The researchers are currently experimenting with carbon-based self-healing composites and self-healing transistors. (Stock image) Credit: © praisaeng / Fotolia
Flexible sensors have been developed for use in 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 sensors they can be easily scratched and otherwise damaged, potentially destroying functionality. Researchers in the Dept of Chemical Engineering at the Technion, Israel, who were inspired by the healing properties in human skin, have developed materials that can be integrated into flexible devices to “heal” incidental scratches or cuts. It uses a new kind of synthetic polymer with self-healing properties that mimic human skin, which means that e-skin “wounds” can quickly “heal” themselves in remarkably short time – less than a day.
“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 has superior healability at extreme temperatures of -20 -40 C. This property can extend applications to areas of extreme climates.
The healing polymer works quickest from 0 – 10C, 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 20X or more cutting/healing cycles than prior to healing. ie healing makes the self-healing sensor even stronger.
The researchers are currently experimenting with carbon-based self-healing composites and self-healing transistors. “One day, the self-healing sensor could serve as a platform for biosensors that monitor human health using electronic skin.”
http://www.healthnews.uc.edu/news/?/26864
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