Humidity-Compromised Urine Test Strip Detection via Infrared Reference Dye
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Solution Overview
Problem
Moisture-sensitive reagents in urine test strips, particularly those detecting proteases and protease inhibitors, are prone to false results due to environmental moisture, requiring accurate humidity control to maintain stability and performance, but existing methods for measuring moisture are not very accurate.
Innovation Solution
A method using an infra-red reference dye to measure light reflectance at specific wavelengths before and after a sample is applied, allowing for the identification and rejection of moisture-compromised reagents by comparing reflectance ratios, thereby correcting for humidity-induced errors in analyte concentration measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If moisture-sensitive reagents are used to detect proteases and protease inhibitors, then detection capability is improved, but reliability deteriorates due to sensitivity to environmental moisture
Solution Approach 1:
An infra-red reference dye is introduced as an intermediary element on the test strip that does not participate in the biochemical reaction but serves as a stable reference for moisture measurement. This reference dye allows differentiation between signal changes caused by analyte detection versus those caused by moisture exposure, thereby resolving the reliability issue while maintaining detection capability
Solution Approach 2:
The patent utilizes color change properties of both the moisture-sensitive reagent and the infra-red reference dye. By measuring reflectance at specific wavelengths characteristic of each dye, the system can distinguish between color changes due to protease detection and those due to moisture exposure, enabling reliable differentiation between functional and compromised reagents
2Device complexity
If conventional moisture measurement methods are used, then simplicity is maintained, but measurement precision deteriorates
Solution Approach 1:
The patent replaces conventional mechanical or physical moisture measurement methods with an optical measurement system. By using light reflectance measurement at specific wavelengths characteristic of the infra-red dye, the system achieves high measurement precision while maintaining relative simplicity through the use of standard optical components
3Stability of the object's composition
If test strips are stored in a dry environment, then stability is improved, but device complexity increases due to required humidity control
Solution Approach 1:
The infra-red reference dye is incorporated into the test strip during manufacturing, performing preliminary preparation for future moisture detection. This pre-integrated reference system allows the strip to self-monitor its moisture status without requiring external humidity control devices, thereby maintaining stability while avoiding increased device complexity
Solution Approach 2:
The test strip becomes self-monitoring through the inclusion of the infra-red reference dye. The strip can independently detect and report its own moisture status through reflectance measurement, eliminating the need for external humidity control systems or additional monitoring equipment
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 approach effectively differentiates between humidity-compromised and functional reagents, ensuring accurate detection of analytes by flagging or discarding results affected by excessive moisture, thus preventing unsafe use and correcting for moisture-affected results.
Implementation Method 1
measuring the reflectance of light at a first wavelength and at a second wavelength... The reflectance of light at the first light wavelength is in the range of from 520 to 570 nm... The reflectance at the second wavelength is in the range of from 700 to 2500 nm
Implementation Method 2
These proteases and protease inhibitor strips rely on hydrolysis of proteolytic substrates by proteases to generate detectable signals
Implementation Method 3
The reflectance at the second wavelength is in the range of from 700 to 2500 nm... and is a characteristic wavelength of the infra-red reference dye
Data Source
Figure 1
AI summary
The timing of the reaction of moisture-sensitive reagents for detecting the presence of analytes, e.g. leukocytes in urine samples, is used to detect when the reagents have been compromised by excess humidity. The ratio of light reflectance at wavelengths characteristic of the products of reaction between the reagents and the analyte and an infra-red reference dye is measured at two preset times after a urine sample has been applied to a test strip and used to determine whether the reagents have been compromised by excessive humidity. The presence of unusually dark samples is determined from the reflected light at 470 and 625 nm in order to confirm that the test strips are humidity-compromised.