2019/10/24 by Adrià Canós Valero, D. A. Kislov, Valero, Adrià Canós +13 · 2 citations
Engineering · Physics and Astronomy · #Applied Physics (physics.app-ph) #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Micro and Nano Robotics #Microfluidic and Bio-sensing Technologies #Optics (physics.optics) #Orbital Angular Momentum in Optics
paper · pdf · doi:10.48550/arxiv.1910.11707
openalex publication_date 2019/10/24 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The ever-growing field of microfluidics requires precise and flexible control\nover fluid flow at the micro- and nanoscales. Current constraints demand a\nvariety of controllable components for performing different operations inside\nclosed microchambers and microreactors. In this context, novel nanophotonic\napproaches can significantly enhance existing capabilities and provide new\nfunctionalities via finely tuned light-matter interaction mechanisms. Here we\npropose a novel design, featuring a dual functionality on-chip: boosted\noptically-driven particle diffusion and nanoparticle sorting. Our methodology\nis based on a specially designed high-index dielectric nanoantenna, which\nstrongly enhances spin-orbit angular momentum transfer from an incident laser\nbeam to the scattered field. As a result, exceptionally compact, subwavelength\noptical nanovortices are formed and drive spiral motion of peculiar plasmonic\nnanoparticles via the efficient interplay between curled spin optical forces\nand radiation pressure. The nanovortex size is an order of magnitude smaller\nthan that provided by conventional beam-based approaches. The nanoparticles\nmediate nano-confined fluid motion enabling nanomixing without a need of moving\nbulk elements inside a microchamber. Moreover, precise sorting of gold\nnanoparticles, demanded for on-chip separation and filtering, can be achieved\nby exploiting the non-trivial dependence of the curled optical forces on the\nnanoobject size. Altogether, this study introduces a versatile platform for\nfurther miniaturization of moving-part-free, optically driven microfluidic\nchips for fast chemical synthesis and analysis, preparation of emulsions, or\ngeneration of chemical gradients with light-controlled navigation of\nnanoparticles, viruses or biomolecules.\n