November 8, 2013
EcoBots: Robots With ‘Hearts’ And Powered By Urine, Waste
Brett Smith for redOrbit.com – Your Universe Online
Whiz kids at the University of Bristol have taken another step toward creating an autonomous waste-driven robot by developing a heart-like pump that moves urine as it draws power from it.The latest technological splash expands on previous work from the Bristol Robotics Laboratory. The joint endeavor between the University of the West of England and the University of Bristol has produced four generations of ‘EcoBots’ that are powered by the conversion of waste organic matter by live microorganisms into low-level power.
The Bristol scientists said these EcoBots could be used as monitors in hazardous areas because such little human maintenance is needed to keep them running. The robots have already shown the capacity to generate energy from rotten fruits and vegetables, dead flies, wastewater and sludge, as well as human urine.
"We speculate that in the future, urine-powered EcoBots could perform environmental monitoring tasks such as measuring temperature, humidity and air quality,” said study author Peter Walters from the University of the West of England. “A number of EcoBots could also function as a mobile, distributed sensor network.
"In the city environment, they could re-charge using urine from urinals in public lavatories. In rural environments, liquid waste effluent could be collected from farms,” he added.
According to Walters, previous efforts to power a robot with urine were hampered by solid material precipitating out of the urine and blocking up conventional pumps.
To solve this problem, the UK engineering team created a heart-like structure that contracts and expands based on the presence of an electric current. The pump sends urine into microbial fuel cells (MFCs) that metabolize it and generate a small electric current as a byproduct.
The contracting motion of the heart-like pump was achieved through the use of ‘artificial muscles’ made from a group of smart materials that can 'remember' their original shape, known as shape memory alloys.
When a urine-generated current heats the device’s artificial muscles, they compress a soft region in the middle of the pump, causing the liquid waste to be sent through an outlet and up into to an EcoBot's fuel cells. Next, the artificial muscles cool and return to their original shape, causing the heart-pump to expand and draw fluid from a reservoir for the next cycle.
According to the team’s report in the journal Bioinspiration & Biomimetics, a pile of 24 MFCs powered on urine were able to create enough electricity to charge a capacitor. The charged capacitor could then start another cycle of pumping the artificial heart.
"The artificial heartbeat is mechanically simpler than a conventional electric motor-driven pump by virtue of the fact that it employs artificial muscle fibers to create the pumping action, rather than an electric motor, which is by comparison a more complex mechanical assembly," Walters said.
The Bristol team said they would continue to work on improving their eco-friendly device as well as determining how it might be used to power the next generation of EcoBots.