Micro-capillary-Based Self-Referencing Surface Plasmon Resonance Fiber-Optic Biosensor

In this paper, we propose and demonstrate a novel self-referencing surface plasmon resonance (SPR) fiber-optic sensor which provides a Fabry-Perot (FP) interference referencing signal for temperature compensating. The sensor is fabricated by splicing a capillary partly coated with gold film between multimode fibers. The multimode fibers act as the lead-in and lead-out fibers while the capillary is used as sensing element. Because the FP interference and SPR effects can occur in the capillary simultaneously, the spectrum of the sensor exhibits SPR absorption and FP interference fringes. Due to the FP interference fringe sensitive to temperature while insensitive to refractive index (RI), it can be used as referencing signal and the SPR absorption was used as measuring signal. Experimental results show that this approach we presented can compensate temperature effect and develop this sensor as a practicable high-sensitivity sensing device. Moreover, as a self-referencing fiber-optic SPR sensor, this simple and low-cost element can be used for highly sensitive biosensing for further investigations.