Figure 1
From: Detection of a and b waves in the acceleration photoplethysmogram
Fingertip photoplethysmogram signal measurement [[8]]. (a) Fingertip photoplethysmogram. (b) Second derivative wave of photoplethysmogram. The photoplethysmogram waveform consists of one systolic wave and one diastolic wave, while the second derivative photoplethysmogram waveform consists of four systolic waves (a, b, c, and d waves) and one diastolic wave (e wave).