Robots small enough to roam the human body and powered by living heart muscle have been built by scientists in Korea.

Sukho Park at Chonnam National University, Korea, and colleagues have designed a cell-powered microrobot. Park's team made the robot by growing heart muscle tissue from a rat onto tiny robotic skeletons made from polydimethylsiloxane (PDMS). PDMS is a biocompatible polymer making the robot suitable for use in biomedical applications.

What is special about these robots, says Park, is that they do not need an external power supply. Instead it is the relaxing and contracting heart muscle cells, which gain their energy from a glucose culture medium, that provide the power. These self-beating cells allow the robot to move its six legs. 

The heart cells are grown onto a moulded plastic skeleton

The robot has three short front legs (400 micrometres long) and three longer back legs (1200 micrometres long), which are all attached to a central rectangular body.  As the heart cells contract, the longer rear legs bend inwards.  This creates a difference in friction between the front and rear legs, which pushes the robot forward.  The scientists measured the robot's average speed at about 100 micrometres per second.

Park says these crab-like robots could be used inside the body to clear blocked tubes or arteries. The robots could travel along the length of a blocked vessel, releasing a dissolving agent to clear the blockage as they go.

Sarah Corcoran