Zhang Zhiliang, Zhao Feng, Gao Renxian, Jao Chih-Yu, Ma Churong, Li Jie, Li Xiangping, Guan Bai-Ou, Cetin Arif E, Chen Kai
Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 511443, China.
Department of Physics, Xiamen University, Xiamen, 361005, China.
Nanophotonics. 2022 Jan 12;11(3):507-517. doi: 10.1515/nanoph-2021-0563. eCollection 2022 Jan.
Plasmonic sensors exhibit tremendous potential to accomplish real-time, label-free, and high-sensitivity biosensing. Gold nanohole array (GNA) is one of the classic plasmonic nanostructures that can be readily fabricated and integrated into microfluidic platforms for a variety of applications. Even though GNA has been widely studied, new phenomena and applications are still emerging continuously expanding its capabilities. In this article, we demonstrated narrow-band high-order resonances enabled by Rayleigh anomaly in the nanohole arrays that are fabricated by scalable colloidal lithography. We fabricated large-area GNAs with different hole diameters, and investigated their transmission characteristics both numerically and experimentally. We showed that mode hybridization between the plasmon mode of the nanoholes and Rayleigh anomaly of the array could give rise to high-quality decapole resonance with a unique nearfield profile. We experimentally achieved a refractive index sensitivity, i.e., RIS up to 407 nm/RIU. More importantly, we introduced a spectrometer-free refractive index sensing based on lens-free smartphone imaging of GNAs with (intensity) sensitivity up to 137%/RIU. Using this platform, we realized the label-free detection of BSA molecules with concentration as low as 10 M. We believe our work could pave the way for highly sensitive and compact point-of-care devices with cost-effective and high-throughput plasmonic chips.
表面等离子体传感器在实现实时、无标记和高灵敏度生物传感方面展现出巨大潜力。金纳米孔阵列（GNA）是经典的表面等离子体纳米结构之一，能够轻松制备并集成到微流控平台中以用于各种应用。尽管GNA已得到广泛研究，但新现象和应用仍在不断涌现，持续拓展其功能。在本文中，我们展示了通过可扩展的胶体光刻技术制备的纳米孔阵列中，由瑞利异常引发的窄带高阶共振。我们制备了具有不同孔径的大面积GNA，并通过数值模拟和实验研究了它们的传输特性。我们表明，纳米孔的等离子体模式与阵列的瑞利异常之间的模式杂化能够产生具有独特近场分布的高质量偶极共振。我们通过实验实现了高达407 nm/RIU的折射率灵敏度，即RIS。更重要的是，我们基于对GNA的无透镜智能手机成像引入了一种无需光谱仪的折射率传感方法，其（强度）灵敏度高达137%/RIU。利用该平台，我们实现了对浓度低至10 M的牛血清白蛋白分子的无标记检测。我们相信我们的工作能够为具有经济高效且高通量表面等离子体芯片的高灵敏度和紧凑型即时检测设备铺平道路。
