Inkjet printing of sensors for Surface-enhanced Raman spectroscopy

Surface-enhanced Raman spectroscopy (SERS) has been an attractive, high molecular selective, and surface-sensitive analytical technique commonly used in detecting trace chemicals. In this regard, SERS sensors with high response is essential to achieve optimal sensing. As such, the study focuses on ink-jet printing of SERS sensors on flexible substrates and optimizing their sensitivity. Silver nanoparticle (JS-B25) dot arrays were printed on flexible substrates, namely A4 paper, PET (polyethylene terephthalate), photo paper, and laminate, utilizing an Epson L130 inkjet printer. The printed arrays were sintered in a thermal oven and subsequently used for Raman detection of Methylene Blue (MB). The substrate type, printing parameters, and sintering temperature were optimized to yield the best SERS sensor. It was determined that the A4 paper exhibited the best results for printing electrodes, yielding the highest Analytical Enhancement Factor (AEF) value of 8 ± 1. Furthermore, the optimum sintering temperature was determined to be 100 ℃. The printing quality settings that yielded the ideal outcomes were "Paper plane" for paper type and "Extra High" for paper quality. Subsequently, an optimized sensor was employed to determine the Limit of Detection (LOD) for MB. The experimental LOD value obtained for MB was found to be 37.93 ppb, and the analytical enhancement factor was calculated as (1.4 ± 0.7) × 10³. The results suggest that a regular inkjet printer designed for document printing can be effectively used to fabricate sensors suitable for SERS.