Piezoelectric Bimorph Actuator With Integrated Strain Sensing Electrodes

This paper describes a new method for estimating the tip displacement of piezoelectric benders. Two resistive strain gauges are fabricated within the top and bottom electrodes using an acid etching process. These strain gauges are employed in a half bridge electrical configuration to measure the surface resistance change, and estimate the tip displacement. Experimental validation shows a 1.1% maximum difference between the strain sensor and a laser triangulation sensor. Using the presented method, a damping-integral control structure is designed to control the tip displacement of the integrated bender.

I. Introduction

Piezoelectric actuators are used in a wide range of positioning applications such as micro-manipulating [1], vibration control [2], and Atomic Force Microscopy [3]. Piezoelectric benders are a sub-type that are widely used in industrial and commercial applications. [4]. Bender actuators can primarily be classified as either pinned benders or bonded benders. Disk benders are an example of a pinned type bender [5], [6]. They consist of one or two circular piezoelectric elements glued to a non-piezoelectric layer. The outer edge of the disk is pinned to a stationary base while an electric field is applied to the bender developing a net displacement and force at the center of the disk.