Dynamic transmission-reflection dichroism based on humidity-responsive metal-hydrogel-metal nanocavities Dandan Wang, Qiang Li, Yunbin Ying, Runhu Li, Mingliang Cheng, Yingxin Chen, Jian Zhang and Xuefeng Zhang EPJ Appl. Metamat., 9 (2022) 18 Published online: 07 December 2022 DOI: 10.1051/epjam/2022016