Immunosensor is a powerful tool in healthcare and clinic, food and drug industry, and environmental protection. Label-free fiber-optic immunosensors have shown a myriad of advantages, such as high sensitivity, anti-electromagnetic interference, and afield measurement via the fiber network. However, the fiber-optic based sensor may bear the temperature cross-talk, especially under the warming condition for bio-activating the immune molecules. In this study, we proposed a highly birefringent microfiber Bragg grating for immunosensing with the temperature-compensation. The birefringent microfiber was drawn from the elliptical cladding multimode fiber that was ablated by the CO₂ laser. The considerably large energy overlap region offered by the original multimode fiber favored the efficient inscription of FBG with high reflectivity. The dual resonances derived by the orthogonal polarization states presented similar temperature responsivities but significantly different ambient refractive index sensitivities, allowing the temperature-compensational RI sensing. The human immunoglobulin G (IgG) molecules were anchored on the surface of the microfiber grating probe by the covalent functionalization technique to enable the specific detection of the anti-IgG molecule. The proposed method promises a high-efficiency and low-cost design for the microfiber Bragg grating-based biosensor without being subjected to the temperature cross-sensitivity.

Graphic abstract

中文翻译：

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在高双折射椭圆超细纤维中有效写入布拉格光栅，用于带温度补偿的无标记免疫传感

免疫传感器是医疗保健和诊所、食品和药品行业以及环境保护的有力工具。无标记光纤免疫传感器具有灵敏度高、抗电磁干扰、通过光纤网络进行现场测量等诸多优点。然而，基于光纤的传感器可能会承受温度串扰，特别是在生物激活免疫分子的变暖条件下。在这项研究中，我们提出了一种高双折射微纤维布拉格光栅，用于具有温度补偿的免疫传感。双折射超细光纤是从被 CO ₂烧蚀的椭圆包层多模光纤拉制而成的。激光。原始多模光纤提供的相当大的能量重叠区域有利于高效刻录具有高反射率的 FBG。由正交偏振态导出的双共振具有相似的温度响应性，但环境折射率敏感性显着不同，允许温度补偿 RI 感测。通过共价功能化技术将人免疫球蛋白 G (IgG) 分子锚定在微纤维光栅探针的表面，以实现抗 IgG 分子的特异性检测。所提出的方法有望为基于微纤维布拉格光栅的生物传感器提供高效、低成本的设计，而不会受到温度交叉敏感性的影响。

图形摘要