Researchers at the Bristol Robotics Laboratory (BRL - alliance between the University of the West of England and University of Bristol) have found a cheap, eco-friendly way to charge future robots.

Researchers have created a device that converts human waste to power EcoBots.

The artificial device that functions similar to a human heart uses artificial muscles made from smart materials called shape memory alloys. The muscles compresses the body of the pump (the middle part of the device) and forces the human urine out into the machine's bacterially-driven 'engine room.'

These autonomous waste-driven EcoBot, in future, can be used in areas where there might be dangerous levels of pollution or predators. They also have the ability to 'perform environmental monitoring tasks such as measuring temperature, humidity and air quality, or act as a mobile, distributed sensor network.'

Previous studies have proved that EcoBots can generate energy from rotten fruit, vegetables, dead flies, waste water, sludge and human urine.

"We speculate that in the future, urine-powered EcoBots could perform environmental monitoring tasks such as measuring temperature, humidity and waste water quality. A number of EcoBots could also function as a mobile, distributed sensor network, Lead author of the study Peter Walters, from the Centre for Fine Print Research, said in a statement.

"In the city environment, they could recharge using urine from urinals in public lavatories. In rural environments, liquid waste effluent could be collected from farms."

Explaining the functioning of the device the team said that when the artificial muscles get heated with an electric current, they compress a soft region in the centre of the heart-pump and cause the fluid to eject through a channel, which is then pumped up to reach the EcoBot's fuel cells.

Dr Ioannis Ieropoulos from the BRL said that the technology used to generate electricity from Microbial Fuel Cells (MFCs) to power a mobile phone, is being employed in the device. The artificial heart has 24 MFCs. The cells are bio-electrochemical transducers that convert the energy found in organic matter to electricity. Live microorganisms that are present inside the MFCs digest waste organic matter like urine and generate low-level power as a by-product, along with carbon dioxide.

"The artificial muscles are then cooled and returned to their original shape when the electric current was removed, causing the heart-pump to relax and prompting fluid from a reservoir to be drawn in for the next cycle," the team said.

The device has been tested and the results have been presented Thursday, Nov. 8, in IOP Publishing's journal 'Bioinspiration and Biomimetics'.