Effect of pressure and padding on motion artifact of textile electrodes

BackgroundWith the aging population and rising healthcare costs, wearable monitoring is gaining importance. The motion artifact affecting dry electrodes is one of the main challenges preventing the widespread use of wearable monitoring systems. In this paper we investigate the motion artifact and ways of making a textile electrode more resilient against motion artifact. Our aim is to study the effects of the pressure exerted onto the electrode, and the effects of inserting padding between the applied pressure and the electrode.MethodWe measure real time electrode-skin interface impedance, ECG from two channels, the motion artifact related surface potential, and exerted pressure during controlled motion by a measurement setup designed to estimate the relation of motion artifact to the signals. We use different foam padding materials with various mechanical properties and apply electrode pressures between 5 and 25 mmHg to understand their effect. A QRS and noise detection algorithm based on a modified Pan-Tompkins QRS detection algorithm estimates the electrode behaviour in respect to the motion artifact from two channels; one dominated by the motion artifact and one containing both the motion artifact and the ECG. This procedure enables us to quantify a given setup’s susceptibility to the motion artifact.ResultsPressure is found to strongly affect signal quality as is the use of padding. In general, the paddings reduce the motion artifact. However the shape and frequency components of the motion artifact vary for different paddings, and their material and physical properties. Electrode impedance at 100 kHz correlates in some cases with the motion artifact but it is not a good predictor of the motion artifact.ConclusionFrom the results of this study, guidelines for improving electrode design regarding padding and pressure can be formulated as paddings are a necessary part of the system for reducing the motion artifact, and further, their effect maximises between 15 mmHg and 20 mmHg of exerted pressure. In addition, we present new methods for evaluating electrode sensitivity to motion, utilizing the detection of noise peaks that fall into the same frequency band as R-peaks.

[1]  P.S. Hamilton,et al.  Comparison of methods for adaptive removal of motion artifact , 2000, Computers in Cardiology 2000. Vol.27 (Cat. 00CH37163).

[2]  Robert Puers,et al.  Towards the integration of textile sensors in a wireless monitoring suit , 2004 .

[3]  Refet Firat Yazicioglu,et al.  Motion artifact reduction in ambulatory ECG monitoring: an integrated system approach , 2011, Wireless Health.

[4]  Konstantina S. Nikita,et al.  Wireless Mobile Communication and Healthcare , 2012, Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering.

[5]  Nicola Vanello,et al.  Independent component analysis applied to the removal of motion artifacts from electrocardiographic signals , 2008, Medical & Biological Engineering & Computing.

[6]  S. Leonhardt,et al.  Influence of contact pressure and moisture on the signal quality of a newly developed textile ECG sensor shirt , 2008, 2008 5th International Summer School and Symposium on Medical Devices and Biosensors.

[7]  Jarmo Verho,et al.  System for ECG and heart rate monitoring during group training , 2008, 2008 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society.

[8]  R C Barr,et al.  Skin‐Electrode Impedance and Its Effect on Recording Cardiac Potentials , 1966, Circulation.

[9]  S. Leonhardt,et al.  Characterization of textile electrodes and conductors using standardized measurement setups , 2010, Physiological measurement.

[10]  Jarmo Verho,et al.  Wearable System for EKG Monitoring - Evaluation of Night-Time Performance , 2011, MobiHealth.

[11]  Wilhelm Stork,et al.  Reliable motion artifact detection for ECG monitoring systems with dry electrodes , 2008, 2008 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society.

[12]  Enzo Pasquale Scilingo,et al.  Performance evaluation of sensing fabrics for monitoring physiological and biomechanical variables , 2005, IEEE Transactions on Information Technology in Biomedicine.

[13]  E Marani,et al.  Low Frequency Changes in Skin Surface Potentials by Skin Compression: Experimental Results and Theories , 2003, Archives of physiology and biochemistry.

[14]  M.G. Pecht,et al.  Reduction of Skin Stretch Induced Motion Artifacts in Electrocardiogram Monitoring Using Adaptive Filtering , 2006, 2006 International Conference of the IEEE Engineering in Medicine and Biology Society.

