Patent ID: 8754740

Claim:
A stand-alone electronic implement adapted for use in a circuit conveying an electric current, having no power source external to the circuit, and for autonomously modifying the circuit, the implement adapted to convey a full electrical current of the circuit, the implement comprising: at least one active material element selectively operable to undergo a reversible change exclusively in response to Joule heating of the at least one active material element to a first threshold temperature to activate the at least one active material; a tuned spring load to oppose the reversible change wherein the first threshold temperature is adjustable by adjusting the spring load; and a first electrical contact attached to the at least one active material element, in electrical communication with the at least one active material element, and selectively connectable with a second electrical contact to close the circuit in a first position or open the circuit in a second position; wherein: the Joule heating is caused exclusively by the same electric current passing through the circuit and the at least one active material element; the Joule heating causes the at least one active material element to rise to the first threshold temperature when the current passing through the at least one active material element is greater than a threshold current; the at least one active material element is configured such that the reversible change opens or closes the circuit; and the at least one active material element has a two-way shape memory, so as to be operable to move the first contact back to the first position when the change is reversed by cooling to a second threshold temperature.