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Microfluidic converging/diverging channels optimised for homogeneous extensional deformation.

Biomicrofluidics·2016
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Optimization of flow-focusing devices for homogeneous extensional flow.

Francisco Pimenta1, Renato G Sousa1, Manuel A Alves1

  • 1CEFT, Departamento de Engenharia Química, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.

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Optimized flow-focusing devices create uniform extensional flow for microfluidics. These devices effectively stretch DNA molecules, offering precise control over Hencky strain and strain-rate.

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Area of Science:

  • Fluid Dynamics
  • Microfluidics
  • Biophysics

Background:

  • Homogeneous extensional flow is crucial for microfluidic applications.
  • Designing devices for precise control of flow characteristics remains a challenge.

Purpose of the Study:

  • To develop and optimize flow-focusing devices for generating wide regions of homogeneous extensional flow.
  • To evaluate the performance of these devices under various conditions and their utility in biomolecule manipulation.

Main Methods:

  • Utilized a computational methodology involving an optimizer, finite-volume solver, and mesh generator.
  • Parameterized device geometries using Bézier curves for shape optimization.
  • Performed Brownian dynamics simulations to study DNA molecule stretching and relaxation.

Main Results:

  • Optimized devices successfully generated homogeneous extensional flow across typical microfluidic conditions.
  • Device performance was validated against varying Reynolds numbers, velocity ratios, and fluid rheologies.
  • DNA molecule extension in optimized devices closely mimicked ideal planar extensional flow at high Weissenberg numbers.

Conclusions:

  • The optimized flow-focusing devices provide a robust platform for generating controlled homogeneous extensional flows.
  • These devices offer precise control over Hencky strain and strain-rate, beneficial for microfluidic applications.
  • The study demonstrates the potential of these devices for applications involving biomolecule stretching and analysis.