Actuator

An actuator having first and second portions formed of substantially the same material as each other, said material being a shape memory material having shape memory properties, the second portion being treated to reduce the shape memory properties relative to the first portion, the first portion being movable from a first position to a second position at a temperature above the phase transition temperature of the shape memory material of the first portion, and the second portion being arranged to urge the first portion from the second portion to the first position at a temperature below the phase transition temperature of the shape memory material, said actuator comprising a tube, wherein a first axially extending region of the tube constitutes the first portion, and a second axially extending region of the tube constitutes the second portion, wherein the tube moves between a first position and a second position when the first portion moves as aforesaid.

An actuator having first and second portions formed of substantially the same material as each other, said material being a shape memory material having shape memory properties, the second portion being treated to reduce the shape memory properties relative to the first portion, the first portion being movable from a first position to a second position at a temperature above the phase transition temperature of the shape memory material of the first portion, and the second portion being arranged to urge the first portion from the second portion to the first position at a temperature below the phase transition temperature of the shape memory material, wherein the actuator is formed as a single piece, and includes a support portion extending between the first and second portions, the first and second portions being integrally attached to the support portion at first ends of the first and second portions, and wherein the first and second portions include opposite free second ends which can be connected to one another.