Biopotential Signal Detection with Electrode Impedance Compensation
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Solution Overview
Problem
Existing bio-signal monitoring devices struggle to accurately measure biopotential signals due to impedance changes caused by movement artifacts and sweat accumulation, which they cannot fully compensate for, and fail to identify which electrodes are displaced or shunted.
Innovation Solution
The apparatus uses two skin electrodes and a reference electrode with variable controlled resistance loads and a signal generator to apply alternating signals, allowing the controller to adjust resistance and gain in response to amplitude changes, differentiating between signal origins and compensating for movement artifacts and sweat effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional bio-signal monitoring devices are used, then the device structure remains simple, but the measurement precision deteriorates due to impedance changes caused by movement artifacts and sweat accumulation
Solution Approach 1:
The patent divides the monitoring system into multiple independent channels, each with its own signal generator and variable resistance load. This segmentation allows independent compensation for movement artifacts and sweat effects on each electrode, improving measurement precision while managing complexity through modular design
Solution Approach 2:
The patent introduces variable controlled resistance loads that can dynamically adjust their impedance values in response to detected signal changes. This dynamic adaptation enables real-time compensation for impedance variations caused by movement and sweat, maintaining measurement accuracy throughout the monitoring period
2Reliability
If no compensation mechanism is applied, then the device complexity remains low, but the reliability deteriorates due to inability to compensate for impedance changes
Solution Approach 1:
The patent implements feedback loops where the controller continuously monitors the amplitude of alternating signals from each electrode and adjusts the variable resistance loads accordingly. This feedback mechanism ensures reliable continuous monitoring by automatically compensating for impedance changes without requiring manual intervention
Solution Approach 2:
The system performs self-diagnosis and self-compensation by detecting amplitude changes in the alternating signals and automatically adjusting the variable resistance loads. This self-service capability improves reliability by enabling the system to correct its own measurement errors without external assistance
3Measurement precision
If amplitude-based differentiation is used to identify signal origins, then the measurement precision improves, but the difficulty of detecting and measuring increases
Solution Approach 1:
The patent uses amplitude magnitude as a distinguishing characteristic (analogous to color differentiation) to identify the origin of detected signals. By comparing the relative amplitudes of alternating signals from different electrodes, the system can determine which electrode is displaced or shunted, improving measurement precision through intuitive amplitude-based identification
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 solution enables accurate and continuous measurement of biopotential signals by fully compensating for impedance changes caused by movement artifacts and sweat, ensuring reliable monitoring of bio-signals over time.
Implementation Method 1
impedance changes caused by external factors such as motion or movement artifacts and dust, dirt, oil, and sweat
Data Source
AI summary
A method and apparatus for measuring a biopotential signal together with impedance changes uses electrodes on a subject’s skin and for compensating for such impedances to increase accuracy and usability of such devices for short-and long-term monitoring of biosignals. The apparatus can include a first terminal for connection to a first electrode, a second terminal for connection to a second electrode, a first circuitry configured for measuring the biopotential signal from the first and the second terminal, a third terminal for connection to the reference skin electrode, a first variable controlled resistance load connected to the first terminal, and a second variable controlled resistance load connected to the second terminal.