Small, fast and tough: an overview of our silicone-based actuators

At the Microsystems for Space Technologies Laboratory, EPFL, we design and manufacture miniaturised silicone-based dielectric elastomer actuators (DEAs). We love silicone, because even though the achievable strain is generally smaller than what you can get with acrylic elastomers, they lead to fast devices, which are reliable and have a long lifetime. Because silicones can be bought in their uncrosslinked state and are available in a broad range of Shore hardness, they offer unlimited design flexibility, as they can be casted to any desired thickness. Over the years, we have developed a mature DEA fabrication process, including silicone membrane casting on high quality PET foil coated with a sacrificial layer, followed by the release of the membrane in a water bath and its prestretching, as well as electrode application. For small-size devices (electrodes typically smaller than 10mm), it is important to be able to precisely pattern the electrodes on the dielectric membrane. Two methods will be discussed: 1) Gold ion implantation for high-conductivity compliant electrodes that can be patterned down to 100 um with a shadow mask, or down to 1 um with a lift-off process, and 2) Stamped conductive rubber, for electrodes that can be very rapidly and precisely applied on an elastomeric membrane. Finally different applications using this fabrication technology will be presented, such as a rotary motor, a rolling robot, an energy-harvesting device, and tuneable lenses.