A Label-Free and Anti-Interference Dual-Channel SPR Fiber Optic Sensor With Self-Compensation for Biomarker Detection

In this work, we report a self-compensating, label-free, and anti-interference surface plasmon resonance (SPR) fiber biosensor based on a cascaded U-shaped multimode fiber and a single-mode fiber and both coated with gold film. In the traditional dual-channel SPR sensor structure, in order to obtain two independent SPR signals on one probe, different metal films need to be coated on two sensing channels. We proposed a U-shaped cascade dual-channel SPR optical fiber sensor, two channels are covered with gold film, and two independent SPR signals can be obtained by controlling the U-bend radius. In order to achieve self-compensating in detection of biomarkers, the U-shaped multimode fiber area of sensing probe is biologically functionalized as a detection channel, and the straight single-mode fiber without functionalized used as a reference channel. During the process of measuring biomarkers concentration, the existence of reference channel can be used to eliminate the effect of impurities' physical adsorption in the detection channel on the result. This sensor was used to detect the IgG concentration in complex samples, achieving the high precision detection with a limit of detection of 0.104\mu g/mL. A small-in-size, simple-to-manufacture, dual-channel SPR sensor with self-compensation was proposed and demonstrated in this article which has an excellent application prospect in the clinical monitoring of various biomarkers.