Academics at the Bristol Robotics Laboratory (BRL) have developed a robot that feeds on organic matter in dirty water, potentially a step in the development of autonomous robots capable of long-term self-power.

The “Row-bot" mimics the way that an aquatic insect known as the water boatman feeds on organisms in water. Like the water boatman, it uses a broad, beaklike mouth to sweep both fluid and suspended particulate matter into its microbial fuel cell (MFC) "stomach," opening and closing the mouth-like orifice at each end through the bending of a flexible acetate envelope structure.

The Row-bot with its "mouth" open. Image credit: Hemma Philamore, University of Bristol/BRL.The MFC stomach uses the bio-degradation of organic matter to generate electricity using bio-inspired mechanisms. When it has recharged its electrical energy stores, the Row-bot swims to a new location, ready for another gulp of water. The prototype robot combines two subsystems: a bio-inspired energy source and bio-inspired actuation. The first subsystem shows the power-generation capability of the robot. A second duplicate system starts the refueling process and moves the robot with an energy requirement that is less than the energy generated by the first system. This is achieved by feeding on chemical energy contained in its surrounding fluid to support microbial metabolism inside its MFC stomach.

By using both these systems, the robot can be totally independent in water, providing enough energy is available in the fluid.
"Most robots require recharging or refueling, often requiring human involvement,” says Jonathan Rossiter, professor of robotics at the University of Bristol and BRL. The Row-bot project aims to develop an autonomous swimming robot able to operate in remote, unstructured locations by scavenging its energy from the environment.

The researchers say that the Row-bot ultimately could be used in clean-ups of environmental contaminants, such as oil spills and harmful algal bloom, as well as in long-term autonomous environmental monitoring of hazardous environments—for example, areas hit by natural or man-made disasters.