As the trend of miniaturisation in electronic devices continues, most of these devices tend to have high power requirements due to a high degree of various functional integrations.
Batteries of various sizes are widely used as power supply sources for almost all electrical and electronic devices, but space constraints tend to favour micro-batteries. As space constraints grow ever tighter, researchers are envisioning that the energy for tomorrow’s miniature electronic devices could come from tiny micro-batteries about half the size of a human cell and built with viruses.
Massachusetts Institute of Technology (MIT) engineers have developed a way to at once create and install such micro-batteries by stamping them onto a variety of surfaces. These batteries could one day power a range of miniature devices, from labs-on-a-chip to implantable medical sensors.
Batteries consist of two opposite electrodes – the anode and cathode – separated by an electrolyte. In the current work, the MIT team created both the anode and the electrolyte. First, on a clear, rubbery material the team used a common technique called soft lithography to create a pattern of tiny posts either four or eight millionths of a metre in diameter. On top of these posts, they then deposited several layers of two polymers that together act as the solid electrolyte and battery separator.
The next step involved viruses that self-assemble atop the polymer layers on the posts, ultimately forming the anode. They altered the virus’s genes so that it formed protein coats that collect molecules of cobalt oxide to form ultra-thin wires. The final result: a stamp of tiny posts each covered with layers of electrolyte and the cobalt oxide anode. This was then turned over and transferred to a platinum structure.
This pioneering method used by the researchers to fabricate and position micro-battery electrodes, and achieve virus-based assembly does not involve any expensive equipment, and is done at room temperature. The resulting electrode arrays exhibit full electrochemical functionality.
In a recent issue of the Proceedings of the National Academy of Sciences, the team describes assembling and successfully testing two of the three key components of a battery. In addition to developing the third part of a full battery – the cathode – via the viral assembly technique, the team is also exploring a stamp for use on curved surfaces and integrating the batteries with biological organisms.
For more information contact Patrick Cairns, Frost & Sullivan, +27 (0)21 680 3274, [email protected], www.frost.com
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