Fiber Balloon-Shaped SPR Sensor for Specific Detection of Cr(VI) Ions

Hexavalent chromium [Cr(VI)], as a highly toxic and carcinogenic heavy metal ion, poses a serious threat to the environment and human health. Therefore, the specific detection of it is of great significance. Based on this, this article proposes a balloon-shaped fiber SPR sensor with a microsphere structure for specific detection of hexavalent chromium ions. The balloon structure facilitates the formation of insertable sensing probe, and the microsphere structure located on one side of the balloon structure can adjust the incidence angle of light in the sensing area to enhance the sensitivity of the sensor, resulting in a maximum refractive index sensitivity of 5068 nm/RIU. Modifying 4-mercaptoethylpyridine (MEP) on the surface of the gold film of the sensor can achieve specific recognition of Cr(VI). The experimental results indicate that the balloon-shaped SPR sensor with microspheres proposed in this article has a detection limit of as low as 0.57 ng/mL for Cr(VI) in the detection range of 1 ng/mL– $100~\mu $ g/mL, with a detection time of 3 min, providing a new method for rapid, low concentration, and specific detection of Cr(VI).