针对日益严峻的食品安全问题, 特别是食源性致病菌的快速检测, 本文提出一种基于表面改性石墨烯粗锥型马赫-曾德尔干涉结构的光纤大肠杆菌传感器。首先, 截取一根4 cm的实心光子晶体光纤, 两端分别与两根单模光纤进行粗锥熔接, 形成基于马赫-曾德尔干涉原理的传感结构; 接着, 制备一种表面改性石墨烯敏感材料, 将它涂覆在实心光子晶体光纤的表面, 使传感器对大肠杆菌溶液有较高的灵敏度; 最后, 将上述传感器置于水槽中, 以此检测大肠杆菌溶液浓度。实验结果表明, 在大肠杆菌溶液浓度为50~600 cfu/mL内, 随着菌液的浓度增大, 传感器的干涉光谱发生了明显的蓝移, 灵敏度为3.43 pm/(cfu·mL-1), 菌液浓度与波长偏移的线性度为0.956 49, 检测限为67.18 cfu/mL, 响应时间为15 s。该传感器成本低、体积小、响应时间快, 适用于低浓度大肠杆菌浓度的快速检测。

To solve increasingly serious food safety problems, especially the rapid detection of food-borne viruses, an E. coli sensor based on the surface-modified graphene enlarged-cone Mach-Zehnder interference structure was proposed in this study. First, a 4 cm solid photonic crystal fiber was intercepted and coarsely fused with two single-mode fibers to form an interference structure based on the Mach-Zehnder principle. Next, surface-modified graphene sensitive material was prepared. The modified graphene, coated on the surface of the solid photonic crystal fiber, allowed the sensor to have a higher sensitivity to E. coli solutions. Finally, the above sensor is placed in a water tank to detect the concentration of the E. coli. The experimental results show that the interference spectrum of the sensor has a significant blue shift with a sensitivity of 3.43 pm/(cfu·mL-1) in the range of 50-600 cfu/mL of the E. coli solution. The linearity between the bacterial concentration and wavelength shift is 0.956 49, detection limit is 67.18 cfu/ml, and response time is 15 s. The sensor has low cost, small volume, fast response time, and is suitable for the rapid detection of low concentration E. coli.