Glucose Meter Oxygen Error Correction via Decay Time
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Solution Overview
Problem
Electrochemical test strips used for glucose detection face variability in measurements due to oxygen presence, which interacts with reduced enzymes and mediators, leading to artificially low glucose readings, especially in blood samples with high hematocrit levels.
Innovation Solution
An additive correction method is applied to account for oxygen presence by determining an oxygen carrying capacity-based correction factor, using the time required for the potential between electrodes to decay after switching off the applied potential, which is then used to modify the raw analyte reading, thereby correcting for oxygen-related errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional electrochemical detection is used without correction, then the measurement process is simple, but the measurement precision deteriorates due to oxygen interference
Solution Approach 1:
The patent applies preliminary action by measuring the decay time constant before using it to correct the glucose measurement. The decay time constant measurement is performed as a preliminary step to determine the oxygen carrying capacity, which then informs the correction factor applied to the glucose reading. This resolves the contradiction by adding a preliminary measurement step that improves accuracy without fundamentally changing the electrochemical detection mechanism.
Solution Approach 2:
The patent implements feedback by using the measured decay time constant to calculate a correction factor that is then applied to the glucose measurement. The system measures the decay characteristics, processes this information to determine oxygen carrying capacity, and feeds this back into the calculation to produce a corrected glucose value. This feedback loop resolves the contradiction between simple measurement and accurate results.
2Measurement precision
If hematocrit correction is applied to account for oxygen carrying capacity, then measurement accuracy improves, but the calculation complexity increases
Solution Approach 1:
The patent replaces direct hematocrit measurement with an electrical measurement of the decay time constant. Instead of mechanically or physically determining hematocrit values, the system uses electrical impedance or voltage decay measurements to infer oxygen carrying capacity. This substitution resolves the contradiction by using a simpler electrical measurement to achieve what would otherwise require complex hematocrit determination.
Solution Approach 2:
The patent changes the parameter being measured from direct hematocrit to decay time constant. By measuring the electrical decay characteristics of the electrochemical cell rather than directly measuring hematocrit, the system obtains information about oxygen carrying capacity through a different parameter that is easier to measure and process, thereby reducing calculation complexity while maintaining accuracy.
3Measurement precision
If oxygen correction is applied to blood samples, then measurement accuracy improves, but the processing time increases
Solution Approach 1:
The patent merges the oxygen correction measurement with the glucose measurement process itself. The decay time constant measurement is performed using the same electrochemical cell and similar electrical measurements already required for glucose detection. By combining these measurements into a unified process rather than separate steps, the patent resolves the contradiction between improved accuracy and increased processing time.
Solution Approach 2:
The patent applies universality by using a single electrochemical measurement process to achieve multiple functions: determining glucose concentration, measuring oxygen carrying capacity through decay characteristics, and calculating correction factors. This multi-functional approach resolves the contradiction by obtaining correction information as a byproduct of the glucose measurement rather than requiring separate dedicated measurement steps.
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 corrects for oxygen-induced errors in glucose measurements, providing more accurate analyte concentrations by accounting for oxygen's impact on mediator mobility and hematocrit levels, enhancing the reliability of glucose detection in blood samples.
Implementation Method 1
Electrochemical detection of glucose is conventionally achieved by applying a potential to an electrochemical cell containing a sample to be evaluated for the presence/amount of glucose, an enzyme that oxidizes glucose, such as glucose oxidase, and a redox mediator. Oxidized mediator reacts with the reduced enzyme to regenerate the active oxidase and produce a reduced mediator. Reduced mediator is oxidized at one of the electrodes
Data Source
AI summary
The presence of oxygen or red blood cells in a sample applied to an electrochemical test strip that makes use of a reduced mediator is corrected for by an additive correction factor that is determined as a function of the temperature of the sample and a measurement that reflects the oxygen carrying capacity of the sample. The measured oxygen carrying capacity can also be used to determine hematocrit and to distinguish between blood samples and control solutions applied to a test strip.