In the present investigation, we demonstrated a simple, rapid, and highly sensitive cladding-modified optical fiber urea sensor based on the evanescent wave absorption (EWA) technique. Cladding modification was performed over a 2-cm unclad portion of optical fiber using a polyaniline-zinc oxide (PANI-ZnO) matrix with enzyme-Urease (Urs) cross-linked to it using glutarldehyde as a cross-linking agent. The PANI-ZnO matrix was characterized by X-ray diffraction, scanning electron microscopy, ultraviolet-visible, and Fourier transform-infrared spectroscopy to explore its various properties. The developed sensor shows a linear response to urea concentration in the range 10 nM−1 M in the form of the absorption spectrum at a wavelength of ~250 nm with specific selectivity. Under the proper conditions (storage at temperature 4°C after each measurement), it shows 40-day stability without any decrement in the intensity of the absorption spectrum. Thus, the developed sensor is highly sensitive, stable, and specific, with a lower detection limit of a urea concentration of 10 nM.

在本研究中，我们展示了一种基于van逝波吸收（EWA）技术的简单，快速且高度灵敏的包层改性光纤尿素传感器。使用具有戊二醛作为交联剂的酶-脲酶（Urs）交联的聚苯胺-氧化锌（PANI-ZnO）基质，在光纤的2 cm裸露部分上进行包覆改性。通过X射线衍射，扫描电子显微镜，紫外可见光和傅立叶变换红外光谱对PANI-ZnO基质进行表征，以探索其各种特性。研发的传感器对尿素浓度在10 nM-1 M范围内表现出线性响应，在约250 nm波长处具有特定选择性的吸收光谱形式。在适当的条件下（每次测量后在4°C的温度下存储），它显示了40天的稳定性，吸收光谱的强度没有任何下降。因此，开发的传感器是高度灵敏，稳定且特有的，尿素浓度的检测下限较低，仅为10 nM。