Biosensor Electrode Break Detection via Impedance Ratios
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Solution Overview
Problem
Inexpensive disposable electrochemical biosensors face issues with electrode breaks and reagent film cracking due to physical stresses during manufacturing and storage, leading to inaccurate impedance measurements and erroneous analyte concentration results.
Innovation Solution
A method involving the application of low amplitude, high frequency AC signals between perimeter and proximal/distal electrodes to detect impedance deviations, allowing for the identification of electrode breaks and reagent defects, and a failsafe mechanism to assess electrode integrity by comparing impedance ratios, thereby preventing erroneous measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If inexpensive disposable electrochemical biosensors are used with thin conductive layers, then manufacturing cost is reduced, but electrode breaks and trace disruptions occur due to physical stresses
Solution Approach 1:
The patent applies preliminary action by performing impedance measurements on electrodes before the actual analyte measurement. The system measures impedance between working electrode and counter electrode, and between reference electrode and counter electrode, to detect breaks or disruptions in electrode traces prior to using the biosensor for its intended function. This allows defective sensors to be identified and discarded before they produce erroneous results.
Solution Approach 2:
The patent implements feedback by using impedance measurement results to determine whether to proceed with analyte measurement. The system continuously monitors electrode integrity through impedance measurements and uses this feedback to control the measurement process - stopping or aborting the analyte measurement if electrode breaks are detected, thereby preventing erroneous results from being reported.
2Productivity
If reagent film is applied continuously during manufacturing, then manufacturing efficiency is improved, but reagent film cracking occurs due to physical stresses and humidity exposure
Solution Approach 1:
The patent detects reagent film cracking indirectly through impedance measurements performed before analyte measurement. Since reagent cracks can extend into underlying conductive traces and cause electrode breaks, the preliminary impedance measurement serves as an early warning system that identifies sensors with compromised reagent films before they are used for measurements.
Solution Approach 2:
The system uses feedback from impedance measurements to determine whether the reagent film integrity is sufficient to proceed with analyte measurement. If impedance values indicate electrode disruptions caused by reagent cracking, the system aborts the measurement process, preventing erroneous results from being generated by sensors with compromised reagent films.
3Reliability
If electrode breaks occur in active reaction area, then biosensor functionality is compromised, but detection of these breaks is difficult and erroneous results are produced
Solution Approach 1:
The patent implements a feedback mechanism where impedance measurements are continuously monitored and compared against expected ranges. When impedance values fall outside acceptable ranges, indicating possible electrode breaks in the active reaction area, the system generates feedback to abort the measurement and alert the user, preventing erroneous results from being reported.
Solution Approach 2:
The patent uses impedance measurement as an intermediary indicator to detect electrode breaks in the active reaction area. Rather than directly observing the physical integrity of electrodes during measurement, the system uses electrical impedance as an intermediary parameter that reflects electrode condition, enabling indirect detection of breaks that would otherwise be difficult to identify.
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
Effectively detects electrode breaks and reagent defects, ensuring accurate analyte concentration measurements by minimizing the impact of physical stresses and manufacturing variations, and providing a reliable error-checking mechanism for biosensor functionality.
Implementation Method 1
A low amplitude, high frequency AC signal is applied between a perimeter electrode and a proximal electrode, and a first impedance is measured. A similar AC signal is applied between the same perimeter electrode and a more distal electrode, and a corresponding second impedance is measured.
Data Source
AI summary
A method and system for determining a failsafe value for a biosensor having two perimeter electrodes, a distal electrode, and a proximal electrode are disclosed. A liquid measuring medium is applied to a capillary channel of the biosensor. The method includes applying an alternating voltage to the perimeter electrode and the proximal electrode, measuring conductivity to determine a first impedance between the perimeter electrode and the proximal electrode, applying the alternating voltage to the perimeter electrode and the distal electrode, measuring conductivity to determine a second impedance between the perimeter electrode and the distal electrode, determining a value using the first impedance and the second impedance, and providing an error message to the user if the value is out of tolerance. If the value is out of tolerance, then defects or breaks in the electrodes and/or reagent in a reaction area are present and the method disallows the test result.