Design and optimization of in-plane actuator driven cantilever with high sensitivity sensors

We present a new mode of actuation and excitation for cantilevers, which endows cantilevers with large deflection for the specific application. Differing from all of the conventional methods in which the deflection is aroused by the vertical drive of cantilever itself or external vibration, the bending and oscillating actuation here is by means of the in-plane actuators, where the out-of-plane motion of the cantilever is driven by the actuation of integrated in-plane actuators combined with curl-shaped cantilever. Because the driving force of the horizontal actuator can be converted through curl-shaped cantilever into a bending moment that results in cantilever deflection, out-of-plane actuation source for cantilever deflection is independent of the cantilever itself. An in-plane electrostatic actuator with comb-drive structures that has two sets of fixed fingers and one set of moving fingers was introduced for both statically bending and dynamically oscillating the cantilever. The optimal structure was obtained through an analytical model and finite element simulation; it achieves a substantially greater deflection and a concentrated stress distribution located on the hinges, in which the integrated piezoresistive sensors are embedded to suffer from larger stress for high sensitive sensing.