I read Green Futures from cover to cover (which I rarely do with magazines these days). It’s so full of inspiration and really thought-provoking stuff.
A biodegradable battery which dissolves in water has been developed by researchers at the University of Illinois. The battery design could be scaled for a variety of uses, from powering temporary medical implants to other limited-duration electronics.
The recent development in transient electronics has opened the door for a revolution in medical devices. Traditionally, electronic medical implants – such as cochlear devices, for improved hearing; or brain pacemakers, used for pain relief – have been semi-permanent. Once installed, additional surgery has been required to remove them.
Transient electronics, on the other hand, can dissolve within the body – allowing implants to degrade once their function has been fulfilled. This could enable a new generation of applications: from temporary, internal monitoring to support for healing a wound or tumour.
With a magnesium foil anode, phosphate-buffered saline electrolyte and a cathode made from iron, molybdenum or tungsten, the battery developed by John Rogers and his colleagues may be the ideal solution. The device is biocompatible, can be scaled for a variety of uses and dissolves away with time. The demonstration battery, for example, degraded completely in water after three weeks, leaving behind only a tiny amount of residual magnesium hydroxide.
Beyond implants, such batteries could have a wide variety of non-medical applications. One possibility is in wireless sensors for environmental uses, such as to monitor ongoing clean-up efforts following an oil spill. Alternatively, the batteries could be employed within limited-use devices, so that they could safely decompose in waste streams. While the researchers have not conducted a cost-analysis of their design, Rogers claims the price should be reasonable compared with other solutions.
Christopher Bettinger, a Professor of Biomedical Engineering at Carnegie Mellon University who was not involved in the project, says, “Fabricating power supplies that have unique combinations of biocompatible materials and adequate charge storage capacities is an exciting new direction for materials scientists.” Late last year, Bettinger and his colleagues reported the creation of a similar, biodegradable sodium-ion battery, with melanin anodes made from squid ink.
Reza Montazami, a biomedical device expert from Iowa State University, who was also not involved in this study, calls the idea of transient batteries “game-changing”. These, he adds, are “of utmost importance in the development of transient electronics, which will have a paramount impact on the future of electronic devices”.
With their prototype tested, the researchers are now investigating ways to increase the duration of their battery, alongside developing designs for use with both environmental sensors and implantable devices.
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