Surface Modification of Anisotropic Dielectric Elastomer Actuators with Uni- and Bi-axially Wrinkled Carbon Electrodes for Wettability Control

Kiwoo Jun,Il-Kwon Oh,Seunghwa Ryu,Donggyu Kim

doi:10.1038/s41598-017-06274-0

Kiwoo Jun, Il-Kwon Oh + Show 2 more

Open Access

https://doi.org/10.1038/s41598-017-06274-0

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Abstract

Interest in soft actuators for next-generation electronic devices, such as wearable electronics, haptic feedback systems, rollable flexible displays, and soft robotics, is rapidly growing. However, for more practical applications in diverse electronic devices, soft actuators require multiple functionalities including anisotropic actuation in three-dimensional space, active tactile feedback, and controllable wettability. Herein, we report anisotropic dielectric elastomer actuators with uni- and bi-axially wrinkled carbon black electrodes that are formed through pre-streching and relaxation processes. The wrinkled dielectric elastomer actuator (WDEA) that shows directional actuation under electric fields is used to control the anisotropic wettability. The morphology changes of the electrode surfaces under various electric stimuli are investigated by measuring the contact angles of water droplets, and the results show that the controllable wettability has a broad range from 141° to 161° along the wrinkle direction. The present study successfully demonstrates that the WDEA under electrically controlled inputs can be used to modulate the uni- or bi-axially wrinkled electrode surfaces with continous roughness levels. The controllable wrinkled structures can play an important role in creating adaptable water repellency and tunable anisotropic wettability.

Highlights

With an arranged carbon nanotube (CNT) sheet provided vastly improved directional strain response at a relatively low electric field (100 Vμm−1)
To produce the uni-axially wrinkled pattern on the elastomer surface, the elastomer was stretched by 100% more in the x-direction while the y-axis was maintained in the 100% pre-strained state
We report the control of the anistropic wetting utilizing wrinkled dielectric elastomer actuators (WDEAs) that were fabricated with mechanically buckled carbon black electrodes on elastomer surfaces through bi-axial pre-stretching and controlled relaxation processes

Summary

Introduction

With an arranged carbon nanotube (CNT) sheet provided vastly improved directional strain response at a relatively low electric field (100 Vμm−1). The morphological changes of the wrinkles on the elastomer film were verified by measuring the contact angle of water droplets under various surface conditions, resulting in a broad range of tunable wettability states from 141° to 161° along the wrinkle direction. Those findings supported that the various roughness levels in the controllable anisotropic micropatterns played an important role in tunable water repellence and the anisotropic behaviors of water droplets

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