Israeli scientists used a new synthetic polymer to develop a self-healing, flexible sensor that mimics the self-healing properties of human skin.

Imagine an artificial skin that heals itself. Imagine a prosthetic limb that has a sense of touch.

These incredible advances are a step closer to reality thanks to chemical engineering researchers at the Technion-Israel Institute of Technology in Haifa.

Inspired by the natural healing properties of human skin, Prof. Hossam Haick and postdoctoral researcher Tan-Phat Huynh used a new kind of synthetic polymer to develop a self-healing, flexible sensor.

Flexible sensors have already been developed for use in consumer electronics, robotics, healthcare and space flight. However, these sensors are easily damaged. Several scientific groups have succeeded in synthesizing self-healing materials but have not succeeded in integrating them into working devices.

The Israelis therefore experimented with a new material that can be integrated into flexible devices to “heal” incidental scratches or damaging cuts that might otherwise compromise the functionality of the device.

Beyond devices, however, the sensor’s self-healing properties could be incorporated into electronic skin of the future, giving it the critical ability to “heal” itself in less than a day. Theoretically, sensors could also be built into prostheses that would allow wearers to feel changes in their environment.

Haick — the well-known inventor of such futuristic advances as the NaNose cancer sensor — and Huynh published a paper outlining the characteristics and applications of the unique self-healing sensor in the journal Advanced Materials.

Stronger with each healing

“The vulnerability of flexible sensors used in real-world applications calls for the development of self-healing properties similar to how human skin heals,” said Haick. “Accordingly, we have developed a complete, self-healing device in the form of a bendable and stretchable chemi-resistor where every part — no matter where the device is cut or scratched — is self-healing.”

The Israeli sensor platform is comprised of a self-healing substrate, high-conductivity electrodes and molecularly modified gold nanoparticles.

“The gold particles on top of the substrate and between the self-healing electrodes are able to ‘heal’ cracks that could completely disconnect electrical connectivity,” said Haick.

The self-healing sensor is stable from sub-freezing cold to equatorial heat, so it could be used in any part of the world. However, it works most efficiently at temperatures between 0 degrees C and 10 degrees C, when moisture condenses and is then absorbed by the substrate. Condensation makes the substrate swell, allowing the polymer chains to begin to flow freely and, in effect, begin “healing.”

Once healed, the chemi-resistor was shown to retain high sensitivity to touch, pressure and strain under vigorous testing. Surprisingly, it becomes even stronger with each healing cycle.

“The self-healing sensor raises expectations that flexible devices might someday be self-administered, which increases their reliability,” explained Huynh, whose work focuses on the development of self-healing electronic skin.