Photoplethysmography Sensors Concept and Advancements: A Review

With the healthcare industry growing at a rapid pace, advancements in medical diagnostics are taking high strides. One of the most eminent developments in this field, is the concept of Photoplethysmography. It is a very simple and inexpensive optical method to measure the Heart rate. PPG uses a non-invasive method that uses a light source along with a photodetector placed near the surface of the skin to measure changes in the volume of blood during its circulation. In recent times there is an increasing need of devices to measure heart-rate and other important vitals of patients in a very comfortable way. Devices employing PPG sensors are the solution to this requirement. Since they can be placed at a single location and still give quite accurate readings, they also have the potential to detect many other defects such as vascular ageing, arterial stiffness etc. along with heart rate and Spo2 oxygen level measurement. The second derivative PPG wave can give this important information, thus studying this wave can be very beneficial to doctors to predict future possible cardiac diseases. Here a comprehensive review of PPG devices is done reviewing the most prominent developments in this field. Although the PPG technology is very promising for the healthcare industry, it still poses many challenges. As PPG sensors are greatly affected by the presence of motion artifacts (MA), they are not completely reliable. The true potential of the concept of Photoplethysmography is immense, hence with this review we finally conclude that the PPG technology is indeed very promising and an upcoming concept which, with a few improvements can prove to be a boon to the health care industry.