WIRELESS AND BATTERYLESS SURFACE ACOUSTIC WAVE SENSORS FOR HIGH TEMPERATURE ENVIRONMENTS

International audienceSurface acoustic wave (SAW) devices are widely used as filter, resonator or delay line in electronic systems in a wide range of applications: mobile communication, TVs, radar, stable resonator for clock generation, etc. The resonance frequency and the delay line of SAW devices are depending on the properties of materials forming the device and could be very sensitive to the physical parameters of the environment. Since SAW devices are more and more used as sensor for a large variety of area: gas, pressure, force, temperature, strain, radiation, etc. The sensors based SAW present the advantage to be passive (batteryless) and/or wireless. These interesting properties combined with a small size, a low cost radio request system and a small antennas when operating at high frequency, offer new and exiting perspectives for wireless measurement processes and IDTAG applications. When the materials constituting the devices are properly selected, it becomes possible to use those sensors without embedded electronic in hostile environments (as high temperature, nuclear site, …) where no solutions are currently used. General principle of the SAW sensor in wired and wireless configurations will be developed and a review of recent works concerning the field of high temperature applications will be presented with specific attention given to the choice of materials constituting the SAW device

A Simplified Spice Model for IGBT

A simplified IGBT (Insulated Gate Bipolar Transistor) SPICE macromodel, based on its equivalent circuit, is proposed. This macromodel is provided to simulate various mechanisms governing the behavior of the IGBT, and it takes into account specific phenomena limiting its SOA (Safe Operating Area), such as forward and reverse biased SOA, as well as latch-up. The validity of this model is confirmed by comparison between simulation and experimental results as well as the data sheets. This comparison is tested for two IGBT devices showing two different powers and switching speeds, and a good agreement is recorded for both IGBT devices

Elaboration of a Novel Design Pirani Pressure Sensor for High Dynamic Range Operation and Fast Response Time

AbstractWe report a novel design for realizing Pirani sensor with a working range from a 1kPa up to pressure over than atmospheric one. The sensor is specifically designed to achieve high sensitivity, fast response time and high robustness. The proof of concept is composed of four metallic resistors interconnected to form a Wheatstone bridge. Two of them act simultaneously as the heating and sensing elements and the two others are used as a temperature reference. The heating element consists of a metallic wire of platinum Pt (3μm width, 1mm length) maintained on each lateral side by periodic silicon oxide SiO2 micro-bridges. The sensor design, fabrication technologies, electrical characterizations and voltage-pressure responses are described and shown. A future perspective is given, which describe the extension of this concept to elastic wave transduction of pressure using a combination of heater element and thin plate elastic waveguide

High-temperature SAW electrodes based on Ir-Rh thin films

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PANI/ZnO/Quartz structure for Love wave gas sensor

Everyone knows the importance of sensors in our society and the huge attempt to improve their properties in order to obtain better sensitivity and selectivity. In this paper, we are more particularly focused on gas sensors based on surface acoustic waves (SAW) device. In a previous work, we have developed and studied a structure composed of a 90° rotated ST quartz crystal covered with a ZnO layer. By developing inter-digital transducers (IDT) on this structure, we can generate different types of acoustic waves. Love waves which are confined near the surface are known to be very sensitives to fluids (liquids or gases). The aim of this work is to present the way we have developed this optimal structure and to test it with a specific polymer. This polymer is polyaniline (PANI). Its main advantage is that it should be deposited by cold pulsed plasma process

Investigations on nitrogen addition in the CH4-H2 gas mixture used for fiamond deposition for a better understanding and the optimisation of the synthesis process.

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