010, including target ozone profiles from ozone sondes, ACE- FTS and MLS-AURA. To make maximum use of tropospheric information in the spectra, the data were partitioned into several sets of different cloud fraction ranges with the GOME-2 FOV, on which specialized retrieval networks are being trained. For the final ozone retrieval processing the different specialized networks are combined. The resulting retrieval system is very stable and does not show any systematic dependence on solar zenith angle, scan angle or sensor degradation. We present several sensitivity studies with regard to cloud fraction and target sensor type, as well as the performance in several latitude bands and with respect to independent validation stations. A visual cross-comparison against high-resolution ozone profiles from the KNMI EUMETSAT Ozone SAF product has also been performed and shows some distinctive features which we will briefly discuss. Overall, we demonstrate that a complex retrieval system can now be constructed with a minimum of ma- chine learning knowledge, using automated algorithms for many design decisions previously requiring expert knowledge. Provided sufficient training data and computation power of GPUs is available, the method can be applied to almost any kind of retrieval or, more generally, regression problem.

An Ensemble Successive Project Algorithm for Liquor Detection Using Near Infrared Sensor.

PubMed

Qu, Fangfang; Ren, Dong; Wang, Jihua; Zhang, Zhong; Lu, Na; Meng, Lei

2016-01-11

Spectral analysis technique based on near infrared (NIR) sensor is a powerful tool for complex information processing and high precision recognition, and it has been widely applied to quality analysis and online inspection of agricultural products. This paper proposes a new method to address the instability of small sample sizes in the successive projections algorithm (SPA) as well as the lack of association between selected variables and the analyte. The proposed method is an evaluated bootstrap ensemble SPA method (EBSPA) based on a variable evaluation index (EI) for variable selection, and is applied to the quantitative prediction of alcohol concentrations in liquor using NIR sensor. In the experiment, the proposed EBSPA with three kinds of modeling methods are established to test their performance. In addition, the proposed EBSPA combined with partial least square is compared with other state-of-the-art variable selection methods. The results show that the proposed method can solve the defects of SPA and it has the best generalization performance and stability. Furthermore, the physical meaning of the selected variables from the near infrared sensor data is clear, which can effectively reduce the variables and improve their prediction accuracy.

BODIPY-Based Fluorescent Sensor for the Recognization of Phosgene in Solutions and in Gas Phase.

PubMed

Xia, Hong-Cheng; Xu, Xiang-Hong; Song, Qin-Hua

2017-04-04

As a highly toxic and widely used chemical, phosgene has become a serious threat to humankind and public security because of its potential use by terrorists and unexpected release during industrial accidents. For this reason, it is an urgent need to develop facile, fast, and selective detection methods of phosgene. In this Article, we have constructed a highly selective fluorescent sensor o-Pab for phosgene with a BODIPY unit as a fluorophore and o-phenylenediamine as a reactive site. The sensor o-Pab exhibits rapid response (∼15 s) in both colorimetric and turn-on fluorescence modes, high selectivity for phosgene over nerve agent mimics and various acyl chlorides and a low detection limit (2.7 nM) in solutions. In contrast to most undistinguishable sensors reported, o-Pab can react with phosgene but not with its substitutes, triphosgene and biphosgene. The excellent discrimination of o-Pab has been demonstrated to be due to the difference in highly reactive and bifunctional phosgene relative to its substitutes. Furthermore, a facile testing paper has been fabricated with poly(ethylene oxide) immobilizing o-Pab on a filter paper for real-time selective monitoring of phosgene in gaseous phase.

In Vitro Selection for Small-Molecule-Triggered Strand Displacement and Riboswitch Activity.

PubMed

Martini, Laura; Meyer, Adam J; Ellefson, Jared W; Milligan, John N; Forlin, Michele; Ellington, Andrew D; Mansy, Sheref S

2015-10-16

An in vitro selection method for ligand-responsive RNA sensors was developed that exploited strand displacement reactions. The RNA library was based on the thiamine pyrophosphate (TPP) riboswitch, and RNA sequences capable of hybridizing to a target duplex DNA in a TPP regulated manner were identified. After three rounds of selection, RNA molecules that mediated a strand exchange reaction upon TPP binding were enriched. The enriched sequences also showed riboswitch activity. Our results demonstrated that small-molecule-responsive nucleic acid sensors can be selected to control the activity of target nucleic acid circuitry.

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

Yu, Zongchao; Wang, Fengqin, E-mail: wangfengqin@tjpu.edu.cn; Lin, Xiangyi

Metal-organic frameworks (MOFs) are porous crystalline materials with high potential for applications in fluorescence sensors. In this work, two solvent-induced Zn(II)–based metal-organic frameworks, Zn{sub 3}L{sub 3}(DMF){sub 2} (1) and Zn{sub 3}L{sub 3}(DMA){sub 2}(H{sub 2}O){sub 3} (2) (L=4,4′-stilbenedicarboxylic acid), were investigated as selective sensing materials for detection of nitroaromatic compounds and metal ions. The sensing experiments show that 1 and 2 both exhibit selective fluorescence quenching toward nitroaniline with a low detection limit. In addition, 1 exhibits high selectivity for detection of Fe{sup 3+} and Al{sup 3+} by significant fluorescence quenching or enhancement effect. While for 2, it only exhibits significantmore » fluorescence quenching effect for Fe{sup 3+}. The results indicate that 1 and 2 are both promising fluorescence sensors for detecting and recognizing nitroaniline and metal ions with high sensitivity and selectivity. - Graphical abstract: Two MOFs have been selected as the fluorescence sensing materials for selectively sensing mitroaromatic compounds and metal ions. The high selectivity makes them promising fluorescence sensors for detecting and recognizing nitroaniline and Fe{sup 3+} or Al{sup 3+}.« less

Biocompatible hydrogel membranes for the protection of RNA aptamer-based electrochemical sensors

NASA Astrophysics Data System (ADS)

Schoukroun-Barnes, Lauren R.; Wagan, Samiullah; Liu, Juan; Leach, Jennie B.; White, Ryan J.

2013-05-01

Electrochemical-aptamer based (E-AB) sensors represent a universal specific, selective, and sensitive sensing platform for the detection of small molecule targets. Their specific detection abilities are afforded by oligonucleotide (RNA or DNA) aptamers employed as electrode-bound biorecognition elements. Sensor signaling is predicated on bindinginduced changes in conformation and/or flexibility of the aptamer that is readily measurable electrochemically. While sensors fabricated using DNA aptamers can achieve specific and selective detection even in unadulterated sample matrices, such as blood serum, RNA-based sensors fail when challenged in the same sample matrix without significant sample pretreatment. This failure is at least partially a result of enzymatic degradation of the RNA sensing element. This degradation destroys the sensing aptamer inhibiting the quantitative measurement of the target analyte and thus limits the application of E-AB sensors constructed with RNA aptamer. To circumvent this, we demonstrate that a biocompatible hydrogel membrane protects the RNA aptamer sensor surface from enzymatic degradation for at least 3 hours - a remarkable improvement over the rapid (~minutes) degradation of unprotected sensors. To demonstrate this, we characterize the response of sensors fabricated with representative DNA and RNA aptamers directed against the aminoglycoside antibiotic, tobramycin in blood serum both protected and unprotected by a polyacrylamide membrane. Furthermore, we find encapsulation of the sensor surface with the hydrogel does not significantly impede the detection ability of aptamer-based sensors. This hydrogel-aptamer interface will thus likely prove useful for the long-term monitoring of therapeutics in complex biological media.

Safety Sensor Testing Laboratory | Hydrogen and Fuel Cells | NREL

Science.gov Websites

collaborations, trainings and workshops, and academic research and development support. Work in the laboratory (temperature, pressure, and relative humidity) and gas parameters (flow and composition) Quantitative sensor services to assist end-users on sensor selection and use Assist developers in quantitative assessment of

Body-Worn Sensors in Parkinson's Disease: Evaluating Their Acceptability to Patients.

PubMed

Fisher, James M; Hammerla, Nils Y; Rochester, Lynn; Andras, Peter; Walker, Richard W

2016-01-01

Remote monitoring of symptoms in Parkinson's disease (PD) using body-worn sensors would assist treatment decisions and evaluation of new treatments. To date, a rigorous, systematic evaluation of the acceptability of body-worn sensors in PD has not been undertaken. Thirty-four participants wore bilateral wrist-worn sensors for 4 h in a research facility and then for 1 week at home. Participants' experiences of wearing the sensors were evaluated using a Likert-style questionnaire after each phase. Qualitative data were collected through free-text responses. Differences in responses between phases were assessed by using the Wilcoxon rank-sum test. Content analysis of qualitative data was undertaken. "Non-wear time" was estimated via analysis of accelerometer data for periods when sensors were stationary. After prolonged wearing there was a negative shift in participants' views on the comfort of the sensor; problems with the sensor's strap were highlighted. However, accelerometer data demonstrated high patient concordance with wearing of the sensors. There was no evidence that participants were less likely to wear the sensors in public. Most participants preferred wearing the sensors to completing symptom diaries. The finding that participants were not less likely to wear the sensors in public provides reassurance regarding the ecological validity of the data captured. The validity of our findings was strengthened by "triangulation" of data sources, enabling patients to express their agenda and repeated assessment after prolonged wearing. Long-term monitoring with wrist-worn sensors is acceptable to this cohort of PD patients. Evaluation of the wearer's experience is critical to the development of remote monitoring technology.

