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Canadian Journal of Cardiology

QUANTITATIVE COMPARISON OF ELECTROCARDIOGRAM FROM SKIIN FULLY TEXTILE CHEST BAND AGAINST STANDARD GEL ELECTRODES

      Background

      The Skiin Underwear system is a wearable medical device in the form of undergarments that comes with a magnetically attached recording module. The system captures 3 channels of ECG besides temperature and activity and transmits them via Bluetooth Low Energy (BLE) to Skiin companion software, and from there to backend and a web portal.

      Methods and Results

      Ten adult participants (5 men and 5 women) worn appropriate-size Skiin chestband (M-XL for men and 2XS-S for women) at subpectoral level, and gel electrodes were placed at closest locations beneath the chest band electrodes (Figure 1). Skiin under the chest band was moisturized without any residue of the moisturizer (Lubriderm). A reference ECG recording system (NorthEast DR200) was used for simultaneous ECG recording of the same ECG leads. The study was performed under the study approved by the University of Toronto Research Ethics Board (RIS HP #00041274). For each subject, ECG recordings were aligned using cross correlation analysis. Signals were filtered 0.5-35Hz using a 4th order butterworth filter and smoothed with a 3 point moving average. Then, sample by sample root mean square error (RMSE) was calculated for 30 sec of signals. The RMSE was 0.069 mV on average (0.032 to 0.185 mV). The RMSE expressed as a percentage of R-peak-to-peak amplitude was 5.3% on average (3.7% to 7.7%). The peak-to-peak amplitude was systematically higher with Skiin ECG with textile electrodes (1.23±0.61mV) compared to the clinical standard with gel electrodes (0.83±0.52mV), supposedly as gel electrodes were placed beneath the band, further from the heart. Table 1 presents the detailed results. To further compare the details of ECG waveforms, the average template beats were obtained for each 30 sec of recorded ECG, and plotted for each channel overlaid (Figure 1). Visual comparison highlighted that the wireless Skiin system with fully textile electrodes provided the same information as the clinical standard device with gel electrodes at sitting position.

      Conclusion

      The results obtained in this study show that the ECG obtained from the Skiin chest band at sitting position is comparable to the reference ECG system. The small difference in ECG amplitude was likely due to the slightly lower placement of the gel electrodes compared to the Skiin chest band.
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