Smart skin made of stretchable silicone that can 'feel' touch, temperature and more (via Kim et al/Nature Communications)
Researchers from Seoul National University, Korea have developed a silicone smart skin that can stretch over prosthetic limbs to enable touch sensations for the user. Previous attempts at enabling senses in prosthetic limbs have focused on sensing pressure to avoid the user applying too much or too little pressure ( think: me Hulk, me smash).
This skin is the first to develop the ability to sense multiple factors including pressure, humidity, and temperature, all in one. The synthetic skin is made of stretchable silicone which can give touch sensations throughout the entire prosthetic limb, not just in the fingers.
Dae-Hyeong Kim leads this team of scientists who have embedded the skin with nanoribbons made up of single crystalline silicone. This ribbons allow the skin to have an array of sensors which include pressure arrays, strain sensors, temperature arrays, humidity sensors, and electro-resistive heaters. The skin also has stretchable mufti-electrode arrays to stimulate nerves making the device compatible with prototype interface methods for prosthetics using this skin.
This allows the skin to sense the wetness or heat of an object, while the strain sensors help keep the prosthetic limb moving within a realistic movement spectrum which they determined through recording natural hand movements.
While the sensors allow the user to get a more realistic sensation of touch using a robotic, prosthetic limb, the electro-resistive heaters exist for the sole purpose of bringing the skin up to body temperature to give the hand a real-life feel to others.
The sensor arrays are layered on top of each other in a thin film to operate effectively with little interference. Most interestingly, platinum nanowires and ceria nanoparticles are used to form an interface with the nerves of the user. This allows the device an opportunity to meld with the human nervous system for a real sensory experience, and possibly grow with further development of mind-controlled prosthetic technologies. These nanoparticles also reduce inflammation which could be caused by the device.
Within their tests, which are documented in a journal article in Nature, the team successfully designed the current skin and hand to perform tasks including human to human contact, touching dry/wet surfaces, hand shaking, and holding a cup.
This skin looks like a promising step towards adding real-life touch sensations to prosthetic devices. Couple this with mind-controlled hands, like the one DARPA is funding, and we could have lifelike robotic replacement limbs for future Earth-dwellers.
This skin builds on a previous experimental array from the Georgia Institute of Technology which researchers there and in China have been working on for the past couple years. However, this skin by Kim and his team seems to be the first one yielding applicable results in a working prototype.
As nanotechnologies advance in the next few years, this skin could become more sophisticated and feature in future robotic prosthetic limbs. It would be a great addition and could give users a new lease on life as they can sense their way through the world once more.
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