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A team of researchers from the Helmholtz-Zentrum Berlin has demonstrated that generating electricity does not have to be an expensive task. All that is required is a pencil, a sheet of paper and a conductive ink!

Residual heat is one of the largest unused energy sources in the world. Now, researchers at Helmholtz-Zentrum Berlin have made a breakthrough in their research into suitable thermoelectric materials that could be used to tap this potential energy source.

The thermoelectric effect

The thermoelectric effect was discovered by German physicist Thomas Johann Seebeck in 1821. Seebeck found that when two different metals are exposed to a temperature gradient and brought together an electric current is produced.

Although the residual heat is partially converted into electrical energy, the effect generates a relatively insignificant amount of energy in ordinary metals. This is because a typical metal’s high thermal conductivity results in temperature differences disappearing quickly before much electrical energy can be generated.

Research and innovation in this area have, therefore, focused on identifying materials with high electrical conductivity but low thermal conductivity.

Helmholtz-Zentrum Berlin

The team at Helmholtz-Zentrum Berlin, led by Professor Norbert Nickel, investigated graphite and co-polymer coating films as a possible thermoelectric material. The team covered a small area of ordinary photocopy paper with graphite using an ordinary HB-grade pencil, then applied a transparent, conductive co-polymer paint.

Using a scanning electron microscope and spectroscopic methods, the team found that the pencil deposit left on the paper formed a surface characterised by unordered graphite flakes, some graphene, some clay – creating a surface that maintained good electrical conductivity but with reduced thermal conductivity that is environmentally friendly, inexpensive and non-toxic.

The team now expect their findings could be used to print thermoelectric components onto paper or even onto the human body. In this way, body heat could be used to power small devices or sensors.

Find out more: www.helmholtz-berlin.de

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