Wavelength-division-multiplexed fiber Bragg grating sensor integrated with surface plasmon resonance with the capability of multipoint, real-time remote sensing

The investigation of using FBGs to sense chemical and biological reactions/targets is relatively new, the main reason is that the evanescent field generated in FGBs is largely confined within the core, resulting in its insensitivity to the environment. Several approaches have been proposed to enhance the evanescent field of FBGs, e.g. decladding, long period grating optical fiber biosensor, the coupled cladding mode by tilted FBG, functionalized Penta micro-structured optical fiber with FBG. All the approaches above require sophisticated manipulation of FBG or complicated sensor system design, or have extreme limits on the RI range of targets, which induce uncertainty in the preparation of the sensors, reduce the repeatability and accuracy of these methodologies, and increase the biosensor cost. This paper proposes a methodology to combine Surface Plasmon Resonance (SPR) and FBGs. SPR biosensor has been reported to deliver a sensitivity of the order of 10-7 RIU, which is about 100 times better than the sensitivity that can be achieved by FBG biosensors according to published results so far. Microfluidic system is specially designed for this SPR-FBG biosensor, enabling specified various types of surface treatment for each SPR-FBG binding site while minimizing the request of sample volume. The FBGs is designed in such a way that the sensing sites can be rearranged to arbitrary pattern in order to best fit into applications, possessing a potential of manufacturing compact and wearable sensitive biosensors in the future.