Biological electronic materials are receiving growing attention from diverse research fields, motivated by a fundamental interest in the underlying electro-optical mechanisms and in the potential future role in emerging domains such as bio-electronics, biodegradable electronics, biobased energy harvesting, and electronic biological materials (e-biologics) [1]. In the long-term these materials could open novel avenues for upcoming electronic challenges such as the growing problem of electronic waste, the localized power generation in the ubiquitous electronics of the Internet of Things, and could play a role in the diverse “More than Moore” technology platforms for future electronic applications.  In the development of next generation electro-optical applications, nature can be of great inspiration and important lessons can be learned from mechanisms occurring in living organisms, ranging from photosynthesis to long distance electron transport.

Light-induced charge-transfer mechanisms are at the heart of both photosynthesis and photovoltaics, and of new hybrid concepts such as bio-photovoltaics (e.g. Plant Microbial Fuel Cells) [2]. The underlying photophysical mechanisms occurring within photosynthesis and so-called emerging photovoltaics (e.g. organic and dye sensitized solar cells) show striking similarities [3] and a cross-fertilization between these two worlds can yield novel creative applications. A recent crossover example is given by so-called “Photovoltaic Photographs” [4], i.e. semi-transparent solar cells with integrated photoactive images realized through control of light-induced patterning processes and underlying physicochemical mechanisms.

In nature, biological ‘nanofibers/nanowires’ in electroactive microorganisms such as Geobacter sulfurreducens, Shewenalla oneidensis and the more recently discovered Cable Bacteria (CB) demonstrate remarkable electrical transport properties. Cable Bacteria are filamentous microorganisms consisting of more than 10⁴ cells, forming unbranched filaments of up to several centimeters long, characterized by a distinct morphology with parallel ridges along the length of the filament. They have developed a unique energy metabolism which requires charge transport over centimeter distances, extending the known length scale of biological transport by several orders of magnitude [5].  The obtained results so far on the intrinsic electrical properties of the conductive fibres in Cable Bacteria offer promising perspectives for both fundamental studies of biological long-range electron transport as well as alternative electronic materials for emerging fields such as bioelectronics, biohybrid electronics and biodegradable electronics [6].