Enabling spatial analysis of living cell/electrode interfaces

In bioelectronic devices, connectivity of bacterial layers to the electrode surface is of paramount importance, yet difficult to characterise. Here, we provide a multimodal characterisation of the interfacial structure between cyanobacteria and conductive surfaces by combining complementary analytical techniques including neutron reflectometry, quartz crystal microbalance with dissipation and confocal fluorescence microscopy. We show that after many hours of gravitational settling, most bacteria remain separated from the surface by a large (over 1 μm) distance, but are connected via organic species in the extracellular matrix. Adhesion is improved by pre-coating the surface with a layer of conductive polymer, whereupon the bacteria adhere strongly and form a thick (18 μm), yet porous, film. This work demonstrates new approaches for studying these complex biological/inorganic interfaces in situ, and reveals how the cyanobacterial/electrode interface can be more precisely imaged and tuned.