From New Scientist:
You might expect a robot's heartbeat to be a metallic ticking. But the pulsing in this video isn't completely artificial: it's powered by living material.Note the blasé, almost jaded, en passant ref to Ecobot.
Created by Peter Walters from the University of the West of England in Bristol, UK, and colleagues, the pump uses the gas released by live yeast to generate pressure and distend a membrane, turning it into an artificial muscle. A valve - activated by electricity produced by a microbial fuel cell - controls the movement of the membrane. It opens to release pressure when the muscle is fully expanded, allowing it to shrink back to its resting state again to begin another cycle.
Walters says that using yeast allows a lot of pressure to be generated quickly. The downside is the pong: "With the live yeast, the laboratory smells like a brewery," he says.
Getting rid of the waste that the yeast produces is also a challenge. The team is developing the system in conjunction with Ecobot, a robot that can digest food and sewage to power itself, which could potentially feed off the pump's waste. A new version of the muscle will be able to pump liquid, circulating liquid food and water for Ecobot's microbial fuel cell, which could in turn power the muscle....MORE, including video.