Design and Modeling of Piezoelectrically Driven Micro-Actuator With Large Out-of-Plane and Low Driving Voltage for Micro-Optics

This paper presents the design and modeling of a novel piezoelectrically driven micro-lens actuator capable of delivering large out-of-plane displacement with a low driving voltage and fast speed. The design architecture, parameter optimization, modeling and testing of the actuator are presented. The actuator consists of six unimorph piezoelectric beams operating in a d
₃₁
mode to symmetrically displace a micro-lens holding platform. The design methodology exploits the film residual stress levels and thicknesses to achieve an optimal initial static deflection of the actuator beams for generating the largest possible actuation sensitivity. Theoretical modeling shows an enhancement in the average actuation sensitivity from 0.975 μm/kV/cm to 1.317 μm/kV/cm by employing the methodology. The actual actuation sensitivity measured from the fabricated device shows an outstanding result of 1.45 μm/kV/cm with a resonant frequency of 2 kHz. This translates to a displacement of 145 μm at 22 V driving voltage. The static power consumption is measured to be below 3.5 mW under normal operations.