A resonant microaccelerometer with high sensitivity operating in an oscillating circuit.

A new micro-machined uniaxial silicon resonant accelerometer characterized by a high sensitivity and very small dimensions is presented. The device’s working principle is based on the frequency variations of two resonating beams coupled to a proof mass. Under an external acceleration, the movement of the proof mass causes an axial load on the beams, generating opposite stiffness variations, which in turn result in a differential separation of their resonance frequencies. A high level of sensitivity is obtained thanks to an innovative and optimized geometrical design of the device that guarantees a great amplification of the axial loads. The acceleration measure is obtained thanks to a properly designed oscillating circuit. In agreement with the theoretical prediction, the experimental results show a sensitivity of 455 Hz/g (g being the gravity acceleration) with resonant frequency of about 58 kHz and a good linearity in the range of interest.