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Mohsen Shahinpoor, chair of the University of Maine Department of Mechanical Engineering and director of the state's first biomedical engineering lab, and senior Mark Liimakka of Old Town, Maine, demonstrate the use of robotic forceps in heart surgery.
Shahinpoor’s research into intelligent robotics systems began in the 1980s at the University of New Mexico, where he was the Regents Professor in the Department of Mechanical Engineering and professor of surgery and biomedical engineering in the School of Medicine. He studied the biomechanics of mammalian muscle, in which bundles of fibers contract in response to electricity from nearby nerves. By 1993, Shahinpoor’s research led to a patent for the first electroactive polymer — a charged material called an ionic polymeric gel that deformed when placed in an electric field.
Within a few years, his intelligent materials lab in New Mexico was a breeding ground for artificial muscles that squirmed and writhed like living things with the help of two thin electrodes surrounding a soft plastic saturated with lithium ions. The artificial muscles move when low-volt electric current sends positively charged ions shuttling toward the negatively charged foil, bending the material and exerting force.
Take the wisp of shiny metal — a piece of flexible ionic Teflon sandwiched between platinum electrodes — snipped into the shape of a human hand that Shahinpoor keeps on the desk in his office. When attached to as little as 5 volts of electricity, the fingers on the cutout stir to life, clenching and releasing without the help of gears, levers, pulleys or bearings. Charged ions in the polymer migrate, distorting the shape of the material. Reverse the current and the artificial muscle bends in the opposite direction.
Shahinpoor envisions a day when life-size hands or legs made of supple artificial muscles attached to electrodes are transformed into noiseless prosthetics for amputees. He sees great promise in using plastic muscle to assist in the pumping of a diseased heart, and already holds patents for a multifingered band of electrically controlled artificial muscle that could compress a congestive heart.
Because they flex, artificial muscles could also be used to make pumps for delivering drugs, such as insulin, to the body, Shahinpoor says, and to drain the liquid from a swollen brain or from inside the eye of a person with glaucoma. They could be used in orthopedic applications to enhance joint movements, or for humanlike prostheses controlled by the brain.
“There are many needs in medicine that could benefit from this,” says Shahinpoor, whose research has led to multiple patents, hundreds of papers and a book in the artificial-muscle field. “My goal with this technology is to help people.”
At UMaine, Shahinpoor hopes to make his biomedical engineering lab into a center of innovation and learning, where faculty and students can work with the state’s medical institutions to solve problems using robotics and artificial muscles.
“It would be a synergy of engineering and medicine that may lead to many inventions that could revolutionize medicine,” says Shahinpoor. “And that’s what motivates students when they get involved in these areas. They know what they’re researching may impact people through health engineering.”