Two-mode elliptical-core weighted fiber sensors for vibration analysis

NASA Technical Reports Server (NTRS)

Vengsarkar, Ashish M.; Murphy, Kent A.; Fogg, Brian R.; Miller, William V.; Greene, Jonathan A.; Claus, Richard O.

1992-01-01

Two-mode, elliptical-core optical fibers are demonstrated in weighted, distributed and selective vibration-mode-filtering applications. We show how appropriate placement of optical fibers on a vibrating structure can lead to vibration mode filtering. Selective vibration-mode suppression on the order of 10 dB has been obtained using tapered two-mode, circular-core fibers with tapering functions that match the second derivatives of the modes of vibration to be enhanced. We also demonstrate the use of chirped, two-mode gratings in fibers as spatial modal sensors that are equivalents of shaped piezoelectric sensors.

Function of an Implanted Tissue Glucose Sensor for More than One Year in Animals

PubMed Central

Gough, David A.; Kumosa, Lucas S.; Routh, Timothy L.; Lin, Joe T.; Lucisano, Joseph Y.

2015-01-01

An implantable sensor capable of long-term monitoring of tissue glucose concentrations by wireless telemetry has been developed for eventual application in people with diabetes. In a recent trial, the sensor-telemetry system functioned continuously while implanted in subcutaneous tissues of two pigs for a total of 222 days and 520 days respectively, with each animal in both non-diabetic and diabetic states. The sensor detects glucose via an enzyme electrode principle that is based on differential electrochemical oxygen detection, which reduces the sensitivity of the sensor to encapsulation by the body, variations in local microvascular perfusion, limited availability of tissue oxygen, and inactivation of the enzymes. After an initial two-week stabilization period, the implanted sensors maintained stability of calibration for extended periods. The lag between blood and tissue glucose concentrations was 11.8 ± 5.7 minutes and 6.5 ± 13.3 minutes respectively, for rising and falling blood glucose challenges (mean ± SD). The lag was determined mainly by glucose mass transfer in the tissues, rather than the intrinsic response of the sensor, and showed no systematic change over implant test periods. These results represent a milestone in the translation of the sensor system to human applications. PMID:20668297

Effect of structure on sensing performance of a target induced signaling probe shifting DNA-based (TISPS-DNA) sensor.

PubMed

Yu, Xiang; Yu, Zhigang; Li, Fengqin; Xu, Yanmei; He, Xunjun; Xu, Lan; Shi, Wenbing; Zhang, Guiling; Yan, Hong

2017-05-15

A type of "signal on" displacement-based sensors named target induced signaling probe shifting DNA-based (TISPS-DNA) sensor were developed for a designated DNA detection. The signaling mechanism of the signaling probe (SP) shifting different from the classical conformation/flexibility change mode endows the sensor with high sensitivity. Through using thiolated or no thiolated capturing probe (CP), two 3-probe sensing structures, sensor-1 and sensor-2, were designed and constructed. The systematical comparing research results show that both sensors exhibit some similarities or big differences in sensing performance. On the one hand, the similarity in structures determines the similarity in some aspects of signaling mechanism, background signal, signal changing form, anti-fouling ability and versatility; on the other hand, the slight difference in structures also results in two opposite hybridization modes of gradual increasing resistance and gradual decreasing resistance which can affect the hybridization efficiency between the assistant probe (AP) and the SP, further producing some big differences in sensing performance, for example, apparently different signal enhancement (SE) change, point mutation discrimination ability and response speed. Under the optimized fabrication and detection conditions, both sensors feature high sensitivity for target DNAs with the detection limits of ∼10 fM for sensor-1 and ∼7 fM for sensor-2, respectively. Among many acquired sensing virtues, the sensor-1 shows a peculiar specificity adjustability which is also a highlight in this work. Copyright © 2017 Elsevier B.V. All rights reserved.

Status report on the USGS component of the Global Seismographic Network

NASA Astrophysics Data System (ADS)

Gee, L. S.; Bolton, H. F.; Derr, J.; Ford, D.; Gyure, G.; Hutt, C. R.; Ringler, A.; Storm, T.; Wilson, D.

2010-12-01

As recently as four years ago, the average age of a datalogger in the portion of the Global Seismographic Network (GSN) operated by the United States Geological Survey (USGS) was 16 years - an eternity in the lifetime of computers. The selection of the Q330HR in 2006 as the “next generation” datalogger by an Incorporated Research Institutions for Seismology (IRIS) selection committee opened the door for upgrading the GSN. As part of the “next generation” upgrades, the USGS is replacing a single Q680 system with two Q330HRs and a field processor to provide the same capability. The functionality includes digitizing, timing, event detection, conversion into miniSEED records, archival of miniSEED data on the ASP and telemetry of the miniSEED data using International Deployment of Accelerometers (IDA) Authenticated Disk Protocol (IACP). At many sites, Quanterra Balers are also being deployed. The Q330HRs feature very low power consumption (which will increase reliability) and higher resolution than the Q680 systems. Furthermore, this network-wide upgrade provides the opportunity to correct known station problems, standardize the installation of secondary sensors and accelerometers, replace the feedback electronics of STS-1 sensors, and perform checks of absolute system sensitivity and sensor orientation. The USGS upgrades began with ANMO in May, 2008. Although we deployed Q330s at KNTN and WAKE in the fall of 2007 (and in the installation of the Caribbean network), these deployments did not include the final software configuration for the GSN upgrades. Following this start, the USGS installed six additional sites in FY08. With funding from the American Recovery and Reinvestment Act and the USGS GSN program, 14 stations were upgraded in FY09. Twenty-one stations are expected to be upgraded in FY10. These systematic network-wide upgrades will improve the reliability and data quality of the GSN, with the end goal of providing the Earth science community high quality seismic data with global coverage. The Global Seismographic Network is operated as a partnership among the National Science Foundation, IRIS, IDA, and the USGS.

Joint Energy Supply and Routing Path Selection for Rechargeable Wireless Sensor Networks.

PubMed

Tang, Liangrui; Cai, Jinqi; Yan, Jiangyu; Zhou, Zhenyu

2018-06-17

The topic of network lifetime has been attracting much research attention because of its importance in prolonging the standing operation of battery-restricted wireless sensor networks, and the rechargeable wireless sensor network has emerged as a promising solution. In this paper, we propose a joint energy supply and routing path selection algorithm to extend the network lifetime based on an initiative power supply. We develop a two-stage energy replenishment strategy to supplement the energy consumption of nodes as much as possible. Furthermore, the influence of charging factors on the selection of next-hop nodes in data routing is considered. The simulation results show that our algorithm effectively prolong the network lifetime, and different demands of network delay and energy consumption can be obtained by dynamically adjusting parameters.

Highly sensitive oligothiophene-phenylamine-based dual-functional fluorescence "turn-on" sensor for rapid and simultaneous detection of Al3+ and Fe3+ in environment and food samples.

PubMed

Guo, Zongrang; Niu, Qingfen; Li, Tianduo

2018-07-05

Developing low-cost and efficient sensors for rapid, selective and sensitive detection of the transition metal ions in environmental and food science is very important. In this study, a novel dual-functional fluorescent "turn-on" sensor 3TP based on oligothiophene-phenylamine Schiff base has been synthesized for discrimination and simultaneous detection of both Al 3+ and Fe 3+ ions with high selectivity and anti-interference over other metal ions. Sensor 3TP displayed a very fast fluorescence-enhanced response towards Al 3+ and Fe 3+ ions with low detection limits (0.177μM for Al 3+ and 0.172μM for Fe 3+ ) and wide pH response range (4.0-12.0). The Al 3+ /Fe 3+ sensing mechanisms were investigated by fluorescence experiments, 1 H NMR titrations, FT-IR and ESI-MS spectra. Importantly, sensor 3TP was served as an efficient solid material for the highly sensitive and selective detection of Fe 3+ on TLC plates. Moreover, the sensor 3TP has been successfully used to detect trace Al 3+ and Fe 3+ in environment and food samples with satisfactory results and good recoveries, revealing a convenient, reliable and accurate method for Al 3+ and Fe 3+ analysis in real samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Highly sensitive oligothiophene-phenylamine-based dual-functional fluorescence "turn-on" sensor for rapid and simultaneous detection of Al3+ and Fe3+ in environment and food samples

NASA Astrophysics Data System (ADS)

Guo, Zongrang; Niu, Qingfen; Li, Tianduo

2018-07-01

Developing low-cost and efficient sensors for rapid, selective and sensitive detection of the transition metal ions in environmental and food science is very important. In this study, a novel dual-functional fluorescent "turn-on" sensor 3TP based on oligothiophene-phenylamine Schiff base has been synthesized for discrimination and simultaneous detection of both Al3+ and Fe3+ ions with high selectivity and anti-interference over other metal ions. Sensor 3TP displayed a very fast fluorescence-enhanced response towards Al3+ and Fe3+ ions with low detection limits (0.177 μM for Al3+ and 0.172 μM for Fe3+) and wide pH response range (4.0-12.0). The Al3+/Fe3+ sensing mechanisms were investigated by fluorescence experiments, 1H NMR titrations, FT-IR and ESI-MS spectra. Importantly, sensor 3TP was served as an efficient solid material for the highly sensitive and selective detection of Fe3+ on TLC plates. Moreover, the sensor 3TP has been successfully used to detect trace Al3+ and Fe3+ in environment and food samples with satisfactory results and good recoveries, revealing a convenient, reliable and accurate method for Al3+ and Fe3+ analysis in real samples.

