Dual-Channel S-Shaped SPR Fiber Biosensor for IgG Biomarker and Temperature Detection

In this research, a novel S-shaped fiber surface plasmon resonance (SPR) biosensor was first developed to achieve simultaneous dual-channel detection of temperature and immunoglobulin G (IgG) biomarkers. The construction of this sensor involves the integration of multi-mode fiber, coreless fiber, and single-mode fiber. The single-mode fiber is heated using an alcohol lamp to form part of the S-shaped sensing region and coated with the Au film, titanium dioxide (TiO2), and Au nanoparticles (Au-NPs) dedicated to the detection of IgG biomarkers. The coreless fiber is also heated by an alcohol lamp to form another part of the S-shaped sensing region and is coated with the Au film and polydimethylsiloxane (PDMS) for temperature detection. The sensor demonstrated a detection sensitivity of 6.025 nm/(μg/ml), a limit of detection (LOD) of 1.66 ng/ml, and a temperature sensitivity of -1.2214 nm/°C for IgG biomarkers. In addition, the sensor also performed well in terms of stability and reproducibility, with a relative standard deviation (RSD) of 0.026% for reproducibility testing, a maximum detection error of 0.08 μg/ml for IgG detection, and a maximum error of 0.31°C for temperature detection. The maximum percentage error is 0.03% and 0.06%, respectively. The sensor demonstrated high specificity in biomarker detection. The sensor is simple to prepare, low-cost, and compact, which provides a new direction for the application of fiber SPR sensors in the field of trace bio-detection and shows a broad application prospect in the multi-parameter monitoring of complex environments, chronic infections, and the early diagnosis of chronic liver diseases.