Simulation of a Highly Sensitive Piezoresistive Differential Pressure Microsensor

In this paper, a highly sensitive piezoresistive differential pressure microsensor is proposed. This microsensor is consisted of a silicon microcantilever (Length=145 µm; Width=100 µm; Thickness=0.29 µm) and two piezoresistors were mounted (via proper connections) on the microsensor for measuring the created pressure difference. Applying pressure to the microcantilever induces longitudinal and transverse stresses in the piezoresistors, changing their electric resistance and, consequently, the output voltage in the reading circuit of the microsensor. Longitudinal and transverse stresses, different relative sensor resistances resulting from different pressures, voltage variations along the piezoresistors, and microcantilever deflection resulting from different pressures were investigated. To improve the sensor sensitivity, effect of doping concentration, piezoresistors width, and the width of the structure placed under the piezoresistors were studied. In addition, we studied how increasing the width and length of the beam influenced the sensitivity of the sensor. Based on analysis results, the sensor sensitivity was increased from 0.26 W/Pa to 15.78 W/Pa (~60 times). To evaluate the behavior and performance of the proposed microsensor, the following characteristics were analyzed: maximum microcantilever displacement, von Mises stress distribution along the beam and microsensor resistance variations.