Plasmonic Metasurface with Hexagonal Nanobumps on Flexible Substrate for Sensing

A plasmonic metasurface with sub-wavelength nanobumps of shallow height arranged in a hexagonal pattern on a polymer surface is studied. The metasurface is fabricated through two-step soft lithography technique using an inexpensive colloidal photonic crystal as master. A gold film of 25 nm thickness is sufficient to excite the plasmon mode, resulting in refractive index sensing with a sensitivity of 633 nm/RIU.