Plastic printing shrinks the thermoelectric generator

April 09, 2018 // By Christoph Hammerschmidt
Otego, a spin-off of the Karlsruhe Institute of Technology (KIT) in Germany, is making thermoelectric generators (TEG) as small as a sugar cube for industrial and consumer power applications.

The Otego team is making thermoelectric generators (TEG) suitable for the mass market by means of new materials and large-scale industrial production processes; production of a prototype series is to start before the end of this year. The innovative energy converter "oTEG" promises numerous application possibilities in the areas of Industry 4.0 and Smart Home.

Just as solar cells convert light into electrical energy, TEGs can generate electricity from ambient heat and thus ensure a continuous supply. "This means that a wide variety of sensors, evaluation electronics and radio connections can be operated without batteries: From simple products such as a wirelessly communicating data tracker to distributed sensor nodes in industrial plants and in future also electronic thermostats on radiators," says Frederick Lessmann, one of the company founders.

The Seebeck effect makes it possible to convert the energy from the ambient heat: If there is a temperature gradient within a thermoelectric semiconductor material, an electrical voltage is built up in it. If another semiconductor material is combined with voltage behavior that is as contradictory as possible, the potential of this "thermocouple" can be used as a voltage source for small consumers. Thousands of these thermocouples are connected in series in the oTEG. The generated voltage is in the single-digit voltage range and is sufficient to supply microelectronic circuits. The special feature of the oTEGs is the production process developed in-house: "We print the electrical conductor tracks on extremely thin plastic films - this is about as fast as with newspaper printing," explains Lessmann. The printed films are then formed into a compact shape with the aid of a special automated origami folding process.

This means that the TEGs are not only an energy source for convenient applications in the domestic environment, but can also be used to supply a large number of self-sufficient industrial sensors in larger systems. Polymer materials make the oTEG mechanically flexible and insensitive to shocks and