A comparative analysis of reflective and transmissive PPG sensor in pulse acquisition system

This study aimed to compare the performance of PPG (Photoplethysmography) sensors, based on time domain signals, frequency domain spectra, correlation coefficients, mean square errors, and signal-to-noise ratios (SNR). Two types PPG sensors were used: reflective and a transmissive PPG sensor. MAX30100 is a reflective PPG sensor used to acquiring the signal from the fingertip. Time domain signals acquired using the reflective PPG sensor contained more noise and motion artifacts than those acquired using the transmissive PPG sensor. The IR and RED-light absorption patterns from the MAX30100 were similar in time domain. The transmissive PPG sensor provided clearer pulse features than the reflective PPG sensor. The systolic wave phase showed more fluctuations in the IR and RED reflective PPG sensor. The correlation coefficients indicated a strong correlation between IR and RED PPG sensors and moderate correlation between IR and transmissive PPG sensor and RED and transmissive PPG sensor. The SNR values were found to be 14 dB for IR PPG, 11 dB for Red PPG, and 41 dB for transmissive PPG. These results suggest that transmissive PPG sensors are more reliable for pulse analysis compared to reflective PPG sensors.