Figure 2.

Summary of key measurements and technologies used in wearable health devices, including accelerometry, electrocardiography (ECG), photoplethysmography (PPG), pulse wave velocity (PWV), seismocardiography (SCG), and ballistocardiography (BCG). Each technology is described along with its primary applications, advantages, and limitations. The figure provides an overview of how these sensors contribute to monitoring various physiological parameters such as heart rate, blood pressure, physical activity, and sleep patterns, highlighting the potential and challenges of each measurement method.²⁵