Scientists at the University of California, Los Angeles (UCLA), have successfully built and tested a “muscle-powered” microdevice that merges silicon technology with biology. The contraption was made of a silicon microdevice connected to “legs” made of bundles of rat heart cells grown on gold. The microdevice was able to “walk” because of the natural contractions of these heart cells, heralding a day when such devices walk through our cells looking for and perhaps repairing damage.