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1. US20160144091 - Electroactive actuators

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[ EN ]

Claims

1. An actuator comprising:
an inner tubular structure; and
an outer tubular structure surrounding the inner tubular structure;
wherein:
the outer tubular structure comprises a plurality of layers of a dielectric elastomeric material;
the outer tubular structure comprises a tubular elastic support structure;
the tubular elastic support structure is configured to maintain a pre-stress in the plurality of layers of the dielectric elastomeric material;
the outer tubular structure is configured to contract in a radial direction around the inner tubular structure upon application of an actuation voltage signal across the dielectric elastomeric material layers; and
the tubular elastic support structure comprises an auxetic structure configured such that a ratio between expansion in the circumferential direction and contraction in the axial direction of the tubular elastic support structure when unconstrained is zero or negative.
2. The actuator of claim 1 wherein the inner tubular structure is a braided tubular structure.
3. An implantable device comprising the actuator according to claim 1 and an electronic controller configured to apply the actuation voltage signal to the plurality of layers of the dielectric elastomeric material.