A Survey on Metasurface-Based Environmental Sensing for Perceptive 6G Networks

Emerging environmental monitoring requirements necessitate a shift from standalone sensors to real-time, distributed sensing under dynamic and long-term operating conditions. Currently, perceptive 6G networks offer a transformative platform to embed sensing directly into the wireless communication infrastructure through shared signal processing, hardware, and spectrum resources. Within this context, metasurface-based electromagnetic sensors offer a compact interface between the environment and the network. This paper presents a condensed, multidimensional taxonomy to classify metasurface-based sensors based on their sensing mechanism, operating frequency, and degree of reconfigurability. Using this framework, key design trade-offs related to sensitivity, robustness, and system complexity are identified. The analysis shows that environmental sensing in perceptive 6G systems is governed by multifaceted system-level constraints that are under-represented in existing ISAC and metasurface-sensing frameworks. The observations presented herein aim to support the development of robust and scalable metasurface-based sensing solutions for next-generation wireless systems.