Fig. 3.

(a) The simulated results for PPG and (b) SPG. The PPG signal increases in amplitude percent as the arterial layer thickness increases, with the green wavelength having the highest sensitivity. The SPG signal at the three wavelengths increases in amplitude percent as the flow speed increases, and the NIR wavelength has the largest dynamic range. The SPG signals at all wavelengths have a much larger range than the PPG signals at all wavelengths.