Researchers are developing a synthetic stomach for a robot so that it can eat food for power. Developed by the Bristol Robotics Lab, the Ecobot III is not the first robot that employs a microbial fuel cell that uses bacteria to "digest" food as a fuel source. But it is the first that has a system to crap out the waste. Apparently, its current diet is processed sewage containing "minerals, salts, yeast extracts and other nutrients." Eventually, they hope to feed it flies. From New Scientist:
"Diarrhoea-bot would be more appropriate," Melhuish admits. "It's not exactly knocking out rabbit pellets." Even so, he says, it marks the first demonstration of a biomass-powered robot that can operate unaided for some time.
The key to getting this gut to work, says Ieropoulos, is a recycling system that relies on a gravity-fed peristaltic pump which, like the human colon, applies waves of pressure to squeeze unwanted matter out of a tube.