Pulsed DC Block for Hematocrit Correction in Electrochemical Biosensors
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Solution Overview
Problem
Current methods for electrochemically measuring analytes in fluidic samples are affected by confounding variables such as hematocrit, temperature, and reagent thickness, leading to inaccuracies in glucose concentration measurements.
Innovation Solution
The use of alternating current (AC) and direct current (DC) blocks with specific signal patterns to provide information about the biosensor and fluidic sample, allowing for correction of confounding variables and accurate analyte concentration determination. These blocks include low-amplitude AC signals and pulsed DC sequences, with closed circuit conditions during DC blocks to enable sophisticated digital signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional electrochemical measurement methods are used, then the measurement process is simple, but the accuracy is reduced due to confounding variables such as hematocrit, temperature, and reagent thickness
Solution Approach 1:
The measurement process is divided into multiple sequential electrical signal blocks (AC block, DC block, measurement block) that each serve a specific function. The AC block characterizes the biosensor and sample, the DC block applies correction potentials, and the measurement block captures the analyte signal. This segmentation allows systematic correction of confounding variables while maintaining a structured, manageable measurement protocol.
Solution Approach 2:
The patent varies multiple electrical signal parameters including amplitude, frequency, duration, and potential values across different blocks. The AC signal uses low amplitude (e.g., 10-100 mV) at specific frequencies to minimize faradaic currents, while the DC block applies higher potentials (e.g., 0-450 mV) for correction. These parameter changes enable differentiation between capacitive and faradaic currents, improving measurement accuracy.
2Measurement precision
If AC and DC blocks with specific signal patterns are used to correct confounding variables, then measurement accuracy is improved, but the measurement sequence becomes more complex
Solution Approach 1:
The measurement process employs periodic electrical signal blocks with defined durations and intervals. The AC block alternates between positive and negative cycles, the DC block provides periodic correction pulses, and measurement windows are scheduled at specific intervals. This periodic structure systematicaly collects correction data and analyte signals over time, enabling accurate compensation for confounding variables while maintaining efficient timing.
Solution Approach 2:
The AC characterization block and DC correction block are executed before the final analyte measurement. These preliminary blocks establish baseline characteristics of the biosensor-sample system and apply corrections for confounding variables like hematocrit and temperature effects. By performing these actions in advance, the subsequent measurement block captures only the analyte-specific signal with minimal interference.
3Object-affected harmful factors
If low-amplitude AC signals are used to characterize the biosensor and sample, then capacitive current effects are minimized, but the signal strength for detection is reduced
Solution Approach 1:
The patent dynamically adjusts signal amplitude based on the measurement phase. During the AC characterization block, low amplitude signals (10-100 mV) are used to minimize faradaic currents and capacitive interference. During the DC correction and measurement blocks, higher potentials (0-450 mV) are applied to generate sufficient faradaic current for accurate analyte detection. This dynamic amplitude adjustment optimizes the signal-to-noise ratio across different measurement objectives.
Solution Approach 2:
The AC signal serves as an intermediary characterization step that provides information about the biosensor-sample system without directly measuring the analyte. By using low-amplitude AC signals, the system characterizes capacitive properties and interface conditions that affect subsequent measurements, without generating significant faradaic currents. This intermediary characterization enables better interpretation of the final analyte signal.
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 reliability of analyte concentration measurements by mitigating the effects of confounding variables, providing a more precise determination of analyte concentrations, such as glucose, in fluidic samples.
Implementation Method 1
electrochemically measuring an analyte in a fluidic sample that has been applied to an electrochemical biosensor
Implementation Method 2
providing a test sequence of at least one DC block to the fluidic sample, where the DC block includes at least one excitation potential
Data Source
AI summary
Methods are disclosed for measuring an analyte concentration in a fluidic sample. Such methods further allow one to correct and/or compensate for confounding variables such as hematocrit (Hct), temperature or both before providing an analyte concentration. The measurement methods utilize information obtained from test sequences having at least one AC block and at least one pulsed DC block, where pulsed DC block includes at least one recovery potential, and where a closed circuit condition of the electrode system is maintained during the DC block. Also disclosed are devices, apparatuses and systems incorporating the various measurement methods.