How robot muscles could be built from DNA-inspired ‘supercoiling’ fibers

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My coworkers and I found a simple method to make effective rotating artificial muscle fibers by just twisting artificial yarns.These yarn fibers might turn by untwisting when we expanded the volume of the yarn by warming it, making it take in small molecules, or by charging it like a battery. We made composite fibers with two polyester sewing threads, each covered in a hydrogel that swells up when it gets damp and then the set twisted together.Swelling the hydrogel by immersing it in water caused the composite fiber to untwist. If the fiber ends were secured to stop untwisting, the fiber started to supercoil instead.

Image via Geoff Spinks, author providedAs a result, the fiber shrank by up to 90% of its original length. In the procedure of diminishing, it did mechanical work equivalent to putting out 1 joule of energy per gram of dry fiber.For comparison, the muscle fibers of mammals like us only diminish by about 20% of their initial length and produce a work output of 0.03 joules per gram. Artificial muscles maintain a high work and power output at little scales.To show their prospective applications, we used our supercoiling muscle fibers to open and close mini tweezers.

By imitating the structure of this complicated genetic particle we have actually found a way to make artificial muscle fibers far more powerful than those found in nature, with prospective applications in numerous kinds of miniature machinery such as prosthetic hands and dextrous robotic devices.The power of the helixDNA is not the only helix in nature. My associates and I found an easy way to make powerful turning synthetic muscle fibers by just twisting artificial yarns.These yarn fibers could rotate by untwisting when we broadened the volume of the yarn by warming it, making it soak up little molecules, or by charging it like a battery. Diminishing the fiber triggered the fibers to re-twist. We made composite fibers with 2 polyester sewing threads, each covered in a hydrogel that swells up when it gets wet and then the pair twisted together.Swelling the hydrogel by immersing it in water caused the composite fiber to untwist. If the fiber ends were secured to stop untwisting, the fiber started to supercoil rather.