Working with colleagues at the Lawrence Berkeley National Laboratory in Berkeley, California, the researchers call the result a "multilayer conductive bacterial-composite film" (MCBF). Microscopic analysis of the film shows an interleaved structure of Shewanella oneidensis bacteria and the PEDOT:PSS conducting polymers that can be up to 80 μm thick, much thicker than it can be without this specific technique.
"Our experiments show that more than 90% of the bacteria are viable, and that the MCBF increases the flow of electrons in the external circuit. When our film is used as anode in microbial electrochemical cells, the current is 20 times higher than it is when using unmodified anodes, and remains so for at least several days," said Gábor Méhes (above), a researcher at Linköping University and one of the lead authors of the scientific article recently published in Scientific Reports.
Coupling biological processes with readable electrical signals is valuable for environmental sensors which require rapid response times, low energy consumption, and the ability to use many different receptors. Researchers have recently demonstrated how to use Shewanella oneidensis to produce electrical currents in response to arsenic, arabinose (a type of sugar) and organic acids, among others.
"This technology represents a type of "living electrode" where the electrode material and the bacteria are amalgamated into a single electronic biofilm. As we discover more about the essential role that bacteria play in our own health and wellness, such living electrodes will likely become versatile and adaptable tools for developing new forms of bioelectronic technologies and therapies," said Daniel Simon, principal investigator in Organic Bioelectronics at the Laboratory of Organic Electronics.