Self-healing sensor brings 'electronic skin' closer to reality

November 19, 2015
Self-healing sensor brings 'electronic skin' closer to reality

Flexible sensors have been developed for use in consumer electronics, robotics, health care, and space flight. Future possible applications could include the creation of 'electronic skin' and prosthetic limbs that allow wearers to 'feel' changes in their environments.

One problem with current flexible , however, is that they can be easily scratched and otherwise damaged, potentially destroying their functionality. Researchers in the Department of Chemical Engineering at the Technion - Israel Institute of Technology in Haifa (Israel), who were inspired by the healing properties in human skin, have developed materials that can be integrated into to "heal" incidental scratches or damaging cuts that might compromise device functionality. The advancement, using a new kind of synthetic polymer (a polymer is a large molecule composed of many repeated smaller molecules) has self-healing properties that mimic , which means that e-skin "wounds" can quickly "heal" themselves in remarkably short time – less than a day.

A paper outlining the characteristics and applications of the unique, self-healing sensor has been published in the current issue of Advanced Materials.

"The vulnerability of flexible sensors used in real-world applications calls for the development of self-healing properties similar to how human skins heals," said self-healing sensor co-developer Prof. Hossam Haick. "Accordingly, 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."

The new sensor 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 Prof. Haick.

Once healed, the polymer substrate of the self-healing sensor demonstrates sensitivity to volatile organic compounds (VOCs), with detection capability down to tens of parts per billion. It also demonstrates superior healability at the extreme temperatures of -20 degrees C to 40 degrees C. This property, said the researchers, can extend applications of the self-healing sensor to areas of the world with extreme climates. From sub-freezing cold to equatorial heat, the self-healing sensor is environment-stable.

The healing polymer works quickest, said the researchers, when the temperature is 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 nonbiological, chemiresistor still has high sensitivity to touch, pressure and strain, which the researchers tested in demanding stretching and bending tests.

Another unique feature is that the electrode resistance increases after healing and can survive 20 times or more cutting/healing cycles than prior to healing. 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 researchers are currently experimenting with carbon-based self-healing composites and self-healing transistors.

"The self-healing sensor raises expectations that flexible devices might someday be self-administered, which increases their reliability," explained co-developer Dr. Tan-Phat Huynh, also of the Technion, whose work focuses on the development of self-healing electronic skin. "One day, the self-healing sensor could serve as a platform for biosensors that monitor human health using ."

Explore further: Electrical circuit made of gel can repair itself

More information: Tan-Phat Huynh et al. Self-Healing, Fully Functional, and Multiparametric Flexible Sensing Platform, Advanced Materials (2015). DOI: 10.1002/adma.201504104

Related Stories

Electrical circuit made of gel can repair itself

August 25, 2015

(Phys.org)—Scientists have fabricated a flexible electrical circuit that, when cut into two pieces, can repair itself and fully restore its original conductivity. The circuit is made of a new gel that possesses a combination ...

Research collaboration over drug for chronic wounds

November 13, 2015

The biotech company Omnio based in Swedish Umeå, and led by researcher Tor Ny at Umeå University, launches a research collaboration with the Canadian pharmaceutical company ProMetic to develop a new drug for slow-healing ...

Light-powered healing of a wearable electrical conductor

June 2, 2015

Mechanical failure along a conductive pathway can cause the unexpected shutdown of electronic devices, ultimately limiting device lifetimes. In particular, wearable electronic devices, which inevitably undergo dynamic and ...

Water heals a bioplastic

September 1, 2015

A drop of water self-heals a multiphase polymer derived from the genetic code of squid ring teeth, which may someday extend the life of medical implants, fiber-optic cables and other hard to repair in place objects, according ...

New self-healing plastics developed

April 11, 2014

Scratches in the car finish or cracks in polymer material: Self-healing materials can repair themselves by restoring their initial molecular structure after the damage. Scientists of the Karlsruhe Institute of Technology ...

Recommended for you

Volvo to supply Uber with self-driving cars (Update)

November 20, 2017

Swedish carmaker Volvo Cars said Monday it has signed an agreement to supply "tens of thousands" of self-driving cars to Uber, as the ride-sharing company battles a number of different controversies.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.