Lighter and Stronger: Cofabricated Electrodes and Variable Stiffness Elements in Dielectric Actuators

Vivek Ramachandran,Dario Floreano,Yegor Piskarev,Michael D. Dickey,Jun Shintake,Neil Baugh

doi:10.1002/aisy.202000069

Abstract

The inherent compliance of soft robots often makes it difficult for them to exert forces on surrounding surfaces or withstand mechanical loading. Controlled stiffness is a solution to empower soft robots with the ability to apply large forces on their environments and sustain external loads without deformations. Herein, a compact, soft actuator composed of a shared electrode used for both electrostatic actuation and variable stiffness is described. The device operates as a dielectric elastomer actuator, while variable stiffness is provided by a shared electrode made of gallium. The fabricated actuator, namely variable stiffness dielectric elastomer actuator (VSDEA), has a compact and lightweight structure with a thickness of 930 μm and a mass of 0.7 g. It exhibits a stiffness change of 183×, a bending angle of 31°, and a blocked force of 0.65 mN. Thanks to the lightweight feature, the stiffness change per mass of the actuator (261× g−1) is 2.6 times higher than that of the other type of VSDEA that has no shared electrode.

Highlights

The inherent compliance of soft robots often makes it difficult for them to exert forces on surrounding surfaces or Machines and robots provide value by performing tasks that withstand mechanical loading
The novelty of the variable stiffness dielectric elastomer actuators (VSDEAs) described in this article consists of using a shared electrode for both electrostatic actuation and variable stiffness in a single device structure
The proposed VSDEA displays significantly higher stiffness change and actuation performance compared with a VSDEA with different stiffness and actuation structures, resulting in a stiffness change per mass that is almost three times higher

Summary

Introduction

The inherent compliance of soft robots often makes it difficult for them to exert forces on surrounding surfaces or Machines and robots provide value by performing tasks that withstand mechanical loading. Dickey Department of Chemical and Biomolecular Engineering North Carolina State University between solid and liquid states, thereby changing the stiffness of the overall structure This feature has enabled LMPAs to be combined with different types of soft actuators, such as dielectric elastomer actuators (DEAs),[20,25] shape-memory alloy actuators,[26] and pneumatic actuators.[19] in these devices, the vari-. The variable stiffness dielectric elastomer actuators (VSDEAs) have been previously fabricated based on different variable stiffness technologies such as LMPAs[20] shape-memory polymers (SMPs),[16] and thermoplastics.[12] Shintake et al.[20] developed a VSDEA by merging together the DEA with the soft variable stiffness tissue In this case, the variable stiffness change occurs due to the LMPA traces encapsulated into the silicone matrix.[22]. Together with the simplicity of the architecture of the device, the fabrication process is simpler, easier, and faster than those of previous studies.[16,20]

VSDEA Structure and Working Mechanism

Fabrication Process

Results and Discussion

Conclusions

Experimental Section

Conflict of Interest