PZT-Actuated and -Sensed Resonant Micromirrors with Large Scan Angles Applying Mechanical Leverage Amplification for Biaxial Scanning.

Shanshan Gu-Stoppel,Wolfgang Benecke,Thorsten Giese,Hans-Joachim Quenzer,Ulrich Hofmann

doi:10.3390/mi8070215

Shanshan Gu-Stoppel, Wolfgang Benecke + Show 3 more

Open Access

https://doi.org/10.3390/mi8070215

Copy DOI

Journal: Micromachines	Publication Date: Jul 6, 2017
Citations: 20	License type: CC BY 4.0

Affiliation: Fraunhofer Institute for Silicon Technology

Abstract

This article presents design, fabrication and characterization of lead zirconate titanate (PZT)-actuated micromirrors, which enable extremely large scan angle of up to 106° and high frequency of 45 kHz simultaneously. Besides the high driving torque delivered by PZT actuators, mechanical leverage amplification has been applied for the micromirrors in this work to reach large displacements consuming low power. Additionally, fracture strength and failure behavior of poly-Si, which is the basic material of the micromirrors, have been studied to optimize the designs and prevent the device from breaking due to high mechanical stress. Since comparing to using biaxial micromirror, realization of biaxial scanning using two independent single-axial micromirrors shows considerable advantages, a setup combining two single-axial micromirrors for biaxial scanning and the results will also be presented in this work. Moreover, integrated piezoelectric position sensors are implemented within the micromirrors, based on which closed-loop control has been developed and studied.

Highlights

Either for biomedical [1], automotive [2] or for entertainment uses like pico-projector [3], micromirrors are attract increasing interest due to the miniaturized size, low power consumption and low production cost compared to conventional scanning devices
Thermal micromirrors reach large deflections driven by low driving voltages [4]
Piezoelectric materials [8,9,10], for example lead zirconate titanate (PZT), deliver high driving force at low driving voltage, so that piezoelectrically driven micromirrors achieve large deflection even operated under ambient conditions

Summary

Introduction

Either for biomedical [1], automotive [2] or for entertainment uses like pico-projector [3], micromirrors are attract increasing interest due to the miniaturized size, low power consumption and low production cost compared to conventional scanning devices. Previous works show that very good results regarding high light density can be realized, if the two axes have a frequency difference of 60 Hz [13] Such low frequency difference causes inevitably so strong mechanical coupling of the two axes, that complex controlling is needed to decouple the biaxial motions [11]. Quasi-statically driven vector micromirrors request high-resonant frequency for better mechanical robustness and low settling time [15]. These two requirements are contradictory to each other, since high frequency demands high stiffness, while large displacement requires low stiffness of the devices. One of the focuses of this work is to utilize analytic modelling, where the micromirror plate and actuators are considered as an entire system, to improve the mechanical efficiency for realizing high frequency, large displacement and low consumption. In contrast to them, integrated piezoelectric sensors cost no extra fabrication steps and deliver measuring signals with large signal-to-noise-ratio (SNR) as well

Dynamic Leverage Amplification

Conclusions