Novel MOSFET Based Pressure Sensor That Uses Combined Channel Piezoresistance and Gate Capacitance Effects

The paper considers modeling and analysis of a square and circular diaphragm Suspended Gate MOSFET based pressure sensor using COMSOL Multiphysics. Two structures, one a square with an n-channel MOSFET at the center and the second a circle with a p-channel MOSFET at the edge of the diaphragm were simulated. The piezoresistance effect of the channel and capacitance variation due to the suspended gate have been exploited in designing the sensor. The combined effect of the two has not been reported in literature so far and this is the first attempt at combining the two effects for transduction. Channel is modelled separately as an equivalent piezoresistor and the capacitance variation is also simulated in COMSOL. The MOSFET characteristics in the unstrained and strained conditions are modelled using COMSOL and MATLAB. The MOSFETs are operated in their linear region. This novel MOSFET design has a promising application and has a better sensitivity compared to MOSFET exploiting a single effect or a similar piezoresistive or capacitive sensor.