Atrial Fibrillation Detection from At-Rest PPG Signals Using an SDOF-TF Method

Figures

• 

  Figure A1. The PPG signal (segment: 730–810 s) of Subject 4 in the non−AF group: (a) xPPG(t), x0(t), and xb(t) (green line: baseline of x0(t)); (b) x1(t) and x2(t) containing xtvsp(t) (green line: baseline of x1(t) and x2(t)); (c) x0(t), xtvsp(t), and xnoise(t).

• 

  Figure A2. Comparison of APW between time-varying HR and constant HR: (a) Subject 11; (b) Subject 14; (c) Subject 15 in the AF group.

• 

  Figure 1. The tissue–contact–sensor (TCS) stack between a PPG sensor and an artery. (a) Schematic; (b) an SDOF model of MA in a PPG signal.

• 

  Figure 2. All the factors (except sensor noise) involved in PPG signal measurement and their quantitative manifestation in a PPG signal via the SDOF model of MA in a PPG signal.

• 

  Figure 3. A block diagram of the SDOF-TF method for quantifying and removing MA and noise from a PPG signal and extraction of APW, HR, and respiration parameters (note that the parameters in red font are the identified indices for AF detection with 100% accuracy).

• 

  Figure 4. The PPG signal (segment: 945~1025 s) of Subject 2 in the non−AF group: (a) xPPG(t), x0(t), and xb(t) (green line: baseline of x0(t)); (b) frequency spectra of x0(t), xHVD(t), xtf(t), xcf(t), and xtvsp(t); (c) instant parameters of the harmonics; (d) reconstructed pulse signal xtf(t) with fi(t); (e) reconstructed pulse signal xcf(t) with f0; (f) HRi(t) and HRϕi(t); and (g) ϕ0i(t) −based respiration parameters.

• 

  Figure 5. The PPG signal (segment: 955~1035 s) of Subject 2 in the AF group: (a) xPPG(t), x0(t), and xb(t) (green line: baseline of x0(t)); (b) frequency spectra of x0(t), xHVD(t), xtf(t), xcf(t), and xtvsp(t); (c) instant parameters of the harmonics; (d) reconstructed pulse signal xtf(t) with fi(t); (e) reconstructed pulse signal xcf(t) with f0; (f) HRi(t) and HRϕi(t); and (g) ϕ0i(t)−based respiration parameters.

• 

  Figure 6. Comparison of xtvsp(t) versus xnoise(t) in the PPG signal x0(t) free of BD xb(t): (a) Subject 2 in the non−AF group; (b) Subject 2 in the AF group.

• 

  Figure 7. The signals of x0(t), the first harmonic x1(t), and the second harmonic x2(t): (a) Subject 2 in the non−AF group; (b) Subject 2 in the AF group (note: green line—the baseline of a signal connecting the start and end points of pule cycles).

• 

  Figure 8. Extraction of HR in the time domain from x0(t), x1(t), and x2(t) in Figure 7: (a) Subject 2 in the non-AF group; (b) Subject 2 in the AF group.

• 

  Figure 9. Comparison of APW between time-varying HR and constant HR: (a) xtf(t) and xcf(t) of Subjects 3, 4, and 5 in the non−AF group; (b) xtf(t) and xcf(t) of Subjects 3, 4, and 5 in the AF group.

• 

  Figure 10. Comparison of AF versus non−AF Acf_i/Acf_1 and ϕ¯0i − ϕ¯01 of the harmonics of the PPG signals: (a) Acf_i/Acf_1 and (b) ϕ¯0i − ϕ¯01.