Patent ID: 8661810

Claim:
A shape memory alloy (SMA) actuator configured to couple to and move a load, comprising: an SMA element, wherein the SMA element is activated by a 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 that surrounds and coats the SMA element, such that the flexible outer layer is adhered to or bonded to the SMA element along an interface between the SMA element and the flexible outer layer, wherein the flexible outer layer has a predetermined non-circular geometric cross-sectional shape and a material composition that collectively optimizes the heat transfer characteristics of the SMA actuator, thereby reducing a cycle time required for completing the actuation cycle; wherein the flexible outer layer is configured to compress or shorten in an axial direction along with the SMA element during the activation phase.