One day soon, your iPhone or Android mobile device will be sporting not a glass screen, but a flexible polymer one, making it possible to use touch technology in more innovative ways – from developing a flexible phone or tablet that can fold, to “electronic skin” that can repair a scratched screen automatically.
According to researchers at the Technion in Haifa, the same technology could also be used for things such as artificial skin, with the polymer that they developed integrated into the skin of burn victims, providing them with a new, healable layer of artificial skin that can repair itself, just like real skin.
The real-life sci-fi technology was developed in the lab of Prof. Hossam Haick, who worked on the project together with Technion researcher Dr. Tan-Phat Huynh.
“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. “We have developed a complete, self-healing device in the form of a bendable and stretchable chemiresistor where every part, no matter where the device is cut or scratched, is self-healing.”
Flexible sensors are the next big thing in electronics. Far more responsive than glass touch displays where the backplane sensor on the inside of the glass measures just the input (which pixels are being touched), “front loaded” flexible embedded sensors on a polymer cover can measure pressure as well.
With flexible sensors, for example, passwords could become a thing of the past, as sensors will be able to precisely measure the makeup and touch of a user, ensuring that only their finger or thumb is the one that a device responds to. Flexibility has other uses as well, and Apple, among others, has patented a system to create portable devices made almost exclusively from flexible components, essentially a foldable iPhone or iPad.
The technology for flexible sensors has been around for several years, and it is already used in consumer electronics, robotics, health care and space technology. So why don’t we have flexible iPhones yet? One reason is that the technology is not quite ready for prime time. Because of their sensitivity and the fact that they are on the surface of the device and not behind glass, the sensors can be easily scratched and otherwise damaged, potentially destroying their functionality.
That won’t happen with the new Technion technology, said Haick. Researchers who were inspired by the healing properties in human skin have developed materials that can be integrated into flexible devices to “heal” scratches or damaging cuts that might compromise device functionality.
The advancement, using a new kind of synthetic polymer (a large molecule composed of many repeated smaller molecules), includes self-healing properties that mimic human skin, so that like human skin “wounds” and scratches can quickly heal themselves in a remarkably short time – less than a day, Haick added.
The results of the research were published in the latest issue of the professional journal Advanced Materials. According to the study, the Technion team has developed “a non-biological and flexible self-healing platform with tailored sensitivity toward one or a combination of pressure, strain, gas analytes and temperature. For demonstration, a complete self-healing device is described in the form of a bendable and stretchable chemiresistor, where every part is self-healing.”
Essentially a reworking of current sensors, the new self-healing sensor is comprised of a substrate with 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,” the lab said. Condensation makes the substrate swell, allowing the polymer chains to begin to flow freely and, in effect, begin “healing.” Once healed, the nonbiological, chemiresistor still has high sensitivity to touch, pressure and strain, which the researchers tested in demanding stretching and bending tests.
The material can also heal itself even at extreme temperatures of -20°C to 40°C (-4°F to 104°F). This property, said the researchers, can extend applications of the self-healing sensor to areas of the world with extreme climates.
Even more impressive, the healed area — because of the interaction of the chemicals on that spot — becomes even “stronger” and more resistant to scratching. Essentially, healing makes the self-healing sensor even stronger. The researchers noted in their paper that “the healing efficiency of this chemiresistor is so high that the sensor survived several cuttings at random positions,” the lab said.
If it works on iPhones, it will work on humans, too, said co-developer Dr. Tan-Phat Huynh. “The self-healing sensor raises expectations that flexible devices might someday be self-administered, which increases their reliability. One day, the self-healing sensor could serve as a platform for biosensors that monitor human health using electronic skin.”