Plasmonic dual-parameter optical fiber sensor for cortisol and glucose detection

The concentration of cortisol in the human body is related to health. Research has shown that the cortisol level in the body correlates with glucose. Therefore, simultaneously and sensitively measuring cortisol and glucose levels is very important for diabetic patients. A combination of biomolecules and metal nanoparticle surfaces can change the refractive index and induce a shift in the surface plasmon resonance (SPR) wavelength. Therefore, a sensor for cortisol and glucose detection is designed and fabricated. The logarithmic sensitivity of cortisol and glucose concentrations reach 5.267 nm/log(ng ml -1 ) and 9.878 nm/log(mM), respectively. The limits of detection (LODs) for the cortisol and glucose concentrations reach 0.0126 ng ml -1 and 1.136 × 10 −3 mM respectively. The detection range covers a concentration variation range of human saliva. The proposed sensor has a compact structure. In this work, it is proven that the sensor has good specificity and selectivity through experiments, and the technical methods of the sensor can be extended to applications in medical, biological and environmental detection.