Reactance Biosensor for Prothrombin Time and Hematocrit

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Solution Overview

Problem

Conventional methods for measuring prothrombin time (PT) and hematocrit (HCT) are time-consuming, require substantial resources, and often result in inaccurate test results due to issues with sample and reagent contact, especially when using non-porous substrates and impedance measurements.

Innovation Solution

A biosensor device utilizing reactance measurements with a test card assembly featuring porous substrates and precious metal electrodes, which improves sample and reagent contact, and an alternating current (AC) system for accurate determination of PT and HCT, reducing test errors and increasing precision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If conventional impedance measurement methods are used to measure prothrombin time and hematocrit, then the measurement process is simple, but the test results are inaccurate due to hematocrit and electrolyte concentration differences among blood samples

Engineering Contradiction:
Improvemeasurement process simplicityVSAvoidtest result accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent changes the measurement parameter from impedance to reactance. By measuring reactance instead of impedance, the system eliminates the influence of hematocrit and electrolyte concentration variations, achieving accurate PT measurement without requiring complex sample preparation or calibration procedures.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the conventional impedance measurement approach with a reactance measurement approach. This substitution fundamentally changes how the electrical properties of the blood sample are analyzed, allowing for accurate PT determination independent of sample variability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If non-porous substrates are used in test card assemblies, then the device structure is simple, but sample and reagent contact is insufficient leading to test errors

Engineering Contradiction:
Improvesubstrate structure simplicityVSAvoidsample contact adequacy
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent employs porous substrates in the test card assembly instead of non-porous materials. The porous structure increases the surface area and provides capillary action, enabling complete and uniform contact between the blood sample, reagents, and reaction zones, thereby eliminating test errors related to insufficient contact.

Inventive Principle:
Principle #31Porous materials

3Measurement precision

If optical detection methods are used to measure prothrombin time, then measurement accuracy is high, but substantial blood samples and reagents are required and the process is time-consuming

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidtest speed and resource efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent replaces optical detection methods with electrical reactance measurement. This substitution enables rapid, automated measurement using minimal sample volumes and reagents, achieving both high accuracy and high throughput suitable for modern clinical laboratories.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the detection parameter from optical properties to electrical reactance. This change allows for faster measurement kinetics and reduced sample requirements while maintaining or improving measurement accuracy compared to conventional optical methods.

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 reactance measurement method provides faster, more accurate results with reduced standard deviation and improved linear regression, overcoming the limitations of traditional impedance-based methods by enhancing sample dispersion and contact area.

Implementation Method 1

using reactance measurements taken from a sample to calculate PT... Alternating current (AC) provided by the sensor device is used to measure and calculate the prothrombin time and HCT of the blood sample using the reactance analysis

Methodology Applied
Scientific EffectReactance measurement: Electrical Impedance Tomography

Data Source

PatentEP2395353B1Device and method for measuring prothrombin time and hematocrit by analyzing change in reactance in a sample
Publication Date: 2018.08.22 APEX BIOTECH CORP
  • EP2395353B1 patent drawingFigure 1
  • EP2395353B1 patent drawingFigure 2
  • EP2395353B1 patent drawingFigure 3A~3B

AI summary

Devices and methods for measuring prothrombin time and hematocrit (HCT) by analyzing the change in reactance in a sample are presented. A diagnostic device for measuring HCT and prothrombin time of a fluid includes a relative electrode-type sensor device and a blood test card assembly including one or more pairs of electrodes, wherein alternating current (AC) provided by the sensor device is used to measure and calculate prothrombin time and HCT of blood test using the reactance analysis.