Noise reduction for non-contact electrocardiogram measurement in daily life

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 unconstrained ECG measurement. Although the CC-electrode has the advantage of non-contact measurement, common mode noise is increased, which decreases the signal-to-noise ratio (SNR). 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 to those of driven-right-leg circuit and conductive sheet was employed for driven electrode to contact uniformly to the body over clothes. 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 SNR of ECG. As the results, as contact area became larger and gain became higher, SNR increased.