Microfluidic refractive index sensor with D-shape fiber and microtube coupling

Based on the coupling between D-shape fiber and microtube resonator in whispering gallery mode, combined with microfluidics, a refractive index sensor is proposed this paper, which region fully encapsulated. This requires very little liquid sample (about 5 nL), not fragile, has better resistance to environmental perturbation, portability repeatability than general fiber-microcavity-coupled sensor. By numerical simulation, resonance properties of microfluidic are investigated, sensing performance analyzed. The research results show that thickness mircotube-wall have great influence performance. shift wavelength good linear relationship index. Meanwhile, sensitivity high (510.5–852.7 nm/RIU), <i>Q</i>-factor reaches up 5.53×10<sup>4</sup>, detection limit can arrive at 2.11 × 10<sup>–6</sup>.