Tunable Graphene/Copper Metasurface Coupled With 1D-MIIG Diodes For Ultra-Efficient Wifi Energy Harvesting in Ambient, Low-Power Environments

Low-power devices, such as small sensing and wearable electronics (pacemakers, insulin monitors, health strips), are incapable of effectively harvesting surrounding Wifi, LTE and Bluetooth radiation that is otherwise dissipated in wireless power transfer, leading to inefficient operation cycles. The bottlenecks of ambient energy harvesting have prevailed for decades due to poor rectification efficiencies of state-of-the-art diodes at ambient Radio Frequency (RF) power levels (-20 to -10 dBm), as well as high capacitance limiting their cutoff frequencies. Engineering hyper-efficient rectennas with a RF–DC power conversion efficiency greater than ~50% for such low-power modes currently remains practically challenging. New energy-capture approaches such as metamaterials have proven to significantly boost the frequency-selectivity and power reach of diode architecture and scale the next generation of power management integrated circuits (PMICs) for low-power environments. This research presents a novel approach to RF energy harvesting by integrating a tunable, polarization-agnostic impedance-matching metamaterial absorber antenna based on graphene, with a complementary metal-oxide-semiconductor (CMOS)-compatible cross coupled differential drive (CCDD) rectifier circuit that employs metal-insulator-graphene (MIG) diodes. The proposed model geometry, impedance matching network, and its equivalent RLC circuit, simulated using COMSOL Electromagnetic Waves and Circuit modules, are designed to apply dynamic bias voltages based on incident Wifi power levels, subsequently influencing the resonating ability of the metasurface. The integration of advanced materials such as graphene offers a unique advantage in terms of tunability and adaptability, yielding significant absorption in the 2.4–6GHz Wifi broadband at all times. Furthermore, the design’s novel approach towards simulating the time-dependent characteristic behavior of the rectenna setup through the incorporation of MIG diodes positions this work at the forefront of emerging, industrially useful materials systems for ambient Wifi/RF harvesting.