Fabrication of SERS Substrates by 3D‐Positioned Spark Discharges: Advanced Performance Refinement Using Raman Mapping of Adenine and Its Derivatives

ABSTRACT A novel, cost‐effective and environment‐friendly method for fabrication of highly efficient surface‐enhanced Raman spectroscopy (SERS) substrates is introduced. It is based on high‐voltage spark discharges between a metal pin and a conductive substrate distributed across the desired area with the aid of a 3D positioning device. The developed substrates were characterized using dark‐field microscopy, SEM, UV‐VIS reflectance, and cyclic voltammetry; the pin movement pattern and velocity during sparking were optimized with respect to SERS efficiency using high‐throughput evaluation of dense Raman maps. The optimized substrates achieved the limit of detection of M (better than 0.01 ppb) for adenine, chosen as benchmark molecule because of its affinity to silver and gold without exhibiting resonant properties in the visible range. To demonstrate versatility of the spark discharge‐prepared SERS probes, spectra of selected bio‐relevant derivatives of adenine have been successfully acquired at low concentration.