Adsorption of gas molecules on a manganese phthalocyanine molecular device and its possibility as a gas sensor.

PubMed

Zou, Dongqing; Zhao, Wenkai; Cui, Bin; Li, Dongmei; Liu, Desheng

2018-01-17

A theoretical investigation of the gas detection performance of manganese(ii) phthalocyanine (MnPc) molecular junctions for six different gases (NO, CO, O 2 , CO 2 , NO 2 , and NH 3 ) is executed through a non-equilibrium Green's function technique in combination with spin density functional theory. Herein, we systematically studied the adsorption structural configurations, the adsorption energy, the charge transfer, and the spin transport properties of the MnPc molecular junctions with these gas adsorbates. Remarkably, NO adsorption can achieve an off-state of the Mn spin; this may be an effective measure to switch the molecular spin. In addition, our results indicate that by measuring spin filter efficiency and the changes in total current through the molecular junctions, the CO, NO, O 2 , and NO 2 gas molecules can be detected selectively. However, the CO 2 and NH 3 gas adsorptions are difficult to be detected due to weak van der Waals interaction between these two gases and central Mn atom. Our findings provide important clues to the application of nanosensors for highly sensitive and selective based on MnPc molecular junction systems.

Application of EREP, LANDSAT, and aircraft image data to environmental problems related to coal mining

NASA Technical Reports Server (NTRS)

Amato, R. V.; Russell, O. R.; Martin, K. R.; Wier, C. E.

1975-01-01

Remote sensing techniques were used to study coal mining sites within the Eastern Interior Coal Basin (Indiana, Illinois, and western Kentucky), the Appalachian Coal Basin (Ohio, West Virginia, and Pennsylvania) and the anthracite coal basins of northeastern Pennsylvania. Remote sensor data evaluated during these studies were acquired by LANDSAT, Skylab and both high and low altitude aircraft. Airborne sensors included multispectral scanners, multiband cameras and standard mapping cameras loaded with panchromatic, color and color infrared films. The research conducted in these areas is a useful prerequisite to the development of an operational monitoring system that can be peridically employed to supply state and federal regulatory agencies with supportive data. Further research, however, must be undertaken to systematically examine those mining processes and features that can be monitored cost effectively using remote sensors and for determining what combination of sensors and ground sampling processes provide the optimum combination for an operational system.

Effects of horizontal acceleration on the superconducting gravimeter CT #036 at Ishigakijima, Japan

NASA Astrophysics Data System (ADS)

Imanishi, Yuichi; Nawa, Kazunari; Tamura, Yoshiaki; Ikeda, Hiroshi

2018-01-01

In the gravity sensor of a superconducting gravimeter, a superconducting sphere as a test mass is levitated in a magnetic field. Such a sensor is susceptible to applied horizontal as well as vertical acceleration, because the translational degrees of freedom of the mass are not perfectly limited to the vertical direction. In the case of the superconducting gravimeter CT #036 installed at Ishigakijima, Japan, horizontal ground acceleration excited by the movements of a nearby VLBI antenna induces systematic step noise within the gravity recordings. We investigate this effect in terms of the static and dynamic properties of the gravity sensor using data from a collocated seismometer. It is shown that this effect can be effectively modeled by the coupling between the horizontal and vertical components in the gravity sensor. It is also found that the mechanical eigenfrequency for horizontal translation of the levitating sphere is approximately 3 Hz.[Figure not available: see fulltext.

High-Sensitivity GaN Microchemical Sensors

NASA Technical Reports Server (NTRS)

Son, Kyung-ah; Yang, Baohua; Liao, Anna; Moon, Jeongsun; Prokopuk, Nicholas

2009-01-01

Systematic studies have been performed on the sensitivity of GaN HEMT (high electron mobility transistor) sensors using various gate electrode designs and operational parameters. The results here show that a higher sensitivity can be achieved with a larger W/L ratio (W = gate width, L = gate length) at a given D (D = source-drain distance), and multi-finger gate electrodes offer a higher sensitivity than a one-finger gate electrode. In terms of operating conditions, sensor sensitivity is strongly dependent on transconductance of the sensor. The highest sensitivity can be achieved at the gate voltage where the slope of the transconductance curve is the largest. This work provides critical information about how the gate electrode of a GaN HEMT, which has been identified as the most sensitive among GaN microsensors, needs to be designed, and what operation parameters should be used for high sensitivity detection.

Enhanced NH3 gas sensing properties of a QCM sensor by increasing the length of vertically orientated ZnO nanorods

NASA Astrophysics Data System (ADS)

Minh, Vu Anh; Tuan, Le Anh; Huy, Tran Quang; Hung, Vu Ngoc; Quy, Nguyen Van

2013-01-01

Vertically aligned ZnO nanorods were directly synthesised on a gold electrode of quartz crystal microbalance (QCM) by a simple low-temperature hydrothermal method for a NH3 gas sensing application. The length of vertically aligned ZnO nanorods was increased to purpose enhancement in the gas sensing response of the sensor. The length of ZnO nanorods increased with an increase in growth time. The growth time of ZnO nanorods was systematically varied in the range of 1-4 h to examine the effect of the length of the ZnO nanorods on the gas sensing properties of the fabricated sensors. The gas sensing properties of sensors with different ZnO nanorods lengths was examined at room temperature for various concentrations of NH3 (50-800 ppm) in synthetic air. Enhancement in gas sensing response by increasing the length of ZnO nanorods was observed.

Ultrasensitive sensing with three-dimensional terahertz metamaterial absorber

NASA Astrophysics Data System (ADS)

Tan, Siyu; Yan, Fengping; Wang, Wei; Zhou, Hong; Hou, Yafei

2018-05-01

Planar metasurfaces and metamaterial absorbers have shown great promise for label-free sensing applications at microwaves, optical and terahertz frequencies. The realization of high-quality-factor resonance in these structures is of significant interest to enhance the sensing sensitivities to detect minute frequency shifts. We propose and demonstrate in this manuscript an ultrasensitive terahertz metamaterial absorber sensor based on a three-dimensional split ring resonator absorber with a high quality factor of 60.09. The sensing performance of the proposed absorber sensor was systematically investigated through detailed numerical calculations and a maximum refractive index sensitivity of 34.40% RIU‑1 was obtained. Furthermore, the absorber sensor can maintain a high sensitivity for a wide range of incidence angles up to 60° under TM polarization incidence. These findings would improve the design flexibility of the absorber sensors and further open up new avenues to achieve ultrasensitive sensing in the terahertz regime.

Multi-Sensor Registration of Earth Remotely Sensed Imagery

NASA Technical Reports Server (NTRS)

LeMoigne, Jacqueline; Cole-Rhodes, Arlene; Eastman, Roger; Johnson, Kisha; Morisette, Jeffrey; Netanyahu, Nathan S.; Stone, Harold S.; Zavorin, Ilya; Zukor, Dorothy (Technical Monitor)

2001-01-01

Assuming that approximate registration is given within a few pixels by a systematic correction system, we develop automatic image registration methods for multi-sensor data with the goal of achieving sub-pixel accuracy. Automatic image registration is usually defined by three steps; feature extraction, feature matching, and data resampling or fusion. Our previous work focused on image correlation methods based on the use of different features. In this paper, we study different feature matching techniques and present five algorithms where the features are either original gray levels or wavelet-like features, and the feature matching is based on gradient descent optimization, statistical robust matching, and mutual information. These algorithms are tested and compared on several multi-sensor datasets covering one of the EOS Core Sites, the Konza Prairie in Kansas, from four different sensors: IKONOS (4m), Landsat-7/ETM+ (30m), MODIS (500m), and SeaWIFS (1000m).

