Acquisition of PPG signal for diagnosis of parameters related to heart

Optical sensors that use photons as sensing elements are increasingly becoming important and relevant in the field of non-invasive diagnostics. The reason is that they are simple in construction, easy to use and relatively inexpensive in comparison with tools such as EEG, MRI and FMRI that can be used for research purposes without much investment. Among the various optical sensors available, the photoplethysmographic sensors that are capable of measuring the blood volumetric changes in subcutaneous vessels are used in present study. Objective is to diagnose different parameters like heart rate, blood pressure, respiratory rate, with the help of reflectance type PPG sensor. Real time PPG signal is captured from the sensor and with the help of microcontroller and RS 232 serial communication, the real time acquisition of PPG signal is observed on MATLAB. Detailed analysis of frequency spectrum of PPG signal shows a cardiac peak around 1Hz corresponding to 60 pulsations a minute and respiratory peak around 0.25 Hz corresponding to 15 inspiration/expiration cycles per minute. After the analysis of PPG signal, all the parameters are calculated and with the help of graphic user interface (GUI), all the parameters can simultaneously be seen on GUI window.