A hybrid microbial dielectric elastomer generator for autonomous robots

Abstract

We are developing a hybrid Dielectric Elastomer Generator (DEG)-Microbial Fuel Cell (MFC) energy harvester . The system is for EcoBot, an Autonomous Robot (AR) that currently uses its MFCs to extract electrical energy from biomass, in the form of flies. MFCs, though reliable are slow to store charge. Thus, EcoBot operations are characterized by active periods followed by dormant periods when energy stores recover. Providing an alternate energy harvester such as a DEG, driven by wind or water, could therefore increase active time and also provide high voltage energy for direct use by on-board systems employing dielectric elastomer actuators (DEAs). Energy can be harvested from a DEG when work is done on its elastomer membrane.. However, the DEG requires an initial charge and additional charge to compensate for losses due to leakage. The starting charge can be supplied by the EcoBot MFC capacitor. We have developed a self-primer circuit that uses some of the harvested charge to prime the membrane at each cycle. The low voltage MFC initial priming charge was boosted using a voltage converter that was then electrically disconnected. The DEG membrane was cyclically stretched producing charge that replenished leakage losses and energy that could potentially be stored. A further study demonstrated that the DEG with self-primer circuit can boost voltage from very low values without the need for a voltage converter, thus reducing circuit complexity and improving efficiency.