Millimeter-sized piezoelectric flextensional actuators with improved mechanical efficiency

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Abstract: A millimeter-sized piezoelectric actuator with a flexible displacement-amplification frame incorporates design enhancements to achieve an increase in mechanical efficiency from 33 to 70% relative to existing designs. The basic insight enabling this improvement is a familiar one: to maximize the force transfer through a flexible transmission, the serial compliance of the transmission should be minimized. The execution is more complex, particularly due to the small size of the actuators, requiring careful material selection, design, and fabrication. We provide simple guidelines based on lumped parameter modeling and scaling analysis to assist designers in this challenging task and in customizing to specific size and output requirements. These actuators can be used as building blocks in millimeter-sized devices in which precise, linear motion is needed, and the method of analysis employed should be broadly useful to designers of similar devices looking to distill a complex mechanics problem down to a set of simple design guidelines.