Purpose This paper aims to simplify the fabrication and broaden the applications of hollow fiber-based surface plasmon resonance (SPR) sensors for low refractive index (RI) detection. Design/methodology/approach The authors propose an external coating design that innovatively allows the hollow fiber to function as a no-core fiber. Gold film deposited on the hollow fiber outer surface excites plasmonic waves, with the sensor directly immersed in the analyte that serves as the cladding. The inherent air hole facilitates phase matching between the core-guided mode and the surface plasmon polariton mode, thereby enhancing sensitivity. The authors theoretically analyze the sensor’s maximum detection range and sensitivity by using the finite element method, while also examining the effects of the central hole diameter and gold film thickness on performance. Findings The simulation results demonstrate sensor’s capability to detect RI in the range of 1.24–1.40, covering the RIs of skin, cervical, blood, adrenocortical carcinoma and breast cancer cells, with respective sensitivities of 3,400, 4,708.33, 5,142.85, 6,000 and 6,533.33 nm/refractive index unit. Moreover, the sensitivity can be further improved by selecting a fiber with a larger central hole diameter. Originality/value This design uses an external coating and analyte deposition, which not only simplifies the fabrication process but also demonstrates that hollow fiber-based SPR sensors can achieve low RI detection, extending the RI detection range of previous hollow fiber-based SPR sensors, thereby enabling potential sensing applications across a broader range of RI for various fields.
Wang et al. (Wed,) studied this question.