Manipulation of a Micro-object Using Topological Hydrodynamic Tweezers

TL;DR

This paper introduces a novel topological hydrodynamic tweezers method for micro-object manipulation that is inherently resistant to external disturbances by utilizing a toroidal vortex trapping mechanism in gas flow.

Contribution

The paper presents a new non-contact micro-manipulation technique based on topological gas flow vortices, offering disturbance immunity and precise control.

Findings

Micro-droplets can be trapped in a toroidal vortex ring.

Micro-droplets can be transported along the vortex ring.

The method automatically bypasses external perturbations.

Abstract

Manipulating micro-scale object plays paramount roles in a wide range of fundamental researches and applications. At micro-scale, various methods have been developed in the past decades, including optical, electric, magnetic, aerodynamic and acoustic methods. However, these non-contact forces are susceptible to external disturbance, and so finding a way to make micro-scale object manipulation immune to external perturbations is challenging and remains elusive. Here we demonstrate a method based on new trapping mechanism to manipulate micro-scale object in a gas flow at ambient conditions. We first show that the micro-droplet is entrapped into a trapping ring constructed by a particular toroidal vortex. The vortex works as tweezers to control the position of the micro-droplet. We then show that the micro-droplet can be transported along the trapping ring. By virtue of the topological character of the gas flow, the transport path is able to bypass external strong perturbations automatically. We further demonstrate a topological transfer process of the micro-droplet between two hydrodynamic tweezers. Our method provides an integrated toolbox to manipulate a micro-scale object, with an intrinsic mechanism that protects the target object from external disturbances.