Non-Contact Monitoring of ECG in the Home Environment—Selecting Optimal Electrode Configuration

Figures

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  Figure 1. Measurement system enabling recording contact and non-contact electrocardiograms.

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  Figure 2. Developed FEM model used in the study.

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  Figure 3. Exemplary results of the potential distribution, on the chest and back, respectively, at the moment of the R wave of the ECG for two selected heart axis directions which differ in the azimuthal angle value, (a,b) present the potential distribution, respectively, on the chest and the back for azimuthal angle π/2, while (c,d) present the potential distribution, respectively, on the chest and the back for azimuthal angle 3π/4. Note that the azimuthal angle is determined in reference to the x-axis and that different scales are accepted for the figures.

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  Figure 4. Electric field distribution on the back (a) Ex, (b) Ey, and (c) Ez components, respectively.

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  Figure 5. (a–d) Configuration of the leads (see text for details) used in the study for measuring ECG on the back (illustrative figures). Two signals were recorded simultaneously using contact (red circle) and non-contact (green square), respectively. Reference to sub-figures inside text.

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  Figure 6. Developed capacitive electrode: (a) circuit diagram, (b) measurement system (DRL electrode not shown), (c) frequency characteristic of the measurement system as determined by an AD8232.

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  Figure 7. Simultaneous recording of ECG and cECG using different leads presented in Figure 5; (a) A’A lead, (b) B’B lead, and (c) DD’ lead. The signals were recorded for the person; the heart’s electrical axis was almost parallel to the I Eindhoven lead.

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  Figure 8. Relation between averaged values of R-wave as measured on the chest and the back using the optimal leads for the whole group of volunteers.

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  Figure 9. Relation between the R-wave amplitudes as measured for different leads including the optimal one (marked blue) and two others. Avg0 represents the optimal lead, while Avg15 and Avg30 represent the leads, forming angles of 15 and 30 degrees from the optimal ones, respectively.

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  Figure 10. Example of cECG signal recorded for a period of 15 minutes (a) and part of the signal shown for a different time scale (b).

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  Figure 11. Detection of the R wave in the QRS complex—vertical red lines indicate the positions of the R-wave detected.