Amro M Elshurafa, et al., "Microscale Electrostatic Fractional Capacitors using Reduced Graphene Oxide Percolated Polymer Composites" Applied Physics Letters 102, 2013, 232991.
Abstract: We show that graphene-percolated polymer composites exhibit fractional capacitance response in the frequency range of 50 kHz–2 MHz. In addition, it is shown that by varying the loading of graphene within the matrix from 2.5% to 12%, the phase can be controllably tuned from −67° to −31°, respectively. The electrostatic fractional capacitors proposed herein are easy to fabricate and offer integration capability on electronic printed circuit boards.