A fiber optic sensor for monitoring mercuric (Hg²⁺) ions in the aqueous sample have been developed based on modified cladding. To fabricate a D-shaped sensing zone onto the multimode optical fiber lengthwise polishing was utilized using a mechanical end and edge polishing system. The produced sensing region has dimensions of 10 mmנ125 μmנ62 μm (lנwנh). A 2 μm thin layer of Al₂O₃ nanoparticles sensitized with 4-(2-pyridylazo)-resorcinol was deposited onto the sensing element of multimode fiber optic sensor to make it sensitive and selective for Hg²⁺ ions. The analytical results demonstrate that the sensing device has a linear response for Hg²⁺ ions concentration over a range from 4 to 16 ppm along with a 4 ppm limit of detection in an aqueous sample at room temperature. The selectivity of the sensor is examined for the recognition of Hg²⁺ ions in presence of other cations such as zinc and/or lead ions up to 16 ppm in an aqueous solution. The main merits of this fabricated sensor are easy and safe installation, rapid response, enhanced linear response range, and better selectivity towards Hg²⁺ ions.

基于改良包层开发了一种用于监测水样中汞 (Hg ²⁺ ) 离子的光纤传感器。为了在多模光纤上制造 D 形传感区，使用机械端部和边缘抛光系统进行纵向抛光。产生的感测区域的尺寸为 10 mmנ125 μ mנ62 μ m ( lנwנh )。A 2 μ级的Al薄层_2个ö ₃纳米颗粒与4-（2-吡啶基偶氮） -间苯二酚致敏沉积到多模光纤传感器的感测元件，使其灵敏度和选择性对Hg ²⁺离子。分析结果表明，传感装置对4 至 16 ppm 范围内的Hg ²⁺离子浓度具有线性响应，并且在室温下水性样品中的检测限为 4 ppm。在水溶液中存在其他阳离子（例如锌和/或铅离子）时，检测传感器识别 Hg ²⁺离子的选择性。这种制造的传感器的主要优点是安装简便、安全、响应迅速、线性响应范围扩大，以及对 Hg ²⁺离子的选择性更好。