Metasurface reflectace characterization was performed using a FTIR spectroscope system (FTIR-6600) with a microscopy attachment unit IRT-1000. Thermal radiation emission was likewise measured with the same FTIR-6600 and IRT-1000 setup by using the MIM metasurface as an external illumination source, connected to the spectroscope via a side port. The reference for reflection was a Au-mirror (98% reflectance at MIR wavelengths) and a paint with 94% emissivity was employed as a blackbody radiation standard. For best comparability the paint was applied directly onto the MIM sample chips near the 1 × 1 mm 2 metasurface areas. Heating in thermal radiation output measurements was applied to the substrate by placing on a Peltier device and fixed with a thermal conductive grease. The devices were heated up to 150 • C. Prior to measurement each sample was allowed to reach a steady thermal state over the course of at least a 30 minute a settling time.