Liquid Metal-Based Flexible Band-Stop Frequency Selective Surface

We report the design, fabrication, and characterization of PDMS encapsulated physically flexible (bendable, foldable) gallium-based liquid metal band-stop frequency selective surface. A band-stop frequency selective surface (FSS) with targeted operation in the X-band (7~11.2 GHz) was designed. Liquid metal was embedded in PDMS microfluidic channels replicated from a deep etched Si mold. Ultra-low pressure (5.75 x 10
^-6
Torr) vacuum at cryogenic temperatures (10 K) was employed for clean encapsulation of liquid metal. An array of 5 x 5 FSS has been fabricated. Characterization of the fabricated FSS was carried out in a waveguide environment. The S-parameter values of the simulated and measured band-stop FSS response showed an excellent agreement.