Directed high-speed motion of nanoscale objects in fluids can have a wide range of applications. However, directed movement and high speed in the nanoscale are rarely compatible. Light is a convenient source that can drive nano objects to move by applying optical forces, but they are too weak to enable fast-moving swimmers in fluids. Here, we report ballistic plasmonic Au nanoparticle (NP) swimmers with unprecedented speeds (~397,000 m s -1 ) realized by not only optical pushing but also pulling forces from a single Gaussian laser beam. The Au NP excited by the laser at the surface plasmon resonance (SPR) peak interact with the NP both thermally and optically, leading unique conditions for ballistic movements and “negative” optical forces. We also show that such light-driven NPs can be deposited on surfaces and work as seeds for surface bubble nucleation. Such plasmonic
surface bubbles can collect solutes in the liquid and accumulate them at the three-phase contact line of the bubble. We show that this feature of plasmonic surface bubbles may potentially be leveraged for bio-sensing applications. Our study may lead to a wide range of nano- and bio-applications and provide new insights to the “negative” optical forces and nano-object manipulation.
Dr. Tengfei Luo, is a Professor in the Department of Aerospace and Mechanical Engineering (AME) with a concurrent appointment in the Department of Chemical and Biomolecular Engineering (CBE) at the University of Notre Dame (UND). Before joining UND, he was a postdoctoral associate at Massachusetts Institute of Technology (2009-2011) after obtaining his PhD from Michigan State University (2009). At UND, Dr. Luo’s research focuses on machine learning, materials informatics, nanoscale thermal transport, electronics thermal management, novel material design, manufacturing, and water treatment. He is an ASME
fellow and received the DuPont Young Professor Award (2016) and the DARPA Young Faculty Award (2015).