Gain Compensation-Enhanced High-Accuracy SPR Biosensor for Glucose Concentration Detection

A novel high-accuracy surface plasmon resonance (SPR) optical fiber sensor based on the gain compensation method (GCM) for glucose concentration detection is presented in this paper. For the first time, we proposed a method of generating emission peak using fluorescent material rhodamine 6G (R6G) to compensate for radiation loss and ohmic loss. This approach achieves the reduction of the full width at half-maximum (FWHM) without compromising the sensitivity, thereby addressing the critical challenge in the field of SPR sensors which the FWHM widens as the sensor sensitivity increases, and significantly enhancing the detection accuracy (DA) of the sensor. The present work conducted numerical analysis on the working principle of the gain-compensated sensor and the material concentration of R6G, along with other relevant parameters, using the finite element method (FEM). Experimental validation confirmed the effectiveness of the GCM in improving the DA of the sensor. Ultimately, the measurement results indicated that the refractive index detection accuracy of the sensor, enhanced through the GCM, was improved by 79%, while its sensitivity remaining stable and maintaining a high level of 4194 nm/RIU. Simultaneously, the proposed sensor demonstrated the DA of 9.6 × 10−3 nm−1 and limit of detection (LOD) of 0.012 mg/mL when detecting glucose solution. This study not only offers a new technical pathway for optimizing the performance of SPR optical fiber sensors but also provides vital support for high-accuracy biomarker detection.