Electrochemical Sensor Segmentation for Drift Reduction
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Solution Overview
Problem
Electrochemical sensors, particularly potentiometric sensors, face inaccuracies due to electrolyte depletion and interference from diffusion and streaming potentials, leading to continuous drift in measured values over time.
Innovation Solution
Implementing a method using two reference half cells with different measuring intervals, where a second reference half cell measures discontinuously with a controllable liquid junction to slow electrolyte depletion and contamination, allowing for recalibration and adjustment of the first reference half cell, and utilizing a superordinated unit to determine process variables from continuous and discontinuous electrical measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If continuous measurement is performed with the first reference half cell, then measurement precision is maintained, but electrolyte depletion occurs leading to measurement drift
Solution Approach 1:
The reference electrode system is segmented into two separate reference half cells: a first reference half cell for continuous measurement and a second reference half cell for discontinuous measurement and recalibration. This segmentation allows each half cell to serve its specific function optimally, with the first handling continuous monitoring and the second providing periodic reference updates to maintain precision without continuous electrolyte consumption.
Solution Approach 2:
The second reference half cell performs discontinuous measurements at predetermined intervals to recalibrate the first reference half cell. This periodic action resets the reference potential and compensates for drift accumulated during continuous operation, thereby maintaining measurement reliability without requiring continuous electrolyte flow.
2Measurement precision
If the liquid junction is kept open for continuous measurement, then measurement precision is maintained, but electrolyte depletes and contamination occurs
Solution Approach 1:
The liquid junction system is segmented into two separate paths: one for the first reference half cell that remains open for continuous measurement, and another for the second reference half cell that is closed most of the time and opened only periodically for recalibration. This segmentation minimizes electrolyte depletion while maintaining measurement precision through periodic reference updates.
Solution Approach 2:
The liquid junction of the second reference half cell is opened periodically at predetermined intervals to perform recalibration measurements, then closed to prevent further electrolyte depletion and contamination. This periodic opening allows the system to reset reference values without continuous electrolyte consumption.
3Device complexity
If a single reference electrode is used, then device complexity is reduced, but measurement drift occurs over time
Solution Approach 1:
The single reference electrode is divided into two separate reference half cells with distinct functions. The first reference half cell handles continuous measurement while the second reference half cell performs periodic recalibration. This segmentation increases device complexity slightly but significantly improves measurement reliability by eliminating drift through periodic reference resetting.
4Loss of substance
If discontinuous measurement with larger intervals is used, then electrolyte depletion is reduced, but fast changes in process variables may be missed
Solution Approach 1:
The measurement system is segmented into two parallel channels: continuous measurement by the first reference half cell that detects fast changes in real-time, and discontinuous measurement by the second reference half cell that performs periodic recalibration. This segmentation allows the system to maintain both high temporal resolution for detecting fast changes and low electrolyte consumption through periodic reference updates.
Solution Approach 2:
The discontinuous measurement results from the second reference half cell provide feedback for recalibrating the first reference half cell. This feedback mechanism ensures that the continuous measurement channel remains accurate over time without requiring continuous high-frequency measurements that would deplete electrolyte faster.
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 ensures durable and accurate measurement of process variables by detecting fast changes and maintaining sensor accuracy, extending the sensor's lifetime and enabling timely corrective actions.
Implementation Method 1
measuring a first electrical measured variable X1, cont with a first measuring period t1, meas and a first measuring interval t1, int with reference to the first reference half cell
Implementation Method 2
measuring at least a second electrical measured variable X2, discont with a second measuring period t2, meas and a second measuring interval t2, int with reference to the second reference half cell
Implementation Method 3
at least one of the electrodes is immersed in an electrolyte, which has electrolytic contact with the medium via a liquid junction
Implementation Method 4
Disturbing diffusion and streaming potentials can also form, which likewise corrupt the measuring
Data Source
AI summary
A method for determining and/or monitoring at least one process variable of a medium by the utilization of at least of an electrochemical sensor comprising at least a first reference half cell and a second reference half cell, and comprising the method steps as follows: measuring a first electrical measured variable X1, cont with a first measuring period t1, meas and a first measuring interval t1, int with reference to the first reference half cell; measuring at least a second electrical measured variable X2, discont with a second measuring period t2, meas and a second measuring interval t2, int with reference to the second reference half cell; wherein the second measuring interval t2, int is greater than the first measuring interval t1, int; and determining the at least one process variable from at least one electrical measured variable X1, cont or X2, discont. Furthermore, the invention relates to an electrochemical sensor and to a system.