Contactless and continuous monitoring of heart electric activities through clothes on a sleeping bed

Due to the global ageing problem, there is a foreseeable demand of simple, efficient and economical monitoring systems for long-term home healthcare purpose to reduce healthcare expenditure of the society and also to improve the quality of life of the people. However, measuring physiological variables several times a day is inconvenient to most people, especially the elderly and non-hospitalized patients suffering from chronic diseases. Therefore, an awareness-free heart-rate (HR) monitoring system based on a bedsheet, which utilized the continuous and electrically non-contact measurement of electrocardiogram (ECG), was proposed. The proposed system was tested on eight subjects sleeping in different postures. The proposed design of the electrode can eliminate the remarkable decrease in magnitudes of QRS complexes when the subjectpsilas hands were placed in the measuring region. A pre-amplifier connector acting as an impedance matching circuit and as a bridge for the connection between the electrodes and the measuring device was designed. In addition, the proposed system was examined on 30 subjects at rest for one hour. The results showed that the root-mean-square error (RMSE) of HR was 0.66 plusmn 0.57 bpm. A RMSE of 1.24 bpm was also yielded from one sleeping subject for eight hours overnight. Therefore, the proposed system can be potentially used for the long-term recording of HR but further studies are required to enhance its resistivity to motion artifacts.