Capillary Fluid Conduit Layout for Valve-Free Liquid Dilution

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Solution Overview

Problem

Existing microfluidic devices require complex valving and pumping mechanisms for reagent mixing and liquid dilutions, limiting their use to well-equipped laboratory settings and trained personnel, and fail to efficiently mix larger amounts of liquids.

Innovation Solution

A fluid conduit device with a specific design that allows merging of liquids using capillary forces without external actuation, featuring retention ducts, liquid chambers, and bypass ducts with liquid-phobic and liquid-philic barriers to facilitate the merging of liquids in a microfluidic environment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If complex valving and pumping mechanisms are used for reagent mixing and liquid dilutions in microfluidic devices, then the operations can be performed, but the device complexity increases and restricts use to well-equipped laboratory settings

Engineering Contradiction:

Improveease of operationVSAvoiddevice complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The invention extracts and eliminates the complex valving and pumping mechanisms from the microfluidic device, replacing them with passive capillary-driven flow control. The core functionality of liquid manipulation is achieved through carefully designed channel geometries and surface properties rather than active mechanical components.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The device enables self-service operation through capillary forces that automatically drive liquid flow through the channels without external pumping. The retention ducts and liquid-phobic barriers create self-regulating flow control that eliminates the need for external valves and pumps.

Inventive Principle:

Principle #25Self-service

2Device complexity

If passive capillary-driven merging is used without external actuation, then the device complexity is reduced, but the ability to efficiently mix larger amounts of liquids is compromised

Engineering Contradiction:

Improvedevice complexityVSAvoidproductivity

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The invention segments the liquid flow into discrete plugs separated by gas phases, allowing multiple liquid plugs to be processed sequentially through the same channel. This segmentation enables efficient handling of larger total liquid volumes while maintaining the simplicity of passive capillary-driven operation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The liquid chamber is pre-filled with the second liquid before the merging process begins. This preliminary action ensures that when liquid plugs enter the channel, they immediately encounter the pre-positioned second liquid, enabling efficient mixing without requiring additional actuation steps.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If retention ducts with liquid-phobic barriers are used to control liquid flow, then the merging process is simplified, but the device structure becomes more complex

Engineering Contradiction:

Improveease of operationVSAvoiddevice complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The invention replaces mechanical valving systems with liquid-phobic surface treatments and geometric constraints. The liquid-phobic barriers create flow resistance and directional control through surface chemistry and channel geometry rather than mechanical moving parts, simplifying the overall device structure.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The liquid-phobic barriers are implemented using porous materials with controlled surface properties. These porous structures provide selective permeability and flow resistance, enabling passive liquid flow control without mechanical components while adding minimal structural complexity.

Inventive Principle:

Principle #31Porous materials

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

Enables efficient merging of liquids in a microfluidic device without the need for external actuation, allowing for simple and effective liquid mixing suitable for laboratory-on-a-chip applications.

Implementation Method 1

a first liquid-phobic liquid barrier, located further downstream of the bypass duct inlet to allow entry of liquid in the part of the bypass duct between the bypass duct inlet and said first liquid-phobic liquid barrier

Methodology Applied

Scientific EffectLiquid-phobic (hydrophobic) effect: Hydrophobe

Implementation Method 2

a second liquid-phobic liquid barrier, located next to the bypass duct outlet to prevent entry of liquid in the bypass duct through said bypass duct outlet

Methodology Applied

Scientific EffectLiquid-phobic (hydrophobic) effect: Hydrophobe