Scientists create more powerful, less costly artificial muscle

WASHINGTON, Feb. 21 (PNA/Xinhua) — An international team of researchers said Thursday they successfully used fibers, like those used for fishing lines and sewing threads, to create inexpensive but powerful artificial muscles.

In a paper published in U.S. journal Science, the team led by University of Texas and joined by other research institutes from China, Canada, Turkey, Australia and South Korea described a surprisingly simple way to make muscles by twisting high-strength polymer fibers until these coil up just like one would twist the rubber band of a model toy airplane.

“The new muscles are capable of lifting loads 100 times heavier than human muscles of the same length and weight,” one of the paper’s authors Li Na from University of Texas told Xinhua. “They can generate 7.1 horsepower per kg of muscle weight similar to that produced by a jet engine.”

According to Li, the surprising idea was based on their previous success creating muscles using materials like carbon nanotubes as they hoped to bring down manufacturing cost.

Artificial muscles with similar functions and made of nickel-titanium alloys are extremely expensive as these alloys can cost up to 3,000 U.S. dollars per kilogram.

The new muscles only require materials that cost about five dollars per kilogram, however, Li said.

In their study, Li and her colleagues found that compared to natural muscles, which contract by only about 20 percent, these muscles can contract by about 50 percent of their length.

Muscle strokes also are reversible for millions of cycles as the muscles contract and expand under heavy mechanical loads.

The researchers said the muscles could be used for applications where superhuman strengths are sought such as robots and exoskeletons.

Twisting together a bundle of polyethylene fishing lines, whose total diameter is only about 10 times larger than a human hair, produces a coiled polymer muscle that can lift 16 pounds (about 7.3 kilograms).

Operated in parallel, similar to how natural muscles are configured, a hundred of these polymer muscles could lift about 0.8 tons, the researchers said.

Independently operated coiled polymer muscles having diameter less than a human hair could bring life-like facial expressions to humanoid companion robots for the elderly and dexterous capabilities for minimally invasive robotic microsurgery.

Also, those could power miniature “laboratories on a chip” and devices for communicating the sense of touch from sensors on a remote robotic hand to a human hand, the researchers noted.

The new artificial muscles can be triggered by a number of things including temperature.

Li said they used the muscles to successfully make “smart textiles” whose pores reversibly open and close with changes in temperature.

The researchers also demonstrated feasibility of using environmentally powered muscles to automatically open and close windows of greenhouses or buildings in response to ambient temperature changes, thereby eliminating need for electricity or noisy and costly motors, she added. (PNA/Xinhua)