Ultrasensitive terahertz metasensor integrated with EIT-like coupling and liquid flow micro-channels for organic solvent detection and identification.

Terahertz (THz)-based metasurface sensors offer potential and extensive application prospects for organic solvent detection. This study proposed a liquid sensor comprising an electromagnetically induced transparency (EIT)-like THz metasurface covered by a channel. The designed device can exploit variations in the EIT-like resonance peaks to distinguish between the concentrations of three types of organic solvents (ethanol(ET), acetone(AC), and isopropyl alcohol(IPA)). The experimental results indicate that the maximum sensitivity values are 0.442 for ET, 0.365for AC, and 0.129 for IPA. A wavelet transform method was proposed to convert one-dimensional frequency-dependent transmission spectra into two-dimensional coefficient intensity cards, facilitating significant differentiation between solvent concentrations. Radar charts integrating multiple transmission characteristic points were employed to provide multidimensional information to identify three types of organic solutions. This study proposes a liquid sensor for the rapid, label-free detection and identification of organic solvents of different concentrations and types.