Multi-scale structural design of electromagnetic wave absorbers: pathways to improved performance

With the rapid advancement of wireless communication technologies and the proliferation of Internet of Things (IoT) devices over the past decade, electromagnetic interference (EMI) has emerged as a significant challenge. EMI can degrade the performance, stability, and lifespan of advanced electronics and even poses potential health risks. One of the most effective strategies to mitigate this issue is the development of highly efficient electromagnetic wave absorbers (EMAs), a field that has garnered considerable attention. However, achieving the necessary efficiency for widespread adoption remains a challenge. The internal structure of EMAs plays a pivotal role in determining their absorption performance. This review explores the fundamental principles of electromagnetic wave absorption and highlights recent advancements in optimizing internal structures across various length scales, from the atomic to the macroscopic level. We examine design strategies, structure-performance relationships, and fabrication methods for tuning absorption efficiency, either independently or in combination. Finally, we address key challenges and future directions for the next generation of EMAs, offering insights into their potential for practical applications.