Modeling of Temperature Effects on Micromachined Silicon Thermal Wind Sensors

A 2-D micromachined silicon thermal wind sensor measures wind speed and direction by monitoring temperature differences induced by an airflow that passes along the substrate surface. When ambient temperature changes, however, the temperature drift of the sensor will lead to incorrect output values. By examining the thermophysical properties of the airflow, substrate, and temperature sensitive element, this paper has developed a closed-form semi-empirical model to understand the physical origins of temperature drift in the 2-D micromachined silicon thermal wind sensor. Using the model, the temperature drift can easily be compensated by directly extracting two empirical parameters from the uncompensated sensor output. Experiments presented here show that the temperature compensated sensor is working well in a temperature range between -20 °C and 40 °C with the relative error being less than ±3.5%.