Fabrication Process of Silicone-based Dielectric Elastomer Actuators

Abstract

This contribution demonstrates the fabrication process of dielectric elastomer transducers (DETs). DETs are stretchable capacitors consisting of an elastomeric dielectric membrane sandwiched between two compliant electrodes. The large actuation strains of these transducers when used as actuators (over 300% area strain) and their soft and compliant nature has been exploited for a wide range of applications, including electrically tunable optics, haptic feedback devices, wave-energy harvesting, deformable cell-culture devices, compliant grippers, and propulsion of a bioinspired fish-like airship. In most cases, DETs are made with a commercial proprietary acrylic elastomer and with hand-applied electrodes of carbon powder or carbon grease. This combination leads to non-reproducible and slow actuators exhibiting viscoelastic creep and a short lifetime. We present here a complete process flow for the reproducible fabrication of DETs based on thin elastomeric silicone films, including casting of thin silicone membranes, membrane release and prestretching, patterning of robust compliant electrodes, assembly and testing. The membranes are cast on flexible polyethylene terephthalate (PET) substrates coated with a water-soluble sacrificial layer for ease of release. The electrodes consist of carbon black particles dispersed into a silicone matrix and patterned using a stamping technique, which leads to preciselydefined compliant electrodes that present a high adhesion to the dielectric membrane on which they are applied.

Printing low-voltage dielectric elastomer actuators

“…A thin film of silicone elastomer (Sylgard 184, Dow Corning, USA) is stamped (TMP 101, Teca-Print AG, Switzerland) in the shape of a 3 cm wide circle on top of the PAA layer and cured at 80 C for 1 h. 3. A stretchable electrode made of a carbon black-elastomer composite is stamped on top of the silicone film and cured for 30 min at 80 C. 21 4. The membrane is released from the PET substrate by dissolving the sacrificial layer in warm demineralized water.…”

“…For comparison, a second actuator was fabricated using our standard DEA fabrication process. 21 This reference DEA is based on exactly the same materials and geometry, except for having a 30 lm-thick membrane. We refer to the two devices as the 3 lm-DEA and 30 lm-DEA.…”

Assessing the degradation of compliant electrodes for soft actuators

“…The behaviour of the ink (initial resistance and degradation) depends on many parameters, such as the quantity of carbon black, the dispersion time and method, the thickness applied during the printing process, etc. Here, the test actuators were produced according to a protocol we published previously 30 , and which represents the main method of manufacturing actuators and electrodes in our labora- There is a constant increase of both the unstretched and stretched resistances, while the stretch ratio remains constant. B) Radial actuation stretch as a function of applied electric field measured every 50k cycles.…”

Using Pot-Magnets to Enable Stable and Scalable Electromagnetic Tactile Displays

“…Two elastomer membranes are attached on top and bottom surfaces of the pot-magnets and the acrylic plate. For the fabrication of the membranes we used the fabrication process recently reported for our lab [16]. We used the elastomer Sylgard 186 PDMS casted to obtain a 20 µm thick membrane.…”