Pinch Wall Fluid Control in Lateral Flow Assay Cartridges

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Solution Overview

Problem

Lateral flow assay test strips face challenges in ensuring optimal fluid flow, including inadequate saturation, flooding, uneven fluid distribution, and capillary flow along surfaces, which can lead to undesirable results and inaccurate readings.

Innovation Solution

A disposable cartridge system with fluid control features, including a pinch wall to direct fluid flow and support ribs to prevent capillary flow, ensures controlled fluid movement into and through the test strip, maintaining saturation without flooding and promoting even lateral flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the test strip is provided with sufficient fluid supply to ensure full saturation, then the fluid flow through the test strip is improved, but the test strip may be flooded causing capillary flow away from the test strip

Engineering Contradiction:

Improvefluid saturation of test stripVSAvoidflooding and capillary flow away from test strip

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The cartridge is divided into distinct functional zones: a sample receiving pad, a test strip, and a waste pad. Pinch walls segment the fluid flow paths to control where fluid accumulates and where it is directed, preventing flooding of the test strip while ensuring adequate saturation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Pinch walls act as intermediary structures between the sample receiving pad and the test strip. These walls selectively allow fluid to pass through while blocking excessive fluid, mediating the flow to maintain optimal saturation without causing flooding.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If the test strip is allowed to receive fluid freely, then the fluid flow through the test strip is improved, but fluid may flow along the top or bottom surfaces bypassing the reaction

Engineering Contradiction:

Improvefluid flow through test stripVSAvoidfluid flow uniformity and reaction accuracy

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The test strip is designed with different local properties: the top and bottom surfaces have different fluid interaction characteristics. The pinch walls create localized flow channels that direct fluid through the test strip material rather than along the surfaces, ensuring uniform flow and reliable reaction.

Inventive Principle:

Principle #3Local quality

3Quantity of substance

If the sample receiving pad is made large to receive excess fluid, then the fluid capacity is improved, but fluid may splash onto the test strip causing undesirable results

Engineering Contradiction:

Improvefluid capacity of sample receiving padVSAvoidfluid splashing onto test strip

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

Pinch walls serve as intermediary barriers between the sample receiving pad and the test strip. These walls prevent direct contact and splashing of excess fluid from the pad onto the test strip, while still allowing controlled fluid flow through the pad to the test strip.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The cartridge structure segments the sample receiving area from the test strip area using pinch walls. This segmentation contains excess fluid within the pad area and directs it to the waste pad, preventing splashing onto the test strip.

Inventive Principle:

Principle #1Segmentation

4Stability of the object's composition

If the test strip is held firmly to prevent movement, then the structural stability is improved, but fluid flow uniformity may be compromised

Engineering Contradiction:

Improvetest strip position stabilityVSAvoidfluid flow uniformity

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The test strip is held at specific localized points by support ribs rather than being rigidly constrained throughout. This localized holding provides stability while leaving the rest of the test strip free to allow uniform fluid flow through its material structure.

Inventive Principle:

Principle #3Local quality

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

The system effectively controls fluid flow, preventing capillary flow along surfaces and ensuring uniform saturation of the test strip, leading to precise and consistent assay results by directing fluid flow laterally and inhibiting excess fluid from seeping into other areas.

Implementation Method 1

it is also important that the test strip not be flooded (such that fluid may seep away from the test strip by capillary action)

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Implementation Method 2

preventing capillary fluid flow along the top or bottom surfaces of the test strip

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Data Source

PatentUS8574919B2Mechanical cartridge with test strip fluid control features for use in a fluid analyte meter

Publication Date: 2013.11.05 POLYMER TECHNOLOGY SYSTEMS INC

AI summary

A structure for controlling fluid flow from a sample receiving pad into a lateral flow assay test strip, including: a lateral flow assay test strip; a sample pad abutting the lateral flow assay test strip; a pinch wall positioned to direct fluid flow from the sample pad to the lateral flow assay test strip; a top support structure positioned on top of the test strip; and a bottom support structure positioned underneath the test strip, wherein each of the top and bottom support structures comprise a plurality of separate spaced-apart support ribs positioned along the length of the test strip.