Progress of Mimetic Enzymes and Their Applications in Chemical Sensors.

PubMed

Yang, Bin; Li, Jianping; Deng, Huan; Zhang, Lianming

2016-11-01

The need to develop innovative and reformative approaches to synthesize chemical sensors has increased in recent years because of demands for selectivity, stability, and reproducibility. Mimetic enzymes provide an efficient and convenient method for chemical sensors. This review summarizes the application of mimetic enzymes in chemical sensors. Mimetic enzymes can be classified into five categories: hydrolases, oxidoreductases, transferases, isomerases, and induced enzymes. Potential and recent applications of mimetic enzymes in chemical sensors are reviewed in detail, and the outlook of profound development has been illustrated.

Increasing the selectivity and sensitivity of gas sensors for the detection of explosives

NASA Astrophysics Data System (ADS)

Mallin, Daniel

Over the past decade, the use of improvised explosive devices (IEDs) has increased, domestically and internationally, highlighting a growing need for a method to quickly and reliably detect explosive devices in both military and civilian environments before the explosive can cause damage. Conventional techniques have been successful in explosive detection, however they typically suffer from enormous costs in capital equipment and maintenance, costs in energy consumption, sampling, operational related expenses, and lack of continuous and real-time monitoring. The goal was thus to produce an inexpensive, portable sensor that continuously monitors the environment, quickly detects the presence of explosive compounds and alerts the user. In 2012, here at URI, a sensor design was proposed for the detection of triacetone triperoxide (TATP). The design entailed a thermodynamic gas sensor that measures the heat of decomposition between trace TATP vapor and a metal oxide catalyst film. The sensor was able to detect TATP vapor at the part per million level (ppm) and showed great promise for eventual commercial use, however, the sensor lacked selectivity. Thus, the specific objective of this work was to take the original sensor design proposed in 2012 and to make several key improvements to advance the sensor towards commercialization. It was demonstrated that a sensor can be engineered to detect TATP and ignore the effects of interferent H2O2 molecules by doping SnO2 films with varying amounts of Pd. Compared with a pure SnO2 catalyst, a SnO2, film doped with 8 wt. % Pd had the highest selectivity between TATP and H2O2. Also, at 12 wt. % Pd, the response to TATP and H2O2 was enhanced, indicating that sensitivity, not only selectivity, can be increased by modifying the composition of the catalyst. An orthogonal detection system was demonstrated. The platform consists of two independent sensing mechanisms, one thermodynamic and one conductometric, which take measurements from the same catalyst simultaneously and provide a redundancy in response for positive explosive identification. TATP, 2,6-DNT and ammonium nitrate were reliably detected. Each analyte displayed a unique conductometric signature and the results indicated a detection limit at the ppb level. A preconcentrator was designed to enhance the sensitivity of the sensor and was successfully demonstrated. The magnitude of the sensor response increased from by 50% and the preconcentrator could be operated semi-continuously, maintaining one of the most attractive features of this sensor platform: the capability to operate in real time. A method to filter out extraneous heat signals from sensor response using a dynamic control was also successfully demonstrated and will likely be a fixture in all sensor experimentation and design moving forward. Finally, two MEMS based sensor platforms were designed and fabricated. It was theoretically demonstrated that the newest iteration of the MEMS sensor consumes considerably less power due to thinner membranes, a smaller active surface area and an overall smaller thermal mass, allowing for the possibility of creating networks of sensor arrays, even in a portable device.

A microvolume molecularly imprinted polymer modified fiber-optic evanescent wave sensor for bisphenol A determination.

PubMed

Xiong, Yan; Ye, Zhongbin; Xu, Jing; Liu, Yucheng; Zhang, Hanyin

2014-04-01

A fiber-optic evanescent wave sensor for bisphenol A (BPA) determination based on a molecularly imprinted polymer (MIP)-modified fiber column was developed. MIP film immobilized with BPA was synthesized on the fiber column, and the sensor was then constructed by inserting the optical fiber prepared into a transparent capillary. A microchannel (about 2.0 μL) formed between the fiber and the capillary acted as a flow cell. BPA can be selectively adsorbed online by the MIP film and excited to produce fluorescence by the evanescent wave produced on the fiber core surface. The conditions for BPA enrichment, elution, and fluorescence detection are discussed in detail. The analytical measurements were made at 276 nm/306 nm (λ(ex)/λ(em)), and linearity of 3 × 10(-9)-5 × 10(-6) g mL(-1) BPA, a limit of detection of 1.7 × 10(-9) g mL(-1) BPA (3σ), and a relative standard deviation of 2.4% (n = 5) were obtained. The sensor selectivity and MIP binding measurement were also evaluated. The results indicated that the selectivity and sensitivity of the proposed fiber-optic sensor could be greatly improved by using MIP as a recognition and enrichment element. Further, by modification of the sensing and detection elements on the optical fiber, the proposed sensor showed the advantages of easy fabrication and low cost. The novel sensor configuration provided a platform for monitoring other species by simply changing the light source and sensing elements. The sensor presented has been successfully applied to determine BPA released from plastic products treated at different temperatures.

A PEGylated fluorescent turn-on sensor for detecting fluoride ions in totally aqueous media and its imaging in live cells.

PubMed

Zheng, Fangyuan; Zeng, Fang; Yu, Changmin; Hou, Xianfeng; Wu, Shuizhu

2013-01-14

Owing to the considerable significance of fluoride anions for health and environmental issues, it is of great importance to develop methods that can rapidly, sensitively and selectively detect the fluoride anion in aqueous media and biological samples. Herein, we demonstrate a robust fluorescent turn-on sensor for detecting the fluoride ion in a totally aqueous solution. In this study, a biocompatible hydrophilic polymer poly(ethylene glycol) (PEG) is incorporated into the sensing system to ensure water solubility and to enhance biocompatibility. tert-Butyldiphenylsilyl (TBDPS) groups were then covalently introduced onto the fluorescein moiety, which effectively quenched the fluorescence of the sensor. Upon addition of fluoride ion, the selective fluoride-mediated cleavage of the Si-O bond leads to the recovery of the fluorescein moiety, resulting in a dramatic increase in fluorescence intensity under visible light excitation. The sensor is responsive and highly selective for the fluoride anion over other common anions; it also exhibits a very low detection limit of 19 ppb. In addition, this sensor is operative in some real samples such as running water, urine, and serum and can accurately detect fluoride ions in these samples. The cytotoxicity of the sensor was determined to be Grade I toxicity according to United States Pharmacopoeia and ISO 10993-5, suggesting the very low cytotoxicity of the sensor. Moreover, it was found that the senor could be readily internalized by both HeLa and L929 cells and the sensor could be utilized to track fluoride level changes inside the cells. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanowire field-effect transistors for gas sensor applications

NASA Astrophysics Data System (ADS)

Constantinou, Marios

Sensing BTEX (Benzene, Ethylbenzene, Toluene, Xylene) pollutants is of utmost importance to reduce health risk and ensure public safety. The lack of sensitivity and selectivity of the current gas sensors and the limited number of available technologies in the field of BTEX-sensing raises the demand for the development of high-performance gas sensors for BTEX applications. The scope of this thesis is the fabrication and characterisation of high-quality field-effect transistors (FETs), with functionalised silicon nanowires (SiNWs), for the selective sensing of benzene vs. other BTEX gases. This research addresses three main challenges in SiNW FET-sensor device development: i) controllable and reproducible assembly of high-quality SiNWs for FET sensor devices using the method of dielectrophoresis (DEP), ii) almost complete elimination of harmful hysteresis effect in the SiNW FET current-voltage characteristics induced by surface states using DMF solvent, iii) selective sensing of benzene with up to ppb range of sensitivity using calix[4]arene-derivatives. It is experimentally demonstrated that frequency-controlled DEP is a powerful tool for the selection and collection of semiconducting SiNWs with advanced electrical and morphological properties, from a poly-disperse as-synthesised NWs. The DEP assembly method also leads to a controllable and reproducible fabrication of high-quality NW-based FETs. The results highlight the superiority of DEP, performed at high signal frequencies (5-20 MHz) to selectively assemble only high-quality NWs which can respond to such high DEP frequencies. The SiNW FETs, with NWs collected at high DEP frequencies, have high mobility (≈50 cm2 V-1 s-1), low sub-threshold-swing (≈1.26 V/decade), high on-current (up to 3 mA) and high on/off ratio (106-107). The DEP NW selection is also demonstrated using an industrially scalable method, to allow establishing of NW response characteristics to different DEP frequencies in a very short time window of about 60 seconds. The choice of solvent for the dispersion of the SiNW for the DEP process demonstrates a dramatic impact on their surface trap, with DMF solvent acting as a mild oxidising agent on the NW surface shell. This surface state passivation technique resulted in the fabrication of high-quality, hysteresis-free NW FET transducers for sensor applications. Finally, the proof-of-concept SiNW FET transducer decorated with calix[4]arene-derivative gas receptors exhibits selective detection of benzene vs. other BTEX gases up to 30 ppm concentrations, and up to sub-ppm benzene concentration. The demonstrated NW-sensors are low power and compact, and therefore can be easily mounted on a mobile device, providing instantaneous determination of hazardous gases in the surrounding atmosphere. The methodologies developed in this thesis, have a high potential to make a breakthrough in low-cost, selective gas sensors, which can be fabricated in line with printed and flexible electronic approaches.

