Investigation of Polymer Micro-Actuators Based on Electrostrictive Poly(vinylidene fluoride-trifluoroethylene) Copolymers

Abstract

ABSTRACTMicromachined actuators based on the electrostrictive P(VDF-TrFE) copolymer, which possesses a high strain (∼5%) and high elastic energy density (∼ 1 J/cm3), have been designed and fabricated. The performance of the devices have been characterized and modeled in terms of the properties of the copolymer and dimensions of the devices. The experimental results on the device responses under high AC fields (electrostrictive mode), weak AC fields in DC field biased state, and frequency dependence, are very close to the modeling results. Due to the large field induced strain and high frequency capability of the electrostrictive P(VDF-TrFE), the device possesses the capability of operation at non-resonance mode with high displacement and force output, and hence, the device is capable to be used over a broad frequency range. For example, for a device of 1 mm lateral dimension, the displacement output can reach more than 50 μm and the ratio of the displacement/applied voltage is more than 20 nm/Vrms. Furthermore, over more than 3 frequency decades (up to 100 kHz), the dispersion of the displacement is less than 20%. The observed performance of the devices indicates that this class of the electrostrictive P(VDF-TrFE) based micro-actuators is attractive for micropumps and valves.