From Signal Acquisition to Signal Processing Methods in Photoplethysmography Technology: Applications, Comparative Analysis, and Future Perspectives

Photoplethysmography (PPG) is a popular, non-invasive method often used to keep an eye on heart health by tracking subtle changes in blood flow. In this paper, we offer an in-depth overview of the current state of PPG technology. We start by describing how signals are captured and processed, then discuss how these techniques translate into everyday use. We look closely at various measurement methods, carefully comparing their effectiveness. Along the way, we point out common issues like interference from body movements and unwanted environmental noise, both of which often disrupt accurate readings. To address these challenges, we cover several practical solutions, including smarter filtering techniques, multi-color light analysis for clearer signals, and recent approaches involving machine learning. We also acknowledge persistent difficulties, such as why different people often get inconsistent results and how complicated biological factors can make readings less reliable. Looking toward the future, we explore promising developments, including systems that combine data from multiple sensors, round-the-clock health tracking capabilities, and health tools tailored to each individual's needs. Ultimately, our goal is to present a clear summary of todays PPG technology, while encouraging fresh thinking and innovation in the field of wearable health devices.