Plasmonic Gold Nano disk Array Design for Enhanced Surface-Enhanced Raman Spectroscopy (SERS) Sensing Applications

Surface-Enhanced Raman Spectroscopy (SERS) has emerged as a highly promising technique for trace-level molecular detection due to its unique ability to amplify Raman signals via localized surface plasmon resonance (LSPR). However, practical SERS applications face critical challenges, including poor signal reproducibility, non-uniform hotspot distribution, and fabrication complexity that limits scalability. Addressing these limitations, this study presents the rational design and development of a plasmonic gold nanodisk array as a highly uniform and tunable SERS substrate. The primary objective was to fabricate a reproducible, scalable, and optically optimized nanostructure capable of delivering high electromagnetic enhancement and consistent Raman response across large surface areas. The gold nanodisk arrays were fabricated using nanosphere lithography and characterized by SEM and AFM for structural verification. FDTD simulations were employed to optimize disk dimensions for maximum field enhancement near the 785 nm excitation wavelength. Experimental SERS measurements using Rhodamine 6G and 4-MBA confirmed enhancement factors exceeding 10 7 , with a detection limit down to 10 -9 M. Raman mapping demonstrated a spatial coefficient of variation below 8%, indicating excellent uniformity. Additionally, real-time biosensing was validated using Bovine Serum Albumin in a microfluidic system, showing reversible signal kinetics and sensor regenerability. These findings confirm the gold nanodisk array as a high-performance SERS substrate offering sensitivity, reproducibility, and integration compatibility, thereby addressing key obstacles to widespread SERS implementation in biomedical and environmental diagnostics.