Carbon fiber skeleton/silver nanowires composites with tunable negative permittivity behavior Yan An, Jinyuan Qin, Kai Sun, Jiahong Tian, Zhongyang Wang, Yaman Zhao, Xiaofeng Li and Runhua Fan EPJ Appl. Metamat., 8 (2021) 1 Published online: 19 January 2021 DOI: 10.1051/epjam/2020019