Note: an asymmetric flexure mechanism for comb-drive actuators.

This Note presents a new asymmetric flexure design, the double parallelogram-tilted-beam double parallelogram (DP-TDP) flexure, that enables two times higher stroke in electrostatic comb-drive actuators, compared to the traditional symmetrically paired double parallelogram (DP-DP) flexure, while maintaining the same device footprint. Because of its unique kinematic configuration, the DP-TDP flexure provides an improved stiffness ratio between the bearing and actuation directions, thus delaying the on-set of sideways instability. Experimental testing of micro-fabricated comb-drive actuators with flexure beam length 1 mm and comb gap 5 μm demonstrates a stroke of 149 μm (at 86 V) for the proposed DP-TDP flexure, in comparison to 75 μm (at 45 V) for the traditional DP-DP flexure.