Researchers at Graz University in Austria have created an artificial skin that is more sensitive than your fingertip. The skin contains 2,000 sensors per square millimeter, and the researchers designed it to sense humidity, temperature, and pressure, just like human skin. The tiny sensors within the skin material consist of a hydrogel core and a piezoelectric zinc oxide shell. The hydrogel expands or contracts depending on the temperature and also when it absorbs moisture. Pressure can also affect the zinc oxide shell, and these changes lead to an electrical charge, forming the basis of the sensing technology. The material could form a component of advanced prosthetic devices that allow their users to experience their environment more realistically.
Our skin is a sensing marvel, providing us with information on numerous parameters that reflect our environment, from temperature and humidity to physical stimuli, all while protecting our internal tissues. This sensitivity is difficult to mimic in artificial skin, but if prostheses are to provide greater functionality for their users, then such features must be developed. This new technology has paved the way. The key is a high density of small sensors that provide simultaneous information on temperature, humidity, and pressure, all while fitting into an extremely thin structure.
The tiny individual sensors consist of a hydrogel core. The hydrogel can change size and shape in response to moisture, temperature, or physical stimuli. This has an effect on a piezoelectric zinc oxide shell that surrounds the hydrogel, creating an electrical charge that provides information on the measured parameters.
“The hydrogel can absorb water and thus expands upon changes in humidity and temperature. In doing so, it exerts pressure on the piezoelectric zinc oxide, which responds to this and all other mechanical stresses with an electrical signal,” said Anna Maria Coclite, one of the lead creators of the new artificial skin.
The resulting e-skin can outperform our own skin in terms of sensing small objects. Human skin can detect objects that are approximately 1 square millimeter in size, whereas this artificial skin can reportedly detect ones that are up to one thousand times smaller.
The artificial skin is also thinner than our own. Human epidermis is approximately 0.03–2 millimeters in thickness. “The first artificial skin samples are six micrometres thin, or 0.006 millimetres,” said Coclite. “But it could be even thinner.”
Studies in Advanced Materials Technologies: Smart Core‐Shell Nanostructures for Force, Humidity, and Temperature Multi‐Stimuli Responsiveness
Via: Graz University