Shape memory alloy actuator with enhanced heat transfer characteristics

An electro-mechanical system comprising:

• a heating source;
• and
• a shape memory alloy (SMA) actuator configured for coupling to a load, the SMA actuator having:
• an SMA element which is activated by the heating source during an activation phase of an actuation cycle, and deactivated during a deactivation/return phase of the actuation cycle;
• and
• a flexible outer layer surrounding the SMA element;
• wherein the flexible outer layer has a predetermined geometrical cross-sectional shape and a material composition that collectively optimize the heat transfer characteristics of the SMA actuator, thereby reducing a cycle time required for completing the actuation cycle.

A method for reducing a cycle time required for completing an actuation cycle of a shape memory alloy (SMA) actuator, the method comprising:

• providing the SMA actuator, wherein the SMA actuator includes an SMA element surrounded by a flexible outer layer, and wherein the flexible outer layer has a predetermined geometric cross-sectional shape and material properties that collectively optimize the heat transfer characteristics of the SMA actuator;
• connecting an SMA actuator to a load;
• activating the SMA actuator using a heating source to cause a first phase change of the SMA element;
• and
• deactivating the SMA actuator to cause a second phase change of the SMA element, wherein the flexible outer layer increases the speed of at least one of the first phase change and the second phase change;
• wherein the shape is one of:
• a star, an oval, an elongated marquise, and a tear drop.