- Scientists at the National University of Singapore have recently developed a new synthetic self-healing electronic skin.
- Unlike previous self-healing e-skins, this one is unaffected by water.
- Potential applications for this material range from soft robotics to healthcare.
From the 1974 Marvel comics superhero Wolverine to the latest Terminator movie, regenerative superpowers have become a regular feature in entertainment media. Audiences are drawn to the unearthly magic of CGI as a character’s face, ripped in two, is stitched back together right before their eyes. Miraculous healing that would take years of painful treatment occurs in less than a second, just in time to block the next attack.
Until recently, the idea of a synthetic skin that can rapidly re-heal was pure fantasy. However, recent advances in the field of self-healing materials have made such a concept more feasible. Earlier this year, researchers affiliated with the National University of Singapore and Tsinghua University built on previous work published in December 2016 in Advanced Materials. They created a synthetic substance, which in addition to being transparent, conductive and stretchy, can self-heal in wet and dry environments. As a result, supernatural healing powers no longer seem so far-fetched.
Dr. Benjamin Tee, co-developer of the electronic skin, first became interested in the material from his work with sensors at the National University of Singapore. With his team, he discovered a special type of gel dubbed GLASSES (gel-like, aquatic, stretchable and self-healing electronic skin), a name representative of the product’s transparency. The material is made up of part liquid electrolyte (contains charged particles called ions) and part polymer. Developers have compared it to spaghetti, where the noodles are the polymer and the sauce is the ionic liquid. The sauce and the noodles are attracted to one another, thus maintaining their structure.
GLASSES’s self-healing property comes from the ability of the bonds within the solution to reform after being broken apart, similar to how separated magnets can still come together. Unlike super-healing powers depicted in movies, GLASSES does not model the biological process of repair. Instead of replicating cells to heal tissue, the synthetic material responds differently. When the material is severed, the bonds between the separated portions become detached. However, when they are brought back into contact or very close proximity, the bonds reform, and the resulting material has nearly the same mechanical properties as the original.
Beyond its regenerative ability, GLASSES has other valuable properties. The conditions of the material’s surrounding environment, such as acidity, does not influence its potency. For example, when the gel is submerged in fluids like seawater or lemon juice, its self-healing ability does not decrease. This unique property would be especially helpful when manufacturing underwater machinery or devices in the human body (which is similarly a wet environment).
In addition, the researchers found they could manipulate properties like conductivity and elasticity by changing the amount of ionic liquid contained in the gel. When the ionic liquid concentration increases, the conductivity of the material goes up rapidly. The material also becomes more stretchable, achieving a flexibility similar to that of soft rubber. The versatility of this material enables scientists to use it in a wide number of applications.
One example shared by Dr. Tee is soft robotics. Soft robots mirror how “creatures in nature are usually very soft and squishy, which allows them to manipulate objects in different ways.” A popular example for demonstrating the usefulness of this trait is Elastigirl from the Disney movie The Incredibles; just as her extreme elasticity enables her to perform superhuman tasks, soft robots would have the flexibility to perform many tasks that conventional “hard” robots cannot. For example, if a robot is tasked with the objective of picking up living things, a soft robot could conform to the different shapes of the organisms without damaging them. In healthcare, this material could also aid in the development of more realistic prosthetics and skin grafts. Additionally, GLASSES could be used in human-machine interfaces such as smartphone screens. Imagine having a phone with the ability to re-heal when it becomes cracked!
Before expectations go through the roof, Dr. Tee acknowledges there is still work to be done. He concedes that although the “materials are easy to process now,” they have not been made on a large scale. Rest assured, we won’t see Terminators made of GLASSES anytime soon. But the material will undoubtedly play a role in the creation of future devices, whether they are soft robots, self-healing smartphones, or skin that can repair itself.
Benjamin Tee, PhD, is a principal investigator at the National University of Singapore where he researches nature-inspired sensorware. He has been recognized with awards from the MIT Technology Review, Materials Research Society USA, the Singapore National Academy of Sciences, and the World Economic Forum.
- Cao, Yue et al. “Self-healing electronic skins for aquatic environments.” Nature Electronics, vol. 2, 2019, pp. 75–82.
- “Jellyfish-inspired electronic skin can heal itself under water.” Science in the News, 13 March 2019, http://sitn.hms.harvard.edu/flash/2019/jellyfish-inspired-electronic-skin-can-heal-water/.
- National University of Singapore. “Jellyfish-inspired Electronic Skin Can Heal Itself While Wet.” Futurity, 1 April 2019, https://www.futurity.org/electronic-skin-self-healing-jellyfish-2023282/.
- “Soft Robotics.” Harvard Biodesign Lab, https://biodesign.seas.harvard.edu/soft-robotics.
- Cao, Yue et al. “A Transparent, Self‐Healing, Highly Stretchable Ionic Conductor.” Advanced Materials, vol. 29, no. 10, 2017.
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