Flexible electronics that can be stretched up to four times their original length could be incorporated into artificial skin, body sensors and clothing.
Conductive tracks are usually hard printed on a board, but researchers at the Swiss Federal Institute of Technology in Lausanne have demonstrated a new material that is both metallic and partially liquid and can be stretched a million times without cracking or interrupting its conductivity.
The material is almost as flexible as rubber and can be stretched up to four times its original length in all directions.
The team believes it is ideal for artificial skin on prosthetics or robotic machines or it could be integrated into fabric and used in connected clothing. It could also be used for sensors designed to monitor particular biological functions due to its propensity to follow the shape and movements of the human body.
"We can come up with all sorts of uses, in forms that are complex, moving or that change over time," said Hadrien Michaud, one of the study’s authors.
Extensive research went into developing the elastic electronic circuit as traditional components used to make circuits are rigid. The team achieved their flexible material by applying liquid metal, made from an alloy of gold and gallium, to a thin film in polymer supports.
"Not only does gallium possess good electrical properties, but it also has a low melting point, around 30°C," said Arthur Hirsch, co-author of the study.
"So it melts in your hand, and, thanks to the process known as supercooling, it remains liquid at room temperature, even lower."
The layer of gold ensures the gallium remains homogeneous, preventing it from separating into droplets when it comes into contact with the polymer, which would disrupt its conductivity.
"Using the deposition and structuring methods that we developed, it's possible to make tracks that are very narrow - several hundredths of a nanometer thick - and very reliable," said Stéphanie Lacour, who runs the lab.
In October last year Stanford engineers created a plastic ‘skin’ that can detect how hard it is being pressed and relay the information via an electric signal to the brain.
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