Mass-Manufactured Gradient Plasmonic Metasurfaces for Enhanced Mid-IR Spectrochemical Analysis of Complex Biofluids

Area of Science:

• Spectroscopy
• Biomedical Engineering
• Materials Science

Background:

• Mid-infrared (Mid-IR) spectroscopy provides label-free molecular analysis but struggles with complex biological samples.
• Existing methods often lack the sensitivity and spectral coverage for comprehensive analysis of biological specimens.

Purpose of the Study:

• To develop a transformative surface-enhanced infrared absorption spectroscopy (SEIRAS) platform overcoming limitations in biological sample analysis.
• To enable high-throughput, comprehensive molecular fingerprinting of complex biological specimens.

Main Methods:

• High-throughput wafer-scale fabrication of mid-IR plasmonic micro-hole-array (MHA) metasurfaces on silicon nitride membranes.
• Gradient MHA metasurface design supporting spectrally cascaded plasmonic modes for dense spectral coverage (1200-2000 cm⁻¹).
• Validation using model polymer systems and clinical peritoneal fluid from ovarian cancer patients.

Main Results:

• Demonstrated wafer-scale fabrication yielding approximately 400 sensor chips per 6-inch wafer.
• Achieved over 400 sharp resonance peaks across the Mid-IR fingerprint region for comprehensive molecular fingerprinting.
• Successfully resolved complex molecular signatures in clinical peritoneal fluid, revealing obscured vibrational bands.

Conclusions:

• The developed SEIRAS platform offers high-throughput fabrication and simplified optical readout for analyzing complex biological samples.
• This technology provides enhanced spectral coverage and sensitivity, surpassing conventional IR spectroscopy for biomedical applications.
• Establishes a foundation for translating SEIRAS into practical, impactful biomedical applications.