When considering the ultimate flexible appendage, it's hard to argue against the range of an elephant's trunk or the fine motor skills of an octopus's tentacle. For millions of years, the helically wound muscles of these limbs have provided the animals with a profound dexterity thanks to torsional rotation, where muscle fibers cause rotation by contracting against themselves.
In a biomimetic nod to this torsional rotation, an international collaboration of researchers announced the development of new artificial muscles made out of carbon nanotube yarns that twist like an elephant's trunk. However, their rotation is over a thousand times higher than previous artificial muscles and the diameter of each strand is ten times smaller than a human hair.
Researchers from the University of Texas at Dallas, the University of Wollongong in Australia, the University of British Columbia in Canada and Hanyang University in Korea all contributed to the project. The technology will likely be attractive to those using microfluidic pumps, valve drives and mixers.
The nanoscale cylinders of carbon are spun into helical yarns, and when electrically charged, are capable of untwisting. Think of this way: imagine the yarns to be left- and right-handed muscles that can rotate in opposite directions, giving an unparralelled range of motion.
Researchers say the torsional rotation of the nanotube yarns is remarkable, allowing the artificial muscles to accelerate at a 2,000 times heavier paddle — up to 590 revolutions per minute in 1.2 seconds — then reverse their rotation when charged. They are even capable of flexing and unflexing, similar to a Chinese finger trap.
Their findings were announced in the journal Science.