Optical manipulation of a dielectric particle along polygonal closed-loop geometries within a single water droplet

Abstract

We report a new method to optically manipulate a single dielectric particle along closed-loop polygonal trajectories by crossing a suite of all-fiber Bessel-like beams within a single water droplet. Exploiting optical radiation pressure, this method demonstrates the circulation of a single polystyrene bead in both a triangular and a rectangle geometry enabling the trapped particle to undergo multiple circulations successfully. The crossing of the Bessel-like beams creates polygonal corners where the trapped particles successfully make abrupt turns with acute angles, which is a novel capability in microfluidics. This offers an optofluidic paradigm for particle transport overcoming turbulences in conventional microfluidic chips.

Droplet-based mechanical transducers modulated by the symmetry of wettability patterns

“…Droplets, though typically considered as liquid instead of material, are actually a kind of metamaterial 12 , 13 and showcase the advantages of easy accessibility, component diversity, and volume tunability, which might possess the potential for mechanical transformation. Through rational design, droplets can exhibit various appealing metamaterial-possessed properties 14 , showing unique applications in optical modulator 15 , 16 , non-Hookean spring 17 , and hydrodynamical rectifier 18 . In addition, the surface tension and the flowability of the liquid inside the droplet endow it with bizarre mechanical properties different from traditional solid materials, which makes it widely used in micromechanics 19 – 21 .…”