'Making muscles' isn't showing off on electrical engineer's part

Liliana Naydan
May 01, 2004
muscle man in blue speedo

Qiming Zhang isn't a body builder, but he spends a lot of time making muscles. Zhang, professor of electrical engineering at Penn State, creates artificial muscles that look like thin spools of cling wrap. Even though they don't look "real," he says, they have the same function as real muscles. They can be placed inside the body, and they can flex, move, and carry weight just as real muscles can.

In the body, muscular movement results from voluntary and involuntary contractions triggered by impulses from the brain. Zhang gets the same results with a new class of electroactive polymer and a small electrical stimulus. "It's like rope—you can stretch it out or you can roll it up," says Zhang of the new material, pointing to pictures on his lap-top. The curled forms look like uneaten spaghetti noodles left on a dinner plate.

To explain one way in which the polymer moves, Zhang tears two long pieces of Scotch tape, attaches them to his fingertips with the non-stick sides facing each other, then draws his fingers together. Despite his efforts to unite them, the pieces repel each other. The same electrical charge bends a polymer muscle, he says. The bigger the charge, the more the polymer bends. "The polymer I use to make these rolls has a high dielectric constant," Zhang notes. That means it doesn't require much voltage: a AA battery provides enough to cause a contraction, so powering Zhang's muscles is both inexpensive and safe.Currently, Zhang is working with researchers at the Hershey Medical Center to develop a polymer-based micropump that would allow an artificial heart muscle to pump blood."In theory," he says, "a polymer muscle can replace any muscle in the body."

Qiming Zhang, Ph.D., is professor of electrical engineering, 187 Materials Research Lab, University Park, PA 16802; 814-863-8994; qimingzhang@psu.edu.

Last Updated June 23, 2015