Wafer-Level Highly Dense Metallic Nanopillar-Enabled High-Performance SERS Substrates for Molecular Detection

Area of Science:

• Materials Science
• Nanotechnology
• Spectroscopy

Background:

• Surface-enhanced Raman scattering (SERS) technology requires sensitive, large-scale, and low-cost substrates for practical applications.
• Noble metallic plasmonic nanostructures with dense hot spots are crucial for achieving sensitive, uniform, and stable SERS performance.

Purpose of the Study:

• To report a simple fabrication method for wafer-scale ultradense tilted and staggered plasmonic metallic nanopillars.
• To create SERS substrates with numerous nanogaps (hot spots) for enhanced detection capabilities.
• To demonstrate the adaptability of the fabrication approach for creating flexible SERS substrates.

Main Methods:

• Fabrication of ultradense tilted and staggered plasmonic metallic nanopillars on a wafer scale.
• Optimization of SERS substrate performance by adjusting the etching time of the polymethyl methacrylate (PMMA) layer.
• Utilizing crystal violet as a model molecule to determine detection limits and assess substrate performance.

Main Results:

• Achieved optimal SERS substrate with the densest metallic nanopillars by controlling PMMA etching time.
• Demonstrated a detection limit as low as 10^-13 M for crystal violet.
• Exhibited excellent reproducibility and long-term stability of the SERS substrates.
• Successfully prepared flexible SERS substrates and demonstrated their effectiveness in analyzing low-concentration pesticide residues on curved fruit surfaces.

Conclusions:

• The developed fabrication method provides a simple route to wafer-scale ultradense plasmonic nanopillar SERS substrates.
• The substrates exhibit high sensitivity, excellent reproducibility, and long-term stability, suitable for various applications.
• The potential for creating flexible SERS substrates opens avenues for real-life applications, such as environmental monitoring and food safety.