Comparative Design Study for Power Reduction in Organic Optoelectronic Pulse Meter Sensor

Figures

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  Figure 1. Obtaining the photoplethysmogram (PPG) signal based on an organic pulse meter: (A) Transmissive mode; (B) Reflective mode [11].

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  Figure 2. (A) Optical skin schematic model of a human finger, an organic light-emitting diode (OLED) as a light object source, and an organic photodiode (OPD) as a surface receiver, where d is the distance between the edges of the OLED and the OPD, W1 is the diameter of the OLED, and W2 is width of the OPD; (B) The optical simulation results at the surface receiver.

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  Figure 3. (A) Top view of the fabricated optoelectronic Device-A and Device-B; (B) The organic device structure of the OLED and OPD; (C) Electroluminescence spectrum of the OLED with respect to the wavelength (nm); and (D) External quantum efficiency (EQE) of the OPD with respect to the wavelength (nm).

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  Figure 4. Circuit design of the pulse meter. (A) The system structure of the pulse meter; (B) The Bode plot of the bandpass filter (BPF) circuit; (C) The proposed analog circuit for acquiring the photoplethysmogram (PPG) signal from the pulse meter; and (D) The proposed portable pulse meter prototype.

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  Figure 5. Digital low-pass filter effect on the PPG signal, where the signal lost its morphological structure if the cut-off frequency (fc) was set very close to the carrier frequency.

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  Figure 6. Fast Fourier transform waveform to calculate the signal-to-noise ratio (SNR) of the PPG signal.

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  Figure 7. Comparison between the PPG signal from (A) Device-A without a digital filter; (B) Device-B without a digital filter; (C) Device-A after a digital filter; and (D) Device-B after a digital filter.

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  Figure 8. Comparison between the PPG signal on different parts of the body: (A) Index finger; (B) Middle finger; (C) Little finger; (D) The forearm; (E) The wrist; and (F) The forehead.