A super-stretchy, transparent, self-powering sensor that records complex human skin sensations could generate new understanding of patient behavior and robotic actuation, improving the performance of wearable electronics, personal healthcare, and robotics.
Developed by University of Toronto engineering researchers, artificial ionic skin – AlSkin – could become a powerful sensor option in future devices.
“Since it’s hydrogel, it’s inexpensive and biocompatible – you can put it on the skin without any toxic effects. It’s also very adhesive, and it doesn’t fall off, so there are many avenues for this material,” says Professor Xinyu Liu, whose lab focuses on emerging areas of ionic skin and soft robotics.
The AISkin is made from two oppositely charged sheets of stretchable substances known as hydrogels. By overlaying negative and positive ions, researchers created a sensing junction on the gel’s surface. When AISkin is subjected to strain, humidity, or temperature changes, it generates controlled ion movements across the sensing junction. Measuring electrical signals, such as voltage or current, could provide insights into the systems operations.
“If you look at human skin, how we sense heat or pressure, our neural cells transmit information through ions – it’s really not so different from our artificial skin,” Liu explains.
AISkin is also tough and stretchable.
“Our human skin can stretch about 50%, but our AISkin can stretch up to 400% of its length without breaking,” says Binbin Ying, a visiting Ph.D. candidate from McGill University who’s leading the project in Liu’s lab.
AISkin could open doors to skin-like Fitbits that measure multiple body parameters or an adhesive touchpad you can stick onto the surface of your hand, Liu says.
“It could work for athletes looking to measure the rigor of their training, or it could be a wearable touchpad to play games,” he adds.
It could also measure the progress of muscle rehabilitation.
“If you were to put this material on a glove of a patient rehabilitating her hand, the healthcare workers would be able to monitor her finger-bending movements,” Liu notes.
Researchers also envision AISkin being integrated onto soft robots, such as grippers used in manufacturing, to measure data or the pressure necessary to handle delicate, brittle objects.
Future work from Liu’s lab will focus on enhancing AlSkin by shrinking the size of its sensors through microfabrication while also working to add bio-sensing capabilities to the material.
University of Toronto