Session P85.4

Noise Reduction for Non-Contact Electrocardiogram Measurement in Daily Life

KM Lee*, SM Lee, KS Sim, KK Kim, KS Park

Seoul National University
Seoul, Korea

Electrocardiogram (ECG) measurement without skin-contact is essential for u-healthcare. ECG measurement using capacitive-coupled electrode (CC-electrode) is a well-known method for non-contact ECG measurement. Using CC-electrode, ECG can be measured over cloth as a result of a capacitor formed between electrode and skin and an ultra high input impedance of the electrode. Because the CC-electrode does not require a conductive adhesive that makes a person feel uncomfortable, it is adequate for long-term monitoring. Although the CC-electrode has the advantage of long-term monitoring, the missing data increase because it is sensitive to noise like the motion artifact compared with the Ag/AgCl electrode. To minimize the missing data, it is required to adjust the driven signal and the driven electrode. In this study, we proposed non-contact ECG measurement system using CC-electrode and driven circuit to reduce noise. The components of driven circuit were similar with those of driven-right-leg circuit and conductive sheet was employed for driven electrode to contact uniformly to the body over cloth. CC-electrodes were fixed at chest by a belt and ECG was measured from one healthy male subject wearing a normal cotton cloth. Conductive sheet employed for driven electrode was embedded on the chair. The signal was digitized at the sampling rate of 1000 Hz with 16bit resolution using Biopac system (MP-150). We evaluated the performance of the driven circuit under different conditions, including a contact area to the body and a gain of the driven circuit to find out a relationship between them and the signal-to-noise ratio (SNR) of the ECG signals. Conductive sheets whose areas were 12, 36, 72 and 144 cm2 were used for confirming the effect of contact area, and the gains of 30, 60, 100, 300, 500 and 1000 V/V were used for confirming the effect of gain of the driven circuit. As the results, the larger contact area and the higher gain of the driven circuit reduced the noise more. The driven circuit was greatly helpful in reducing the noise, and therefore it would be a method for long-term ECG monitoring.

(Abstract Control Number: 264)