Peltier element
From HvWiki
A peltier element is not a heating element or a cooling element, it is a heat pump. It transfers heat energy from one side to the other, the direction of transfer is decided by the polarity of the electrical current that powers it. This means that for any practical use the peltier element must be mounted on a suitable heatsink or it will destroy itself.
If there is a temperature difference from one side to the other the element will generate a current, the generating efficiency can reach 10% but the hight temperature needed makes it difficult not to destroy the element.
Since a temperature difference generates a current it is possible to use a peltier element to detect heat radiation and with a high gain amplifier it is possible to detect the heat radiated from a human.
