Reduction of Skin Stretch Induced Motion Artifacts in Electrocardiogram Monitoring Using Adaptive Filtering

Abstract

Cardiovascular disease (CVD) is the leading cause of death in many regionsworldwide, accounting for nearly one third of global deaths in 2001. Wearable electrocardiographic cardiovascular monitoring devices have contributed to reduce CVD mortality and cost by enabling the diagnosis of conditions with infrequent symptoms, the timely detection of critical signs that can be precursor to sudden cardiac death, and the long-term assessment/monitoring of symptoms, risk factors, and the effects of therapy. However, the effectiveness of ambulatory electrocardiography to improve the treatment of CVD can be significantly impaired by motion artifacts which can cause misdiagnoses, inappropriate treatment decisions, and trigger false alarms. Skin stretch associated with patient motion is a main source of motion artifact in current ECG monitors. A promising approach to reduce motion artifact is the use of adaptive filtering that utilizes a measured reference input correlated with the motion artifact to extract noise from the ECG signal. Previous attempts to apply adaptive filtering to electrocardiography have employed either electrode deformation or acceleration, body acceleration, or skin/electrode impedance as a reference input, and were not successful at reducing motion artifacts in a consistent and reproducible manner. This has been essentially attributed to the lack of correlation between the reference input selected and the induced noise.In this study, motion artifacts are adaptively filtered by using skin strain as the reference signal. Skin strain is measured non-invasively using a light emitting diode (LED) and an optical sensor incorporated in an ECG electrode. The optical strain sensor is calibrated on animal skin samples and finally in-vivo, in terms of sensitivity and measurement range. Skin stretch induced artifacts are extracted in-vivo using adaptive filters. The system and method are tested for different individuals and under various types of ambulatory conditions with the noise reduction performance quantified.

Effect of pressure and padding on motion artifact of textile electrodes

“…Comparable results are obtained by the implementation of active electrodes [22] and using independent component analysis for artifact removal [23,24]. Using optical devices to gauge skin stretch and using stretch sensors and bend sensors to asses electrode motion decrease the motion artifact [25,26], albeit to a lesser extent than the previous methods.…”

Measuring movement of denim trousers for garment-integrated sensing applications

“…In situations where mechanical countermeasures are impractical or do not provide a clear enough signal, a few other techniques have emerged to detect and/or counteract the generated error or noise. In electrodermal sensing, research has explored using inertial [4] or optical [5] sensors coupled with the electrode to detect and filter movement error, and using capacitive electrodes in place of the traditional conductive contact electrodes (as they are more resistant to movement noise) [6]. In stretch sensing of body position and movement, redundant sensors have been explored as a means of improving accuracy in a noisy and/or imprecise sensor configuration [7].…”

Recurrent Polymorphic Ventricular Tachycardia: The Real Thing or a Soapy Explanation?

“…1 The reduction of ECG motion artifacts through modification of the electrode design and signal processing to mitigate the effects of altered skin-electrode contact continues to be an important objective of biomedical engineering research. [8][9][10] …”