Capillary Blood Test Kit with Sodium-Free Diluent

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Solution Overview

Problem

Existing methods for analyzing small volumes of blood samples suffer from low accuracy and repeatability due to variations in blood collection volume, leading to unreliable measurement results, especially when using capillary action or buffer solutions that contain sodium ions or chloride ions, which are homeostatic components in blood.

Innovation Solution

A blood test kit utilizing a capillary with graduations for precise blood collection, combined with a diluent solution that does not contain sodium ions, allowing for the use of sodium ions as an external standard to accurately determine the dilution factor and maintain a constant blood collection volume, thereby enhancing the accuracy of blood analysis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a small volume of blood sample is collected for analysis, then the invasiveness of blood collection is reduced, but the accuracy and repeatability of measurement results deteriorate due to variations in blood collection volume

Engineering Contradiction:
Improveinvasiveness of blood collectionVSAvoidaccuracy of measurement results
Core Design Contradiction:
Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The capillary is pre-calibrated with graduations to indicate the exact volume needed (e.g., 10 μL). The user simply fills the capillary to the graduation mark before analysis, eliminating the need for post-collection volume measurement and ensuring consistent, accurate volumes are used in every test.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention changes the physical parameter of the collection device by using a capillary with a specifically designed inner diameter and length that, when filled to a certain graduation, automatically provides a precise, repeatable blood volume. This physical design ensures volume consistency without requiring complex measurement procedures.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If buffer solutions containing sodium ions or chloride ions are used for dilution, then the dilution process is simplified, but the accuracy of dilution factor calculation deteriorates because these ions are homeostatic components in blood

Engineering Contradiction:
Improvesimplicity of dilution processVSAvoidaccuracy of dilution factor calculation
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The invention extracts and removes sodium ions and chloride ions from the diluent solution formulation. By using a buffer solution that explicitly excludes these homeostatic ions, the diluent no longer interferes with the measurement of blood sodium levels, allowing accurate dilution factor calculation even though the dilution process remains simple.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention introduces a specialized buffer solution as an intermediary substance that performs the dilution function without containing interfering ions. This buffer acts as a mediator between the blood sample and the analysis system, providing the necessary buffering capacity while avoiding contamination with homeostatic ions that would compromise measurement accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of operation

If capillary action is used for blood collection, then the collection process is simplified and requires minimal equipment, but the volume control precision deteriorates due to variations in capillary phenomenon

Engineering Contradiction:
Improvesimplicity of collection processVSAvoidvolume control precision
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The capillary is pre-calibrated during manufacturing with graduations marked at specific volumes. This preliminary action ensures that when the user fills the capillary to the indicated graduation, they obtain the exact volume needed, combining the simplicity of capillary action with precision volume control.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention optimizes the capillary's physical parameters (inner diameter, length, wall thickness) to ensure consistent capillary action while maintaining volume precision. By carefully controlling these manufacturing parameters, the capillary reliably draws blood to the correct volume through capillary action alone, without requiring additional control mechanisms.

Inventive Principle:
Principle #35Parameter changes

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 solution enables high-accuracy blood analysis with small blood volumes by maintaining a constant collection volume and reducing measurement errors, improving the reliability of dilution factor calculations and overall test accuracy.

Implementation Method 1

the blood collection instrument is a capillary inside which the blood sample can be collected by a capillary phenomenon

Methodology Applied
Scientific EffectCapillary phenomenon: Capillary Action

Data Source

PatentEP3321677B1Blood test kit and analyzing method using the same
Publication Date: 2021.03.24 FUJIFILM CORP
  • EP3321677B1 patent drawingFigure 1
  • EP3321677B1 patent drawingFigure 2
  • EP3321677B1 patent drawingFigure 3

AI summary

An object is to provide a blood test kit and a blood analysis method capable of performing a blood test with a small amount of blood at high accuracy by visualizing a volume of blood collection and keeping the volume constant. Provided is a blood test kit for analyzing a concentration of a target component in a blood sample using a normal component homeostatically present in blood, the kit including: a blood collection instrument for collecting the blood sample; a diluent solution for diluting the collected blood sample; and a storing instrument for storing the diluted blood sample, in which the blood collection instrument is a capillary.