When electrogenic bacteria digest food, electrons pass through them and discharge onto external surfaces such as electrodes. These bacteria, seen here in falsely-colored green, can self-assemble with a conductive polymer (false-colored blue and purple). The resulting 3D structure increases bio-electricity, providing more “electric avenues” to collect the microbes’ electricity for emerging applications. By using bacteria, we could double the potential in certain applications. In wastewater treatment, for example, microbes can eat the waste and produce electricity at the same time, creating the possibility of a net energy neutral treatment process.
Scanning electron microscopy was used to visualize cross-sections of a microbe/conductive polymer composite after one week of collecting biocurrent. The conductive matrix spontaneously formed from a water-soluble polymer, encapsulating the electrogenic bacteria Shewanella oneidensis MR-1. The living composite was fixed with formaldehyde, carefully dehydrated, and then sputtered in gold to preserve the soft features for microscopy imaging.