Nanoimprinted Sticky Hydrophobic SU-8 Nanopillars for Ultra-Sensitive Surface-Enhanced Raman Spectroscopy Applications

This study demonstrates the development of a sticky hydrophobic SU-8 nanopillar substrate combined with silver nanoparticles (AgNPs) for highly sensitive surface-enhanced Raman scattering (SERS) detection. The SU-8 nanopillars were fabricated using nanoimprint lithography (NIL) and modified with fluoride treatments to achieve sticky and hydrophobic properties, which enhance analyte concentration and SERS signal strength. SU-8 was selected for its durability, chemical resistance, and ease of modification, whereas NIL provided cost-effective, scalable, and precise nanoscale patterning, crucial for creating high-performance SERS substrates. Self-synthesized AgNPs, produced via a citrate reduction method, exhibited strong SERS signals due to their irregular shapes and sharp tips, enhancing localized surface plasmon resonance (LSPR) effects. The SERS performance of this system was evaluated using malachite green as a model analyte. Detection limits down to 10–17 M were achieved in deionized water and river water, demonstrating exceptional sensitivity. In seawater, detection was limited to 10–12 M due to salt deposition affecting the LSPR effect. The sticky hydrophobic substrate enabled precise analyte localization and reproducibility across different substrates, making this approach highly effective for ultralow concentration detection. This method presents a cost-efficient, scalable, and highly sensitive platform for SERS applications, offering detection capabilities beyond conventional limits for environmental monitoring and pollutant detection.