Handheld Biosensor Pulsed Amperometry Hematocrit Correction
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Solution Overview
Problem
Conventional amperometric biosensors face inaccuracies due to the non-steady-state nature of current measurements, which are influenced by the hematocrit effect and mediator background, leading to biases in analyte concentration determination.
Innovation Solution
A handheld biosensor device with a sensor interface and signal generator that applies pulsed input signals with duty cycles including excitation and relaxation phases, allowing for rapid measurement of output signals within 300 milliseconds to reduce bias and improve accuracy, utilizing a diffusion barrier layer to isolate measurable species from red blood cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional amperometric measurement is used, then measurement time is reduced, but measurement precision deteriorates due to non-steady-state current and hematocrit bias
Solution Approach 1:
The patent applies periodic pulsed amperometric measurements with multiple duty cycles, where each cycle includes an excitation phase and a relaxation phase. By performing rapid sequential measurements at different time points (e.g., 50ms, 100ms, 150ms after pulse initiation) and calculating the difference between early and late measurements, the system achieves steady-state correction without requiring long measurement times. This periodic action enables both speed and precision.
Solution Approach 2:
The system uses feedback by comparing early-time and late-time current measurements to detect and correct for hematocrit bias and mediator background effects. The difference between measurements taken at different time points provides feedback information that is used to calculate corrected analyte concentrations, thereby improving measurement precision while maintaining rapid measurement capability.
2Productivity
If rapid measurement is performed, then productivity is improved, but measurement precision deteriorates due to non-steady-state conditions
Solution Approach 1:
The patent implements periodic pulsed measurements with multiple duty cycles, performing rapid sequential measurements at early time points (50ms, 100ms, 150ms) after pulse initiation. By calculating the difference between early and late measurements within each duty cycle, the system achieves steady-state correction while maintaining rapid measurement throughput. This approach enables high productivity without sacrificing precision.
Solution Approach 2:
The system performs preliminary measurements at early time points (before steady state is reached) and uses these preliminary data points to calculate corrections for hematocrit bias and mediator background. This preliminary action allows the system to achieve accurate results rapidly, improving productivity while maintaining measurement precision through mathematical correction of the early-time measurements.
3Device complexity
If single pulse measurement is used, then device complexity is reduced, but measurement precision deteriorates due to hematocrit effect and mediator background
Solution Approach 1:
The patent applies periodic pulsed measurements with multiple duty cycles, where each cycle includes excitation and relaxation phases. By performing rapid sequential measurements at different time points within each duty cycle and calculating the difference between early and late measurements, the system corrects for hematocrit bias and mediator background effects. This approach improves measurement precision while maintaining relatively simple device architecture.
Solution Approach 2:
The system performs multiple measurements within each duty cycle (at 50ms, 100ms, 150ms) and calculates the difference between early and late measurements. This partial action approach—measuring multiple times but using only the difference between specific time points—provides correction for hematocrit and mediator effects without requiring full steady-state conditions, thereby improving precision with moderate additional 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
This approach enhances the accuracy and precision of analyte concentration determination by minimizing hematocrit bias and mediator background errors, providing more accurate results in less time.
Implementation Method 1
the analyte concentration is determined from an electrical signal generated by an oxidation/reduction or redox reaction of the analyte or a species responsive to the analyte when an input signal is applied to the sample
Implementation Method 2
utilizing a diffusion barrier layer to isolate measurable species from red blood cells
Data Source
Figure 1
Figure 2~3A
Figure 3B~4
AI summary
A handheld measurement device for determining the concentration of an analyte in a sample is described. Input signals including multiple duty cycles of sequential excitation pulses and relaxations are input to the sample. Each excitation has a pulse width of between about 0.3 seconds and about 0.8 seconds. One or more signals output from the sample within 300 ms of the input of an excitation pulse may be correlated with the analyte concentration of the sample to improve the accuracy and/or precision of the analysis. Determining the analyte concentration of the sample from these rapidly measured output values may reduce analysis errors arising from the hematocrit effect, mediator background, and other error sources.