Using an injection signal to reduce motion artifacts in capacitive ECG measurements

Area of Science:

• Biomedical Engineering
• Signal Processing

Background:

• Capacitive electrodes offer a comfortable alternative to traditional adhesive electrodes for long-term electrocardiogram (ECG) monitoring, enabling integration into everyday objects.
• However, a significant limitation is their susceptibility to motion artifacts, which can degrade signal quality.

Purpose of the Study:

• To investigate and mitigate motion artifacts caused by variations in coupling capacitance in capacitive ECG electrodes.
• To develop a real-time method for artifact reduction that maintains ECG signal integrity.

Main Methods:

• An injection signal technique was employed to track real-time variations in coupling capacitance.
• An adaptive filter was utilized to estimate and cancel the motion artifact from the recorded ECG signal.

Main Results:

• Simulations demonstrated an average reduction of motion artifact amplitude by 29 dB.
• Experiments in a lab environment showed an average reduction of 20 dB.

Conclusions:

• The proposed method effectively reduces motion artifacts within the ECG frequency band.
• This technique does not require prior knowledge of the measurement system, enhancing its practical applicability.