One of the biggest challenges for the advancement of wearable devices, embedded to clothing and accessories, which would be capable, for example, of continuously measuring and transmitting vital sign data, is the availability of power without the need for large batteries.
Thermoelectric materials – in which a temperature difference between two points of the material creates an electric current or vice versa – make it possible to obtain the electrical energy used by the device from the temperature difference between the surface of the human body and the ambient air.
The efficiency of these materials is characterized by their figure of merit zT, which is directly proportional to the electrical conductivity and the absolute temperature of the material and inversely proportional to its thermal conductivity. Thus, obtaining new materials with high value for zT at room temperature and low thermal conductivity is a key element for the development of a new generation of wearable devices based on thermoelectric heat recovery.