Abstract: An actuator comprises an electroactive polymer layer (402) and a stretchable electrode structure (403) disposed at a first side of the electroactive polymer layer and further a counter electrode layer (401) disposed on a second side of the electroactive polymer layer, wherein the ratio YC/YEAP of the elastic modulus YC of the counter electrode layer and the elastic modulus YEAP of the electroactive polymer layer is at least 10. When compressed transversally by the electrodes, the electroactive polymer will expand tangentially and the actuator will relax into a shape wherein the interior of the electroded region is substantially recessed parallel to the plane of the device, while a substantial portion of the area increase is absorbed by out-of-plane bends arising at the electrode boundary (duck mode). The invention can be embodied as optically reflective or refractive devices with variable geometry.

Abstract: An actuator comprises an electroactive polymer layer (402) and a stretchable electrode structure (403) disposed at a first side of the electroactive polymer layer and further a counter electrode layer (401) disposed on a second side of the electroactive polymer layer, wherein the ratio Yc/YEAP of the elastic modulus YC of the counter electrode layer and the elastic modulus YEAP of the electroactive polymer layer is at least 10. When compressed transversally by the electrodes, the electroactive polymer will expand tangentially and the actuator will relax into a shape wherein the interior of the electroded region is substantially recessed parallel to the plane of the device, while a substantial portion of the area increase is absorbed by out-of-plane bends arising at the electrode boundary (duck mode). The invention can be embodied as optically reflective or refractive devices with variable geometry.

Abstract: The invention relates to an actuator device (400) comprising an active layer (410) having directly or indirectly a skin layer (420) on top that can be touched by when in use by a user. The configuration of the active layer (410) can controllably be changed in an extension direction (x, y), and the skin layer (420) comprises a plurality of elevations (E) and intermediate recesses (R). Due to its structure, the skin layer (420) does not hinder conformation changes of the active layer (410) in the extension direction, while it provides favorable tactile characteristics of the actuator device (400). The active layer (410) may particularly comprise an electroactive polymer (EAP). The skin layer (420) may be composed of a plurality of grains isolated from each other, or it may comprise a thin surface layer (421) that is stiffer than the active layer (410).