Temperature sensor for artificial skin

The capacity to detect temperature changes is an important function of the human skin. Researchers at ETH Zurich have now developed a highly sensitive and, at the same time, flexible temperature sensor, which could soon be used in prosthetic limbs and robotic arms.

Serendipity played an important role in the discovery of this temperature sensor. In his research, Raffaele Di Giacomo, who led the project in the laboratory of ETH-professor Daraio, had initially stumbled upon a peculiarity of the vegetable material pectin. Pectin is better known around the household as a gelling agent for puddings and marmalades, but Di Giacomo was interested in a different property of this substance, which is composed of many interconnected sugar molecules.

Experiments on tree branches, whose cell walls contain pectin, had shown that their electrical conductivity depended strongly on temperature. To investigate the mechanism behind that dependence, the researchers in Zurich created an artificial “cyberwood” made from pectin and carbon nanotubes.

By measuring the electrical resistance at different temperatures they eventually found that calcium ions trapped at the contact points between two sugar molecules were responsible for the sensing mechanism. The higher the temperature, the more free calcium ions were present in the artificial wood, and hence the better it conducted electrical current.

Read more at ETH Zurich

Image Credit: ETH Zurich / Raffaele di Giacomo

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