Modeling and Numerical Characterization of High Sensitive Microcantilever Biosensors with Parabolic Piezoresistor

Abstract

The biaxial and planar characteristics of surface stress produce a parabolic differential stress distribution inside the sensing zone of microcantilever biosensors, which can be used to design novel biosensors. The present work studies and compares the effect of parabolic and conventional rectangular-shaped piezoresistor placed inside this sensing zone on sensitivity of the biosensors. Two different cantilevers made of silicon and silicon dioxide with doped silicon as piezoresistor are used in five design variations. The cantilevers are characterized for their deflections, von Mises stresses, resonant frequencies and self-heating temperatures produced using ANSYS. Analytical models for predicting deflections in the cantilevers is presented and compared with numerical results obtained. Results show good compatibility between analytical and numerical values for deflection with a 4–5% average deviation and that parabolic designs have higher sensitivity.