iSkin silicone smartphone controller
Still a prototype for now, iSkin can be stretched and bent without affecting how it works iSkin

Scientists have developed a touch-sensitive silicone which can turn any part of the human body into a surface for controlling a smartphone. One day they hope it could even be powered by energy drawn from the body.

Developed at the Max Planck Institute and Saarland University in Germany, the material, called iSkin, could be used to add music playback controls to a wearer's arm, or a way of quickly answering or rejecting a call by tapping anywhere on their body. iSkin is made from biocompatible silicone rubber which is pressure sensitive and contains carbon to make it conductive.

Unlike regular circuit boards, the iSkin silicone is thin, soft and flexible; it can even detect touches from the wearer – and how hard they are pressing – when it is being bent or stretched by up to 30%. Its developers say it can unlock new ways to interact with mobile devices in ways that current wearable technology cannot.

"Current electronics are mostly using rigid components which are very uncomfortable to wear on the body and are limiting the locations to, for example, the wrist or on the head to be worn," co-developer Martin Weigel told Reuters. "But our sensor is a flexible and stretchable sensor, so it can cover many locations. For example, even the backside of the ear or the forearm. So, we have a much larger input space than current electronics allow for."

The silicone is between 0.3 and 0.7mm thick and supports both taps and firm presses, as well as multiple presses in different locations at once. In testing, iSkin was found to be 92% accurate for taps and over 98% accurate for firm presses.

"(The) technology is initially coming from robotics where it's used to give robots kind of a feeling similar to the human body, to human skin. However, we are the first to look into how we can use it on the body to control mobile devices; so as a kind of second-skin which nicely conforms to your body," said Weigel.

Weigel sees a future where users of iSkin could tap on their arm to answer a phone call or adjust the volume of music they are listening to, without the need to reach for the phone in their pocket or bag. Using medical-grade adhesive, iSkin can easily be peeled off without damaging the skin. For now, the prototype is crudely wired to a computer, but Weigel believes iSkin could one day integrate its own microchips, allowing it to connect to a phone wirelessly over Bluetooth. He also claims it could be possible to integrate an energy-harvesting system which draws energy from the wearer's body the iSkin system.