To monitor the health of agricultural soil, lead (Pb2 + ) ion measurement is essential. The various sensors for lead ion detection reported in the literature earlier are either expensive or have complicated designs. This inspired us to propose a fiber optic sensor that is simple in design, less expensive, and more efficient. A photonic crystal fiber (PCF)-unclad single mode fiber (SMF)-PCF hybrid configuration makes up the suggested sensor, and the sensing mechanism is based on a synergistic application of surface plasmon resonance and interferometry. It is shown that the suggested structure is easy to use for Pb2 + ion detection, in addition to other advantages in limit of detection (LOD) and sensitivity. The proposed structure is optimized to attain a LOD of 8.32 mg / kg, which is much less than the permissible limit of Pb2 + ions permitted in healthy agricultural soil, i.e., 100 to 400 mg / kg. Additionally, a polymer that is attached atop the gold layer and to which only Pb2 + ions can adhere ensures the sensor’s specificity. To the best of our knowledge, our proposed optical fiber-based sensor design and approach adopted to detect lead ions in agricultural soil are the first of their kind.

中文翻译：

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基于表面等离子体共振和干涉测量相结合原理的光子晶体光纤农业土壤健康监测用于铅离子检测

为了监测农业土壤的健康状况，铅（Pb2+）离子测量至关重要。早期文献中报道的用于铅离子检测的各种传感器要么价格昂贵，要么设计复杂。这启发我们提出一种设计简单、成本更低、效率更高的光纤传感器。光子晶体光纤（PCF）-无包层单模光纤（SMF）-PCF混合配置构成了所建议的传感器，其传感机制基于表面等离子体共振和干涉测量的协同应用。结果表明，除了检测限 (LOD) 和灵敏度方面的其他优点外，所提出的结构易于用于 Pb2+ 离子检测。所提出的结构经过优化，LOD 达到 8.32 mg/kg，远低于健康农业土壤中Pb2+离子的允许限量，即100～400mg/kg。此外，附着在金层顶部并且只有 Pb2+ 离子可以粘附的聚合物确保了传感器的特异性。据我们所知，我们提出的用于检测农业土壤中铅离子的基于光纤的传感器设计和方法是同类中的第一个。