Noncontact sensing of electrocardiographic potential and body proximity by in-bed conductive fabrics

Aging populations call for pervasive monitoring of activity of elderly patients and their electrocardiographic potential (ECG) in the hospital or at home. In this study, we propose a noncontact approach for continuous sensing of presence, position and ECG of a human body on a bed. Six pieces of belt-like conductive fabrics were used as sensing electrodes. Three of the pieces were connected to a newly developed ECG amplifier featuring ultra-high input impedance. The other three pieces were connected to two sets of capacitance meters. Capacitances for upper and lower bodies were separately measured. A male volunteer subject was instructed to sit down on a bed, lie on the bed in a supine position, and change to a lateral position atfixed time intervals. In result, the combination of two voltages, inversely proportional to the upper and lower body coupling capacitances, varied in accordance with the change in the subject's position. In addition ECG was detected in the periods when the subject was in supine or lateral position. And distinct QRS complexes and T-waves were confirmed, though some distortion can be observed. These results demonstrate the potential of the proposed approach for Aging populations call for pervasive monitoring of activity of elderly patients and their electrocardiographic potential (ECG) in the hospital or at home. In this study, we propose a noncontact approach for continuous sensing of presence, position and ECG of a human body on a bed. Six pieces of belt-like conductive fabrics were used as sensing electrodes. Three of the pieces were connected to a newly developed ECG amplifier featuring ultra-high input impedance. The other three pieces were connected to two sets of capacitance meters. Capacitances for upper and lower bodies were separately measured. A male volunteer subject was instructed to sit down on a bed, lie on the bed in a supine position, and change to a lateral position at fixed time intervals. In result, the combination of two voltages, inversely proportional to the upper and lower body coupling capacitances, varied in accordance with the change in the subject's position. In addition ECG was detected in the periods when the subject was in supine or lateral position. And distinct QRS complexes and T-waves were confirmed, though some distortion can be observed. These results demonstrate the potential of the proposed approach for noncontact sensing of ECG and lying body capacitance toward awareness-free pervasive and continuous monitoring.noncontact sensing of ECG and lying body capacitance toward awareness-free pervasive and continuous monitoring.