Optical Test Strip Reading Using Dual Thresholds Against False Positives
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Solution Overview
Problem
Adhesion of foreign substances to lateral flow test strips in optical measurement devices can lead to inaccurate sample determination, causing originally negative samples to be falsely determined as positive.
Innovation Solution
An optical measurement device that calculates the difference value between initial and latter measurement values when the measurement value exceeds a first threshold, using a second threshold to distinguish whether the excess is due to a foreign substance, ensuring accurate sample determination by comparing this difference value with the second threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical measurement is used to detect the measurement target substance, then the quantitative analysis capability is improved, but the measurement accuracy deteriorates when foreign substances adhere to the test strip
Solution Approach 1:
The patent performs preliminary measurements at multiple time points (initial measurement and subsequent measurements) before final determination. By measuring the measurement value at an initial time point and then at one or more subsequent time points, the system prepares data in advance to distinguish between foreign substance adhesion (constant values) and actual sample reactions (changing values), thereby ensuring accurate final determination despite foreign substance contamination.
Solution Approach 2:
The patent uses feedback from multiple measurement time points to adjust the final determination. By comparing the initial measurement value with subsequent measurement values, the system provides feedback information about whether foreign substances are present. This feedback mechanism allows the determination unit to correct for foreign substance interference and make accurate final determinations about the measurement target substance.
2Device complexity
If a single threshold value is used for determination, then the device complexity is reduced, but the determination accuracy deteriorates when foreign substances are present
Solution Approach 1:
The patent performs preliminary measurements at multiple time points (initial measurement and subsequent measurements) before final determination. By measuring the measurement value at an initial time point and then at one or more subsequent time points, the system prepares data in advance to distinguish between foreign substance adhesion (constant values) and actual sample reactions (changing values), thereby ensuring accurate final determination despite foreign substance contamination.
Solution Approach 2:
The patent transitions from a static single-threshold comparison to a dynamic multi-time-point comparison approach. Instead of simply comparing a single measurement value against a threshold, the system dynamically compares measurement values across multiple time points to detect changes. This dynamic approach allows the determination unit to distinguish between foreign substance interference (no change over time) and actual sample reactions (change over time), improving determination accuracy without significantly increasing device complexity.
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
Ensures accurate sample determination by differentiating between measurement value increases caused by foreign substance adhesion and actual sample reactivity, preventing false positive results.
Implementation Method 1
a measuring unit that irradiates a detection portion of an immunochromatographic test piece with measurement light and measures light obtained from the detection portion due to the irradiation with the measurement light
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
An optical measurement device 1 includes: a measurement unit which emits measurement light to a detection area 16 of a lateral flow test strip K and measures light obtained from the detection area 16 by the emission of the measurement light; and a determination unit 4 which determines whether or not a sample held by the lateral flow test strip K is negative or positive on the basis of a comparison between a measurement value obtained by the measurement unit and a first threshold value set in advance, wherein the determination unit 4 calculates a difference value between the initial measurement value and the latter measurement value when the measurement value exceeds the first threshold value after the sample is held by the lateral flow test strip K, determines that the sample is positive when the difference value exceeds a second threshold value set in advance, and determines that the sample is negative when the difference value is the second threshold value or less.