Fluidically Switchable Metasurface for Wide Spectrum Absorption.

Metasurfaces, owing to their attractive features, provide a wide range of potential applications. Electromagnetic absorbers based on metasurfaces have significantly improved responses compared to the earlier absorbers made from composite materials. Active metasurfaces, in contrast to the passive designs, can exhibit multifunctional characteristics without repeated fabrication. This paper presents a fluidically-reconfigurable active metasurface that provides switchable wide spectrum absorption. The proposed design is comprised of liquid-metal-encased dielectric substrates, sandwiched between the top resistive pattern and bottom ground plane. With precise control of the liquid metal flow, the structure can exhibit wide absorption bandwidth switching between two frequency regimes. Further, the proposed metasurface has a significant advantage of displaying polarization-insensitive behaviour, unlike the previous fluidically-reconfigured structures. The design has been investigated by illustrating surface current distributions and several parametric variations. Finally, the proposed structure was fabricated using laser etching, and experimentally validated. This work has paved the way towards the realization of reconfigurable metasurfaces with multifunctional characteristics, thus showing great potential in microfluidic technology for diverse applications.