Researchers in Switzerland have developed stretchable electronics that can be bent and extended up to four times their original length, opening up new uses in a number of sectors including connected clothing.

Conductive tracks are usually hard-printed on a board. But those developed at Ecole Polytechnique Fédérale de Lausanne (EPFL) are almost as flexible as rubber and can be stretched up to four times their original length and in all directions.

They can also be stretched a million times without cracking or interrupting their conductivity, according to research published in the journal Advanced Materials.

Both solid and flexible, the new metallic and partially liquid film offers a wide range of possible applications, including integrating it into fabric and used in connected clothing.

Other possibilities include using it to make circuits that can be twisted and stretched – ideal for artificial skin on prosthetics or robotic machines. And because it follows the shape and movements of the human body, it could be used for sensors designed to monitor particular biological functions.

"We can come up with all sorts of uses, in forms that are complex, moving or that change over time," said Hadrien Michaud, a PhD student at the Laboratory for Soft Bioelectronic Interfaces (LSBI) and one of the study authors.

Until now, elastic electronic circuits have been constructed by applying liquid metal to a thin film in polymer supports with elastic properties, which produce relatively thick structures.

"Using the deposition and structuring methods that we developed, it's possible to make tracks that are very narrow – several hundredths of a nanometre thick – and very reliable," said Stéphanie Lacour, holder of the Bertarelli Foundation Chair in Neuroprosthetic Technology and who runs the lab.