In order to create more sensitive and accurate gas sensors, we have studied the interactions of gas mixtures on metal oxide nanoparticle decorated porous silicon interfaces. The nanoparticles control the magnitude and direction of electron transduction from the interaction of analyte gases to an extrinsic porous silicon semiconductor. These interactions can be predicted by the Inverse Hard Soft Acid Base (IHSAB) principle. Moreover, the metal oxide nanoparticles can be functionalized with nitrogen and sulfur, modifying the oxide’s band structure. These modifications are demonstrated to change analyte interactions in line with the IHSAB concept and allow for light enhanced sensors. Further we looked at how the analyte gases interact with other analyte gases on the surface of these sensors. Studying these systems does two things, first the research will lead to cheaper, more accurate gas sensors, and second it helps explore the role of nanoparticles in modifying the interactions between bulk materials (porous silicon) and molecules (analyte gases).

International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / The Army development and test community must demonstrate the functionality and reliability of gun-launched projectiles and munitions systems, especially newer smart munitions. The best method to satisfy this requirement is to combine existing optical and tracking systems data with internal data measured with on-board instrumentation (i.e. spin, pitch, and yaw measurements for standard items and terminal sensor, signal processor, and guidance/navigation system monitoring for smart munitions). Acquisition of internal data is usually limited by available space, harsh launch environments, and high associated costs. A technology development and demonstration effort is underway to provide a new generation of products for use in this high-g arena. This paper describes the goals, objectives, and progress of the Hardened Subminiature Telemetry and Sensor System (HSTSS) program.

This thesis presents two interface circuits for impedimetric chemical sensors: one for passive chemical sensors and the other for ChemFETs. Both interfaces were fabricated in 0.35μm BiCMOS technology and provide the same output data rate of 1Hz. The interface for passive impedimetric sensors is reconfigurable for performing either resistance or capacitance measurements and provides a fully digital output with less than 81.8μW power consumption at VDD = 2.5V. The interface features a 176dB resistance dynamic range (31.6Ω-200MΩ, <±0.8% nonlinearity, and >40dB SNR) realized with only two sub-ranges to minimize calibration efforts and a 102dB capacitance dynamic range (0.8-1000pF, <±0.2% nonlinearity, and >40dB SNR). The ChemFET interface is a highly versatile system that can generate a wide range of bias voltages (VG up to 9.74V and VD up to 16.3V depending on the measurement modes) and perform either constant voltage or constant current mode measurement. At maximum rated output (VG = 9.74V, VD = 16.3V, and IDS = 15μA), the interface consumes only 2.02μW at VDD = 3.3V and provides analog readout noise levels of 0.0476μARMS at 10μA and 0.503mVRMS for IDS and VT, respectively. Besides attempting versatile system architectures, detailed noise and efficiency analysis were performed for the passive sensor interface and the ChemFET interface, respectively. The noise analysis suggests that different types of noise (correlated or uncorrelated) dominate the noise performance in different measurement ranges and, thus, noise suppression techniques, such as chopper stabilization, correlated double sampling (CDS), and oversampling/averaging, are applied to adequate parts of the interface system. The efficiency analysis of the boost capacitor charger in the ChemFET interface concludes that applying a moderate pulsewidth (200-300ns) to drive the boost converter yields the best efficiencies for charging a capacitor. Compared to interfaces described in the literature, the proposed interface for passive sensors achieves better versatility and wide dynamic range with less number of sub-ranges and power consumption. The proposed interface for ChemFETs achieves wider voltage supply range at very low power level. In-house fabricated chemical sensors, including passive chemical sensors and ChemFETs, were interfaced with the developed circuits and gas-phase chemical measurements with the systems were demonstrated. The novel passive chemical sensor tested in this thesis employs a multi-functional design, which can be configured into either a chemoresistor or a chemocapacitor; the tested ChemFET employs a bottom-gate TFT structure to allow the semiconducting film to interact with the analytes.

The philosophy of research at the University of Texas – Robotics Research Group (RRG) is towards creating a foundation for an open architecture, reconfigurable intelligent machines to meet wide breadth of operational needs. An intelligent system is the one which has complete knowledge of its operating characteristics at all times (updated in real-time) and it can make on-the-fly decisions to adapt itself to the different conditions or present the best possible options to the human decision maker under specified and ranked criteria. The reality of all complex system is that they are inherently non-linear with coupled parameters. The traditional approach dealing with such systems assumes linearized models, imposing conservative bounds on the operational domain and thus limiting performance capability of the system. Recent advancements in sensor technology and availability of computational resources (embedded processing) at low cost have made real-time intelligent control feasible for complex systems. The computational intelligence envisioned in modern intelligent machines will enhance the system performance and will provide capabilities such as criteria based control, identification of incipient faults, condition based maintenance, fault tolerance, and ability to monitor performance parameters in real-time. The first step in this process is to equip a system with a comprehensive suite of sensors. These sensors will provide real-time data and awareness about both, the internal system states and the external/environmental operating conditions. The aim of this work is to establish an argument in favor of using multiple sensors in all complex electro-mechanical systems. The report discusses numerous benefits of a multi-sensor environment with suitable examples and attempts to justify its pressing need in all the existing complex mechanical systems. Case studies for a multi-sensor environment in railroad freight cars and vehicle systems are presented. Sensing requirements in freight train and vehicle systems are evaluated and suitable sensor technology and commercial sensor options are suggested for decision makers. In addition to benefits, challenges in a multi-sensor environment such as sensor noise, cabling complexities, signal processing, communication, data validation and data management, sensor fusion, information integration, maintenance etc. are addressed and best practices to alleviate these complexities are discussed in the report. This effort lays out a foundation for developing a multi-sensor system and will enable computational intelligence and structured decision making in the system. / text

This thesis presents an investigation into the application of electrodynamic sensors to a tornographic imaging system. Several sensing mechanisms for measurement using non-intrusive techniques are discussed and their relevance to pneumatic conveying considered. Electrical charge tomography systems are shown to be worthy of investigation. Electrodynamic sensors are inherently low cost and simple in concept. This sensor is used to detect the inherent charge on dry, moving solids. Models are developed to predict the sensitivity of circular and rectangular electrodes. The spatial filtering effect of these sensors is investigated. Cross correlation is briefly reviewed and a software program is presented and tested. For tomographic imaging the forward problem for the individual sensors is modelled, used to solve the inverse problem and derive the linear back projection and filtered back projection algorithms. The design of the electronic circuitry which forms the transducer is presented. The gravity drop flow rig is described and the relationship between sand flow and plastic bead flow relative to the flow indicator setting determined. The dual 16-channel sensor array measurement section is described. Flow models are developed and used to predict the relative output voltage profiles expected from the sensor arrays. The linearity and frequency bandwidth of the sensor electronics is measured. The effect of sensor size on sensitivity and spatial filtering are investigated for circular and rectangular electrodes. Estimates of the solid concentration of flowing particles are made using individual sensors. Concentration profiles are generated and compared with predicted values. Peripheral velocities of the flowing material are determined from transit times calculated by cross correlation of upstream and downstream sensor signals. Concentration profiles are calculated using linear back projection and filtered back projection algorithms from data measured by the sensor arrays. Velocity profiles are obtained by cross correlation of upstream and downstream pixel concentration values. Estimates of the mass flow rate are obtained by combining concentration and velocity profiles. Suggestions for further work on electrodynamic sensors and tomographic measurements are made.

No description available.

No description available.

No description available.

No description available.

No description available.