Microfluidic Particle Trains in Viscoelastic Fluids

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Solution Overview

Problem

Current microfluidic techniques for particle separation and encapsulation in viscoelastic liquids face challenges such as limited understanding of polymer solutions beyond hyaluronic acid, inefficiencies in forming stable particle trains, and difficulties in optimizing flow rates and polymer concentrations for simultaneous droplet and particle ordering, leading to issues like multiple particles in a single droplet or empty droplets.

Innovation Solution

The use of viscoelastic shear-thinning aqueous solutions, specifically Xanthan Gum or hyaluronic acid, in microfluidic devices with optimized channel designs and flow rates to create particle trains with controlled interparticle spacing, combined with immiscible oil flows for efficient encapsulation of particles, minimizing the occurrence of multiple particles in a droplet and increasing encapsulation efficiency above the Poisson limit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If viscoelastic liquids are used for particle separation and ordering, then particle trains can be formed with controlled spacing, but the understanding and optimization of polymer solutions beyond hyaluronic acid is limited

Engineering Contradiction:

Improveparticle spacing controlVSAvoidpolymer solution variety

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The patent systematically varies polymer concentration, molecular weight, and type (hyaluronic acid, xanthan gum, guar gum) to optimize particle train formation. By changing these parameters, the invention expands the range of usable polymer solutions while maintaining controlled particle spacing, thus resolving the contradiction between precision and versatility.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If flow rates and polymer concentrations are optimized for particle ordering, then stable particle trains form, but it becomes difficult to simultaneously optimize for droplet formation and encapsulation

Engineering Contradiction:

Improveparticle train stabilityVSAvoidoptimization parameters

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent establishes particle trains and ordering conditions in the upstream section of the microfluidic device before droplet formation occurs. By pre-ordering particles in the viscoelastic medium, the system simplifies the downstream encapsulation process, reducing the complexity of simultaneous optimization while maintaining train stability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention divides the microfluidic device into distinct functional sections: a particle ordering section where viscoelastic forces create particle trains, and a droplet formation section where encapsulation occurs. This segmentation allows independent optimization of each function, reducing the overall system complexity.

Inventive Principle:

Principle #1Segmentation

3Productivity

If particle trains are formed in microfluidic channels, then encapsulation efficiency can be improved, but multiple particles may still be included in the same droplet or empty droplets may form

Engineering Contradiction:

Improveencapsulation efficiencyVSAvoidsingle particle per droplet

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The viscoelastic medium itself provides the ordering force that spaces particles into stable trains with controlled interparticle distances. This self-organizing property of the medium reduces the need for external control mechanisms and minimizes the formation of multiple particles per droplet or empty droplets, thereby improving both efficiency and precision.

Inventive Principle:

Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables the formation of stable particle trains with preferred spacing, reducing the occurrence of doublets and triplets, and enhances encapsulation efficiency by ensuring single particles per droplet and minimizing empty droplets, thereby improving the compartmentalization of particles and cells.

Implementation Method 1

particles suspended in an aqueous hyaluronic acid solution displaying shear-thinning features self-assembled in an almost equally-spaced structure at the centreline of a microfluidic channel

Methodology Applied

Scientific EffectViscoelastic forces: Viscoelasticity

Implementation Method 2

aqueous viscoelastic shear-thinning liquid such as an aqueous xanthan gum solution or an aqueous hyaluronic acid solution

Methodology Applied

Scientific EffectShear-thinning: Shear Thinning

Implementation Method 3

Particle trains form at sufficiently large particle or cell concentrations as a consequence of hydrodynamic interactions occurring between consecutive particles

Methodology Applied

Scientific EffectHydrodynamic interactions:

Implementation Method 4

simultaneously introducing a water immiscible encapsulation liquid into the microfluidic device via a second inlet

Methodology Applied

Scientific EffectDroplet formation:

Data Source

PatentUS20240198335A1Particle separation systems and methods

Publication Date: 2024.06.20 UNIVERSITY COLLEGE OF SWANSEA

AI summary

The invention relates to methods for separating particles in a microfluidic device and, ideally, encapsulating said particles in at least one or a stream of droplets; and a kit of parts for performing said methods.