Liquid Metal-Based Microfluidic Metasurface for Controllable Electromagnetic Wave Reflection Attenuation

We demonstrated a liquid metal based microfluidic chip that enabled consistent, continuous and large liquid metal unit structure array reconfiguration. The chips were assembled into a metasurface, which preliminary achieved controllable electromagnetic wave reflection attenuation. The chip contained a $5{\times }6$ Galinstan split-ring resonator (SRR) array, and the SRRs could be reconfigured continuously by NaOH solution pressure driven. A fin shaped microvalve was designed and integrated onto the chip, which could withstand a high fluid driving pressure (over 210 kPa), so the SRRs could be reconfigured with a large split angle. The flow resistance of each SRR chamber was analyzed for consistent and robust SRRs deformation. The SRRs enabled more than 250° reconfiguration and showed consistent deformation with a standard derivation less than 8.5°. The metasurface showed 7.5 dB and 13.5 dB attenuation at 3 GHz and 4 GHz respectively. Also, with the different split angles, there could be three attenuation peaks that reach −10 dB when the frequency ranged from 2.9–3.1 GHz, 3.7–4.2 GHz and 4.8–5.0 GHz, respectively. The metasurface we proposed can be potentially used in multiband controllable electromagnetic wave absorption.