Nanovortex‐Driven All‐Dielectric Optical Diffusion Boosting and Sorting Concept for Lab‐on‐a‐Chip Platforms

Abstract

The ever-growing field of microfluidics requires precise and flexible control over fluid flow at the micro-and nanoscales. Current constraints demand a variety of controllable components for performing different operations inside closed microchambers and microreactors. In this context, novel nanophotonic approaches can significantly enhance existing capabilities and provide new functionalities via finely tuned light-matter interaction mechanisms. Here we propose a novel design, featuring a dual functionality on-chip: boosted optically-driven particle diffusion and nanoparticle sorting. Our methodology is based on a specially designed high-index dielectric nanoantenna, which strongly enhances spin-orbit angular momentum transfer from an incident laser beam to the scattered field. As a result, exceptionally compact, subwavelength optical nanovortices are formed and drive spiral motion of peculiar plasmonic nanoparticles via the efficient interplay between curled spin optical forces and radiation pressure. The nanovortex size is an order of magnitude smaller than that provided by conventional beam-based approaches. The nanoparticles mediate nano-confined fluid motion enabling nanomixing without a need of moving bulk elements inside a microchamber. Moreover, precise sorting of gold nanoparticles, demanded for on-chip separation and filtering, can be achieved by exploiting the nontrivial dependence of the curled optical forces on the nanoobjects' size. Altogether, this study introduces a versatile platform for further miniaturization of moving-part-free, optically driven microfluidic chips for fast chemical synthesis and analysis, preparation of emulsions, or generation of chemical gradients with light-controlled navigation of nanoparticles, viruses or biomolecules.

Theory, Observation, and Ultrafast Response of the Hybrid Anapole Regime in Light Scattering

“…Utilizing electric and magnetic Mie‐like resonances of nanoparticles, consisting of low‐loss high‐index semiconductor or dielectric materials, such as Si, TiO 2 , Ge, and GaAs, [ 3,4 ] enables manipulating both the electric and magnetic components of light at the nanoscale. This emerging field has already led to a wide range of exciting applications, such as low‐loss discrete dielectric waveguides, [ 5,6 ] passive and reconfigurable directional sources, [ 7,8 ] efficient high harmonic generation mechanisms, [ 9 ] light‐harvesting and antireflective coatings, [ 10–12 ] all‐dielectric metasurfaces with artificially tailored optical response, [ 13–16 ] dielectric beam deflectors, [ 17 ] and subwavelength all‐optical liquid mixing, [ 18 ] to mention just a few.…”

Optical Manipulation of Nanoparticles: A Selective Excitation Approach Using Highly Focused Orbital Angular Momentum Beams

“…[ 62–65 ] It is also a beneficial analytical platform to compute the scattering characteristics of various ranges of particles. [ 66–69 ]…”

CPA-Lasing Associated with the Quasibound States in the Continuum in Asymmetric Non-Hermitian Structures

“…Being a non-Hermitian generalization of the photonic crystal concept, such a multilayer attracts much attention due to its simplicity for analysis and availability for unusual optical responses, such as anisotropic transmission resonances, resonant scattering, nonlinear saturation effects, − nonlocality, pulse-propagation effects, , effects of disorder, and so forth. From the more general perspective, many of these effects can be treated as “anomalies” in light scattering , being described by means of scattering matrix technique. , The features of light scattering on dielectric structures were deeply studied in recent years. − …”