Piezoelectric Actuators for Tactile and Elasticity Sensing

Abstract

Piezoelectric actuators have achieved remarkable progress in many fields, being able to generate forces or displacements to perform scanning, tuning, manipulating, tactile sensing or delivering functions. In this work, two piezoelectric PZT (lead zirconate titanate) bimorph actuators, with different tip contact materials, were applied as tactile sensors to estimate the modulus of elasticity, or Young’s modulus, of low-stiffness materials. The actuators were chosen to work in resonance, taking advantage of a relatively low resonant frequency of the out-of-plane vibrational modes, associated with a convenient compliance, proven by optical and electrical characterization. Optical measurements performed with a scanning laser vibrometer confirmed that the displacement per applied voltage was around 437 nm/V for the resonator with the lower mass tip. In order to determine the modulus of elasticity of the sensed materials, the stiffness coefficient of the resonator was first calibrated against a force sensor, obtaining a value of 1565 ± 138 N/m. The actuators were mounted in a positioning stage to allow approximation and contact of the sensor tip with a set of target materials. Electrical measurements were performed using the resonator as part of an oscillator circuit, and the modulus of elasticity of the sample was derived from the contact resonant frequency curve of the cantilever–sample system. The resulting sensor is an effective, low-cost and non-destructive solution compared to atomic force microscopy (AFM) techniques. Materials with different modulus of elasticity were tested and the results compared to values reported in the literature.

Modeling the Piezoelectric Cantilever Resonator with Different Width Layers

“…In the open-loop test, the quality factor of the piezoelectric cantilever resonator is 1411.2, therefore, the static tip displacement is 1.62 nm. Back to the proposed model, let the applied voltage be the drive voltage, that is 0.2 V. Substituting the geometry and material parameters to (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18), the static tip displacement is 1.88 nm, which is larger than the measured result. The reason is that there is a feedthrough capacitor in the resonator [32], which will affect the output current.…”

“…The piezoelectric cantilever is one of the most important structures for micro-electro-mechanical system (MEMS) application and it has been used in atomic force microscopes, chemical sensors and biosensors, radio frequency (RF) switches, photon detectors, micromirrors, and energy harvesters [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ]. Tip displacement and resonance frequency are two important characters of the piezoelectric cantilever, especially when setting the height of the cantilever in the RF switch [ 8 ] and tuning the resonance frequency of the energy harvester that matches the ambient vibrating frequency for improving the power efficiency [ 4 ].…”

Design and Experiment of a Clamping-Drive Alternating Operation Piezoelectric Actuator

“…At present, precision positioning devices have been increasingly applied in various fields such as precision machining, optical fiber docking and medical devices etc. [ 1 , 2 , 3 , 4 , 5 , 6 ]. Due to the development of advanced technology, there are more demanding requirements placed on precision actuators that attract widespread attention from researchers due to various advantages such as high precision, fast response, compact structure and self-locking [ 7 , 8 , 9 , 10 ].…”

Tracking Control for Piezoelectric Actuators with Advanced Feed-Forward Compensation Combined with PI Control

“…PEAs are high precision positioning systems with a wide range of usage such as active vibration systems for vehicles [1], sensing [2], energy recovery [3] and stick-slip motors [4]. These devices not only are accurate but also possess a broad stiffness in comparison to their size [5].…”