Improving sensitivity of piezoresistive microcantilever biosensors using stress concentration region designs

To improve the surface-stress sensitivity of piezoresistive microcantilever biosensors, this study presents cantilever designs with circular, square and triangular stress concentration regions (SCRs). The cantilever substrates are made of silicon and silicon dioxide and the piezoresistor is p-doped silicon. The cantilevers are characterized using FEM software for their surface-stress sensitivity and thermal vulnerability by applying surface stress, temperature and bias voltage loads. A relation for the surface-stress sensitivity of a silicon cantilever is also presented. Results show that use of SCRs in a silicon cantilever can improve its sensitivity by up to 55% and that a square SCR is the most suitable design to improve the overall sensitivity. (Some figures may appear in colour only in the online journal)