A new class of soft, stretchable materials can be utilized as a sensor or high-speed actuator. This invention incorporates a simple and low-cost design that can be made fully transparent, highly stretchable, biocompatible and biodegradable. Thus it is well-suited for a range of applications in robotics, adaptive optics, energy harvesting or touch screens in mobile electronics. The device consists of a dielectric elastomer, with layered electrolytes and dielectrics (LEAD), that deforms rapidly under voltage, mimicking the function of a muscle. For sensor applications, the design operates at very low voltages (well below 1V if necessary), thereby broadening the possible application areas, such as wearable electronic, soft robotic or biomedical applications. Implantable applications are possible, since the use of ionic materials are biocompatible. As an actuator, with this elastomer on the display of a smartphone, the entire glass surface becomes a high-fidelity speaker or tactile-sensitive keyboard. Adaptive optics are another promising area, where a new class of eyeglasses are possible that can change from “normal” to “reading” to even “zoom” on command.