基于D型光纤倾斜光栅激励机制微管生物传感器的研究

In recent years, whispering gallery mode (WGM)-based biosensor has been widely studied for biomolecular detection, due to the possibility of realizing label-free single-molecular and single-cell detection. This program is to develop a high-sensitivity, miniature and temperature-calibrated biosensor. A new optical component called D-shaped fiber-based tilted fiber Bragg grating (DF-TFBG), instead of the conventional tapered fiber used to excite WGM in a microcavity, is proposed to excite WGM in a capillary. With this new component, not only the coupling coefficient is improved, but also the utilizing efficiency of the gain medium in the solutions, since the coupling mechanism is changed from point-to-point to line-to-line coupling. Moreover, the proposed scheme can essentially solve the instability existed in the conventional WGM-based sensors. Additionally, the use of TFBG can also provide multi-parametric measurement, realizing temperature-calibration. This not only reduces the design and operation difficulties but also improve the measurable accuracy and stability of the biosensor.

光学回音壁模式生物传感器是近几年来快速发展的一门新兴生物医学传感技术，可实现无标记单分子、单细胞检测，提升人类对于微观生命体认识的准确性。本项目以研制高灵敏度、微型化及温度自校准生物传感器为目标，结合D型光纤与光纤倾斜光栅的优点，提出了基于D型光纤倾斜光栅平行激励微管回音壁模式的新型激励机制，用线耦合代替单点耦合，不仅解决了单点耦合效率低的问题，并从根本上解决传统光学回音壁模式传感器稳定性差的致命性缺陷。而且，这种耦合方式还可以提高有源情况下增益介质的有效利用率。此外，倾斜光栅的引入，还可以为生物传感器提供多参量同时测量的功能，实现温度自校准，在降低生物传感器设计及执行难度的同时提高传感器测量的精确性和稳定性。

生物传感技术是一门新兴发展的传感技术，可实现无标记单分子、单细胞检测，提升人类对于微观生命体认识的准确性。本项目以制作高灵敏生物传感器为目标，提出了两种生物传感器：一种是基于D型光纤倾斜光栅激发微管回音壁模式的传感器；一种是基于倾斜光纤光栅表面修饰的传感器。对于前者，理论及实验表明，D型光纤倾斜光栅可以激发微管回音壁模式，但其对器件参数要求比较严苛，而且稳定性不佳，难以用于实际测量。对于后者，通过对倾斜光纤光栅表面进行材料修饰，可以实现对目标物的高灵敏检测。针对后者，我们开展了三方面的研究。首先，通过对倾斜光栅表面做溴酚蓝修饰，实现了对废水中铵离子的检测，探测极限达到0.02mg/L，并且测量值与商用铵离子检测仪相似。接着，通过对倾斜光纤光栅表面镀金膜，激发表面等离子共振，实现了对小分子AdoHcy的高灵敏探测，其测量极限达到1nM；还完成了对小分子AdoHcy与蛋白Set7的相互作用力监控。最后，通过在金膜上修饰石墨烯，进一步提升传感器的探测极限，实现了对葡萄糖的超高灵敏探测，其测量极限达到了10pM，比没有石墨烯修饰的传感器提升了两个数量级。本项目提出的光纤生物传感器，不仅可用于以上提到的分子及离子检测，还可以通过不同的表面修饰，实现对相应目标物的高灵敏检测。而且，由于光纤的优点，使倾斜光纤光栅传感器可用于传统传感器难以到达的地方，如体内活体检测。