Processing-structure-property relationships of carbon nanotube and nanoplatelet enabled piezoresistive sensors

NASA Astrophysics Data System (ADS)

Luo, Sida

Individual carbon nanotubes (CNTs) possess excellent piezoresistive performance, which is manifested by the significant electrical resistance change when subject to mechanical deformation. In comparison to individual CNTs, the CNT thin films, formed by a random assembly of individual tubes or bundles, show much lower piezoresistive sensitivity. Given the progress made to date in developing CNT ensemble based-piezoresistive sensors, the related piezoresistive mechanism(s) are still not well understood. The crucial step to obtain a better understanding of this issue is to study the effects of CNT structure in the dispersion on the piezoresistivity of CNT ensemble based-piezoresistive sensors. To reach this goal, my Ph.D. research first focuses on establishing the processing-structure-property relationship of SWCNT thin film piezoresistive sensors. The key accomplishment contains: 1) developing the combined preparative ultracentrifuge method (PUM) and dynamic light scattering (DLS) method to quantitatively characterized SWCNT particle size in dispersions under various sonication conditions; 2) designing combined ultrasonication and microfluidization processing protocol for high throughput and large-scale production of high quality SWCNT dispersions; 3) fabricating varied SWCNT thin film piezoresistive sensors through spray coating technique and immersion-drying post-treatment; and 4) investigating the effect of microstructures of SWCNTs on piezoresistivity of SWCNT thin film sensors. This experimental methodology for quantitative and systematic investigation of the processing-structure-property relationships provides a means for the performance optimization of CNT ensemble based piezoresistive sensors. As a start to understand the piezoresistive mechanism, the second focus of my Ph.D. research is studying charge transport behaviors in SWCNT thin films. It was found that the temperature-dependent sheet resistance of SWCNT thin films could be explained by a 3D variable range hopping (3D-VRH) model. More importantly, a strong correlation between the length of SWCNTs and the VRH parameter T0, indicating the degree of disorder of the electronic system, has been identified. With the structure dependent transport mechanism study, a very interesting topic - how T0 changes when SWCNT thin film is under a mechanical deformation, would be helpful for better understanding the piezoresistive mechanism of SWCNT thin film sensors. As demonstrated in transport mechanism study, SWCNT thin film exhibits a negative temperature coefficient (NTC) of resistance. In contrast, another family of carbon nanomaterials, graphite nanoplatelets (GNPs), shows positive temperature coefficient (PTC) of resistance, attributed to their metallic nature. Therefore, upon a wise selection of mass ratio of SWCNTs to GNPs for fabrication of hybrid SWCNT/GNP thin film piezoresistive sensors, a near zero temperature coefficients of resistance in a broad temperature range has been achieved. This unique self-temperature compensation feature along with the high sensitivity of SWCNT/GNP hybrid sensors provides them a vantage for readily and accurately measuring the strain/stress levels in different conditions. With the unique features of SWCNT/GNP hybrid thin film sensors, my future work will focus on application exploration on SWCNT/GNP thin film sensor based devices. For example, we have demonstrated that it is potential for man-machine interaction and body monitoring when coating the hybrid sensor on highly stretchable nitrile glove. The structure health monitoring (SHM) of composite materials could also be realized by coating the thin film sensor on a glass fiber surface and then embedding the fiber sensor in composite structure.

AOI [3] High-Temperature Nano-Derived Micro-H 2 and - H 2S Sensors

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

Sabolsky, Edward M.

2014-08-01

The emissions from coal-fired power plants remain a significant concern for air quality. This environmental challenge must be overcome by controlling the emission of sulfur dioxide (SO 2) and hydrogen sulfide (H 2S) throughout the entire coal combustion process. One of the processes which could specifically benefit from robust, low cost, and high temperature compatible gas sensors is the coal gasification process which converts coal and/or biomass into syngas. Hydrogen (H 2), carbon monoxide (CO) and sulfur compounds make up 33%, 43% and 2% of syngas, respectively. Therefore, development of a high temperature (>500°C) chemical sensor for in-situ monitoring ofmore » H 2, H 2S and SO2 2 levels during coal gasification is strongly desired. The selective detection of SO 2/H 2S in the presence of H 2, is a formidable task for a sensor designer. In order to ensure effective operation of these chemical sensors, the sensor system must inexpensively function within harsh temperature and chemical environment. Currently available sensing approaches, which are based on gas chromatography, electrochemistry, and IR-spectroscopy, do not satisfy the required cost and performance targets. This work focused on the development microsensors that can be applied to this application. In order to develop the high- temperature compatible microsensor, this work addressed various issues related to sensor stability, selectivity, and miniaturization. In the research project entitled “High-Temperature Nano-Derived Micro-H 2 and -H 2S Sensors”, the team worked to develop micro-scale, chemical sensors and sensor arrays composed of nano-derived, metal-oxide composite materials to detect gases like H 2, SO 2, and H 2S within high-temperature environments (>500°C). The research was completed in collaboration with NexTech Materials, Ltd. (Lewis Center, Ohio). NexTech assisted in the testing of the sensors in syngas with contaminate levels of H 2S. The idea of including nanomaterials as the sensing material within resistive-type chemical sensor platforms was to increase the sensitivity (as shown for room temperature applications). Unfortunately, nanomaterials are not stable at high temperatures due to sintering and coarsening processes that are driven by their high surface to volume ratio. Therefore, new hydrogen and sulfur selective nanomaterial systems with high selectivity and stability properties in the proposed harsh environment were investigated. Different nano-morphologies of zirconate, molybdate, and tungstate compounds were investigated. The fabrication of the microsensors consisted of the deposition of the selective nanomaterial systems over metal based interconnects on an inert substrate. This work utilized the chemi-resistive (resistive- type) microsensor architecture where the chemically and structurally stable, high temperature compatible electrodes were sputtered onto a ceramic substrate. The nanomaterial sensing systems were deposited over the electrodes using a lost mold method patterned by conventional optical lithography. The microsensor configuration with optimized nanomaterial system was tested and compared to a millimeter-size sensor e outcomes of this research will contribute to the economical application of sensor arrays for simultaneous sensing of H 2, H 2S, and SO 2.« less

Self-assembled near-infrared dye nanoparticles as a selective protein sensor by activation of a dormant fluorophore.

PubMed

Anees, Palapuravan; Sreejith, Sivaramapanicker; Ajayaghosh, Ayyappanpillai

2014-09-24

Design of selective sensors for a specific analyte in blood serum, which contains a large number of proteins, small molecules, and ions, is important in clinical diagnostics. While metal and polymeric nanoparticle conjugates have been used as sensors, small molecular assemblies have rarely been exploited for the selective sensing of a protein in blood serum. Herein we demonstrate how a nonspecific small molecular fluorescent dye can be empowered to form a selective protein sensor as illustrated with a thiol-sensitive near-IR squaraine (Sq) dye (λabs= 670 nm, λem= 700 nm). The dye self-assembles to form nonfluorescent nanoparticles (Dh = 200 nm) which selectively respond to human serum albumin (HSA) in the presence of other thiol-containing molecules and proteins by triggering a green fluorescence. This selective response of the dye nanoparticles allowed detection and quantification of HSA in blood serum with a sensitivity limit of 3 nM. Notably, the Sq dye in solution state is nonselective and responds to any thiol-containing proteins and small molecules. The sensing mechanism involves HSA specific controlled disassembly of the Sq nanoparticles to the molecular dye by a noncovalent binding process and its subsequent reaction with the thiol moiety of the protein, triggering the green emission of a dormant fluorophore present in the dye. This study demonstrates the power of a self-assembled small molecular fluorophore for protein sensing and is a simple chemical tool for the clinical diagnosis of blood serum.

Evaluation of platinum resistance thermometers

NASA Technical Reports Server (NTRS)

Daryabeigi, Kamran; Dillon-Townes, Lawrence A.

1988-01-01

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

Two-range magnetoelectric sensor

NASA Astrophysics Data System (ADS)

Bichurin, M.; Petrov, V.; Leontyev, V.; Saplev, A.

