12 December, Washington
Normally we flush it down the toilet, but science wise, urine is tipped to be a fuel for the future. At least, that’s what this team of researchers thinks, because they’ve made a pair of socks that uses the liquid to generate electricity.
A pair of socks embedded with miniaturised microbial fuel cells (MFCs) and fuelled with urine pumped by the wearer’s footsteps has powered a wireless transmitter to send a signal to a PC. This is the first self-sufficient system powered by a wearable energy generator based on microbial fuel cell technology.
In a lab-based experiment, 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.
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.
University of the West of England’s Ioannis Ieropoulos said that this work 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.
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.
The scientific paper is published in Bioinspiration and Biomimetics.