Monolithic Stacked Dielectric Elastomer Actuators.

Jun Shintake,Keita Shimizu,Ryo Kanno,Daiki Ichige,Toshiaki Nagai

doi:10.3389/frobt.2021.714332

Jun Shintake, Keita Shimizu + Show 3 more

Open Access

https://doi.org/10.3389/frobt.2021.714332

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Abstract

Dielectric elastomer actuators (DEAs) are a promising actuator technology for soft robotics. As a configuration of this technology, stacked DEAs afford a muscle-like contraction that is useful to build soft robotic systems. In stacked DEAs, dielectric and electrode layers are alternately stacked. Thus, often a dedicated setup with complicated processes or sometimes laborious manual stacking of the layers is required to fabricate stacked actuators. In this study, we propose a method to monolithically fabricate stacked DEAs without alternately stacking the dielectric and electrode layers. In this method, the actuators are fabricated mainly through two steps: 1) molding of an elastomeric matrix containing free-form microfluidic channels and 2) injection of a liquid conductive material that acts as an electrode. The feasibility of our method is investigated via the fabrication and characterization of simple monolithic DEAs with multiple electrodes (2, 4, and 10). The fabricated actuators are characterized in terms of actuation stroke, output force, and frequency response. In the actuators, polydimethylsiloxane (PDMS) and eutectic gallium–indium (EGaIn) are used for the elastomeric matrix and electrode material, respectively. Microfluidic channels are realized by dissolving a three-dimensional printed part suspended in the elastomeric structure. The experimental results show the successful implementation of the proposed method and the good agreement between the measured data and theoretical predication, validating the feasibility of the proposed method.

Highlights

Dielectric elastomer actuators (DEAs) are one of the soft actuator technologies commonly used in the soft robotics fields (Brochu and Pei, 2010; Anderson et al, 2012; Romasanta et al, 2015; Rosset and Shea, 2016; Gu et al, 2017; Hines et al, 2017; Rich et al, 2018; Shintake et al, 2018; Gupta et al, 2019) due to their excellent characteristics: large actuation strains [e.g., areal strain more than 1,000% (Li et al, 2013)], fast responses [e.g., actuation at 600 Hz (Ji et al, 2019)], and theoretically high electromechanical efficiency of up to 90% (Brochu and Pei, 2010)
Elastomeric membranes used in DEAs are usually thin, ranging from 1 μm Monolithic Stacked DEAs
The experimental results demonstrate the successful implementation of the proposed method for fabricating monolithic stacked DEAs, from which the objective of this study—validation of the proposed method—was achieved

Summary

Introduction

Dielectric elastomer actuators (DEAs) are one of the soft actuator technologies commonly used in the soft robotics fields (Brochu and Pei, 2010; Anderson et al, 2012; Romasanta et al, 2015; Rosset and Shea, 2016; Gu et al, 2017; Hines et al, 2017; Rich et al, 2018; Shintake et al, 2018; Gupta et al, 2019) due to their excellent characteristics: large actuation strains [e.g., areal strain more than 1,000% (Li et al, 2013)], fast responses [e.g., actuation at 600 Hz (Ji et al, 2019)], and theoretically high electromechanical efficiency of up to 90% (Brochu and Pei, 2010). Previous studies have presented various methods for fabricating stacked DEAs where the dielectric and electrode layers are alternately staked (Kovacs et al, 2009; Matysek et al, 2011; Ji et al, 2019), blade-casted (Li et al, 2018), spin coated (Lotz et al, 2011; Duduta et al, 2019), printed (Araromi et al, 2011; Reitelshöfer et al, 2016; McCoul et al, 2017; Chortos et al, 2020), or folded together (Carpi et al, 2007; Nguyen et al, 2014). These fabrication methods often require a dedicated setup with complicated processes or sometimes require laborious manual stacking of the layers, which may increase the failure rate of the actuators

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