A micromachine that walks using muscles that it grew for itself has been developed in a US laboratory.

The remarkable device could eventually lead to muscle-based nerve stimulators that let paralysed patients breathe without a ventilator, or to nanobots that clear away plaque from inside the walls of a human coronary artery.

Scientists at the University of California in Los Angeles grew a length of muscle about 100 microns long on the underside of a silicon frame measuring 200 microns. The cells were taken from a rat’s heart and grown in a culture that mimics natural biological conditions. The muscle contracts and relaxes by feeding on glucose in a solution, the contractions causing the tiny structure to shuffle along.

Previously the team had to manually attach developed muscle tissue to a micromachine – a complex procedure which invariably causes damage to the tissue.

They built the new micromachine by etching the silicon structure using photolithography before coating the frame with a polymer and selectively depositing gold and chromium. The polymer acts as a mould for the muscle to grow along and the gold provides points to which the growing muscle cells can attach.

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