What is the function of bimetal switches in the mat?

Bimetal switches or strips consist of two strips of different metals or ceramics, which expand at different rates as they are heated. 

The different expansions force the flat strip to bend one way if heated and in the opposite direction if cooled below its initial temperature. 

The metal with the higher coefficient of thermal expansion is on the outer side of the curve when the strip is heated and on the inner side when cooled. 

These bi-metal strips function as the power switches connecting or disconnecting electrical wires. 

The bimetal switches are assembled into the emergency safety system activated if the mat main safety system fails and it overheats to 170 F. 

The bimetal extension cuts electric wires if an overheat occurs. 

We use lower EMF emission ceramic switches (less than 2-3 mG) and position them near the edges of the mats to minimize the contact between the body and their locations.