Controlling the morphology of 2D laser-induced periodic surface structures (LIPSS) for surface-enhanced Raman spectroscopy applications

The creation of Laser-Induced Periodic Surface Structures (LIPSS) with near-submicron dimensions has significantly altered the surface properties of materials, as demonstrated in the past decade. These properties, particularly the hydrophobic characteristics, can be enhanced when combined with the dense nanostructures in LIPSS, making them ideal for highly Sensitive Surface-Enhanced Raman Spectroscopy (SERS) applications. However, a key challenge lies in precisely controlling the morphology of these nanostructures and their surface contact properties to effectively concentrate analyte molecules in specific regions for detection at extremely low concentrations. Here we show how single and double femtosecond laser pulse irradiation can be used to achieve different LIPSS morphologies. We generate 1D and 2D periodic nanostructures on 304 stainless steel substrates by adjusting the polarization and inter-pulse delay between fs pulses. From the preliminary experimental results, the dense hotspots in these LIPSS-based sensors allow for the detection of Rhodamine 6G at concentrations as low as 10−10 M, with an analytical enhancement factor of 2 × 107 for consistent and repeatable measurements. These findings provide important insights into the control of laser-induced submicron morphologies by adjusting experimental parameters, offering a straightforward and cost-efficient approach for detecting molecules at ultra-trace levels.