Design and simulation of low pressure piezoresistive NEMS sensor using analytical models for biomedical applications

Pressure micro sensors are designed to operate in linear range and presently the most widely used devices are micro electromechanical systems (MEMS) sensors and have gained popularity in biomedical applications, automotive and avionics Industries. Nano electomechanical systems (NEMS) sensors form the next miniaturization step for MEMS sensors and are expected to have better performance and lower cost. Due to further miniaturization, NEMS sensor find important application in biomedical field for invasive pressure measurements like intra-cranial pressure, arterial blood pressure monitoring, central venous pressure monitoring etc. In present work also a low pressure square diaphragm piezoresistive NEMS sensor of diaphragm length 1500 nm and thickness 100 nm (aspect ratio (h/L=0.07)) respectively has been designed using the analytical models for NEMS pressure sensors. The designed sensor has been characterized through FEM simulation using MEMS CAD software tools and the analytical and simulation results have been found to be in good agreement. Also, the finite element method simulation has been used to calculate maximum stress location which is useful for placement of piezoresistive sensing element at high stress region necessary to get maximum output. The analytical and simulation results show that the designed sensor has full scale output (FSO) of 0.16mV/V and is linear in its operating range of 5kPa pressure. This work may be potentially useful for piezoresistive pressure sensor designers and researchers.