Capillary Fluidic Trench Structure Prevents Edge Wicking

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Solution Overview

Problem

Capillary-driven fluidic systems face challenges in connecting multiple substrates due to undesired wicking along the edges of fluidic connections, which can compromise system functionality.

Innovation Solution

The implementation of a trench structure in the substrates, where the microfluidic channel meets the edge, creates a sudden expansion in cross-section, reducing capillary pressure and preventing fluid from leaving the system, thereby stopping wicking at the edge.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If two or more substrates are connected using edge coupling or through hole connection, then the system can be extended and combined with other microfluidic structures, but undesired capillary flows (wicking) occur along the fluidic connections compromising system functionality

Engineering Contradiction:

ImproveAbility to extend and combine microfluidic structuresVSAvoidSystem functionality compromised by wicking

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

A bridge structure is introduced as an intermediary element between two substrates. The bridge comprises a first portion on the first substrate, a second portion on the second substrate, and a connecting portion linking them. This intermediary structure provides a controlled fluidic connection path while preventing unwanted capillary wicking along the edge interface between substrates.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The connection methodology transitions from planar edge coupling to a three-dimensional bridge structure that extends vertically and horizontally. The bridge connecting portion creates a new spatial dimension for fluid transport, elevating the connection above the substrate edge plane where wicking would occur.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Ease of manufacture

If edge coupling is used to connect substrates side by side, then the structures can share a common plane and be easily combined, but continuous wicking along the edge causes fluid to unintentionally leave the capillary driven fluidic system

Engineering Contradiction:

ImproveEase of combining microfluidic structuresVSAvoidWicking causing fluid to leave the system

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The bridge structure serves as a mediator between the microfluidic channels on different substrates, providing a controlled transition path that prevents direct edge-to-edge contact. This intermediary connection eliminates the continuous wicking path while maintaining fluidic connectivity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The harmful wicking path along the substrate edge is extracted and replaced by a controlled bridge structure. The bridge isolates the fluidic connection from the problematic edge interface, removing the source of unwanted capillary flows while preserving the desired fluid transport function.

Inventive Principle:

Principle #2Taking out (Extraction)

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 solution effectively prevents fluid from unintentionally leaving the capillary-driven fluidic system, ensuring robust and reliable control over wicking, even with small structural alterations achievable through etching techniques.

Implementation Method 1

creates a sudden expansion in cross-section, reducing capillary pressure and preventing fluid from leaving the system

Methodology Applied

Scientific EffectCapillary pressure: Capillary Pressure

Implementation Method 2

This may be realized by utilizing the capillary forces that arise within the sub-millimeter tubes

Methodology Applied

Scientific EffectCapillary forces: Capillary Action

Data Source

PatentUS11458471B2Arrangement in a capillary driven fluidic system and a diagnostic device comprising the arrangement

Publication Date: 2022.10.04 MIDIAGNOSTICS NV

AI summary

The disclosure relates to an arrangement (100′) in a capillary driven fluidic system for preventing wicking of a fluid along an edge (105) between a first substrate (110′) and a second substrate (120′), said arrangement comprising: a first substrate (110′) including a microfluidic channel (114) arranged to house the fluid, a second substrate (120′) arranged to cover a portion of the first substrate (110′), wherein the microfluidic channel (134) of the first substrate (110′) meets the second structure (120′) at a position (124) along an edge (105) defined between the first (110′) and second (120′) substrates, wherein the first and the second substrate collectively define a trench (130) for stopping wicking of the fluid along the edge (105), said trench (130) being arranged in at least one of the first substrate (110′) and the second substrate (120′), and located at a distance from said position (124) along the edge (105) and intersecting the edge (105).