High Water Content Prediction of Oil–Water Emulsions Based on Terahertz Electromagnetically Induced Transparency-like Metamaterial

This work aims to investigate the electromagnetically induced transparency-like (EIT-like) metamaterial for high water cut emulsions' detection in the terahertz band. The electromagnetic responses of the selected metamaterial covering emulsions exhibit red-shifted resonant frequency with increasing water volume from 60 to 98%. Three numerical models coinciding with theory analysis were built based on the extracted resonant frequencies at the transmission peak and dips to predict water concentration. The results show that the built models accurately predicted the water content with absolute errors less than 0.26, 0.41, and 0.24%, respectively. The EIT-like resonance is introduced by coupled bright and dark modes, making it similar to a weakened plasma resonance. Consequently, the permittivity-dependent frequency would help develop both economically feasible and socially beneficial sensors for high water content prediction.