Surface-enhanced Raman scattering (SERS) sensors typically employ nanophotonic structures that support high-field confinement and enhancement in hotspots to increase the Raman scattering from target molecules by orders of magnitude. In general, high field and SERS enhancement can be achieved by reducing the critical dimensions and mode volumes of the hotspots to nanoscale. To this end, a multitude of SERS sensors employing photonic structures with nanometric hotspots have been demonstrated. However, delivering analyte molecules into nanometric hotspots is challenging, and the trade-off between field confinement/enhancement and analyte delivery efficiency is a critical limiting factor for the performance of many nanophotonic SERS sensors. Here, a new type of SERS sensor employing solid-metal nanoparticles and bulk liquid metal is demonstrated to form nanophotonic resonators with a nanoparticle-on-liquid-mirror (NPoLM) architecture, which effectively resolves this trade-off. In particular, this unconventional sensor architecture allows for the convenient formation of nanometric hotspots by introducing liquid metal after analyte molecules are efficiently delivered to the surface of gold nanoparticles. In addition, a cost-effective and reliable process is developed to produce gold nanoparticles on a substrate suitable for forming NPoLM structures. These NPoLM structures achieve two orders of magnitude higher SERS signals than the gold nanoparticles alone.

中文翻译：

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采用液体镜上纳米颗粒 (NPoLM) 架构的表面增强拉曼散射传感器

表面增强拉曼散射 (SERS) 传感器通常采用纳米光子结构，支持高场限制和热点增强，从而将目标分子的拉曼散射增加几个数量级。一般来说，高场和SERS增强可以通过将热点的临界尺寸和模式体积减小到纳米级来实现。为此，已经展示了多种采用具有纳米热点的光子结构的 SERS 传感器。然而，将分析物分子输送到纳米热点具有挑战性，并且场限制/增强和分析物输送效率之间的权衡是许多纳米光子SERS传感器性能的关键限制因素。在这里，一种采用固体金属纳米粒子和块状液态金属的新型SERS传感器被证明可以形成具有液体镜上纳米粒子（NPoLM）架构的纳米光子谐振器，有效地解决了这种权衡。特别是，这种非常规的传感器架构可以在分析物分子有效地传递到金纳米颗粒表面后引入液态金属，从而方便地形成纳米热点。此外，还开发了一种经济高效且可靠的工艺，可在适合形成 NPoLM 结构的基底上生产金纳米颗粒。这些 NPoLM 结构实现的 SERS 信号比单独的金纳米颗粒高两个数量级。