基于光力捕获效应的高灵敏度硅基纳米梁微腔传感器研究

High sensitivity, miniaturization and intelligent sensing are main characteristics requirements of future biosensors. Sensors based on silicon microcavities have been widely investigated due to the potential for lab-on-a-chip applications. The surface of the cavities must be functionalized with receptors, antibodies before they can be utilized for bio/chemical sensing. Thus, it will be difficult to identify the molecules with small weight or analytes with low concentration and small affinity. . The project will address the above issues. We will explore the mechanisms of optical sensors based on photonic crystal (PhC) nanobeam cavities with optical force induced trapping. Optical gradient force induced trapping effect will be utilized to capture the particles/biomolecules, avoiding the surface functionalization processes. To achieve a higher sensitivity, higher-order modes will be utilized instead of the fundamental one to enhance the light-matter interaction. Due to the self-locating trapping effect, the region with the strongest optical field will interact with the analyte molecules and the induced spectrum shift will be the maxima. Furthermore, the influence of the ambient temperature will be eliminated by using dual polarization or multi-mode characteristics of the PhC nanobeam cavities. The real-time quantitative measurement of polystyrene will be demonstrated.

高灵敏度、集成化、智能化是生物传感器发展方向，硅光子集成微腔传感器因其优良的特性以及与微电子结合最终实现片上实验室芯片的潜在可能成为国际上的研究热点之一。目前的传感测量多是在表面功能化修饰的基础上完成的，识别原始状态的小分子量、低浓度以及小亲和性分析物，仍然有非常大的难度。. 针对以上问题，本项目将探索利用光力的捕获效应将待测分子束缚至微腔表面进行传感探测，从而避免对传感器表面进行功能化修饰。针对微量探测的要求，利用高阶模式的倏逝波增强效应，通过相位匹配实现高阶模选择性激发，结合光力捕获的自定位效应，使光场与待测分子的作用达到最强，实现高灵敏度传感。利用新型复合微腔结构，深入分析强局域电磁场对传感灵敏度的增强机理，实现传感灵敏度、微腔Q值，模式体积的全局优化。充分利用纳米梁微腔可双偏振、多模式工作的特点，消除环境温度的交叉影响，最终实现待测物分子的实时量化测量。

项目围绕基于光力捕获效应的高灵敏度硅基光子传感器的研制开展了系列工作。采用数值方法对光波导高阶模式的特性进行研究，优化其结构从而通过倏逝场增强效应使得倏逝场与被测媒介间作用的最大化，以提高光学传感灵敏度。深入研究纳米梁腔的谐振谱特性，并进行结构优化，验证基于高阶模式光波导纳米梁腔的传感特性。利用新型的一维光子晶体纳米梁腔实现了一种高灵敏度的硅光子生物传感器。该腔能够在刻蚀圆孔的低折射率区域，特别是在纳米触手间隙附近，实现较大的光功率分布增强，从而使得光场与分析物之间的重叠区域极大增加，同时SSPhC腔的灵敏度有了显著提高。提出了一种利用级联微腔实现的双参量传感器，实现了在不增加系统复杂度的情况下，消除环境温度的交叉影响。完成利用光力捕获效应探测聚苯乙烯小球的方案，利用光力实现小球捕获的自定位效应，确定了适合于小球捕获与传感的纳米梁腔结构。实现整个传感器的制作及测试，比较测试结果与理论预期，进行详细分析，得到灵敏度、探测极限等参数。