A Highly Compact Metasurface Absorber Incorporating Piezoelectrics for Hybrid RF–Vibration Energy Harvesting

This work presents an innovative compact metasurface perfect absorber (MPA) for hybrid energy harvesting (EH), marking a substantial breakthrough in the advancement of sustainable power sources. The unique design integrates two distinct EH techniques [radio frequency (RF) and vibration] through the use of a piezoelectric material as the substrate for the metasurface. The metasurface elements additionally serve as electrodes to capture the voltage generated from vibrations, with the entire structure functioning as a cantilever resonator, a widely recognized mechanical resonator used in vibration harvesting applications. The interdigitated geometry of the metasurface elements and the incorporation of a high-dielectric-constant piezoelectric material allow for the creation of a miniaturized metasurface element, measuring only$0.12 \lambda $at 2.4 GHz. The design achieves an absorption efficiency exceeding 96%, while ensuring robust performance and insensitivity to changes in polarization and incident angles. Experimental validations demonstrate that the proposed hybrid harvester operates efficiently under both microwave and mechanical excitations, providing a reliable and sustainable power solution. This novelty in design and approach establishes the proposed hybrid energy harvester as a sustainable power source with significant potential impact.