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Machines Like Us

Researchers engineer light-activated skeletal muscle

Sunday, 02 September 2012
by Jennifer Chu

Technique may enable robotic animals that move with the strength and flexibility of their living counterparts.

Many robotic designs take nature as their muse: sticking to walls like geckos, swimming through water like tuna, sprinting across terrain like cheetahs. Such designs borrow properties from nature, using engineered materials and hardware to mimic animals’ behavior.

Now, scientists at MIT and the University of Pennsylvania are taking more than inspiration from nature — they’re taking ingredients. The group has genetically engineered muscle cells to flex in response to light, and is using the light-sensitive tissue to build highly articulated robots. This “bio-integrated” approach, as they call it, may one day enable robotic animals that move with the strength and flexibility of their living counterparts. The researchers’ approach will appear in the journal Lab on a Chip.

Harry Asada, the Ford Professor of Engineering in MIT’s Department of Mechanical Engineering, says the group’s design effectively blurs the boundary between nature and machines.

“With bio-inspired designs, biology is a metaphor, and robotics is the tool to make it happen,” says Asada, who is a co-author on the paper. “With bio-integrated designs, biology provides the materials, not just the metaphor. This is a new direction we’re pushing in biorobotics.”

Seeing the light

Asada and MIT postdoc Mahmut Selman Sakar collaborated with Roger Kamm, the Cecil and Ida Green Distinguished Professor of Biological and Mechanical Engineering, to develop the new approach. In deciding which bodily tissue to use in their robotic design, the researchers set upon skeletal muscle — a stronger, more powerful tissue than cardiac or smooth muscle. But unlike cardiac tissue, which beats involuntarily, skeletal muscles — those involved in running, walking and other physical motions — need external stimuli to flex.

Normally, neurons act to excite muscles, sending electrical impulses that cause a muscle to contract. In the lab, researchers have employed electrodes to stimulate muscle fibers with small amounts of current. But Asada says such a technique, while effective, is unwieldy. Moreover, he says, electrodes, along with their power supply, would likely bog down a small robot.