Flexing Muscle Sheets Made With Rat Heart Cells

September 6, 2007

Imagine origami that can fold itself into the shape of a fish or a slug—and then swim or crawl around under its own power.

Researchers at Harvard University have created thin sheets of elastic film studded with rat heart muscle cells that are bringing that fantastic scenario closer to reality.

Like Dr. Frankenstein using lightning to bring his monster to life, the research team—led by biomedical engineer Kit Parker—zapped their muscle-bound sheets with electricity.

This coaxed the muscle cells to contract, bending and flexing the polymer sheets. Sometimes the movement continued spontaneously; other times, it proceeded only in tandem with the electrical inputs.

By cutting out triangles, rectangular strips, and other shapes of this material, the researchers were able to make living origami that could swim, grab, and crawl.

The researchers are optimistic that the findings could point the way to sophisticated new "soft robots," effective replacement organs, and better prosthetic devices. (Related: "Flexible Electronics One Step Closer With New Circuits" [December 15, 2005].)

The findings appear in this week's issue of the journal Science.

Swimmers, Claws, and Mini-Machines

After growing sheets of this "muscular thin film," the researchers cut out various shapes according to the kind of gadget they wanted to create.

Triangular sheets of the material behaved like zebrafish, which swim by swinging their tailfin to one side and then straightening their tail and coasting.

The new triangular swimmers aren't going to set any speed records. They moved only a fraction of their length—about an inch (2.4 centimeters)—each minute.

But by making these swimmers, the researchers showed that their muscular thin films can flex quickly and with force.

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