Multilayer dielectric elastomer unimorph actuators for self-folding shape-shifting surfaces

For the design of a shape changing display, unimorph bending actuators are investigated. To achieve deformations still visible from a distance, the displacements of the envisioned actuator need to be maximized. The designed actuator is made of a multilayered silicone laminate, which is bonded to a passive, inextensible layer made of nylon "rip-stop" material with low thickness and density but high tensile strength. Applying a voltage induces a maxwell pressure in the active material and causes an area expansion. The passive layer constraints extension and thus forces a curvature of the device. Approximating the geometry with a circular arc, the device is modeled both statically and dynamically. Experiments are conducted by tracking the tip of the actuator with a image processing software. Static deflection angles of 150° are achieved. Evaluating the step response to a 2500 V voltage step, the resonance frequency of 4.3 Hz is obtained. The findings will be used to maximize stroke, while minimizing the driving voltage. Actuators of this kind can also find application in robots, such as for biomimetic wings or fins.