On the Temperature Compensation of Parallel Piezoresistive Microcantilevers in Biosensors

Microcantilever with embedded piezoresistor has been applied to in-situ surface stress measurement of biochemical reaction, where parallel microcantilever design by using an active cantilever for biosensing and another reference cantilever for noise cancellation has previously been proposed. This paper shows that the measurement is sensitive to the temperature effect induced by the piezoresistor. The temperature difference between the two cantilevers can reach 40°C at 10V operation because of their difference thermal capacitance. For the microcantilever of 125×65×0.75 μm, the offset voltage of the parallel microcantilever is 1.65 mV and the temperature drift is 0.01 mV/°C. An improved parallel microcantilever design is developed using the stripe pattern design on the immobilized layer and the signal conditioning circuit for temperature compensation in biosensors. Analyses and experiments show that the performance of a CMOS sensor chip can be significantly improved.