A shape memory alloy, SMA, actuator for use in a device comprising a static portion (2,3) and a moveable portion (1) which is moveable relative to the static portion. The shape memory alloy actuator comprises an SMA wire (5) which is connectable between the static portion (2) and the moveable portion (1) of a device and which is arranged, by contraction, to drive movement of the moveable portion from a first position to a second position. The actuator also comprises a restoring element (4) which is connectable to the moveable portion (1) to return the moveable portion to the first position from the second position; and a strain relief mechanism (6) which is connected to the SMA wire (5) to allow contraction of the SMA wire (5) when the moveable portion (1) is immobilised.
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