2017-01-01

In this study, we present a two-range magnetoelectric ME sensor design comprising of permendur (alloy of Fe-Co-V), nickel, and lead zirconate titanate (PZT) laminate composite. A systematic study was conducted to clarify the contribution of magnetostrictive layers variables to the ME response over the applied range of magnetic bias field. The two-range behavior was characterized by opposite sign of the ME response when magnetic dc bias is in different sub-ranges. The ME coefficient as a function of magnetic bias field was found to be dependent on the laminate composite structure.

DNAzyme sensors for detection of metal ions in the environment and imaging them in living cells

PubMed Central

McGhee, Claire E.; Loh, Kang Yong

2017-01-01

The on-site and real-time detection of metal ions is important for environmental monitoring and for understanding the impact of metal ions on human health. However, developing sensors selective for a wide range of metal ions that can work in the complex matrices of untreated samples and cells presents significant challenges. To meet these challenges, DNAzymes, an emerging class of metal ion-dependent enzymes selective for almost any metal ion, have been functionalized with fluorophores, nanoparticles and other imaging agents and incorporated into sensors for the detection of metal ions in environmental samples and for imaging the metal ions in living cells. Herein, we highlight the recent developments of DNAzyme-based fluorescent, colorimetric, SERS, electrochemical and electrochemiluminscent sensors for metal ions for these applications. PMID:28458112

Selective Detection of Formaldehyde Gas Using a Cd-Doped TiO2-SnO2 Sensor

PubMed Central

Zeng, Wen; Liu, Tianmo; Wang, Zhongchang; Tsukimoto, Susumu; Saito, Mitsuhiro; Ikuhara, Yuichi

2009-01-01

We report the microstructure and gas-sensing properties of a nonequilibrium TiO2-SnO2 solid solution prepared by the sol-gel method. In particular, we focus on the effect of Cd doping on the sensing behavior of the TiO2-SnO2 sensor. Of all volatile organic compound gases examined, the sensor with Cd doping exhibits exclusive selectivity as well as high sensitivity to formaldehyde, a main harmful indoor gas. The key gas-sensing quantities, maximum sensitivity, optimal working temperature, and response and recovery time, are found to meet the basic industrial needs. This makes the Cd-doped TiO2-SnO2 composite a promising sensor material for detecting the formaldehyde gas. PMID:22291551

Naphthaldimine-based simple glucose derivative as a highly selective sensor for colorimetric detection of Cu2+ ion in aqueous media

NASA Astrophysics Data System (ADS)

Dolai, Bholanath; Bhaumik, Atanu; Pramanik, Nabakumar; Ghosh, Kalyan Sundar; Atta, Ananta Kumar

2018-07-01

Naphthaldimine-based glucose derivatives 1 and 3 have been designed, synthesized and characterized. In aqueous media, glucose derivative 1, exhibited high selectivity and sensitivity towards Cu2+ ion in comparison with various cations and anions. In presence of Cu2+, sensor 1 has provided significant naked-eye detectable color change. The formation of 1-Cu2+ complex has been analyzed by UV-vis spectroscopy, 1H NMR titration experiments, mass spectrometry and DFT (density functional theory) calculations. Limit of detection of 1 as a colorimetric sensor for Cu2+ ion is found to be 0.23 μM, much lower than recommended value of World Health Organization (WHO), which makes to Cu2+ sensor 1 more effective and useful.

A selective optical sensor for picric acid assay based on photopolymerization of 3-(N-methacryloyl) amino-9-ethylcarbazole.

PubMed

Hu, Yan-Jun; Tan, Shu-Zhen; Shen, Guo-Li; Yu, Ru-Qin

2006-06-16

A novel optical sensor based on covalent immobilization for picric acid assay has been described. To improve the stability of the sensor, a terminal double bond was attached to the fluorescent compound, 3-amino-9-ethylcarbazole (AEC), via methacryloyl chloride. The resultant compound, 3-(N-methacryloyl) amino-9-ethylcarbazole (MAEC) was copolymerized with 2-hydroxypropyl methacrylate on surface-modified quartz glass plates by UV irradiation. The resulting optical sensor (optode membrane) was used to determine picric acid based on fluorescence quenching. It shows a linear response toward picric acid in the concentration range of 9.33 x 10(-8) to 9.33 x 10(-5) mol l(-1), with rapid response, high stability and good selectivity to picric acid.

THE SYSTEMATICS OF STRONG LENS MODELING QUANTIFIED: THE EFFECTS OF CONSTRAINT SELECTION AND REDSHIFT INFORMATION ON MAGNIFICATION, MASS, AND MULTIPLE IMAGE PREDICTABILITY

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

Johnson, Traci L.; Sharon, Keren, E-mail: tljohn@umich.edu

Until now, systematic errors in strong gravitational lens modeling have been acknowledged but have never been fully quantified. Here, we launch an investigation into the systematics induced by constraint selection. We model the simulated cluster Ares 362 times using random selections of image systems with and without spectroscopic redshifts and quantify the systematics using several diagnostics: image predictability, accuracy of model-predicted redshifts, enclosed mass, and magnification. We find that for models with >15 image systems, the image plane rms does not decrease significantly when more systems are added; however, the rms values quoted in the literature may be misleading asmore » to the ability of a model to predict new multiple images. The mass is well constrained near the Einstein radius in all cases, and systematic error drops to <2% for models using >10 image systems. Magnification errors are smallest along the straight portions of the critical curve, and the value of the magnification is systematically lower near curved portions. For >15 systems, the systematic error on magnification is ∼2%. We report no trend in magnification error with the fraction of spectroscopic image systems when selecting constraints at random; however, when using the same selection of constraints, increasing this fraction up to ∼0.5 will increase model accuracy. The results suggest that the selection of constraints, rather than quantity alone, determines the accuracy of the magnification. We note that spectroscopic follow-up of at least a few image systems is crucial because models without any spectroscopic redshifts are inaccurate across all of our diagnostics.« less

Review of Portable and Low-Cost Sensors for the Ambient Air Monitoring of Benzene and Other Volatile Organic Compounds

PubMed Central

Kok, Gertjan; Persijn, Stefan; Sauerwald, Tilman

2017-01-01

This article presents a literature review of sensors for the monitoring of benzene in ambient air and other volatile organic compounds. Combined with information provided by stakeholders, manufacturers and literature, the review considers commercially available sensors, including PID-based sensors, semiconductor (resistive gas sensors) and portable on-line measuring devices as for example sensor arrays. The bibliographic collection includes the following topics: sensor description, field of application at fixed sites, indoor and ambient air monitoring, range of concentration levels and limit of detection in air, model descriptions of the phenomena involved in the sensor detection process, gaseous interference selectivity of sensors in complex VOC matrix, validation data in lab experiments and under field conditions. PMID:28657595

Review of Portable and Low-Cost Sensors for the Ambient Air Monitoring of Benzene and Other Volatile Organic Compounds.

PubMed

Spinelle, Laurent; Gerboles, Michel; Kok, Gertjan; Persijn, Stefan; Sauerwald, Tilman

2017-06-28

This article presents a literature review of sensors for the monitoring of benzene in ambient air and other volatile organic compounds. Combined with information provided by stakeholders, manufacturers and literature, the review considers commercially available sensors, including PID-based sensors, semiconductor (resistive gas sensors) and portable on-line measuring devices as for example sensor arrays. The bibliographic collection includes the following topics: sensor description, field of application at fixed sites, indoor and ambient air monitoring, range of concentration levels and limit of detection in air, model descriptions of the phenomena involved in the sensor detection process, gaseous interference selectivity of sensors in complex VOC matrix, validation data in lab experiments and under field conditions.

Comments on airborne ISR radar utilization

NASA Astrophysics Data System (ADS)

Doerry, A. W.

2016-05-01

A sensor/payload operator for modern multi-sensor multi-mode Intelligence, Surveillance, and Reconnaissance (ISR) platforms is often confronted with a plethora of options in sensors and sensor modes. This often leads an over-worked operator to down-select to favorite sensors and modes; for example a justifiably favorite Full Motion Video (FMV) sensor at the expense of radar modes, even if radar modes can offer unique and advantageous information. At best, sensors might be used in a serial monogamous fashion with some cross-cueing. The challenge is then to increase the utilization of the radar modes in a manner attractive to the sensor/payload operator. We propose that this is best accomplished by combining sensor modes and displays into `super-modes'.

Single mode variable-sensitivity fiber optic sensors

NASA Technical Reports Server (NTRS)

Murphy, K. A.; Fogg, B. R.; Gunther, M. F.; Claus, R. O.

1992-01-01

We review spatially-weighted optical fiber sensors that filter specific vibration modes from one dimensional beams placed in clamped-free and clamped-clamped configurations. The sensitivity of the sensor is varied along the length of the fiber by tapering circular-core, dual-mode optical fibers. Selective vibration mode suppression on the order of 10 dB was obtained. We describe experimental results and propose future extensions to single mode sensor applications.

