Wearables For Optical Cardiovascular Monitoring: Designing The PPG Sensor In The ActiGraph LEAP®

Wearable digital health technologies (DHTs) are transforming cardiovascular health monitoring by enabling continuous, real-world assessment through optical sensors like photoplethysmography (PPG). This non-invasive technique measures blood volume changes using light absorption and reflection, providing real-time insights into heart rate, arterial oxygen saturation (SpO₂), and more advanced cardiovascular parameters. Unlike traditional methods such as ECG or echocardiography, PPG offers a practical, cost-effective solution for long-term monitoring outside clinical settings, especially through reflectance-mode PPG used in wrist-worn wearables.

Explore a technical overview of PPG signal principles and their integration into the ActiGraph LEAP® wearable device. This paper details the dual components of the PPG signal—AC for pulsatile arterial flow and DC for baseline tissue absorption—and the influence of biological, cardiovascular, and mechanical factors on signal quality. By addressing critical challenges such as motion artifacts and skin tone variability, we learn strategies in opto-mechanical design and signal processing to enhance reliability. PPG’s growing applications include heart rate variability analysis, atrial fibrillation detection, blood pressure estimation, sleep staging, and pulse oximetry. With continued innovation and integration with other sensors, wearable PPG technologies are poised to become foundational tools in cardiovascular health research, clinical trials, and personalized healthcare.