Terahertz Shielding Enabled by the Micro-Porous Structure of Melamine Resin Sponge

Melamine resin sponges have a porous cell structure on the micrometer scale, comparable to the terahertz wavelength. Hydrating the sponge with water introduces a micro-scale rough surface which greatly attenuates the terahertz reflection. When combined with the high absorption of water, the hydrated sponge shows a perfect shielding characteristic by reflecting less than 1% of the light intensity in 0.75-3.5 THz.