Microbial fuel cell (MFC) is a type of bioelectrochemical fuel cell system[1] also known as micro fuel cell that generates electric current by diverting electrons produced from the microbial oxidation of reduced compounds (also known as fuel or electron donor) on the anode to oxidized compounds such as oxygen (also known as oxidizing agent or electron acceptor) on the cathode through an external electrical circuit. MFCs produce electricity by using the electrons derived from biochemical reactions catalyzed by bacteria.

I've designed this MFC for iGEM 2022 Evry team - Home | Evry_Paris-Saclay - iGEM 2022. It's open source and you're welcome to use it.
PEM stands for protein exchange membrane. Hence, places where there is PEM applied. It is adviced, that the model is priten with waterproof materials such as PETG or special PLA.