Using the TangoPlus material from Stratasys, researchers at the Bristol Robotics Laboratory (BRL) in the UK have done the unimaginable, unthinkable and undrinkable — and made a robotic heart that runs on urine. The idea, so brilliant and, yet, so simple that most of us came up with it when we were 8, is to create electrical power from human waste and use it to pump an artificial heart. And, while the prototype is still just a prototype, the researchers have made progress in turning this urine-soaked nightmare of a modern society into an eco-friendly and sustainable utopia.
Published this month in the journal Bioinspiration and Biomimetics, the Bristol Robotics Laboratory has detailed the creation of an artificial robot heart that runs on electricity generating microbes that digest waste. In this, the fourth iteration of the lab’s EcoBot projects, the researchers were able to use the microbes, feeding off of 22 ml of urine, to generate 3.5 volts to pump a robotic heart 33 times. The microbial fuel cells (MFCs) in this study, digested the waste and, as a result, give off an electrical charge, allowing them to pump an artificial heart in the following way:
The pump has a hollow body, which is filled with fluid (figure 1(a)). The body of the pump has a soft, flexible region that is compressed by the action of a pair of shape memory alloy ‘artificial muscle’ fibres. The fibres contract when heated by electric current. As they contract, they compress the soft region of the pump body, forcing fluid upwards, to be ejected out of the top of the pump (figure 1(b)). When the electric current is removed, the artificial muscle fibres cool and relax. The soft region re-expands, and fresh fluid is drawn into the body of the pump in readiness for the next cycle of actuation (figure 1(c)). One-way ball valves are employed to regulate the flow of fluid through the pump.
The study’s lead author, Peter Walters, envisions a world in which EcoBots, running on waste-powered MFCs, might serve as environmental stewards,
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. 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.
The paper admits that the prototype is still quite weak, producing an energy efficiency of the heart was only about .11%, which the authors explain is “very low” compared with “electric motor-driven impeller pump[s]”, such as this here. Instead, this heart pump is meant to be a proof of concept.
3D printing was used in this study to determine if it might be possible to 3D print their EcoBots in the future. The researchers discovered that TangoPlus may not be the most effective material to use to construct their robotic heart, finding silicon to be much better suited to the task. Seeing that, while not as effective as silicon, the 3D-printed heart did work and with the successful printing of robot parts in the past, the researchers determined that 3D printing robots was potentially feasible.
Source: 3D Printing Industry