Layered Creatinine Test Strip for Portable Optical Measurement
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Solution Overview
Problem
Existing methods for measuring creatinine levels are complex, costly, and require unstable enzymes, making them unsuitable for portable use outside a laboratory setting, and are prone to interference from endogenous creatine.
Innovation Solution
A dry-chemistry test strip with a layered active component assembly that performs multi-step enzymatic reactions without stabilizing enzymes, using commercially available enzymes to convert creatinine into a chromophoric species, and an optical sensing device for direct measurement, coupled with a mobile device for quantification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If unstable enzymes are used for creatinine measurement, then measurement capability is achieved, but reliability and ease of operation deteriorate due to requiring stabilization and refrigeration
Solution Approach 1:
The patent employs a disposable test strip containing the enzyme creatinine amidohydrolase that is used once and then discarded. This eliminates the need to stabilize and store expensive, unstable enzymes, as each new strip contains fresh enzyme activity. The strip is designed for single-use in portable devices, making the system reliable without requiring refrigeration or complex stabilization protocols.
2Measurement precision
If differential measurements are performed to account for endogenous creatine interference, then measurement precision is improved, but device complexity and time consumption increase
Solution Approach 1:
The patent extracts and removes endogenous creatine from the sample matrix before the creatinine measurement is performed. This is achieved by adding a creatine-specific enzyme (creatine kinase) that converts creatine to creatinine, which is then separated or removed from the sample. By taking out the interfering substance, the patent eliminates the need for complex differential measurements while maintaining high measurement precision.
Solution Approach 2:
The patent performs preliminary removal of endogenous creatine interference before the actual creatinine quantification step. The test strip is designed to first convert and remove creatine, then measure creatinine in a single sequential process. This preliminary action simplifies the overall measurement procedure compared to performing separate differential measurements at different time points.
3Measurement precision
If multiple membranes and liquid handling steps are used, then measurement accuracy is improved, but ease of operation and productivity deteriorate
Solution Approach 1:
The patent merges multiple functions into a single integrated test strip structure. The strip combines the sample application area, enzymatic reaction zones for creatine removal and creatinine detection, and optical readout window into one compact unit. This eliminates the need for separate liquid handling steps and multiple membranes, making the device easy to operate while maintaining measurement accuracy through the integrated design.
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
Enables accurate and portable creatinine measurement without enzyme stabilization, interference from endogenous creatine, and additional liquid handling, reducing complexity and cost.
Implementation Method 1
an optical sensing device for direct measurement
Implementation Method 2
multi-step enzymatic reactions without stabilizing enzymes, using commercially available enzymes to convert creatinine into a chromophoric species
Implementation Method 3
convert creatinine into a chromophoric species
Data Source
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AI summary
Platforms for enzymatic assays for biomarkers, including systems, methods, and measuring devices by which a biomarker, such as creatinine, is measured using a small amount of biological fluid, such as blood, plasma, or serum. The measuring device or biosensor can be a test strip including a layered active component assembly positioned between two outer layers which enables multi-step enzymatic reactions operating in kinetic and/or endpoint (in which the reaction is allowed to near completion), and generally includes multiple layers with primary enzyme(s), coupling enzyme(s), and reagents to produce an optical signal correlated to the concentration of a biomarker in the sample. The test strip can be read using a portable optical reader coupled to a smart phone or tablet.