Powering a personal wireless network with urine

By Nick Flaherty www.flaherty.co.uk

I've been following the development of miniaturised microbial fuel cells (MFCs) at the Bristol Robotics Laboratory for a couple of years now, and it's great to see a prototype with a good use case.

Microbial fuel cells (MFCs) replicate biological processes to generate energy, and researchers at UWE in Bristol have embedded the technology in a pair of socks. The key is that the MFCs take in urine and produce enough energy to power a wireless transceiver, creating a personal area network (PAN) link without having to use batteries.  This is the first self-sufficient system powered by a wearable energy generator based on microbial fuel cell technology and the research paper, ‘Self-sufficient Wireless Transmitter Powered by Foot-pumped Urine Operating Wearable MFC’, is published in Bioinspiration and Biomimetics.

The paper describes a lab-based experiment led by Professor Ioannis Ieropoulos, of the Bristol BioEnergy Centre at the University of the West of England (UWE Bristol). The Bristol BioEnergy Centre is based in Bristol Robotics Laboratory, a collaborative partnership between the University of the West of England (UWE Bristol) and the University of Bristol.

Researchers at UWE have developed socks that convert urine into energy to
power a wireless transceiver for a personal area network without batteries

Soft MFCs embedded within a pair of socks was supplied with fresh urine, circulated by the human operator walking.  Normally, continuous-flow MFCs would rely on a mains powered pump to circulate the urine over the microbial fuel cells, but this experiment relied solely on human activity, which is a key step forward (pun intended). The manual pump was based on a simple fish circulatory system and the action of walking caused the urine to pass over the MFCs and generate energy. Soft tubes, placed under the heels, ensured frequent fluid push–pull by walking. The wearable MFC system successfully ran a wireless transmission board, which was able to send a message every two minutes to the PC-controlled receiver module.

“Having already powered a mobile phone with MFCs using urine as fuel, we wanted to see if we could replicate this success in wearable technology. We also wanted the system to be entirely self-sufficient, running only on human power – using urine as fuel and the action of the foot as the pump,” said Professor Ieropoulos. “This opens up possibilities of using waste for powering portable and wearable electronics. For example, recent research shows it should be possible to develop a system based on wearable MFC technology to transmit a person’s coordinates in an emergency situation. At the same time this would indicate proof of life since the device will only work if the operator‘s urine fuels the MFCs.”

The challenge now is how the MFC cells are refuelled with urine.

Microbial fuel cells (MFCs) use bacteria to generate electricity from waste fluids. They tap into the biochemical energy used for microbial growth and convert it directly into electricity.  This technology can use any form of organic waste and turn it into useful energy without relying on fossil fuels, making this a valuable green technology. Parts of this work were funded by the UK Engineering & Physical Sciences Research Council (EPSRC) and the Bill & Melinda Gates Foundation.

The research is important in other areas of robotics as it would allow autonomous systems to generate power from waste materials to operate for days or even months at a time.