Sensitive in plane motion detection of NEMS through semiconducting (p+) piezoresistive gauge transducers

We present a novel design for nano-electromechanical systems (NEMS) in plane motion detection using suspended Si (p+) doped piezoresistive nanowire gauge transducers. The devices are electrostatically actuated by a lateral electrode and detected through piezoresistive transduction using a synchronous down-mixing principle. This geometry enables a first order piezoresistive detection with the suspended gauges acting as strain collectors. The two piezoresistive gauges used in balanced bridge configuration offer remarkable background reduction. Maximizing the strain on the gauges and reducing the background resulted in a highly efficient NEMS motion detection technique providing unprecedented signal to background ratio (SBR) of 60 dB with 40 dB improvement on the state of the art. These devices were fabricated using CMOS compatible processes enabling very large scale integration and mass production.