Image Number 2 for United States Patent #4134092.
An irreversible heat-activatable switch includes a heat-shrinkable plastic sleeve and a pair of elongate resilient electrical conductors mounted in cantilevered manner within the sleeve interior. The conductors have a pair of diverging-converging (e.g. arcuate) portions including regions proximate the sleeve. Each arcuate portion extends from the mounted end portion of its conductor and terminates in another end portion provided with an electrical contact. The end portions are so opposed that the open-closed electrical circuit character of the pair of contacts irreversibly changes responsive to movement of the arcuate portions resulting from heat-shrinking the sleeve.