A MEMs scanning device has a variable resonant frequency. In one embodiment, the MEMs device includes a flexible arm that extends from a oscillatory body. An electrical field applies a force to the flexible arm, thereby bending the flexible arm to shift the moment of inertia of the oscillatory body and...http://www.google.com.tw/patents/US6256131?utm_source=gb-gplus-share專利 US6256131 - Active tuning of a torsional resonant structure
