Researchers at Leibniz Institute of Photonic Technology are developing a self-sufficient energy supply based on textiles. In this way, it should be even easier in the future to supply mobile electronic devices worn close to the body with energy, even when no external power supply is available.
Smart textiles use the warmth emitted by the human body and convert it into electricity. Their also cooling properties make the new materials interesting for safety-relevant applications and at the same time ensure increased wearing comfort and well-being.
Miniaturized electronic devices worn on the body, so-called wearables, check vital functions, count steps or provide information about traffic and weather. In order to continuously supply these technical companions with power, researchers at Leibniz Institute of Photonic Technology (Leibniz IPHT), Jena/Germany, the ITP GmbH, Weimar/Germany, and the textile manufacturer E. CIMA, Sabadell/Spain, developed a material that supplies the required energy independently of external power sources: Modern, intelligent textiles convert body warmth into electricity using thermoelectric effects, which can be stored in a battery.
For power generation the Leibniz IPHT uses thermoelectric generators, which convert the body’s own warmth into electrical energy (Seebeck effect). For this purpose, thin-film coatings in the form of aluminum-doped zinc oxide (Al:ZnO) are applied to textile fabrics as a thermoelectric functional layer. The researchers were able to measure thermoelectric effects with outputs of up to 0.2 μW by means of temperature differences between the user’s skin surface and the ambient temperature or by means of industrial waste heat. The electricity generated could be stored in a battery to meet the energy needs of electronic devices for health or sports. This makes the energy supply of devices self-sufficient.
The thermoelectric effect can also be used for cooling by means of electrical energy and thus be used for cooling applications and temperature regulation (Peltier effect). A possible area of application is in the steel industry: Workers at blast furnaces are exposed to high levels of heat.
In tests, Peltier cooling demonstrated a temperature difference of up to 12 °C, which is unique for textile thermoelectric elements.