摘要 |
A switch, such as an electromechanical or optical switch, whose state is responsive to temperature history, for example temperature excursions above or below a critical temperature. An element of the sensor made from shape memory alloy changes shape when exposed, even temporarily, to temperatures above the Austenitic start temperature As or below the Martensite start temperature Ms of the shape memory alloy sensor element. The shape change of the SMA element causes the sensor to change between two readily distinguishable states. The sensor can include a one-way stop element that creates a persistent indication of the temperature history. The switch also has built-in stops allowing the sensor to be manufactured and stored at temperatures above the Austenitic temperature without causing the indication of an over-temperature event, before the actual use.
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