Fiber-optic conical microsensors for surface plasmon resonance using chemically etched single-mode fiber

A new type of the fiber-optic microsensor for surface plasmon resonance (SPR) was created on the basis of the fabrication technology of optical fiber probes in near-field scanning optical microscopy (NSOM). The newly developed SPR microsensors were prepared by coating a gold-metallic film on the chemically etched single-mode fiber containing a conical core. They were applied to the real-time monitoring of the refractive index (RI) of transparent liquids flowing in the microfluidic device. When SPR microsensors were chemically modified with a self-assembled monolayer presenting a hydroxyl group, they successfully responded to the refractive index from 1.33 to 1.40 RI with a sensitivity of 0.008 RI units that covers the interesting regions for SPR biosensor operated in a water solution.