Ras Labs artificial muscles reimagine the future of prosthetics

Lenore Rasmussen, founder of Ras Labs, with samples of her synthetic muscles. (Photo: Gretchen Ertl for The Boston Globe)
Lenore Rasmussen, founder of Ras Labs, with samples of her synthetic muscles. (Photo: Gretchen Ertl for The Boston Globe)

When the SpaceX Falcon 9 rocket was launched from Cape Canaveral this month, its cargo included the usual stash of supplies for the crew of the International Space Station. But tucked into the Dragon spacecraft was a science experiment that one day could help artificial limbs move with the grace and agility of real hands and legs.

The material is a small block of gel-like substance with the bounce and elasticity of gummy bears. They are synthetic muscles that, when powered with an electrical charge, contract and expand like human tissue and could one day make artificial limbs move in lifelike motions.

The material was created by Lenore Rasmussen, who credits the idea to a long-ago day back in college at Virginia Tech. In a biochemistry lab, she noticed that a blob of gel wobbled oddly when a current was passed through it.


“To be honest, it was a screw-up in the lab,” Rasmussen said. “That was hard to replicate.”

The image came back to her two years later, when she researched prostheses after her cousin almost lost a foot in a farming accident. She discovered there were few devices that both looked and worked like a human limb.


“The functional prosthetics don’t look human. Then you have your realistic-looking ones that are works of art down to fingernails and freckles, but they don’t function,” Rasmussen said. “My question was: Why can’t we bridge the two?”

Rasmussen continued to experiment at night in her home while teaching science at Raritan Valley Community College in New Jersey.

“I was zapping stuff down in my basement,” contact lenses, diaper liners, anything that absorbed water and reacted to electricity.


Polymer chemists have long studied “electroactive” polymers, a family of squishy, water-logged materials that move to an electrical current. She made a breakthrough in 2006, when instead of bending as expected, one solution contracted like a living tissue.

Over the next decade, she worked to more precisely manipulate how the material moved with current. She also beefed up the gel substance to make it more durable.

“It’s hard to find things that can take the dose that this material was exposed to, that maintains itself as a single entity that doesn’t fall apart or doesn’t turn into a mushy gel,” said Charles Gentile, a researcher at the Princeton Plasma Physics Lab in Princeton, N.J., where Rasmussen has conducted research.

Rasmussen, 52, received a PhD in chemistry from Virginia Tech and launched Ras Labs in Quincy in 2003. Eric Sandberg, the company’s chief executive, joined in 2014.

The pair’s near-term goal is to use the material to line the sockets of prostheses and provide a more natural, comfortable fit with the human body. In February, Ras Labs won $25,000 from the Philadelphia Pediatric Medical Device Consortium to test this in artificial limbs for children.

Rasmussen’s material is being tested at the Space Station to determine its durability in an environment with high levels of radiation.

After Ras Labs was a finalist in the MassChallenge startup competition in 2013, the Center for the Advancement of Science in Space, which manages science experiments on the Space Station, selected its materials for testing.


It turns out that one of the challenges in long-distance space travel is the corrosive effect radiation has on manmade and natural materials. Rasmussen has learned that her soup mix of substances made the gel-like material practically indestructible. Dry, the slabs are as hard as stale biscuits, but they return to a supple form with a splash of water. They can withstand high heat and extreme cold, and even the pressure of a deep-water environment.

Her initial experiments have indicated the synthetic muscles could survive a trip to Mars.

Strength, flexibility, and durability constitute a rare combination of traits; for this, Ras Labs has drawn interest from the US military, which funded some of its tests, and from hospitals, makers of prosthetic devices, and robotics companies.

Rasmussen and her mother, Winola Carman, traveled to Florida in April to watch the SpaceX rocket launch.

“When she took chemistry, her whole life changed, because chemistry was her thing,” Carman said. “It’s absolutely amazing that her material is going up. It’s actually there.”

Nidhi Subbaraman writes about science and research. Email her at nidhi.subbaraman@globe.com.
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