Shape memory alloys are materials that can respond to temperature changes by changing shape. In wire form the wires will contract when heated and stretch when cooled.
Heating of the SMA wire is readily achieved by passing electric current through it; when heated past an upper transition temperature the atoms inside the wire realign into an alternate crystalline structure.
The process is fully reversible making the wire an ideal choice for high-cycle applications.
Kinitics actuators use a nickel-titanium shape memory alloy (the NiTi in Kinitics) in a Bundled Wire arrangement.
Kinitics Automation operates several wire dynometers which have logged more than 2 million cycles on the same piece of SMA wire.