“…In recent years, an alternative sensing system, based on engineered materials or metamaterials (MTMs), MTM-inspired sensors , passive devices ranging from GHz to THz range, has been introduced for testing different substances such as solid (dielectric and metallic) materials [5,14], liquids [2-4, 7, 9-13, 15-23], microparticles [8], and biomolecules [24,35], to name a few. Microfluidic sensors [36] with their label-free, non-destructive characteristics, no-contact, instant measurements, low-cost, and lowprofile [1,2], can be a substitute for optical, electrochemical and biological sensors. It was also shown that a single negative MTM surface can have multifunctional usages, i.e., sensors and absorbers [22].…”