Nanomechanical resonators operating as charge detectors in the nonlinear regime

We present measurements on nanomechanical resonators machined from silicon- on-insulator substrates. The resonators are designed as freely suspended Au /Si beams of lengths on the order of 1-4 mu m and a thickness of 200 nm. Th e beams are driven into nonlinear response by an applied modulation at radi o frequencies;and a static magnet:ic field in plane. The strong hysteresis of the magnetomotive response allows sensitive charge detection by varying the electrostatic potential of a gate electrode.