Comparative Assessment of Smartwatch Photoplethysmography Accuracy

Nowadays, photoplethysmography (PPG) sensor integrated into smartwatches monitors heart health. Despite its convenience, PPG is susceptible to motion artifacts and noise. In this work, we rigorously investigate the smartwatch's PPG accuracy against medical-grade electrocardiogram (ECG) and PPG devices during different activities (i.e., sitting, standing, and walking). We conducted a user study with 32 healthy student participants and computed different heart rate (HR) features from the devices. Our analysis shows that the smartwatch PPG features, pnn50, low-frequency power (LF), and high-frequency power (HF), differ significantly from the ECG device during the activities. However, other time-domain features, such as HR, mean normal, standard deviation of normal, and root mean square of successive differences do not differ significantly during different activities. Furthermore, both the medical-grade and smartwatch PPG measurements (pnn50, HF, and LF) differed significantly from the ECG during standing and walking. The smartwatch's PPG accuracy compared with the ECG device reinforces its potential as an alternative health monitoring device.