Temperature Dependence Of Output Research Articles

Датчик гидростатического давления на основе микрокристаллов антимонида галлия

Currently, silicon and germanium, the most common materials in the production of discrete semiconductor devices and integrated circuits, do not always meet all the requirements to the sensing elements of mechanical quantities sensors. Therefore, it is logical to research the properties of other semiconductor materials that could be used as sensing elements in such sensors. A3B5 semiconductor compounds seem promising for such purpose. Effect of hydrostatic pressure up to 5000 bar on the resistance of n-type antimonide gallium whiskers doped by Se or Te was studied. Coefficient of hydrostatic pressure for this crystals was determined, it equals Kh = (16,5—20,0)•10–5 bar–1 at 20°N. Temperature dependence of resistance and coefficient Kh for this crystals in the temperature range ±60°N was studied. Design of the developed hydrostatic pressure sensor based on GaSb whiskers and its characteristics are presented. The possibility to decrease the temperature dependence of sensitive element resistance by mounting GaSb whiskers on the substrates fabricated from materials with different temperature coefficient of expansion was examined. It was shown that mounting of GaSb crystals on Cu substrate gives the optimal result, in this case the temperature coefficient decrease to 0,05%•°N–1, that leads to decrease of output temperature dependence. The main advantages of developed pressure sensor are: the simplified design in comparison with pressure sensors with strain gauges mounted on spring elements; the high sensitivity to pressure that is constant in the wide pressure range; the improvement of sensors metrological characteristics owing to hysteresis absence. The possible application fields of developed sensors are measuring of high and extremely high pressure, chemical and oil industries, measuring of pressure in oil bore-holes, investigation of explosive processes.

In situ High Temperature Heat Flux Sensor Calibration

Recent advances in heat flux measurement have resulted in the development of a robust thermopile heat flux sensor intended for use in extreme thermal environments. The High Temperature Heat Flux Sensor (HTHFS) is capable of simultaneously measuring thermopile surface temperature and heat flux at sensor temperatures up to 1000 °C. The need for high temperature heat flux calibration of the HTHFS has resulted in the development of a new wide angle radiation calibration system, which operates with the sensor at elevated temperatures. The temperature dependence of the sensor output over the range of 100–900 °C has been successfully characterized with acceptable uncertainty limits. The calibrated HTHFS sensitivity agrees well with a theoretical sensitivity model, suggesting that the primary cause for the sensor’s output temperature dependence is due to the change in thermal conductivity of the sensor elements with temperature.

Comparison of IR LED gas sensors with thermal source products

Physical principles for infrared gas sensing using LEDs as sources are examined. A number of LEDs from different sources are compared for power output, polar diagram and temperature dependence of output. Some of these have been incorporated in a practical gas sensor based on the Edinburgh Sensors' Gascard. Thus a direct comparison of signal levels between thermal sources and LEDs has been made using thermal detectors. Gas sensing is demonstrated for CO/sub 2/. The paper describes the ranges, accuracies and stability with time and temperature presently exhibited by thermal source sensors and suggests criteria for the widespread use of LED sensors. Some advanced concepts are mentioned with respect to future sensing requirements.