Electrochemical Test Strip AC Impedance Insertion Detection
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Solution Overview
Problem
Conventional electrochemical test strips fail to determine correct insertion into a measurement instrument and adequate sample coverage of electrodes, leading to measurement inaccuracies, especially due to reliance on DC current without considering AC electrical properties.
Innovation Solution
An electrochemical test strip and system utilizing an insulating substrate with a set of measurement and identifying electrodes, along with a resistive path, that uses AC power to ensure correct insertion and sample coverage, measuring AC electrical characteristics to calibrate DC measurements and reduce errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If DC current measurement is used, then the measurement system is simple, but measurement accuracy is poor due to inability to detect sample characteristics
Solution Approach 1:
The patent applies parameter changes by switching from DC current measurement to AC impedance measurement. The measurement system uses an AC signal source to generate alternating current and measures impedance changes at different frequencies. This parameter change enables detection of sample characteristics such as hematocrit and viscosity that are invisible to DC measurement, thereby improving measurement accuracy without significantly complicating the device structure.
Solution Approach 2:
The patent employs periodic action by using AC signals of different frequencies to probe the sample. The system applies periodic AC voltage at multiple frequencies and measures the corresponding periodic current responses. This periodic measurement approach allows extraction of both resistive and reactive components of sample impedance, providing richer information about sample properties compared to continuous DC measurement.
2Device complexity
If conventional DC measurement is used, then the device structure is simple, but the ability to determine correct insertion and sample coverage is insufficient
Solution Approach 1:
The patent applies segmentation by dividing the measurement function into multiple independent electrode pairs. Each electrode pair is positioned to detect specific conditions: one pair detects insertion status, another detects sample coverage, and measurement electrodes detect analyte concentration. This segmentation allows each electrode pair to be optimized for its specific detection function, improving reliability without requiring complex integrated circuits.
Solution Approach 2:
The patent implements feedback by using the measured impedance values to verify correct operation. The system measures impedance across electrode pairs and compares the values against expected ranges. If the impedance indicates incorrect insertion or insufficient sample coverage, the system can alert the user or reject the measurement, providing feedback that ensures reliable operation before final results are reported.
3Measurement precision
If AC power measurement is added, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the electrode system to serve multiple functions simultaneously. The same electrode pairs used for AC impedance measurement also function for DC amperometric measurement of glucose. The identifying electrodes detect insertion and coverage status while also serving as measurement electrodes. This multi-functionality reduces the need for separate dedicated components for each measurement type, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent merges the AC impedance measurement circuitry with the existing DC measurement system. The microcontroller unit that controls DC measurement is extended to also generate and process AC signals. The same analog-to-digital converters and signal processing hardware are used for both AC and DC measurements, combining multiple measurement functions into a unified system architecture that minimizes 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
The solution effectively determines correct insertion and sample coverage, improving measurement accuracy by using AC power to assess sample characteristics like viscosity and hematocrit, thereby reducing measurement errors.
Implementation Method 1
measuring an AC electrical characteristic, such as a capacitance value or an AC impedance value, between the first identifying electrode and the second identifying electrode
Implementation Method 2
applying a DC voltage between the reference electrode and the work electrode to measure a current corresponding to the applied DC voltage
Data Source
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AI summary
An electrochemical test strip, an electrochemical test system, and a measurement method using the same are provided. The electrochemical test strip includes an insulating substrate, an electrode system formed on the insulating substrate, and an insulating layer formed on the electrode system. The electrode system includes a set of measurement electrodes, a set of identifying electrodes, and a resistive path having a predetermined resistance value. The set of identifying electrodes is made of metal material, and the resistive path is made of non-metal material. The set of measurement electrodes includes a reference electrode and a working electrode insulated from each other, and the set of identifying electrodes includes a first identifying electrode and a second identifying electrode connected with each other through the resistive path. The insulating layer covers a part of the electrode system, wherein a part of the electrode system not covered by the insulating layer forms a reaction region with a supply port. When a sample is injected into the supply port of the reaction region, the injected sample reaches the set of measurement electrodes and the set of identifying electrodes in sequence.