A 5.8-GHz Electromagnetic Energy-Harvesting Metasurface for Batteryless Wireless Sensor Networks

Abstract

Energy autonomy has emerged as a fundamental challenge in the development of Wireless Sensor Networks (WSNs), as well as for a wide range of emerging miniaturized electronic systems. With the rapid expansion of the Internet of Things (IoT), the demand for compact, long-lifetime, and maintenance-free devices continues to grow. However, existing battery technologies impose significant limitations in terms of size, environmental impact, and finite operational lifespan. To address this, we present a novel energy-harvesting metasurface based on a metamaterial perfect absorber unit-cell. The unit-cell consists of a printed dipole feeding a rectifying diode, with the dipoles input impedance directly matched to the rectifier impedance, eliminating the need for a matching network. Simulation results show that this metasurface achieves a high radiation-to-AC conversion efficiency of approximately 90.67% at 5.8 GHz. A prototype comprising a 6 × 6 array of unit-cells was fabricated and tested experimentally, demonstrating a peak DC voltage at 5.8 GHz under power densities of a few microwatts per cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>, validating our numerical results. As a proof of concept, the metasurface was successfully used to power a battery-free wireless sensor node. These findings strongly suggest that metasurfaces can serve as an effective solution for powering low-consumption devices in WSNs, offering a promising alternative to conventional battery-powered systems.