Soft and Printable Electrodes for Flexible Elastomer Actuators

摘要

Having a multitude of electromechanical and robotic applications, most flexible elastomer actuators require electrically conductive electrode components as well as nonconductive substrate components to operate. Various analytical models of flexible actuators typically show that several properties of the elastomer, such as thickness, permittivity, and softness, directly influence the actuation capability. As such, the optimization of flexible actuators, particularly in dielectric elastomer actuator (DEA), has focused on improving the elastomer while electrodes are often overlooked. However, the electrodes with high modulus of elasticity, thickness, and low stretchability can reduce the amount of actuator performance. In addition, inadequate electrical conductivity increases the actuator's power requirement and influences the viscoelastic properties of DEA materials through resistive heating. Furthermore, besides material composition of electrode, manufacturing methods also govern the actuator performances. Therefore, a thorough investigation of both electrode properties and manufacturing methods is crucial to attain high-performance DE As. In this work, a microdispensing additive manufacturing technique was used to produce high-quality electrodes and to fabricate test coupons composed of PEDOTPSS (conductive and transparent polymer) and Triton X-100 (surfactant plasticizer). These coupons, as well as some molded coupons, were used to investigate important mechanical, electrical, and thermal properties of DEAs. Through the testing, the electrode showed satisfactory stretchability up to 55% for a PDMS-supported sample. Although Young's modulus of PEDOT:PSS was decreased largely by adding Triton X-100, the value was still relatively high (8.3 MPa) that needed to be lowered more to be effectively used for DEA application. The electrode maintained its conductivity above 50 S/cm when tested in the deformed state (up to 50% of strain) or at different temperatures (25-55 °C). Finally, the applicability of electrode composition was verified by electromechanical tests performed on a fully printed single layer DEA with 20 microns thick electrodes.