Optimizing Power Output of Graphene Energy Harvesting

Free standing graphene has been found to invert its curvature over time by researchers at the University of Arkansas. Recently, they have been working on building a chip for converting kinetic energy from the system to electrical energy by using a variable capacitor principle. In this study we investigate the macroscopic models of graphene energy harvesting (GEH) with the goal of finding the output power optimal conditions. We present a GEH circuit model, which contains a manually-driven variable capacitor in series with a DC voltage source, diodes components for rectification, and a storage capacitor for storing the harvested charge. The DC experiment, however, presents difficulties with measuring efficiency, controlling the frequency, and reaching high voltage limits. Therefore, we design an equivalent AC experiment, in which we replace the DC voltage with an AC source and the variable capacitor with a fixed one. Our power studies reveal that the maximum efficiency of is reached at the maximum power output point, which happens at the time of times the time constant of the circuit.