Temperature compensation in CNT-composite distributed strain sensors

A temperature compensation method is proposed for CNT-composite strain sensors. CNT-composite sensors are fabricated on an elastic polymer substrate having known thermo-mechanical properties to introduce thermo-mechanical strain and further calibration of the sensor. Strain is induced on the sensor by bending the substrate as a cantilever configuration. Response of the sensor is measured using a bridge circuit method. Induced strain in the beam is determined using beam theory. The sensors are characterized for different CNT concentrations and at various temperatures. A model based temperature compensation scheme is proposed and verified experimentally. The result proves the ability of CNT-nanocomposite strain sensors to be used under varying temperature applications. A method is proposed to determine the strain and temperature simultaneously. The CNT sensors are simple to fabricate in complex patterns with excellent repeatability and do not require bonding layer.

Suspended core-shell Pt-PtOx nanostructure for ultrasensitive hydrogen gas sensor

High sensitivity gas sensors are typically realized using metal catalysts and nanostructured materials, utilizing non-conventional synthesis and processing techniques, incompatible with on-chip integration of sensor arrays. In this work, we report a new device architecture, suspended core-shell Pt-PtOx nanostructure that is fully CMOS-compatible. The device consists of a metal gate core, embedded within a partially suspended semiconductor shell with source and drain contacts in the anchored region. The reduced work function in suspended region, coupled with builtin electric field of metal-semiconductor junction, enables the modulation of drain current, due to room temperature Redox reactions on exposure to gas. The device architecture is validated using Pt-PtO2 suspended nanostructure for sensing H-2 down to 200 ppb under room temperature. By exploiting catalytic activity of PtO2, in conjunction with its p-type semiconducting behavior, we demonstrate about two orders of magnitude improvement in sensitivity and limit of detection, compared to the sensors reported in recent literature. Pt thin film, deposited on SiO2, is lithographically patterned and converted into suspended Pt-PtO2 sensor, in a single step isotropic SiO2 etching. An optimum design space for the sensor is elucidated with the initial Pt film thickness ranging between 10 nm and 30 nm, for low power (< 5 mu W), room temperature operation. (C) 2015 AIP Publishing LLC.

Accurate Indoor Positioning of Firefighters using Dual Foot-mounted Inertial Sensors and Inter-agent Ranging

A real-time cooperative localization system, utilizing dual foot-mounted low-cost inertial sensors and RF-based inter-agent ranging, has been developed. Scenario-based tests have been performed, using fully-equipped firefighters mimicking a search operation in a partly smoke-filled environment, to evaluate the performance of the TOR (Tactical lOcatoR) system. The performed tests included realistic firefighter movements and inter-agent distances, factors that are crucial in order to provide realistic evaluations of the expected performance in real-world operations. The tests indicate that the TOR system may be able to provide a position accuracy of approximately two to three meters during realistic firefighter operations, with only two smoke diving firefighters and one supervising firefighter within range.

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

One of the most interesting predicted applications of graphenemonolayer-based devices is as high-quality sensors. In this article, we show, through systematic experiments, a chemical vapor sensor based on the measurement of lowfrequency 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-densityfluctuation-based model to explain the superior characteristics of a noisemeasurement-based detection scheme presented in this article.

Part II: A Fully Integrated RF PA in 28-nm CMOS With Device Design for Optimized Performance and ESD Robustness

In this paper, we report drain-extended MOS device design guidelines for the RF power amplifier (RF PA) applications. A complete RF PA circuit in a 28-nm CMOS technology node with the matching and biasing network is used as a test vehicle to validate the RF performance improvement by a systematic device design. A complete RF PA with 0.16-W/mm power density is reported experimentally. By simultaneous improvement of device-circuit performance, 45% improvement in the circuit RF power gain, 25% improvement in the power-added efficiency at 1-GHz frequency, and 5x improvement in the electrostatic discharge robustness are reported experimentally.

