Shoaling vibration amplifier with flattened transfer function and suppressed spurious modes

An in-plane vibration sensor with off-resonant band-pass displacement amplification and a differential capacitive readout is presented. The minimum mechanical amplification of 16 dB (i.e. a factor of 6.6) within the designed frequency band from 3-13 kHz is independent of pressure in the range of 6.3 to 64 mbar with a less than 10% change. For a flattened transfer-function a pressure close to 30 mbar is preferred in order to damp the mechanical resonance peaks. The device can be used for low power detection of broadband vibration signals e.g. in monitoring of infrastructure such as bridges and pipelines.