Analog Motion Artifact Extraction in Biosignal Monitoring Circuits
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Solution Overview
Problem
Existing biosignal monitoring systems face challenges in effectively reducing motion artifacts from biopotential electrical signals, such as ECG, EEG, and EMG, due to changes in the skin-electrode interface caused by movement, which affect the accuracy and reliability of the signals.
Innovation Solution
A biosignal monitoring system comprising a signal processing module, a motion artifact extraction module with an analog domain electronic circuit and filter network, and a subtraction module, which extracts and attenuates differential mode signals, allowing for accurate and efficient reduction of motion artifacts by passing a representation of the motion artifact signal up to a specific frequency and subtracting it from the biopotential electrical signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If digital adaptive filtering with electrode-skin impedance measurement is used for motion artifact removal, then motion artifact reduction capability is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent extracts the motion artifact signal from the biopotential signal by measuring electrode-skin impedance changes, which correlate with motion artifacts. The extracted motion artifact signal is then removed from the original signal through subtraction, achieving motion artifact reduction without requiring complex digital adaptive filtering algorithms.
Solution Approach 2:
The patent replaces complex digital signal processing (software-based adaptive filtering) with a simpler analog/electrical measurement approach. By measuring impedance changes at the electrode-skin interface and using these to generate motion artifact estimates, the system achieves artifact removal through electrical measurements rather than computationally intensive digital filtering.
2Reliability
If accelerometer-based noise reference signal is used in adaptive filter, then motion artifact removal is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes the electrode-skin interface serve multiple functions: it not only captures the biopotential signal but also provides impedance measurements that correlate with motion artifacts. This eliminates the need for separate accelerometers or additional sensors, as the existing electrode-skin interface is utilized for dual purposes.
Solution Approach 2:
The system uses its own electrode-skin interface to generate the reference signal needed for motion artifact removal. The impedance measurements taken at the same interface provide the necessary information about motion artifacts, making the system self-sufficient without requiring external accelerometers or additional reference sensors.
3Measurement precision
If analog domain motion artifact extraction with frequency-selective filtering is used, then power efficiency and measurement precision are improved, but device complexity increases
Solution Approach 1:
The patent changes the frequency domain characteristics of the motion artifact signal by applying frequency-selective filtering in the analog domain. The filter network is designed to pass motion artifact frequencies while attenuating other frequencies, enabling precise extraction of motion artifacts based on their spectral characteristics without requiring complex digital processing.
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 system enables more precise and controlled reduction of motion artifacts, improving the accuracy of biopotential signal monitoring by effectively isolating and attenuating motion artifact signals within specific frequency ranges, enhancing the reliability of ECG, EEG, and EMG readings.
Implementation Method 1
a filter network, configured for attenuating differential mode signals of the biopotential electrical signal input from a first frequency, and passing a representation of the motion artifact signal from the biopotential electrical signal input up to a second frequency
Data Source
AI summary
The disclosure includes a biosignal monitoring system for reducing a motion artifact from a biopotential electrical signal input, including a signal processing module, a motion artifact extraction module, and a subtraction module. The motion artifact extraction module and the signal processing module receive the biopotential electrical signal input and the subtraction module receives an extracted signal from an output of the motion artifact extraction module and a biopotential electrical signal from an output of the signal processing module. The subtraction module subtracts the extracted signal from the biopotential electrical signal. The motion artifact extraction module is an analog domain electronic circuit and includes a filter network configured for attenuating differential mode signals of the biopotential electrical signal input from a first frequency, and passing the motion artifact signal from the biopotential electrical signal input up to a second frequency at the output of the motion artifact extraction module.