The implementation of metasurface absorbers for advanced sensing applications in the infrared spectral range is gaining prominence. Nevertheless, scale-up is challenging because their subwavelength features require complex fabrication techniques. Here, we present centimeter-sized nanostructured metasurface absorbers, prepared using the nanoporous anodic aluminum oxide template method, which exhibit a high and polarization-insensitive absorptivity at near-infrared wavelengths. Their sensing potential as surface-enhanced Raman spectroscopy substrates is demonstrated by analyzing Raman spectra of methyl parathion pesticides at concentrations as low as 100 ppb. Our results offer a stable, cost-effective, scalable, and uniform solution for metasurface-based molecular detection applications with a high sensitivity.
