Urine Specific Gravity Test Strip Manufacturing to Reduce pH Sensitivity
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Solution Overview
Problem
Existing urine-specific gravity measurement methods, such as urinometers and refractometers, are cumbersome, inaccurate, and not suitable for home use due to calibration requirements, while commercial test strips suffer from pH sensitivity issues leading to unreliable results.
Innovation Solution
A method for manufacturing a test strip involving a polyelectrolyte, such as poly(methyl vinyl ether-alt-maleic anhydride), neutralized to a pH of 10-11 and buffered at 7.0-7.5, combined with a pH-sensitive color indicator like bromothymol blue, to create a test strip that provides accurate and reliable specific gravity readings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If commercial test strips use conventional polyelectrolyte formulations, then the test strip can detect specific gravity, but the measurement is highly sensitive to urine pH changes leading to unreliable results
Solution Approach 1:
The patent changes the pH parameter of the polyelectrolyte solution from conventional ranges to a specific range of pH 10-11 during manufacturing. This parameter change creates a polyelectrolyte formulation that is less sensitive to urine pH variations, thereby improving measurement reliability while reducing pH sensitivity interference.
Solution Approach 2:
The patent uses a composite approach by combining a specific polyelectrolyte (poly(methyl vinyl ether-alt-maleic anhydride)) with a pH indicator (bromothymol blue) in a buffered solution system. This composite material formulation creates a test strip that maintains stable performance across varying urine pH conditions.
2Measurement precision
If a urinometer is used to measure specific gravity, then direct measurement is obtained, but the method is cumbersome and requires large volumes of urine
Solution Approach 1:
The patent replaces the mechanical urinometer system with a chemical test strip system. Instead of using a physical floating instrument that requires manual reading, the invention uses a chemical reaction-based test strip with a pH indicator that changes color according to specific gravity, enabling simple visual or instrumental reading without cumbersome mechanical operations.
Solution Approach 2:
The patent creates a simplified copy of the urinometer measurement principle by using a test strip that replicates specific gravity detection through chemical means rather than mechanical means, making the measurement process easier while maintaining measurement capability.
3Measurement precision
If refractometry is used to measure specific gravity, then accurate results are obtained, but daily calibration is required making it unsuitable for home monitoring
Solution Approach 1:
The patent employs a disposable test strip that eliminates the need for complex calibration mechanisms. Each test strip is pre-calibrated during manufacturing with a stable polyelectrolyte formulation, and after use is discarded, removing the burden of daily calibration while maintaining measurement accuracy suitable for home monitoring.
Solution Approach 2:
The patent modifies the chemical parameters of the test strip formulation (pH 10-11 buffered polyelectrolyte solution) to create inherent stability that reduces or eliminates the need for calibration, unlike conventional refractometers that require daily calibration to maintain accuracy.
4Manufacturing precision
If the polyelectrolyte solution pH is not controlled during manufacturing, then the manufacturing process is simpler, but the test strip shows high variability in measurements
Solution Approach 1:
The patent specifies a precise pH parameter range (10-11) for the polyelectrolyte solution during manufacturing and uses buffering agents to maintain this pH. This controlled parameter approach ensures consistent test strip performance and reduces measurement variability, with the added benefit that the buffering system simplifies quality control during manufacturing.
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 method reduces variability and increases sensitivity, enabling rapid and accurate specific gravity determination of urine at home, with improved linearity and reduced sensitivity to urine pH and ion composition.
Implementation Method 1
Sodium ions are captured using polyelectrolytes and hydrogen ions are released
Implementation Method 2
These hydrogen ions are then detected with a pH indicator which shows a change of color
Data Source
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AI summary
The present disclosure concerns a method to manufacture a test strip for measuring specific gravity of a urine sample, the method comprising successively: - providing a polyelectrolyte in a first solution, the polyelectrolyte being poly(methyl vinyl ether-alt-maleic anhydride), - adding to the first solution a base to neutralize the polyelectrolyte and to bring the first solution at a pH between 10 and 11, - adding to the first solution a buffering agent to bring and maintain the first solution at a pH between 7.0 and 7.5, - dipping a paper strip into the first solution, - dipping the paper strip into a second solution comprising a pH sensitive color indicator.