Fully integrated CMOS resonant cantilever sensor for biochemical detection in liquid environments

We present a novel design of a fully integrated resonant cantilever sensor for biochemical detection in liquid environments. Four mass-sensitive, resonant cantilevers are monolithically integrated with a fully differential feedback circuit, a digital counter, and a digital I/sup 2/C interface. The entire system is fabricated in an industrial 0.8-/spl mu/m CMOS (complementary metal oxide semiconductor) process combined with subsequent micromachining. The cantilever with electromagnetic actuation and piezoresistive readout is the frequency-determining element in the feedback system. Detection of protein absorption on the cantilever has been shown with this system.