<title>High-field electrostriction of elastomeric polymer dielectrics for actuation</title>

Abstract

This paper investigates the use of elastomeric dielectric materials with compliant electrodes as a means of actuation. When a voltage is applied to the electrodes, the elastomeric films expand in area and compress in thickness. The strain response to applied electric fields was measured for a variety of elastomers. A nonlinear high-strain Mooney-Rivlin model was used to determine the expected strain response for a given applied field pressure. Using this model, we determined that the electrostatic forces between the free charges on the electrodes are responsible for the observed response. Silicone polymers have produced the best combination of high strain and energy density, with strains exceeding 30% and energy densities up to 0. 15 MJ/m3. Based on the electrostatic model, the electromechanical coupling efficiency is over 50%. This paper also reports recent progress in making highly compliant electrodes. We have shown, for example, that gold traces fabricated in a zig-zag pattern on silicone EPAM retain their conductivity when stretched up to 80%, compared to 1-5% when fabricated as a uniform 2-dimensional electrode. Lastly, the paper presents the performance of various actuators that use EPAM materials. The technology appears to be well-suited for a variety of small-scale actuator applications.

Flexible and stretchable electrodes for dielectric elastomer actuators

“…This step is followed by the etching of the exposed metal (c), and finally the photoresist is stripped from the metal (d). This process, which is the standard patterning method used in the integrated-circuit (IC) industry, has been successfully demonstrated to pattern metallic electrodes on elastomeric membranes for DEA applications by several authors [9,27,50,53,64]. Compared to the shadow mask process, any shape can be realized with photolithography, and features with size down to 5 µm have been demonstrated on soft polymers [9].…”

“…In addition to being quite difficult to handle due to their high sensitivity to static charges, loose powders present several disadvantages: maintaining full coverage at large strains is difficult, [9,27] and the lifetime of the electrode is limited due to the possibility of the conductive particles to detach from the electrode. Consequently, electrodes with loose powders are mainly found in combination with adhesive acrylic elastomers (such as VHB from 3M) as dielectric layer: because this material is intrinsically sticky, the conductive particles become bound to its surface.…”

“…The layer was subsequently patterned by pho- tolithography to form zig-zags with a conductive width down to 5 µm [9,27]. They report that the electrodes can be stretched in the direction of the zigzags up to 80% while remaining conductive.…”

Simple and Robust Direct Drive Wave Power Generation System Using Dielectric Elastomers

“…This attraction leads to a thickness-wise contraction and planar expansion of the elastomer. DE film can be made using several well-known techniques, including spin coating, dip coating and casting [14].…”

“…DE is a new transducer technology which uses rubber-like polymers called elastomers as actuator materials [13][14][15]. The core element of DE is a simple structure comprised of a thin elastomer sandwiched between flexible electrodes.…”