Fabrication of a Multilayer X-Band Band-Pass Metasurface Using Liquid Metal

Fabrication of a physically flexible multi-layer metasurface composed of gallium-based liquid metal encapsulated in polydimethylsiloxane (PDMS) is reported. The second-order bandpass frequency selective surface (FSS) operating in the X-band is comprised of two modified Jerusalem cross resonator layers separated by an aperture layer. The multi-layer spatial filter has a total thickness of 4.81 mm ( $\lambda _{0}$ /7.5). An inverse image mold of the FSS layer patterns is fabricated in silicon, and FSS patterned PDMS is replicated from the silicon mold. The FSS patterned PDMS is spray coated with liquid metal to fabricate a massive array of discrete conductor patterns in PDMS and subsequent encapsulation by an additional layer of PDMS. Multiple versions of the m $\times $ n metasurfaces have been fabricated and have been repeatedly tested for their bendability, stretchability, twistability, and foldability. The fabricated metasurface in a waveguide environment demonstrated a band-pass center frequency at 8.33 GHz which agreed well with the simulated frequency at 8.31 GHz.