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Ro-botany: rotting robots in the garden

There’s something really exciting going on in the compost heap at the Botanic Garden. Don’t believe me? What if I told you that buried deep within the hot and humid milieu of the compost, lay the components of future robots that could help clean up environmental disasters such as oil spills. It might sound like a piece of science fiction, but in fact it’s part of a two year project by the Bristol Robotics Laboratory that is looking at the development of a biodegradable robot.

The aim of the project is to build a robot that is self-powered, can move and biodegrades at the end of its life.  It’s an idea that was conceived by Dr. Jonathan Rossiter from the University of Bristol and Dr. Ioannis Ieropoulos from the University of the West of England (UWE). Rossiter is an expert in the development of artificial muscles and Ieropoulos is an expert in the development of microbial fuel cells. So, when these two put their heads together to think about the future and the biggest challenges that lay ahead, they came up with the biodegradable robot.

Look out - there may be a future robot rotting in the
Botanic Garden's compost heap!
Robots have the potential of conducting large scale clean up of the environment in order to minimize the risk to humans. However, releasing the number of robots necessary to clean up an environmental mess within a reasonable time frame isn’t currently feasible as there is too much effort required to collect them all afterwards. If the robots aren’t collected, they themselves pose a toxic threat as batteries and other components degrade and release chemicals into the environment. The solution? A completely biodegradable robot.

One obvious application of such a robot is in the event of an oil spill. “There are hydrocarbon-degrading organisms that will utilise crude oil,” said Dr. Ieropoulos, a Senior Research Fellow in Engineering Design and Mathematics at UWE. “A futuristic scenario is to release these robots with guts full of microbes that use the crude oil. The robots swim about and the microbes in the fuel cell utilise the crude oil to power the swimming action. By the time they have finished, the robots have biodegraded gracefully into that very same environment without harming it.”

The hard bits, soft bits and active bits...

The workings of a robot can be divided into three main components: 1) the stomach – where energy is generated, 2) the body – which enables movement and 3) the brain – which can receive information from the environment and potentially make decisions. For this project, Rossiter and Ieropoulos are concentrating on developing the first two components – the stomach and body.

The ‘stomach’ is a critical component of the project as it enables the robots to be self-powered. Microbial fuel cells, are a technology that uses microorganisms to directly convert organic matter into electricity.
For the body, the researchers have to identify a range of biodegradable materials: hard bits to give it structure, soft bits that act as skin to hold it all together and active bits to help it move. For this, they are looking to both human-made materials as well as biological materials (such as cellulose).

“There are two approaches really,” said Dr. Rossiter, a Senior Lecturer in the Faculty of Engineering at Bristol. “We take man-made materials that we know work as artificial muscles and see if they degrade and we take materials that we know biodegrade and see if we can build muscles out of them.”

What’s happening in the compost heap...

The researchers are looking at the behaviour of a range of biodegradable materials in different environments. They will compare how the materials decompose in the lab, exposed only to room temperature and air, with how they decompose in the compost heap, and finally how they decompose in a bacterial broth, which replicates the microbial fuel cell environment.

Each week, the materials are weighed to determine how much mass has been lost over time. The results from the compost heap will be compared with those from the lab to determine whether the bacterial broth in the lab is accelerating the biodegradation process, and if so, how much electricity is being generated through that biodegradation.

“We can feed the microbes in the fuel cell things from the environment,” said Ieropoulos, “but if there are biodegrading organisms inside the fuel cell, then at the end of the robot’s lifetime, we want them to consume the chassis and muscles of the robot itself.” 

The project began in August 2012 and will run over two years with support from the Leverhulme Trust. At the end of the two years, Ieropoulos and Rossiter hope to have a proof of concept to show that a self-powered biodegradable robot is possible.

So, next time you visit the Garden and happen to be by the compost, bear in mind that there might be a future robot lurking in there!


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