A capacitance accelerometer includes a housing, and a plate fixed within the housing. A moveable plate is disposed in substantially parallel relation to the fixed plate and is coupled to the housing along at least an edge. The moveable plate and the fixed plate define a distance. The distance varies...http://www.google.co.uk/patents/US7124634?utm_source=gb-gplus-sharePatent US7124634 - Single plate capacitive acceleration derivative detector
