Scientists have been hard at work designing artificial muscle that gets activated when exposed to light:

Sakar and colleagues at MIT teamed up with scientists at the University of Pennsylvania to genetically engineer mouse muscle cells that twinge in response to light. The researchers loaded the cells with a light-activated protein, let the cells fuse into fibers, and mixed them with a special gel to form 3-D strips smaller than the width of a grain of rice. Then, they hit the strips with narrow beams of blue light.

Only the light-zapped fibers jumped; those in the dark stayed still. “I was hoping it would work, but the first time I saw it, it was amazing,” Sakar says. “I was very, very excited.”

Sakar and colleagues even got the muscle fibers to show off a bit of brawn. Tissue strips stretched between two tiny elastic posts pulled the structures together when scientists switched on the light.

Read more at Science News. The full report is on line Lab on a Chip.  The MIT press release is here with a neat video.