On my laminator, it is a diode like 1N4148.
They use then as thermosensor.
Diode have linear temperature coefficient of about 2.3 mV/°C when a forward voltage is supplied across the junction.
According to datasheet it should work up to 200 degrees celcius and above...
There is an example on : http://www.micro-examples.com/public/microex-navig/doc/098-temperature-sensor.html