A material that mimics human skin in strength, stretchability, and sensitivity could be used to collect biological data in real-time. Electronic or e-skin may play a vital role in next generation prosthetics, personalized medicine, soft robotics and artificial intelligence.
“The ideal e-skin will mimic the many natural functions of human skin, such as sensing temperature and touch, accurately and in real-time,” says KAUST postdoc Yichen Cai.
However, making suitable and flexible electronics which can perform such delicate tasks is challenging. Each material involved in the making must be engineered carefully.
E-skins are mostly made by layering an active nanomaterial (a sensor) on a stretchy surface which attaches to human skin.
The durability and sensitivity of the material is reduced as the connection between the layers is often weak. On the other hand, if it is too strong then flexibility becomes limited, making it more likely to crack or break the circuit.
“The landscape of skin electronics keeps shifting at a spectacular pace,” says Cai. “The emergence of 2D sensors has accelerated efforts to integrate these atomically thin, mechanically strong materials into functional, durable artificial skins.”
There is now a durable e-skin which uses hydrogel reinforced with silica nanoparticles. It is strong and stretchy bound together with highly conductive nanowires.
“Hydrogels are more than 70 percent water, making them very compatible with human skin tissues,” explained Jie Shen.
Researchers created conductive pathways to the sensor layer that remained intact even when the material was stretched 28 times more than its original size.
The prototype e-skin can sense objects from 20 centimeters away, and respond to stimuli in less than one-tenth of a second. When used as a pressure sensor, it can distinguish handwriting written upon it.
Such e-skins could monitor a range of biological information, such as changes in blood pressure, which can be detected from vibrations in the arteries to movements of large limbs and joints. This data can then be shared and stored.