Development of a MEMS-based barometric pressure sensor for micro air vehicle (MAV) altitude measurement

A pressure sensor can be used for altimetry as pressure varies with altitude. In this work, a MEMS-based bulk-micromachined piezoresistive pressure sensor is developed for micro air vehicle (MAV) application. The sensor chip has meander shaped diffused piezoresistors, placed at optimum locations determined using FEM simulations for enhancing sensitivity. Post process wet bulk micromachining is carried out to realize the sensor diaphragm, while protecting the processed wafer side. Excellent sensitivity, non-linearity and hysteresis of 34.78 mV/bar, < 0.12% and < 0.2%, respectively is obtained from static characterization of optimum sensor chip. For the operating altitude range of the MAV, the variation of output voltage of pressure sensor module (obtained by integrating the sensor chip with circuitry) with altitude is characterized inside a test chamber.