A self-healing sensing material has been created

The new material can be used in prosthetics, as well as in the creation of electronic devices.

Scientists have been trying for many years to create a material that would imitate human skin, have the same characteristics and perform similar functions. The main qualities of skin that scientists are trying to recreate are sensitivity and the ability to heal. Thanks to these properties, human skin sends signals to the brain about temperature and pressure and serves as a protective barrier against environmental irritants.

Through painstaking work, Stanford University chemical engineering professor Zhenan Bao's team has succeeded for the first time in creating a material that combines these two qualities.

Over the last ten years, many examples of "artificial skin" have been created, but even the most advanced of them had very serious drawbacks. Some of them require high temperatures to "heal", which makes them impossible to use in everyday household conditions. Others are restored at room temperature, but during the restoration their mechanical or chemical structure changes, which makes them, in fact, disposable. But most importantly, none of these materials were good conductors of electricity.

Zhenan Bao and his colleagues have made a major step forward in this direction and have combined the self-healing properties of a plastic polymer and the electrical conductivity of a metal in a single material for the first time.

The scientists started with a plastic that consisted of long chains of molecules connected by hydrogen bonds. This is a fairly weak connection between the positively charged region of one atom and the negatively charged region of the next. This structure allowed the material to effectively self-heal after external influences. The molecules break down quite easily, but then reconnect in their original form. The result was a flexible material that the scientists compared to toffee left in the refrigerator.

Scientists added microparticles of nickel to this elastic polymer, which increased the mechanical strength of the material. In addition, these particles increased its electrical conductivity: current is easily conducted from one microparticle to another.

The result met all expectations. "Most plastics are good insulators, but we got an excellent conductor," Zhenan Bao summed up.

The scientists then tested the material's ability to recover. They cut a small piece of the material in half with a knife. By lightly pressing the two resulting parts together, the researchers found that the material had regained 75% of its original strength and electrical conductivity. Half an hour later, the material had completely regained its original properties.

"Even human skin takes a few days to heal. So I think we've achieved a pretty good result," said Bao's colleague Benjamin Chi Kion Tee.

The new material also successfully passed the next test - 50 cut-recovery cycles.

The researchers are not going to stop there. In the future, they want to make better use of the nickel particles in the material, as they not only make it stronger and improve its electrical conductivity, but also reduce its ability to self-heal. Using smaller metal particles could make the material even more effective.

By measuring the sensitivity of the material, the scientists found that it can detect and respond to pressure with the force of a handshake. That's why Bao and his team are confident that their invention can be used in prosthetic limbs. In addition, they plan to make their material as thin and transparent as possible so that it can be used to coat electronic devices and their screens.

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