With the aid of a 3-D printer, researchers have fashioned soft,
quarter-inch-long biological robots out of gel-like material and
rat heart cells. When the cells beat, the bio-bots take a step.
The robots resemble tiny springboards, each with one long, thin
leg resting on a stout supporting leg. The thin leg is covered
in the heart cells. When the cells beat, the long leg pulses,
propelling the bio-bot forward, according to the research team
from the University of Illinois.