An Energy-Autonomous Robotic Tadpole with Single Membrane Stomach and Tail

We present an energetically autonomous robotic tadpole that uses a single membrane component for both electrical energy generation and propulsive actuation. The coupling of this small bio-inspired power source to a bio-inspired actuator demonstrates the first generation design for an energetically autonomous swimming robot comprised of a single membrane. An ionic polymer metal composite (IPMC) with a Nafion polymer layer is demonstrated in a novel application as the ion exchange membrane and anode and cathode electrode of a microbial fuel cell (MFC), whilst being used concurrently as an artificial muscle tail. In contrast to previous work using stacked units for increased voltage, a single MFC with novel, 0.88ml anode chamber architecture is used to drive artificial muscle actuation. This shows the suitability of the small forces generated by IPMCs for propulsion of a bioenergy source. Similarly, the work shows the suitability of MFCs for powering artificial muscles without the requirement for large voltage step up by showing actuation of an IPMC tail using voltages recorded from the MFC during the experiment with minimal step up. Therefore, the work demonstrates great potential for reducing the mass and complexity of bio-inspired autonomous robots. The performance of the IPMC as an ion exchange membrane is compared to two conventional ion exchange membranes, Nafion and cation exchange membrane (CEM). The MFC anode and cathode show decreased increased resistance following inclusion within the MFC environment.