Performance comparison of a single element piezoresistor with a half-active Wheatstone bridge for miniaturized pressure sensors

In recent years, miniaturized piezoresistive pressure sensors have been extensively explored, especially for biomedical applications. Typically, the electromechanical transduction of a measurand into an equivalent electrical signal is accomplished by a fully active Wheatstone bridge (WSB). Even though, a fully active WSB has advantages in terms of improved sensitivity and noise cancellation, still it suffers from a major limitation in terms of area, especially for applications like cardiac catheters that demand ultra-miniaturized pressure sensors. Hence for miniaturized sensor design, half-active WSB or single element piezoresistor is deployed by various researchers. In this paper, performance of a single element piezoresistor (3TP-1) is compared with a half-active WSB configuration and other single element piezoresistors such as four terminal piezoresistor (4TP), multi-terminal piezoresistor (MTP) and another three terminal piezoresistor (3TP-2) for area constrained applications. Investigation of the 3TP-1 is carried out by using a finite element method (FEM) based numerical simulation tool IntelliSuite® (version 8.7). Simulation results show that compared to a half-active WSB, the 3TP-1 has 35% better performance in terms of output voltage. Furthermore, it is found that compared to other single element piezoresistors, the 3TP-1 is more suited for realizing ultra-miniaturized pressure sensors both in terms of area and performance.