Multi-dimensional terahertz detection for methamphetamine using microporous metal Metasurfaces and multi-wavelength...

Area of Science:

• Optoelectronics
• Spectroscopy
• Materials Science

Background:

• Terahertz (THz) detection methods often lack sensitivity and information dimensionality.
• Methamphetamine detection requires highly sensitive and specific analytical techniques.

Purpose of the Study:

• To develop an enhanced THz time-domain spectroscopy (THz-TDS) detection method for methamphetamine.
• To improve the sensitivity and information dimension of THz detection using microporous metal metasurfaces and multi-wavelength optical pumping.

Main Methods:

• Fabrication of a microporous aluminum metasurface using laser processing.
• Coating methamphetamine standard solution on the metasurface.
• Irradiation with 405 nm, 450 nm, and 780 nm lasers, individually and combined.
• Measurement of THz absorption spectra, refractive indices, and dielectric constants.

Main Results:

• Local field enhancement by the metasurface significantly improved THz wave-sample interaction.
• Multi-wavelength laser pumping modulated THz response by influencing molecular energy levels and carrier concentration.
• The method achieved a linear response for methamphetamine detection (10 μg/mL–100 μg/mL) with R² > 0.997.
• A limit of detection (LOD) of 10 μg/mL was achieved, five orders of magnitude lower than conventional methods.

Conclusions:

• The "metasurface enhancement + multi-wavelength optical pumping" scheme provides a robust theoretical and experimental basis for rapid methamphetamine detection.
• Laser wavelength and metasurface's local surface plasmon resonance (LSPR) effect synergistically enhance THz detection capabilities.
• This approach offers a significant advancement in sensitive and selective chemical detection.