Advancing microwave absorption: Innovative strategies spanning nano-micro engineering to metamaterial design

With the widespread adoption of communication technology, the potential hazards of electromagnetic (EM) radiation to human health and electronic devices operation have also emerged. Therefore, microwave absorption (MA) materials are becoming increasingly vital in the current electronic information age. Currently, extensive researches have been conducted on the MA mechanisms and optimized strategies, leading to significant advancements in improving MA performance. However, there is a lack of systematic summary of various innovative engineering strategies from nano-micro scale to metamaterial. Typically, nano-micro engineering techniques readily introduce heterointerfaces, components, or defects, etc. to boost dielectric loss and/or magnetic loss. And macroscopic strategy focuses on crafting more porous three-dimensional structures (foams, aerogels, films, etc.), which are beneficial for fine-tuning intrinsic impedance and triggering multiple reflections/scattering of EM wave (EMW). While metamaterial design featuring periodic layouts and sub-wavelength scales can also lead to energy loss via EMW resonances. Hence, in this review, we aim to provide a detailed overview of various engineering strategies for enhancing MA performance from nano-micro engineering to macroscopic strategies to metamaterial design. Furthermore, we elaborate the present challenges faced by MA technology and discuss potential future development opportunities and trends. It is our hope that this paper will offer insights and direction for the ongoing improvement of MA performance and achieving practical applications.