A biosensor chip by CMOS process for surface stress measurement in bioanalyte

A 1 cm × 1 cm biosensor chip of integrated piezoresistive microcantilevers and microchannel is developed by CMOS process. The 125 μm × 60 μm × 1.1 μm microcantilever is a 4-layer structure composed of an immobilized surface layer, a top insulation layer, an embedded piezoresistive layer, and a bottom insulation layer to measure in situ the surface stress change induced by biochemical reaction. The temperature drift in biosensing is minimized by operating in the static mode of surface stress measurement, and the intrinsic electrical noise is also effectively reduced by the parallel microcantilever design and on-chip signal conditioning circuit. The biosensor performance is validated by measuring the thiol-modified single strained DNA to demonstrate its measurement sensitivity.