Creatinine Sensing by Raman Spectroscopy in Multilayer Photonic Crystal

Abstract

This study presents the fabrication and characterization of a novel sensor for creatinine detection, based on a combination of one-dimensional multilayer photonic crystals (1DMPC) coated with plasmonic gold (Au) and enhanced by surface-enhanced Raman scattering (SERS) techniques. Scanning electron microscopy (SEM) confirmed a well-defined multilayer structure consisting of ten alternating layers of silicon dioxide (SiO₂) and silicon nitride (SiN), capped with a uniform Au coating. Energy-dispersive X-ray spectroscopy (EDXS) verified the high purity of the elemental composition. Atomic force microscopy (AFM) revealed a textured surface with nanoscale roughness, which is favorable for enhancing electromagnetic fields. Both measured and simulated optical transmission spectra demonstrated the presence of a photonic bandgap (PBG) in the Au-1DMPC structure, which plays a critical role in light confinement and Raman signal amplification. The sensor exhibited a strong linear correlation between Raman intensity and creatinine concentration, achieving a sensitivity of 19.37 ppm (parts per million). The calculated limit of detection (LoD) was 0.902 ppm, highlighting the sensor’s capability for detecting low levels of creatinine. Additionally, the sensor demonstrated excellent selectivity, ensuring accurate chemical identification even in complex environments. These findings indicate that the Au-1DMPC sensor offers significant potential for accurate, low-concentration creatinine detection and can be extended to a wide range of sensing applications in chemical, biomedical, and clinical fields.