A Fundamental Study on Non-Contact Simultaneous Measurement of Electrocardiogram and Pulse Beat Using Capacitive In-Bed Electrode Sensor

Abstract

In this study, we conducted a fundamental study on non-contact simultaneous measurement of electrocardiogram (ECG) and pulse beat (PB) using capacitive in-bed electrode sensors. In the studied system, ECG were measured via clothing by conductive fabric electrodes placed under the upper back and the lower back, respectively. Also, by laying conductive strips under the calf and the heel, two capacitive coupling composed of strip-clothing-body surface were formed, and change in coupling capacitance caused by PB was detected. In this system, however, the signal-to-noise ratio (SNR) of the PB was poor and obtained output was unstable. In the new system, SNR was improved by changing sensor's dimension (strip width). Simultaneous measurement of ECG and PB was conducted for three males in supine position and wearing a commercial cotton sleepwear. As the result, the SNR of PB improved by about 15% on average in the new system.