Wound roll dielectric elastomer actuators: fabrication, analysis and experiments

Abstract

Wound roll Electroactive polymer actuators fabricated with Dielectric Elastomer (DE) materials provide high bandwidth actuation for robots, minipumps, loudspeakers, valves and prosthetic devices. In this paper we develop a DE wound roll actuator fabrication process that produces high strain (13%), reliable (3480 cycles at maximum strain), and stiff (157 N/m) actuators. An axisymmetric Finite Element Method (FEM) model with electrostatic and radial bulk modulus nonlinearity predicts actuator displacement and stress. The maximum compressive radial stress occurs at the center of the innermost active layer. This layer also has the thinnest material, indicating the most likely failure point. The nonlinear model predicts actuator displacement in response to applied voltage and load, and matches experiments to within 1 mm 1

Dielectric elastomers as actuators for upper limb prosthetics: Challenges and opportunities

“…3M VHB series) [28,29,[34][35][36][37][40][41][42][43][44][45][46] and silicone (i.e. Nusil R31-2186 or CF19-2186; Dow Corning HS III RTV) [27,45,[47][48][49][50][51][52][53][54] are common DEs reported in the literature, properties of which are listed in a number of references [23].…”

“…10 −3 S/cm) is acceptable [60]. Common electrode materials include carbon conductive grease [29,30,35,40,42,56], carbon black [30,39,45], carbon powder with [34,43,61] or without silicone oil [43,49,52,57], graphite powders and sprays [53], gold [64], platinum [45,60], and silver [34,45,46,48,50,61]. Table 2 presents a comparison of a few of these electrode options and their associated advantages and limitations.…”

“…DEs can be configured in a variety of ways for linear actuation including diamond-shaped [41,78], helical [49,57], folded stack [52], diaphragm [69,75,79], and rolled [42,43,49,62,73] configurations. In addition to linear actuation, spring roll actuators can also be configured for bending and rotational motion with lateral forces on the order of 1-2 N [62].…”

“…DEs are often suggested for prosthetic applications [25,40,42,43,49,56,71], yet the question remains as to their practical viability. The following discussion concentrates on the potential challenges to be overcome and is organized along the following four themes as drawn from the consumer design concerns presented in Table 1: (1) durability (i.e.…”

“…There is a paucity of information regarding the fatigue of DE actuators [42,83]. One study reported a typical operating life of a rolled actuator of around 1500 cycles activated at 3.5 kV [42], while another reported a cycle life of over 4 million for a bowtie shaped planar actuator activated at 4 kV [83].…”