Piezoresistive bridge microcantilevers biosensor based on SOI wafer for glucose detecting

To measure glucose accurately, a high sensitivity piezoresistive four-set Wheatstone bridge structure microcantilevers glucose biosensor was developed. The microcantilevers with a piezoresistor were fabricated using a series of bulk silicon processes based on a silicon-on-insulator wafer. An improved Wheatstone bridge readout circuit with voltage closed-loop auto-zero and high-gain magnified functions is proposed. The sensing microcantilever gold-coated surface was functionalised by immobilising a self-assembled monolayer of 4-mercaptophenylboronic acid, the reference cantilever was not functionalised. The relationship between a piezoresistive bridgeout caused by the microcantilevers bending and glucose solution concentration was obtained at 5 and 15 mM. Experimental results demonstrated that the output voltage induced by microcantilevers bending is proportional to the glucose concentrations and the sensitivity is up to 0.1 V/mM.