Nanobiosensors and Bioanalytical Applications Group, Research Centre in Nanoscience and Nanotechnology (CIN2) CSIC-ICN & CIBER-BBN, 08193 Bellaterra, Barcelona, Spain.
ACS Nano. 2010 Jan 26;4(1):349-57. doi: 10.1021/nn901024e.
We present a theoretical and experimental study involving the sensing characteristics of wavelength-interrogated plasmonic sensors based on surface plasmon polaritons (SPP) in planar gold films and on localized surface plasmon resonances (LSPR) of single gold nanorods. The tunability of both sensing platforms allowed us to analyze their bulk and surface sensing characteristics as a function of the plasmon resonance position. We demonstrate that a general figure of merit (FOM), which is equivalent in wavelength and energy scales, can be employed to mutually compare both sensing schemes. Most interestingly, this FOM has revealed a spectral region for which the surface sensitivity performance of both sensor types is optimized, which we attribute to the intrinsic dielectric properties of plasmonic materials. Additionally, in good agreement with theoretical predictions, we experimentally demonstrate that, although the SPP sensor offers a much better bulk sensitivity, the LSPR sensor shows an approximately 15% better performance for surface sensitivity measurements when its FOM is optimized. However, optimization of the substrate refractive index and the accessibility of the relevant molecules to the nanoparticles can lead to a total 3-fold improvement of the FOM in LSPR sensors.
我们提出了一项理论和实验研究，涉及基于平面金膜中的表面等离激元（SPP）和单个金纳米棒的局域表面等离激元共振（LSPR）的波长询问等离子体传感器的传感特性。这两个传感平台的可调谐性使我们能够分析其体相和表面传感特性，作为等离子体共振位置的函数。我们证明，一个通用的优值（FOM），在波长和能量尺度上是等效的，可以用来相互比较这两种传感方案。最有趣的是，这个 FOM 揭示了一个光谱区域，在这个区域中，两种传感器类型的表面灵敏度性能都得到了优化，我们将其归因于等离子体材料的固有介电性质。此外，与理论预测非常吻合，我们实验证明，尽管 SPP 传感器具有更好的体相灵敏度，但当优化其 FOM 时，LSPR 传感器在表面灵敏度测量方面的性能大约提高了 15%。然而，优化衬底折射率和相关分子对纳米粒子的可及性可以导致 LSPR 传感器的 FOM 提高 3 倍。
