Nugroho Ferry Anggoro Ardy, Albinsson David, Antosiewicz Tomasz J, Langhammer Christoph
Department of Physics , Chalmers University of Technology , 412 96 Göteborg , Sweden.
Faculty of Physics , University of Warsaw , Pasteura 5 , 02-093 Warsaw , Poland.
ACS Nano. 2020 Feb 25;14(2):2345-2353. doi: 10.1021/acsnano.9b09508. Epub 2020 Feb 3.
The highly localized sensitivity of metallic nanoparticles sustaining localized surface plasmon resonance (LSPR) enables detection of minute events occurring close to the particle surface and forms the basis for nanoplasmonic sensing. To date, nanoplasmonic sensors typically consist of two-dimensional (2D) nanoparticle arrays and can therefore only probe processes that occur within the array plane, leaving unaddressed the potential of sensing in three dimensions (3D). Here, we present a plasmonic metasurface comprising arrays of stacked Ag nanodisks separated by a thick SiO dielectric layer, which, through rational design, exhibit two distinct and spectrally separated LSPR sensing peaks and corresponding spatially separated sensing locations in the axial direction. This arrangement thus enables real-time plasmonic sensing in 3D. As a proof-of-principle, we successfully determine in a single experiment the layer-specific glass transition temperatures of a bilayer polymer thin film of poly(methyl methacrylate), PMMA, and poly(methyl methacrylate)/poly(methacrylic acid), P(MMA-MAA). Our work thus demonstrates a strategy for nanoplasmonic sensor design and utilization to simultaneously probe local chemical or physical processes at spatially different locations. In a wider perspective, it stimulates further development of sensors that employ multiple detection elements to generate distinct and spectrally individually addressable LSPR modes.
维持局域表面等离子体共振（LSPR）的金属纳米颗粒具有高度局域化的灵敏度，能够检测靠近颗粒表面发生的微小事件，并构成了纳米等离子体传感的基础。迄今为止，纳米等离子体传感器通常由二维（2D）纳米颗粒阵列组成，因此只能探测在阵列平面内发生的过程，而三维（3D）传感的潜力尚未得到开发。在此，我们展示了一种等离子体超表面，它由被厚SiO介电层隔开的堆叠Ag纳米盘阵列组成，通过合理设计，该超表面在轴向上呈现出两个不同且光谱分离的LSPR传感峰以及相应的空间分离的传感位置。这种排列因此能够实现三维实时等离子体传感。作为原理验证，我们在单个实验中成功确定了聚甲基丙烯酸甲酯（PMMA）和聚甲基丙烯酸甲酯/聚甲基丙烯酸（P(MMA-MAA)）双层聚合物薄膜的层特异性玻璃化转变温度。我们的工作因此展示了一种纳米等离子体传感器设计和利用策略，可同时探测空间不同位置的局部化学或物理过程。从更广泛的角度来看，它推动了采用多个检测元件以产生不同且光谱上可单独寻址的LSPR模式的传感器的进一步发展。
