A U.S. scientist has created a monster a robot with a taste for flesh.

The "gastrobot" is the first robot that's completely powered by food.

The three-metre robotic train, appropriately named Chew Chew, has a microbial fuel cell for a stomach.

The device uses bacteria, in this case E. coli, to break down food and convert chemical energy into electricity. The energy must charge the robot's battery before it has enough power to move itself. When the power runs out, the robot has to be fed again.

Inventor Stuart Wilkinson, of the University of South Florida in Tampa, says meat is the ideal fuel in terms of energy gain.

But for now, Chew Chew's diet consists of only sugar cubes because they are almost entirely broken down. The little waste that is produced is made up of carbon dioxide and water.

Wilkinson says the long-term goal is to have robots that can feed themselves.

A report in New Scientist magazine says the gastrobot will make its public debut in August at a robotics conference in Hawaii.