Bio-sensor Circuit Applying Ladder Perturbation to Correct Hematocrit
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Solution Overview
Problem
Existing electrochemical bio-sensors face inaccuracies in measuring analyte concentrations due to hematocrit variations, requiring complex modifications or additional circuits, which increase costs and complexity, and existing methods struggle to precisely correct for hematocrit effects without compromising precision or requiring new strip structures.
Innovation Solution
An apparatus using a digital-to-analog converter circuit to apply a constant DC voltage and a Λ-step ladder-type perturbation potential, allowing for the extraction of distinct induced currents to form a calibration equation through multivariable regression analysis, minimizing the matrix effect of hematocrit without altering the electrochemical bio-sensor structure or adding complexity to the measuring apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a filter is added to remove red blood cells before measurement, then hematocrit deviation is minimized, but the manufacturing process becomes complicated and product costs increase
Solution Approach 1:
The patent extracts and removes the harmful component (red blood cells) from the blood sample using a filter before measurement. This extraction approach directly addresses the hematocrit interference problem by separating the analyte-containing plasma from the interfering red blood cells, thereby improving measurement accuracy without requiring complex additional measurement circuits
Solution Approach 2:
The patent introduces a filter as an intermediary component between the blood sample and the measurement system. This intermediary device selectively removes red blood cells while allowing the analyte-containing plasma to pass through, solving the hematocrit interference problem through a dedicated intermediate component rather than modifying the core measurement system
2Measurement precision
If red blood cells are hemolyzed with reagent, then current signal variation is controlled, but the method is limited in effectiveness across a wide range of hematocrit values
Solution Approach 1:
Instead of attempting to chemically modify or hemolyze red blood cells to control their effect, the patent directly extracts and removes them from the sample using a filter. This physical extraction method is universally effective across all hematocrit ranges because it completely eliminates the interfering cells rather than attempting to modify them, thereby achieving both accuracy and wide adaptability
3Measurement precision
If additional devices or extended reaction time are used to improve accuracy, then measurement precision increases, but measurement cost and complexity increase
Solution Approach 1:
The patent performs the blood cell removal action preliminarily, before the measurement process begins. By filtering the blood sample to remove red blood cells in advance, the subsequent measurement can proceed with standard electrochemical methods without requiring extended reaction times or additional complex measurement devices, thereby achieving high accuracy with minimal system 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 enables accurate analyte concentration measurement by minimizing hematocrit-related deviations while maintaining conventional measuring performance and characteristics, using a conventional strip and hardware, and reducing the need for additional processes or circuits, thus improving precision and cost-effectiveness.
Implementation Method 1
a sample cell in which an oxidation/reduction enzyme capable of catalyzing an oxidation/reduction reaction of the analyte and an electron transfer mediator are fixed and a working electrode and an counter electrode are provided
Data Source
AI summary
An apparatus for measuring a concentration of an analyte in a bio-sample using an electrochemical bio-sensor, includes a connector with a sample cell in which an oxidation/reduction enzyme and an electron transfer mediator are fixed and a working electrode and an counter electrode are provided; a digital-to-analog converter circuit configured to apply a constant DC voltage to start the oxidation/reduction reaction of the analyte, proceed with an electron transfer reaction, and apply a Λ-step ladder-type perturbation potential for fluctuating a potential of the sample cell after applying the constant DC voltage; and a microcontroller configured to control the digital-to-analog converter circuit and directly obtain a concentration value of the analyte from a calibration equation using the Λ-step ladder-type perturbation potential. The apparatus can improve measurement accuracy by effectively minimizing a matrix interference effect of a background material in a bio-sample, particularly an inaccuracy caused by a change in hematocrit.