MEMS Tunneling Sensor Without the Feedback Loop

A possibility of fabrication of a microelectromechanical tunneling sensor without a feedback loop is demonstrated. The tunneling gap of less than 10 nm shows a long-term stability at room conditions. The sensor can be used for construction of an accelerometer in which the linear acceleration causes mutual displacements of mobile microelectrodes. Acceleration can be detected due to a strong dependence of the tunneling current on interelectrode gap. The sensor is fabricated on a silicon-on-insulator (SoI) wafer in the planar technology. Experiments have shown the accelerometer resolution to be 2.221 g/Hz
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at frequencies up to 3.17 kHz. The frequency of the first mechanical vibration mode of the sensor was estimated at a few MHz. By lowering this frequency through an increase in the proof mass, it is possible to largely upgrade the resolution of the accelerometer.