Double Helical Loopback Fiber SPR Sensor for Chromium Ion Detection

Traditional methods for chromium ion detection have problems, such as slow detection speed, long detection cycle, and difficulty in on-site detection. Although fiber surface plasmon resonance (SPR) sensor has overcome these problems, their sensitivity cannot meet the detection requirements for chromium ion detection. Based on this, this article proposes a fiber SPR sensor based on a double helix loopback structure. By adjusting the parameters of the double helix structure, the light incidence angle in the sensing area was adjusted to improve the sensitivity. The symmetrical double helix structure increases the surface area of the sensing area and also enhances the structural strength of the sensor, and its optimal sensitivity is 6356 nm/RIU. After functionalizing the surface of the sensing probe, it is used for specific detection of chromium ion concentration, with a detection limit as low as 0.15 ng/mL, which achieves the rapid, real-time, and highly sensitive specific detection of chromium ions.