Figure 4: PPG acquisition using combinations of inorganic and organic LEDs and photodiodes (PDs). | Nature Communications

Figure 4: PPG acquisition using combinations of inorganic and organic LEDs and photodiodes (PDs).

From: All-organic optoelectronic sensor for pulse oximetry

Figure 4

(a) PPG signal acquired using inorganic red and green LEDs and an OPD. Green and red PPG signal amplitudes of 26 and 16 mVp-p were obtained, respectively. (b) PPG signal acquired using OLEDs and silicon PD—absence of lensing epoxy and reduced irradiance of the OLEDs bring down signal magnitude to 16 and 6 mVp-p for green and red excitations. (c) PPG signal acquired using OLEDs and OPD; although signal magnitudes are reduced to 3 and 2.5 mVp-p, the signal is sufficient for resolving the PPG waveform and provide light absorbance ratio information for arterial blood oxygenation calculation.

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