High sensitivity fiber SPR sensor based on a spiral coarse cone structure

A fiber SPR sensor can achieve rapid and portable detection of trivalent arsenic ions (As³⁺) in drinking water or food, but their sensitivity and detection limit need to be further improved and developed toward specific detection. This article proposed the implementation of the SPR sensor using a biased core fiber spiral coarse cone structure. The fine core of the biased core fiber was used to reduce the mode of transmitted light. By controlling the pitch of the spiral core to control the SPR incidence angle, a significant increase in the sensitivity of the fiber SPR sensor was achieved. Meanwhile, the harmless glutathione (GSH) was modified on the surface of the sensing gold film to achieve the specific detection of As³⁺. The experimental results indicate that the spiral coarse cone fiber SPR sensor proposed in this article has a detection sensitivity of 32.48 nm/ppb for As³⁺, with a detection limit as low as 0.011 ppb, meeting the detection requirements of the World Health Organization for As³⁺ in water, which provides a new feasible solution for fast, portable, and highly sensitive detection of metal ions in water and food.