A novel micro-machined biosensor with resonant torsional paddle for direct detection in liquid

We present a novel micro-machined biosensor based on the resonant torsional paddle with electromagnetic excitation which can work in liquid directly. The sensor designed consists of two paddles with resonant torsional mode, in which the energy loss of the resonator during the vibration is so lower that it can be suitable for bio/chemical detection in liquid. FEM analysis was carried out to guarantee the sensitivity of the sensor. MEMS bulk silicon processes were adopted to accomplish the fabrication. To improve the characteristics of the sensor in liquid, the positive-feedback circuits with energy compensation is designed. Experimental tests show that the resonant torsional paddle can work directly in liquid and the Q-factor of the sensor in liquid can be improved from 2.65 to 40.