Design and Finite Element Analysis of Piezoresistive Cantilever with Stress Concentration Holes

We present a design and finite element analysis for piezoresistive cantilever sensor with stress concentration holes. As the magnitude of the forces involved is very small, increasing the sensitivity of the microcantilever sensors involved is a priority. In this paper we are considering to achieve this by structural variation of the cantilevers. Firstly the stress distributions and the vertical displacements of the designed cantilevers were simulated through ANSYS analyzing system. A paddle type cantilever with different number of holes modeled and simulated. The placement of the holes was found to be critical and results in improvements of piezoresistive displacement and force sensitivity, respectively. Then the relative resistance changes of the piezoresistors as a function of the cantilever vertical displacements were measured. As expected, the stresses are concentrated around the holes, which are higher than that of rectangular cantilevers under the same design and simulation parameters.