Some of the computer engineers I worked with years ago used to ‘jokingly’ refer to people as wetware putting us on a continuum with hardware, software, and firmware. Clearly they knew something I didn’t as it seems we’re getting closer to making that joke a reality with the term wetware expanding to include biological systems. Michael Berger in his July 19, 2011 Nanowerk Spotlight essay, Squishy electronics, takes a look at some of the developments in biocompatible electronics [Mar.7.12: duplicate paragraph removed from essay excerpt],
There is a physical and electrical disconnect between the world of electronics and the world of biology. Electronics tend to be rigid, operate using electrons, and are inherently two-dimensional. The brain, as a basis for comparison, is soft, operates using ions, and is three-dimensional. Researchers have therefore been looking to find different routes to create biocompatible devices that work well in wet environments like biological systems.
Berger goes on to highlight some research in North Carolina,
The device fabricated by the NC State team (that included graduate students Ju-Hee So and Hyung-Jun Koo, who also first-authored the paper [research team was led by Orlin Velev and Michael Dickey]) is composed primarily of water-based gels that are, in principle, compatible with biological species including cells, enzymes, proteins, and tissues and thus hold promise for interfacing electronics with biological systems. [emphasis mine]
The novelty of this work is the operating mechanism of the memory device combined with the fact that it is built entirely from materials with properties similar to Jell-O. The memristor-like devices are simple to fabricate and basically consist of two liquid-metal electrodes that sandwich a slab of hydrogel.
This line of work fits in nicely with ‘vampire’ batteries (my latest posting on this topic, July 18k 3011) which can, theoretically, run on blood. Coincidentally, The Scientist published a June 23, 2011 article, by Megan Scudellari which focuses on biological fuel cells that can run on bacteria,
This tiny biological fuel cell, the smallest of its kind with a total volume of just 0.3 microliters, was built using microfluidics and relies on bacteria to produce energy. Bacteria colonize the anode, the negatively charged end of the system, and through their natural metabolism produce electrons that flow to the cathode, creating a circuit. Together, the anode and cathode are only a few human hairs wide, but the tiny circuit generates a consistent flow of electricity.
An undated news item on the Carnegie Mellon University website offers this information,
Carnegie Mellon University’s Kelvin B. Gregory and Philip R. LeDuc have created the world’s smallest fuel cell — powered by bacteria.
Future versions of it could be used for self-powered sensing devices in remote locations where batteries are impractical, such as deep ocean or geological environments.
“We have developed a biological fuel cell which uses microbial electricity generation enabled by microfluidic flow control to produce power,” said Gregory, an assistant professor of civil and environmental engineering at CMU.
No bigger than a human hair, the fuel cell generates energy from the metabolism of bacteria on thin gold plates in micro-manufactured channels.
Those injunctions about not mixing liquids with electricity may soon seem a trifle old-fashioned.