A group of researchers in Brussels have designed soft robots that can heal themselves when damaged, and another group of robotic engineers in Paris have built robots that can adapt their behavior when broken — two attributes once believed beyond the domain of robotic life. Both groups were inspired by their observations of nature, be it the healing characteristic of living organisms or the adjusting behaviors of injured animals, and they built their machines to mimic those attributes.
Robots that Heal…
Like most living organisms, humans have the ability to heal. We scrape our elbows, feel the sting of a paper cut, pull or tear a muscle during a game, or we are one of 6.8 million people in the United States who break or fracture a bone each year. Thankfully, in most cases, we heal without any external aid or influence.
A team of five scientists at Vrije Universiteit in Brussels, Belgium, seek to endow soft robots with this same self-healing property with the use of synthetic materials. The scientists used elastomer, a flexible polymer with elastic properties more commonly known as rubber, in the construction of three self-healing soft pneumatic robots that imitated a hand, a gripper, and muscles.
Soft robots are built to be flexible and durable for a number of purposes, including interaction with humans, handling of delicate objects, moving through small spaces or across rough and unexpected terrain, and absorbing the shock of impact in active and unpredictable environments. But these same tasks leave the elastomer material vulnerable to irreparable injury, including cuts, perforations and tears resulting from wear during operation.
The Brussels team solved this problem by building their soft robots with a specialized, self-healing elastomer that uses heat to heal both microscopic and macroscopic damage Self-healing polymers are relatively new, though they have already appeared in such commercial applications as, target practice products, civil engineering construction, aerospace applications, and cars and mobile phone covers that can automatically fix minute scratches. Soon we will even see self-healing polymers developed for artificial skin and human prostheses.
The scientists used a Diels-Alder polymer for their robots, which is manufactured using a chemical process that creates a thermoreversible covalent network in the composition of the polymer itself. “Thermoreversible” is exactly as it sounds — it is the ability of a substance to revert to a previous condition after exposure to heat. Therein lies the magic of these new soft robots. When their elastomer was damaged during the team’s experiments, whether by puncture or tear, the scar healed with no signs of weakness after applying a mild heat treatment.
The research team now seeks to develop and implement an autonomous self-healing mechanism into the robots so that they can repair with no external influence (i.e. humans or other machines), or heat their own damaged components themselves.
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