Fiber-optic instrumentation: Cryogenic sensor model description. [for measurement of conditions in cryogenic liquid propellant tanks

NASA Technical Reports Server (NTRS)

Sharma, M. M.

1979-01-01

An assessment and determination of technology requirements for developing a demonstration model to evaluate feasibility of practical cryogenic liquid level, pressure, and temperature sensors is presented. The construction of a demonstration model to measure characteristics of the selected sensor and to develop test procedures are discussed as well as the development of an appropriate electronic subsystem to operate the sensors.

Smart single-chip gas sensor microsystem

NASA Astrophysics Data System (ADS)

Hagleitner, C.; Hierlemann, A.; Lange, D.; Kummer, A.; Kerness, N.; Brand, O.; Baltes, H.

2001-11-01

Research activity in chemical gas sensing is currently directed towards the search for highly selective (bio)chemical layer materials, and to the design of arrays consisting of different partially selective sensors that permit subsequent pattern recognition and multi-component analysis. Simultaneous use of various transduction platforms has been demonstrated, and the rapid development of integrated-circuit technology has facilitated the fabrication of planar chemical sensors and sensors based on three-dimensional microelectromechanical systems. Complementary metal-oxide silicon processes have previously been used to develop gas sensors based on metal oxides and acoustic-wave-based sensor devices. Here we combine several of these developments to fabricate a smart single-chip chemical microsensor system that incorporates three different transducers (mass-sensitive, capacitive and calorimetric), all of which rely on sensitive polymeric layers to detect airborne volatile organic compounds. Full integration of the microelectronic and micromechanical components on one chip permits control and monitoring of the sensor functions, and enables on-chip signal amplification and conditioning that notably improves the overall sensor performance. The circuitry also includes analog-to-digital converters, and an on-chip interface to transmit the data to off-chip recording units. We expect that our approach will provide a basis for the further development and optimization of gas microsystems.

Surface plasmon resonance sensor for antibiotics detection based on photo-initiated polymerization molecularly imprinted array.

PubMed

Luo, Qiaohui; Yu, Neng; Shi, Chunfei; Wang, Xiaoping; Wu, Jianmin

2016-12-01

A surface plasmon resonance (SPR) sensor combined with nanoscale molecularly imprinted polymer (MIP) film as recognition element was developed for selective detection of the antibiotic ciprofloxacin (CIP). The MIP film on SPR sensor chip was prepared by in situ photo-initiated polymerization method which has the advantages of short polymerization time, controllable thickness and good uniformity. The surface wettability and thickness of MIP film on SPR sensor chip were characterized by static contact angle measurement and stylus profiler. The MIP-SPR sensor exhibited high selectivity, sensitivity and good stability for ciprofloxacin. The imprinting factors of the MIP-SPR sensor to ciprofloxacin and its structural analogue ofloxacin were 2.63 and 3.80, which is much higher than those to azithromycin, dopamine and penicillin. The SPR response had good linear relation with CIP concentration over the range 10 -11 -10 -7 molL -1 . The MIP-SPR sensor also showed good repeatability and stability during cyclic detections. On the basis of the photo-initiated polymerization method, a surface plasmon resonance imaging (SPRi) chip modified with three types of MIP sensing spots was fabricated. The MIPs-SPRi sensor shows different response patterns to ciprofloxacin and azithromycin, revealing the ability to recognize different antibiotic molecules. Copyright © 2016 Elsevier B.V. All rights reserved.

CRISM Hyperspectral Data Filtering with Application to MSL Landing Site Selection

NASA Astrophysics Data System (ADS)

Seelos, F. P.; Parente, M.; Clark, T.; Morgan, F.; Barnouin-Jha, O. S.; McGovern, A.; Murchie, S. L.; Taylor, H.

2009-12-01

We report on the development and implementation of a custom filtering procedure for Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) IR hyperspectral data that is suitable for incorporation into the CRISM Reduced Data Record (RDR) calibration pipeline. Over the course of the Mars Reconnaissance Orbiter (MRO) Primary Science Phase (PSP) and the ongoing Extended Science Phase (ESP) CRISM has operated with an IR detector temperature between ~107 K and ~127 K. This ~20 K range in operational temperature has resulted in variable data quality, with observations acquired at higher detector temperatures exhibiting a marked increase in both systematic and stochastic noise. The CRISM filtering procedure consists of two main data processing capabilities. The primary systematic noise component in CRISM IR data appears as along track or column oriented striping. This is addressed by the robust derivation and application of an inter-column ratio correction frame. The correction frame is developed through the serial evaluation of band specific column ratio statistics and so does not compromise the spectral fidelity of the image cube. The dominant CRISM IR stochastic noise components appear as isolated data spikes or column oriented segments of variable length with erroneous data values. The non-systematic noise is identified and corrected through the application of an iterative-recursive kernel modeling procedure which employs a formal statistical outlier test as the iteration control and recursion termination criterion. This allows the filtering procedure to make a statistically supported determination between high frequency (spatial/spectral) signal and high frequency noise based on the information content of a given multidimensional data kernel. The governing statistical test also allows the kernel filtering procedure to be self regulating and adaptive to the intrinsic noise level in the data. The CRISM IR filtering procedure is scheduled to be incorporated into the next augmentation of the CRISM IR calibration (version 3). The filtering algorithm will be applied to the I/F data (IF) delivered to the Planetary Data System (PDS), but the radiance on sensor data (RA) will remain unfiltered. The development of CRISM hyperspectral analysis products in support of the Mars Science Laboratory (MSL) landing site selection process has motivated the advance of CRISM-specific data processing techniques. The quantitative results of the CRISM IR filtering procedure as applied to CRISM observations acquired in support of MSL landing site selection will be presented.

Space Station racks weight and CG measurement using the rack insertion end-effector

NASA Technical Reports Server (NTRS)

Brewer, William V.

1994-01-01

The objective was to design a method to measure weight and center of gravity (C.G.) location for Space Station Modules by adding sensors to the existing Rack Insertion End Effector (RIEE). Accomplishments included alternative sensor placement schemes organized into categories. Vendors were queried for suitable sensor equipment recommendations. Inverse mathematical models for each category determine expected maximum sensor loads. Sensors are selected using these computations, yielding cost and accuracy data. Accuracy data for individual sensors are inserted into forward mathematical models to estimate the accuracy of an overall sensor scheme. Cost of the schemes can be estimated. Ease of implementation and operation are discussed.

A microcantilever-based silver ion sensor using DNA-functionalized gold nanoparticles as a mass amplifier

NASA Astrophysics Data System (ADS)

You, Juneseok; Song, Yeongjin; Park, Chanho; Jang, Kuewhan; Na, Sungsoo

2017-06-01

Silver ions have been used to sterilize many products, however, it has recently been demonstrated that silver ions can be toxic. This toxicity has been studied over many years with the lethal concentration at 10 μM. Silver ions can accumulate through the food chain, causing serious health problems in many species. Hence, there is a need for a commercially available silver ion sensor, with high detection sensitivity. In this work, we develop an ultra-sensitive silver ion sensor platform, using cytosine based DNA and gold nanoparticles as the mass amplifier. We achieve a lower detection limit for silver ions of 10 pM; this detection limit is one million times lower than the toxic concentration. Using our sensor platform we examine highly selective characteristics of other typical ions in water from natural sources. Furthermore, our sensor platform is able to detect silver ions in a real practical sample of commercially available drinking water. Our sensor platform, which we have termed a ‘MAIS’ (mass amplifier ion sensor), with a simple detection procedure, high sensitivity, selectivity and real practical applicability has shown potential as an early toxicity assessment of silver ions in the environment.

Boronic acid based imprinted electrochemical sensor for rutin recognition and detection.

PubMed

Wang, Chunlei; Wang, Qi; Zhong, Min; Kan, Xianwen

2016-10-21

Multi-walled carbon nanotubes (MWNTs) and boronic acid based molecular imprinting polymer (MIP) were successively modified on a glassy carbon electrode surface to fabricate a novel electrochemical sensor for rutin recognition and detection. 3-Aminophenylboronic acid (APBA) was chosen as a monomer for the electropolymerization of MIP film in the presence of rutin. In addition to the imprinted cavities in MIP film to complement the template molecule in shape and functional groups, the high affinity between the boronic acid group of APBA and vicinal diols of rutin also enhanced the selectivity of the sensor, which made the sensor display a good selectivity to rutin. Moreover, the modified MWNTs improved the sensitivity of the sensor for rutin detection. The mole ratios of rutin and APBA, electropolymerized scan cycles and rates, and pH value of the detection solution were optimized. Under optimal conditions, the sensor was used to detect rutin in a linear range from 4.0 × 10 -7 to 1.0 × 10 -5 mol L -1 with a detection limit of 1.1 × 10 -7 mol L -1 . The sensor has also been applied to assay rutin in tablets with satisfactory results.

