Microscale solute flow probed with rotating microbead trapped in optical vortex

The dynamics of solute flow in the microscopic chamber can be studied with optical tweezers. A method based on the metallic microbeads trapped in the focused optical vortex beam is proposed. This annular beam of a twisted wavefront exerts torque on a reflective object placed inside the dark core of...

Full description

Saved in:
Bibliographic Details
Published in:Experiments in fluids 2021-06, Vol.62 (6), Article 128
Main Authors: Lamperska, Weronika, Masajada, Jan, Drobczyński, Sławomir
Format: Article
Language:English
Subjects:
Angular velocity
Chambers
Configurations
Dissolution
Electron beams
Engineering
Engineering Fluid Dynamics
Engineering Thermodynamics
Fluid dynamics
Fluid flow
Fluid- and Aerodynamics
Heat and Mass Transfer
Microfluidics
Micrometers
Nanoparticles
Research Article
Rotation
Spatial resolution
Sucrose
Vortices
Wave fronts
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The dynamics of solute flow in the microscopic chamber can be studied with optical tweezers. A method based on the metallic microbeads trapped in the focused optical vortex beam is proposed. This annular beam of a twisted wavefront exerts torque on a reflective object placed inside the dark core of the vortex. The induced rotational movement of the bead is sensitive to local viscosity changes in the surrounding medium, for example, during the ongoing dissolution process. Two experimental configurations are described, both relying on tracing the angular velocity of the bead in time. In one-bead configuration, the dynamics of local solute concentration can be studied. In two-bead case, the direction and speed of solute flow can be probed with a spatial resolution of single micrometers. We approach the elementary problem of sucrose dissolution and diffusion in water. The surprising impression of the reverse solute flow was observed. Further experimental investigation led to the discovery that this phenomenon originates from the sucrose stream-like diffusion in the mid-depth of the measurement chamber. The rotating microbead method applies for various solid and liquid substances and may become a useful technique for microfluidics research. Graphic abstract
ISSN:0723-4864
1432-1114
DOI:10.1007/s00348-021-03223-6