A novel manifestation at optical leaky waveguide modes for sensing applications
A novel manifestation at optical leaky waveguide modes for sensing applications
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DOI：
10.1016/j.snb.2020.127776
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发表时间：
2020-04-15
影响因子：
8.4
通讯作者：
Gupta, Ruchi
中科院分区：
文献类型：
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作者：
Goddard, Nicholas J.;Gupta, Ruchi
我们报告了一个非常简单的生物传感器的基础上直接观察泄漏波导（LW）模式的指数衰减的干涉条纹的反射率曲线。这种现象仅在波导和样品之间的折射率对比低（0.002-0.005）并且LW同时以一系列入射角照射时观察到。LW在角度空间中充当相位物体，导致菲涅耳衍射和每个波导模式的干涉条纹的形成。我们目前的理论，定性的解释和数学模型，这些条纹的形成。分析物与固定在LW中的识别元件的结合改变了其折射率，从而改变了条纹的角位置，这提供了生物传感机制。报道的LW包括在载玻片上的聚丙烯酰胺和共聚物的膜，并且提供高灵敏度、大规模可制造性和简单的仪器。
We report a very simple biosensor based on the direct observation of leaky waveguide (LW) modes as exponentially decaying interference fringes in the reflectivity curve. This phenomenon was only observed when the refractive index contrast between the waveguide and sample was low (0.002-0.005) and the LW was illuminated with a range of angles of incidence simultaneously. The LW acts as a phase object in angle space, resulting in Fresnel diffraction and formation of interference fringes for each waveguide mode. We present theory, a qualitative explanation and a mathematical model governing the formation of these fringes. The binding of an analyte to recognition elements immobilised in the LW changes its refractive index and thus the angular position of the fringes, which provides the biosensing mechanism. The reported LWs comprised a film of polyacrylamide and copolymers on glass slides, and provided high sensitivity, mass manufacturability and simple instrumentation.