Accuracy of human motion capture systems for sport applications; state-of-the-art review.

PubMed

van der Kruk, Eline; Reijne, Marco M

2018-05-09

Sport research often requires human motion capture of an athlete. It can, however, be labour-intensive and difficult to select the right system, while manufacturers report on specifications which are determined in set-ups that largely differ from sport research in terms of volume, environment and motion. The aim of this review is to assist researchers in the selection of a suitable motion capture system for their experimental set-up for sport applications. An open online platform is initiated, to support (sport)researchers in the selection of a system and to enable them to contribute and update the overview. systematic review; Method: Electronic searches in Scopus, Web of Science and Google Scholar were performed, and the reference lists of the screened articles were scrutinised to determine human motion capture systems used in academically published studies on sport analysis. An overview of 17 human motion capture systems is provided, reporting the general specifications given by the manufacturer (weight and size of the sensors, maximum capture volume, environmental feasibilities), and calibration specifications as determined in peer-reviewed studies. The accuracy of each system is plotted against the measurement range. The overview and chart can assist researchers in the selection of a suitable measurement system. To increase the robustness of the database and to keep up with technological developments, we encourage researchers to perform an accuracy test prior to their experiment and to add to the chart and the system overview (online, open access).

M13 Bacteriophage/Silver Nanowire Surface-Enhanced Raman Scattering Sensor for Sensitive and Selective Pesticide Detection.

PubMed

Koh, Eun Hye; Mun, ChaeWon; Kim, ChunTae; Park, Sung-Gyu; Choi, Eun Jung; Kim, Sun Ho; Dang, Jaejeung; Choo, Jaebum; Oh, Jin-Woo; Kim, Dong-Ho; Jung, Ho Sang

2018-03-28

A surface-enhanced Raman scattering (SERS) sensor comprising silver nanowires (AgNWs) and genetically engineered M13 bacteriophages expressing a tryptophan-histidine-tryptophan (WHW) peptide sequence (BPWHW) was fabricated by simple mixing of BPWHW and AgNW solutions, followed by vacuum filtration onto a glass-fiber filter paper (GFFP) membrane. The AgNWs stacked on the GFFP formed a high density of SERS-active hot spots at the points of nanowire intersections, and the surface-coated BPWHW functioned as a bioreceptor for selective pesticide detection. The BPWHW-functionalized AgNW (BPWHW/AgNW) sensor was characterized by scanning electron microscopy, confocal scanning fluorescence microscopy, atomic force microscopy, and Fourier transform infrared spectroscopy. The Raman signal enhancement and the selective pesticide SERS detection properties of the BPWHW/AgNW sensor were investigated in the presence of control substrates such as wild-type M13 bacteriophage-decorated AgNWs (BPWT/AgNW) and undecorated AgNWs (AgNW). The BPWHW/AgNW sensor exhibited a significantly higher capture capability for pesticides, especially paraquat (PQ), than the control SERS substrates, and it also showed a relatively higher selectivity for PQ than for other bipyridylium pesticides such as diquat and difenzoquat. Furthermore, as a field application test, PQ was detected on the surface of PQ-pretreated apple peels, and the results demonstrated the feasibility of using a paper-based SERS substrate for on-site residual pesticide detection. The developed M13 bacteriophage-functionalized AgNW SERS sensor might be applicable for the detection of various pesticides and chemicals through modification of the M13 bacteriophage surface peptide sequence.

Sequestering ability to Cu2+ of a new bodipy-based dye and its behavior as in vitro fluorescent sensor.

PubMed

Papalia, Teresa; Barattucci, Anna; Barreca, Davide; Bellocco, Ersilia; Bonaccorsi, Paola; Minuti, Lucio; Nicolò, Marco Sebastiano; Temperini, Andrea; Foti, Claudia

2017-02-01

A Bodipy (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) derivative has been conceived and synthesized starting from l-aspartic acid, as a selective turn-off sensor of Cu 2+ ions. Its acid-base properties were determined to study the formation of metal/sensor complex species by titration of solutions each containing a different metal ion, such as Cu 2+ , Ca 2+ , Zn 2+ , Pb 2+ and Hg 2+ and different metal/sensor ratios. The speciation models allowed us to simulate the distribution of the metal/sensor complex species at the normal concentrations of the corresponding metals present in biological fluids. The distribution diagrams, obtained by varying the concentration of sensor 1, clearly indicate that sensor 1 responds selectively to Cu 2+ at micromolar concentrations, even in the presence of other more abundant metal cations Ca 2+ . Finally, we analyzed the cellular uptake of sensor 1 on human erythrocytes and its ability to chelate Cu 2+ in the cellular environment. Results indicate that it crosses the plasmatic membrane and colors the cells of a bright fluorescent red. Exposing the fluorescent cells to Cu 2+ results in a complete cellular photobleaching of the red fluorescence, indicating that sensor 1 is able to detect metal changes in the cytosolic environment. Copyright © 2016 Elsevier Inc. All rights reserved.

Satellite sensor requirements for monitoring essential biodiversity variables of coastal ecosystems

EPA Science Inventory

The biodiversity and high productivity of coastal terrestrial and aquatic habitats are the foundation for important benefits to human societies around the world. These globally distributed habitats need frequent and broad systematic assessments, but field surveys only cover a sma...

Application of a taste evaluation system to the monitoring of Kimchi fermentation.

PubMed

Kim, Namsoo; Park, Kyung-Rim; Park, In-Seon; Cho, Yong-Jin; Bae, Young Min

2005-05-15

As an objective method, taste evaluation with an instrument is able to supplement the subjective sensory evaluation and to be applied to the optimization of food processing. Kimchi, a Korean traditional pickle fermented with lactic acid bacteria, is expanding its consumption worldwide. The fermentation control of it has been routinely done by measuring titratable acidity and pH. In this study, an eight-channel taste evaluation system was prepared, followed by an application to the monitoring of Kimchi fermentation. Eight polymer membranes which individually responded to cationic or anionic substances were prepared by mixing electroactive materials such as tri-n-octylmethylammonium chloride, bis(2-ethylhexyl)sebacate as the plasticizer and polyvinyl chloride in the ratio of 1:66:33. Each membrane prepared was separately installed onto the sensitive area of an ion-selective electrode to produce the respective taste sensor. The eight-channel sensor array and a double junction reference electrode were connected to a 16-channel high input impedance amplifier. The amplified sensor signals were stored to a personal computer via a multi-channel A/D converter. Two sensor groups composed of the cation-selective and anion-selective polymer membrane electrodes showed characteristic concentration-dependency to various artificial taste substances. As a whole, the response potentials of the sensor array increased during the fermentation period at 4, 10 and 25 degrees C. Even the response potentials of the anion-selective taste sensors slightly increased possibly due to the protonation of anions by liberated H+ ions, thereby leading to a decrease in the anion concentration. When the signal data were interpreted by principal component analysis (PCA), the first PC at 4 degrees C explained most of the total data variance. A close correlation was found between the values of titratable acidity and the first PC, which indicated a possible applicability of the multi-channel taste sensor of this study to the process monitoring of various pickle.

Microcontact imprinted quartz crystal microbalance nanosensor for protein C recognition.

PubMed

Bakhshpour, Monireh; Özgür, Erdoğan; Bereli, Nilay; Denizli, Adil

2017-03-01

Detection of protein C (PC) in human serum was performed by quartz crystal microbalance (QCM) based on molecular imprinting technique (MIP). The high-resolution and mass-sensitive QCM based sensor was integrated with high sensitivity and selectivity of the MIP technique. The PC microcontact imprinted (PC-μCIP) nanofilm was prepared on the glass surface. Then, the PC-μCIP/QCM sensor was prepared with 2-hydroxyethyl methacrylate (HEMA), ethylene glycol dimethacrylate (EGDMA) and N-methacryloyl l-histidine methylester (MAH) as the functional monomer with copper(II) ions. The polymerization was performed under UV light (100W and 365nm) for 20-25min under nitrogen atmosphere. The characterization studies of QCM sensor were done by observation using atomic force microscopy (AFM), contact angle measurements, ellipsometry and fourier transform infrared spectroscopy (FTIR). Detection of PC was investigated in a concentration range of 0.1-30μg/mL. Selectivity of PC-μCIP and PC non-imprinted/QCM (PC-non-μCIP) sensors for PC determination was investigated by using proteins namely hemoglobin (Hb), human serum albumin (HSA) and fibrinogen solutions. QCM sensor was also used for detection of PC molecules in aqueous solutions and human plasma. The detection limit was determined as 0.01μg/mL for PC analysis. The PC-μCIP/QCM sensor was used for five consecutive adsorption-desorption cycles. According to the results, the PC-μCIP/QCM sensor had obtained high selectivity and sensitivity for detection of PC molecules. Copyright © 2016 Elsevier B.V. All rights reserved.