National Creative Research Initiative Center for Integrated Optofluidic Systems and Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, Daejeon, 305-701, Korea.
Anal Chem. 2011 Dec 1;83(23):9174-80. doi: 10.1021/ac202433x. Epub 2011 Nov 2.
Recent advances in nanofabrication techniques have enabled the creation of various metallic nanostructures in order to engineer the location and properties of electromagnetic hot spots in a controlled manner. However, most previous methods usually require complicated and time-consuming techniques, and the integration of metallic nanostructures into simple, low-cost devices for chemical or biological sensing is still challenging. Here, we report a promising new strategy for the fabrication of large-area gold nanowell arrays with novel geometric features that makes use of the trapping of self-assembled colloidal particles on a polymer surface. Through both systematic experimental and theoretical analysis, we confirm that the strong plasmon resonances of the proposed nanowell structures are associated with localized surface plasmon resonance (LSPR) on the brims of the nanoholes in the top gold films as well as in the bottom gold disks. In addition, we demonstrate a novel optofluidic platform with built-in subwavelength nanowell arrays that exhibits strong plasmon resonances within microfluidic chips. In our optofluidic systems, the plasmon coupling between the brims and the disks of nanowells makes the plasmon resonance more sensitive to surrounding materials. The dependence of the plasmon resonance on the refractive index of the surrounding medium is found to be as high as 570 nm RIU(-1) (refractive index units). These data lead to a figure of merit (FOM), the slope of refractive index sensitivity in eV RIU(-1)/line width (eV), as high as 4.1.
最近的纳米制造技术进展使得能够创建各种金属纳米结构，以便以可控的方式设计电磁热点的位置和性质。然而，大多数先前的方法通常需要复杂和耗时的技术，并且将金属纳米结构集成到用于化学或生物传感的简单、低成本设备中仍然具有挑战性。在这里，我们报告了一种有前途的新策略，用于制造具有新颖几何特征的大面积金纳米凹坑阵列，该策略利用了在聚合物表面上自组装胶体颗粒的捕获。通过系统的实验和理论分析，我们证实了所提出的纳米凹坑结构的强等离子体共振与顶部金膜中的纳米孔边缘以及底部金盘上的局域表面等离子体共振（LSPR）有关。此外，我们展示了一种具有内置亚波长纳米凹坑阵列的新型光流控平台，该平台在微流控芯片内表现出强烈的等离子体共振。在我们的光流控系统中，纳米凹坑的边缘和圆盘之间的等离子体耦合使等离子体共振对周围材料更加敏感。发现等离子体共振对周围介质折射率的依赖性高达 570nm RIU(-1)（折射率单位）。这些数据导致了一个质量因数（FOM），折射率灵敏度的斜率在 eV RIU(-1)/线宽（eV）为 4.1。