pi-Electron rich small molecule sensors for the recognition of nitroaromatics

Selective and discriminative detection of -NO2 containing high energy organic compounds such as picric acid (PA), 2,4,6-trinitrotoluene (TNT) and dinitrotoluene (DNT) has become a challenging task due to concerns over national security, criminal investigations and environment protections. Among various known detection methods, fluorescence techniques have gained special attention in recent time. A wide variety of fluorescent chemosensors have been developed for nitroaromatic explosive detection. In this review article, we provide an overview of the recent developments made in small molecule-based turn-off fluorescent sensors for nitroaromatic explosives with special focus on organic and H-bonded supramolecular sensors. The fluorescent sensors discussed in this review are classified and organized according to their functionality and their recognition of nitroaromatics by fluorescence quenching.

Cadmium Sulfide Nanocrystal Sensitized Vertically Aligned Titanium Dioxide Rods for Large Area Image Sensors on 3-D Substrates

We discuss here a semiconductors assembly comprising of titanium dioxide (TiO2) rods sensitized by cadmium sulfide (CdS) nanocrystals for potential applications in large area electronics on three dimensional (3-D) substrates. Vertically aligned TiO2 rods are grown on a substrate using a 150 degrees C process flow and then sensitized with CdS by SILAR method at room temperature. This structure forms an effective photoconductor as the photo-generated electrons are rapidly removed from the CdS via the TiO2 thereby permitting a hole rich CdS. Current-voltage characteristics are measured and models illustrate space charge limited photo-current as the mechanism of charge transport at moderate voltage bias. The stable assembly and high speed are achieved. The frequency response with a loading of 10 pF and 9 M Omega shows a half power frequency of 100 Hz. (C) 2015 The Electrochemical Society. All rights reserved.

SYNTHESIS OF CONCEPTUAL DESIGNS FOR SENSORS USING SAPPHIRE-LITE

The demand for variety of products and the shorter time to market is encouraging designers to adopt computer aided concept generation techniques. One such technique is being explored here. The present work makes an attempt towards synthesis of concepts for sensors using physical laws and effects as building blocks. A database of building blocks based upon the SAPPhIRE-lite model of causality is maintained. It uses composition to explore the solution space. The algorithm has been implemented in a web based tool. The tool generates two types of sensor designs: direct sensing designs and feedback sensing designs. According to the literature, synthesis using building blocks often lead to vague solutions principles. The current work tries to avoid uninteresting solutions by using some heuristics. A particularly novel outcome of the work described here is the generation of feedback based solutions, something not generated automatically before. A number of patent violations were observed with the set of generated concepts; thus emphasizing some amount of novelty in the designs.

Studies on Carbon Mediated Paste Screen Printed Sensors for Blood Glucose Sensing Application

Ready-to-use screen printed glucose sensors are fabricated using Prussian Blue (PB) and Cobalt Phthalocyanine (CoPC) mediated carbon inks as working electrodes. The reference and counter electrodes are screen printed using silver/silver chloride and graphitic carbon paste respectively. The screen printed reference electrodes (internal reference electrode (IRE)) are found to be stable for more than 60 minutes when examined with saturated calomel electrode. Optimal operating voltage for PB and CoPC screen printed sensors are determined by hydrodynamic voltammetric technique. Glucose oxidase is immobilized on the working electrodes by cross-linking method. PB mediated glucose sensor exhibits a sensitivity of 5.60 mA cm(-2)/mM for the range, 10 to 1000 mu M. Sensitivity of CoPC mediated glucose sensor is found to be 5.224 mu A cm(-2)/mM and amperometeric response is linear for the range, 100 to 1500 mu M. Interference studies on the fabricated glucose sensors are conducted with species like uric acid and ascorbic acid. PB mediated sensors showed a completely interference-free behavior. The sensing characteristics of PB mediated glucose sensors are also studied in diluted human serum samples and the results are compared with the values obtained through standard clinical method. The co-efficient of variation is found to be less than 5%. (C) 2015 The Electrochemical Society. All rights reserved.