Bi-metal actuator

A bi-metal actuator, comprising a shape memory alloy layer thermally activated by a heat source;

• a superelastic alloy layer fixed along at least one part of the shape memory alloy layer;
• and at least one deformation sensor;
• wherein the shape memory alloy layer has an initial shape at or below a transition start temperature TS, a final shape at or above a transition end temperature TE, and a plurality of transitional shapes between the initial shape and the final shape, the plurality, of transitional shapes are formed according to a temperature between the transition start temperature TS and the transition end temperature TE of the shape memory alloy layer;
• wherein the superelastic alloy layer does not retain permanent deformation during motions of the shape memory alloy layer, the superelastic alloy layer opposes the motions of the shape memory alloy layer during a transition from the initial shape to the final shape, and the superelastic alloy layer possesses superelastic properties at a Celsius temperature that is a least 20 degrees below said transition start temperature TS in Celsius;
• and
• wherein the at least one deformation sensor is provided along at least a part of the superelastic alloy layer for measuring a strain of the superelastic alloy layer and the shape memory alloy layer indicating a current form of the shape memory alloy layer.