Capturing Electrocardiogram Signals from Chairs by Multiple Capacitively Coupled Unipolar Electrodes

Abstract

A prototype of an electrocardiogram (ECG) signal acquisition system with multiple unipolar capacitively coupled electrodes is designed and experimentally tested. Capacitively coupled electrodes made of a standard printed circuit board (PCB) are used as the sensing electrodes. Different from the conventional measurement schematics, where one single lead ECG signal is acquired from a pair of sensing electrodes, the sensing electrodes in our approaches operate in a unipolar mode, i.e., the biopotential signals picked up by each sensing electrodes are amplified and sampled separately. Four unipolar electrodes are mounted on the backrest of a regular chair and therefore four channel of signals containing ECG information are sampled and processed. It is found that the qualities of ECG signal contained in the four channel are different from each other. In order to pick up the ECG signal, an index for quality evaluation, as well as for aggregation of multiple signals, is proposed based on phase space reconstruction. Experimental tests are carried out while subjects sitting on the chair and clothed. The results indicate that the ECG signals can be reliably obtained in such a unipolar way.

A Sitting Posture Monitoring Instrument to Assess Different Levels of Cognitive Engagement

“…Some of the proposed solutions relied on the use of wearable sensors [22,23,24,25], while others exploited non-invasive approaches in which the sensors were applied on the environment (e.g., chairs [26,27,28,29,30,31,32,33]). In this way, participants were not aware of being monitored, thus allowing the reproduction of real-life conditions.…”

Common-Mode Voltage Reduction in Capacitive Sensing of Biosignal Using Capacitive Grounding and DRL Electrode

“…In general, the capacitive electrodes have a sensing area in the range of a few cm 2 , e.g., the work by Bednár et al [ 17 ] presents the sensing area of 16 cm 2 , and the work by Hou et al [ 18 ] uses an area of 12.56 cm 2 . Assuming such size of the sensing surface (assumption with clothes with thickness less than a few mm), the C e capacitance between the skin’s surface and the electrode reaches a value range from 10 pF to a few hundreds of pF.…”

Registered report protocol: Developing an artifact index for capacitive electrocardiography signals acquired with an armchair

“…As a major advantage, a cECG a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 records through clothes without the need for body surface contact. Authors reported various applications in vehicles [5][6][7] and apartments, for example in a bed [8][9][10] or chair [11][12][13]. In western countries, people watch television for about 3.5 hours per day [14,15].…”

“…However, the signal-to-noise ratio (SNR) of cECG is affected by several factors, such as movement artifacts [13,17], environmental electromagnetic interferences [17], and variation of the coupling impedance [18]. To increase the reliability and accuracy of cardiac parameters, signal quality assessment (SQA) plays a pivotal role: It allows to determine the periods, in which the SNR is adequate for accurate measurement of cardiovascular parameters.…”

“…For example, Hou et al measured six subjects with four capacitive electrodes attached to an office chair [13]. Based on phase-space reconstruction, they developed an SQA approach to aggregate multiple signals.…”