Fig. 2.

Electrochemical characterisation of a digitally printed bioanode in a hybrid BPV system. a Schematic representation (semi-exploded view) of the BPV unit with printed paper-based anode. Clamping screws (component 1); marine grade stainless steel ring for contacting the CNT anode (component 2); printed CNT anode in black (Ø 60 mm) with printed photosynthetic organisms in green (Ø 40 mm) with a total area of ~ 28.4 cm² (component 3); hydrogel (component 4); Plexiglas vessel (component 5); carbon paper-Pt, with a total area of ~ 3.5 cm² was used as cathode (component 6); silicon O-ring (component 7); stainless steel plate used to clamp all the component together (component 8). ~ 60 ml of BG-11 medium was placed above the printed cells in the chamber formed by the top plate. b Schematic representation of the BPV unit cross-section where electrons, protons and oxygen flow are also shown. Numbering as in a. c Photograph of the experimental setup (excluding the potentiostat and the wiring). Numbering as in a. d Polarization and e power curves for the printed anode in the BPV unit. Printed Synechocystis (incubated for 5 days after printing) on printed CNT anode exposed to light (magenta symbols) and in the dark (grey symbol) was compared with a bare printed anode (black trace). Number of repeats is indicated in parenthesis