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Thermoelectric generators directly convert thermal into electrical energy.

The universe of the Internet of Things (IoT) is rapidly expanding, which means the exponential growth of sensors is required to connect up systems. All these sensors require power – ideally an autonomous, eco-friendly and maintenance-free source of power. In short, thermoelectric generators (TEGs) could provide the answer.

Scientists at the Karlsruhe Institute of Technology (KIT) are currently working on 3D component architecture based on new TEG materials which can be manufactured by additive printing. “Thermoelectric generators directly convert thermal into electrical energy. This technology enables operation of autonomous sensors for the Internet of Things or in wearables, such as smart watches, fitness trackers, or digital glasses without batteries,” explains Professor Uli Lemmer, head of the Light Technology Institute of KIT, in a press release.

Thermoelectric convection technology is not new, but conventional TEGs have to be assembled from many separate components using complex manufacturing methods. The difference is that KIT has developed ground-breaking printable materials – such as thermoelectric inks made by combining organic and inorganic nanoparticles – and new processes for mass production.

In the first step, the 2D pattern is applied to ultrafine substrate foil using screen printing with special inks. Then a “generator” the size of a sugar cube is created by mechanically folding the foil. In a second step, a “3D scaffold” is made which to conduct the ink along its surface. The result is a process which can easily be scaled using additive manufacturing.

The new TEGs could also be used for the recovery of waste heat in industry and heating systems or in the geothermal energy sector. The research was funded by the German Research Foundation, the Federal Ministry of Education and Research, KIT’s MERAGEM Graduate School and the German Federal Environmental Foundation.