The collective oscillation of plasmons in metallic nanostructures generates localized surface plasmons (LSP), which are responsive to their surrounding dielectric environment and can be used for low-cost, label-free sensing platforms. However, the inherently short evanescent decay field saturates the optical response within 10–30 nm of the metal surface, hindering multi-layered functionalization strategies typically used for specific binding due to its limited surface proximity. In this work, we propose the use of tall nanostructures to engineer the plasmonic response for biosensing applications. The resonance mode characteristics are investigated, where the emergence of hybrid modes is found to arise from the decoupling of localized plasmon modes at increasing antenna height. Using high aspect ratio plasmonic nanostructures, we demonstrate its viability with up to 4.3 $\times$ higher sensitivity and 18.4 $\times$ higher figure of merit within the visible range. Coupled with a cost-effective fabrication method, the height provides an additional degree of freedom for tailoring the optical spectrum.

中文翻译：

---

高等离子体纳米结构的共振模式及其在生物传感中的应用

金属纳米结构中等离子体激元的集体振荡产生局域表面等离子体激元 (LSP)，它们响应于周围的介电环境，可用于低成本、无标记的传感平台。然而，固有的短渐逝衰减场使金属表面 10-30 nm 内的光学响应饱和，由于其有限的表面接近度，阻碍了通常用于特异性结合的多层功能化策略。在这项工作中，我们建议使用高纳米结构来设计生物传感应用的等离子体响应。研究了共振模式特性，发现混合模式的出现是由于天线高度增加时局部等离子体模式的去耦引起的。使用高纵横比等离子体纳米结构， $\times$ 更高的灵敏度和 18.4 $\times$ 在可见光范围内具有更高的品质因数。结合具有成本效益的制造方法，高度为定制光谱提供了额外的自由度。