[15]  J. Muehlsteff,et al.  The Challenge of Motion Artifact Suppression in Wearable Monitoring Solutions , 2006, 2006 3rd IEEE/EMBS International Summer School on Medical Devices and Biosensors.

[16]  Malte Kirst,et al.  Using DWT for ECG motion artifact reduction with noise-correlating signals , 2011, 2011 Annual International Conference of the IEEE Engineering in Medicine and Biology Society.

[17]  Patrick Soon-Shiong,et al.  Proceedings of the 2nd Conference on Wireless Health , 2011 .

[18]  John J. Soraghan,et al.  Objective grading of facial paralysis using Local Binary Patterns in video processing , 2008, 2008 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society.

[19]  A. Baba,et al.  Time Based Measurement of the Impedance of the Skin-Electrode Interface for Dry Electrode ECG Recording , 2007, 2007 29th Annual International Conference of the IEEE Engineering in Medicine and Biology Society.

[20]  N. Noury,et al.  A smart cloth for ambulatory telemonitoring of physiological parameters and activity: the VTAMN project , 2004, Proceedings. 6th International Workshop on Enterprise Networking and Computing in Healthcare Industry - Healthcom 2004 (IEEE Cat. No.04EX842).

[21]  J. Malmivuo,et al.  Measurement of noise and impedance of dry and wet textile electrodes, and textile electrodes with hydrogel , 2006, 2006 International Conference of the IEEE Engineering in Medicine and Biology Society.

[22]  J. Lauter,et al.  Wearable approach for continuous ECG - and activity patient-monitoring , 2004, The 26th Annual International Conference of the IEEE Engineering in Medicine and Biology Society.

[23]  John G. Webster,et al.  Medical Instrumentation: Application and Design , 1997 .

[24]  Willis J. Tompkins,et al.  A Real-Time QRS Detection Algorithm , 1985, IEEE Transactions on Biomedical Engineering.

[25]  Be E. Lingwood,et al.  Cerebral impedance following hypoxia/ischaemia in the human infant , 2007 .

[26]  K.-P. Hoffmann,et al.  Flexible dry surface-electrodes for ECG long-term monitoring , 2007, 2007 29th Annual International Conference of the IEEE Engineering in Medicine and Biology Society.

[27]  S Odman.  Changes in skin potentials induced by skin compression. , 1989, Medical & biological engineering & computing.

[28]  M. Harris,et al.  The MyHeart project: A framework for personal health care applications , 2007, 2007 Computers in Cardiology.

[29]  J. Webster,et al.  Minimizing Electrode Motion Artifact by Skin Abrasion , 1977, IEEE Transactions on Biomedical Engineering.

[30]  Edward Grant,et al.  Nonwoven Fabric Active Electrodes for Biopotential Measurement During Normal Daily Activity , 2008, IEEE Transactions on Biomedical Engineering.

[31]  Jarno M. A. Tanskanen,et al.  Independent Component Analysis in ECG Signal Processing , 2012 .

[32]  Stefan Lamparth,et al.  Transferring an Artifact Handling System into a Mobile Long-term ECG Device with Dry Electrodes , 2009 .

[33]  John G. Webster,et al.  Electrocardiographic motion artifact versus electrode impedance , 2005, IEEE Transactions on Biomedical Engineering.

[34]  Rita Paradiso,et al.  A wearable health care system based on knitted integrated sensors , 2005, IEEE Transactions on Information Technology in Biomedicine.

[35]  Crister Ceberg,et al.  Conversion of greyscale intensity values from CBCT images acquired on Elekta XVI to HU for treatment planning dose calculations , 2009 .

[36]  J. Webster,et al.  The origin of skin-stretch-caused motion artifacts under electrodes. , 1996, Physiological measurement.

[37]  L. Kirkup,et al.  A direct comparison of wet, dry and insulating bioelectric recording electrodes. , 2000, Physiological measurement.

[38]  Steffen Leonhardt,et al.  Skin Electrode Impedance of Textile Electrodes for Bioimpedance Spectroscopy , 2007 .