Minute robot powered by living heart muscle

A robot half the width of a human hair has been given legs powered by living heart muscle. It is the first time muscle tissue has been used to propel a micro-machine.

Nasa, the American space agency, which is funding the research, hopes that swarms of crawling "musclebots" might, one day, plug holes in spacecraft made by micrometeorites.

Another possibility is the development of muscle-based nerve stimulators that would allow paralysed people to breathe without the help of a ventilator.

The device, created at the University of California in Los Angeles, is an arch of silicon 50 micrometres wide. Attached to the underside of the arch, a cord of rat heart muscle fibres has been grown. Contraction and relaxation of the heart tissue makes the arch bend and stretch to produce a crawling motion. The muscle, which has to be viewed under a microscope to be seen, is fuelled by a simple glucose nutrient.

New Scientist magazine said yesterday: "While motors need electricity, muscles can draw their energy from glucose; perhaps deposited on the surface where the robot will be working."