A Kirigami Approach of Patterning Membrane Actuators.

Harti Kiveste,Rain Eric Haamer,Rudolf Kiefer,Gholamreza Anbarjafari,Tarmo Tamm

doi:10.3390/polym13010125

Abstract

Ionic electroactive polymer actuators are typically implemented as bending trilayer laminates. While showing high displacements, such designs are not straightforward to implement for useful applications. To enable practical uses in actuators with ionic electroactive polymers, membrane-type film designs can be considered. The significantly lower displacement of the membrane actuators due to the lack of freedom of motion has been the main limiting factor for their application, resulting in just a few works considering such devices. However, bioinspired patterning designs have been shown to significantly increase the freedom of motion of such membranes. In this work, we apply computer simulations to design cutting patterns for increasing the performance of membrane actuators based on polypyrrole doped with dodecylbenzenesulfonate (PPy/DBS) in trilayer arrangements with a polyvinylidene fluoride membrane as the separator. A dedicated custom-designed device was built to consistently measure the response of the membrane actuators, demonstrating significant and pattern-specific enhancements of the response in terms of displacement, exchanged charge and force.

Highlights

There is an increasing demand for smart devices with high functionality operating at low voltages
There have been relatively few works adapting biomimetic principles on bending actuators, like the recently shown reduction of friction by implementing a hydrophobic coating on bilayer rear side doubling bending displacement [7]. Another completely different direction of the biomimetic approach to the improvement of actuator behavior is based upon natureinspired Kirigami designs, like the one taking after Vorticella convallaria [8], in various forms on helical actuators based on dielectric elastomers [9], or in shape memory alloys [10] or conducting polymers [11,12,13]
The most commonly applied conducting polymer is polypyrrole (PPy), often doped with dodecylbenzenesulfonate (PPy/DBS), which belongs among the cation-driven actuators, as the DBS− anions are large enough to remain trapped in the PPy network [19]

Summary

Introduction

There is an increasing demand for smart devices with high functionality operating at low voltages. There have been relatively few works adapting biomimetic principles on bending actuators, like the recently shown reduction of friction by implementing a hydrophobic coating on bilayer rear side doubling bending displacement [7] Another completely different direction of the biomimetic approach to the improvement of actuator behavior is based upon natureinspired Kirigami designs, like the one taking after Vorticella convallaria [8], in various forms on helical actuators based on dielectric elastomers [9], or in shape memory alloys [10] or conducting polymers [11,12,13]. Our goal in this work was to combine the well-established trilayer conducting polymer actuator material PPy/DBS with the kirigami approach of patterning the membrane with cuts of different computer-simulation-approved designs. Square wave potential step measurements were performed and the PPy/DBS trilayer was characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and conductivity measurements

Materials

Findings

Electropolymerization and Pattern Design