Lee Eungkyu, Huang Dezhao, Luo Tengfei
Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN, 46556, USA.
Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN, 46556, USA.
Nat Commun. 2020 May 15;11(1):2404. doi: 10.1038/s41467-020-16267-9.
Directed high-speed motion of nanoscale objects in fluids can have a wide range of applications like molecular machinery, nano robotics, and material assembly. Here, we report ballistic plasmonic Au nanoparticle (NP) swimmers with unprecedented speeds (~336,000 μm s) realized by not only optical pushing but also pulling forces from a single Gaussian laser beam. Both the optical pulling and high speeds are made possible by a unique NP-laser interaction. The Au NP excited by the laser at the surface plasmon resonance peak can generate a nanoscale bubble, which can encapsulate the NP (i.e., supercavitation) to create a virtually frictionless environment for it to move, like the Leidenfrost effect. Certain NP-in-bubble configurations can lead to the optical pulling of NP against the photon stream. The demonstrated ultra-fast, light-driven NP movement may benefit a wide range of nano- and bio-applications and provide new insights to the field of optical pulling force.
纳米级物体在流体中的定向高速运动在分子机器、纳米机器人和材料组装等众多应用领域具有广泛的应用前景。在此，我们报道了弹道等离子体金纳米颗粒（NP）泳者，其通过单束高斯激光束产生的光学推力和拉力实现了前所未有的速度（约336,000μm/s）。光学拉力和高速均由独特的纳米颗粒-激光相互作用实现。在表面等离子体共振峰处被激光激发的金纳米颗粒能够产生纳米级气泡，该气泡可包裹纳米颗粒（即超空化），为其移动创造几乎无摩擦的环境，类似于莱顿弗罗斯特效应。特定的气泡内纳米颗粒构型可导致纳米颗粒逆着光子流产生光学拉力。所展示的超快速、光驱动的纳米颗粒运动可能有益于广泛的纳米和生物应用，并为光学拉力领域提供新的见解。
