MFC stack consisting of 24 small (6.25 mL) units, as assembled for running EcoBot-IV. The yellow motorised gantry system shown on the right is part of the automatic feeding mechanism for uniform MFC maintenance. The inset shows a close-up of a single Nanocure® MFC, with the open to air cathode shown on the right hand side. The small red screw provides pressure control for better electrode-to-membrane contact.