Highly Sensitive Cascaded Fiber-Optic Long-Range SPR Glucose and Temperature Self-Calibration Sensor

The development of optical fiber biosensors is expected towards capabilities of temperature self-calibration and device miniaturization. In this paper, a cascaded dual-channel long range surface plasmon resonance (LRSPR) optical fiber biosensor is proposed for the detection of glucose concentration and temperature. Finite element method is utilized to examine how the LRSPR sensor responds to refractive index (RI) and compare it with that of the regular SPR (rSPR) in traditional single silver film structure. The result shows an ultrahigh RI sensitivity of 5600 nm/RIU and anFOMvalue of 178.41RIU–1within the low RI range of 1.34 to 1.35, whose sensitivity is 2.67 times higher than that based on rSPR. Our proposed sensor generates two resonance peaks, whose sensitivity with respect to diverse parameters varies and is independent without crosstalk. It is demonstrated that, when the glucose concentration is changed within the range of 0%-30%, a sensitivity of 9.93nm/% with a linearity higher than 0.991 is achieved. As the temperature varies from 20 °C to 90 °C, the corresponding sensitivities are -0.84 and -4.23 nm/°C, respectively. An effective coefficient sensitivity matrix is employed to simultaneously monitor the two parameters, thus enabling the sensor to achieve temperature self-calibration. The designed dual-channel LRSPR sensor benefits from a simple, miniaturized and high-precision optical sensing structure, which makes it a potential candidate for biochemical sensing applications, especially in scenarios with a demand for overcoming the temperature interference.