"Thermoelectric generators can convert thermal energy directly into electrical energy. This technology makes it possible to operate energy-autonomous sensors for the Internet of Things or in wearables, such as smartwatches, fitness bracelets or digital glasses, without batteries," says Professor Uli Lemmer, a researcher at the Karlsruhe Institute of Technology (KIT). Furthermore, they could be used in the recovery of waste heat in industry and in heating systems or geothermal energy.
Conventional TEGs have to be assembled from individual parts using relatively complex manufacturing processes. To get around this, the researchers have explored novel printable materials, developing both organic and inorganic nanoparticle-based inks in addition to two innovative processes. These can be used to produce low-cost, three-dimensional printed TEGs, Lemmer says.
In the first method, a 2D pattern of thermoelectric printing inks is applied to a wafer-thin flexible substrate film by screen printing and then an approximately sugar-cube-sized, cuboid generator is folded together using an origami technique. The KIT scientists developed this method together with the InnovationLab in Heidelberg and a KIT spin-off company. In the second method, the researchers first print a 3D basic framework onto whose surfaces they then apply the thermoelectric ink.