Designs of Low-Voltage-Driven Soft Actuators with Various Motions

Abstract

Soft actuators that can show mechanical deformation under various external stimuli have extensively been studied to exploit soft robotics with precise control over their motions. The key challenges for the development of practically useful soft actuators lie in large strain, high mechanical strength, durable actuation motion, and low power consumption. Among them, ionic electroactive polymer (EAP) actuators, composed of ionic polymer sandwiched between two flexible electrodes, have been considered as the most promising candidate for such actuators. Ionic EAP actuators operated under a few volts are applied the voltage, in general, asymmetric volume change near the electrodes occurs due to the difference of van der Waals between cations and anions. However, the motion of such actuators is limited to “bending motion”, committed in the early stages of technologies. One of other EAP actuators, electronic EAP actuators, can show relatively various motion and high strain, but they have the limitation for practical application owing to apply the high voltages (>kV) as compared to those of ionic EAP actuators. In this study, I expected that while all the actuators are based on the same constituents, different actuator designs would lead to largely dissimilar actuation properties under the imposed stimuli. Firstly, geometric changes of the actuators beyond typical trilaminar shape were attempted, based on comprehensive understanding of electric field distribution in the polymer layers. In addition, the theoretical approach was conducted by utilizing simulation software in order to confirm the ion distribution in the polymer layer as well as the expected deformation. Secondly, linear motion that can be a breakthrough in ionic EAP actuator technologies has been attempted by introducing the bilayer polymer membrane and carbon interface. Furthermore, all designed actuators were fabricated in order to affirm the various deformation, excepted to bending motion.Consequently, the resultant actuators showed great promises towards diverse actuation motions such as lateral expansion/shrinkage, and linear behaviour. Given that actuators can be operatable only under few volts, these will represent an opportunity for the development of novel techniques for designing actuators for soft robotics, biosensors, microelectronics, and various biomimetic devices.