Photoplethysmogram(PPG) Signal can be used to monitor cardiovascular status. It is used to detect blood volume changes in the microvascular bed of tissue. Many wearables used to track pulse, blood pressure use the principle of PPG.
Many research indicate that PPG sensors are used to estimate the blood pressure. Research suggest that the morphology of waveform of ABP (Atrial Blood Pressure) is similar or is in-phase with the waveform of the PPG. The blood pressure can be measured using PPG sensors either through finger tips or ear lobes.
There is a great prospects in the future of medical devices that uses this technology.
PS: Shifted towards engineering