Sensor using electro active curved helix and double helix

摘要

Various sensors use an electro-active device ( 11 ) electrically connected to a detector circuit. The electro-active device ( 11 ) comprises an electro-active structure in the form of a continuous electro-active member ( 12 ) curving in a helix around a minor axis ( 13 ) which is in itself curved for example in a helix around a major axis ( 14 ). On activation by relative displacement of the ends ( 16 ) of the device ( 11 ), the electro-active structure twists around the minor axis due to the fact that the minor axis ( 13 ) is curved. The continuous member ( 12 ) has a bender construction of a plurality of layers ( 21 ) and ( 22 ) including at least one layer of electro-active material so that concomitantly with the twisting the continuous member ( 12 ) bends generating an electrical signal detected by the detector circuit. The electro-active device ( 11 ) is advantageous as a sensing element in a sensor because it has a large displacement, high sensitivity and low compliance.