PPG, or photoplethysmography, is an optical measurement technique that does not need any intrusive procedures and is used to monitor changes in blood volume in peripheral tissues. The purpose of this study is to show the design and construction of a data acquisition (DAQ) system that is modular, relatively inexpensive, and capable of recording plethysmographic blood volume changes signals. The fabrication of a sensor geometry that includes both a source and a detector is carried out. A unique analogue front end is incorporated into the system. This front end features a bandpass filter that operates between 0.5 and 5 Hz. It combines a 5th -order high-pass filter with a 7th-order low-pass filter in order to reduce noise and motion artifacts. Following the visualization of the output signal in real time on a Digital Storage Oscilloscope (DSO), the signal is further processed in MATLAB. The findings of the experiments conducted on human volunteers demonstrated clear, periodic waveforms that provided an accurate representation of the heart cycle. The system's efficacy for fundamental biomedical research was demonstrated by the fact that the signal quality received from the system was comparable to that obtained from commercial products. The configuration is especially well-suited for use in research and educational environments, where cost and customization are of utmost importance. There is a possibility that future generations will have wireless connection, digital storage, and integration of microcontrollers. Through the provision of a platform that is easily accessible, this system bridges the gap between theoretical understanding and practical experimentation in the field of physiological signal processing.
Gohel et al. (Thu,) studied this question.