A study of the green light photoplethysmography in the ear using an ear-phone for measurement of pulse rate monitoring in daily life

Abstract

We compared the heart rate (HR) derived from electrocardiogram (ECG) as a reference with the pulse rate (PR) derived from the ear photoplethysmogram (PPG) using green light. In 20 participants (21.7 ± 2.7 S.D. years), simultaneous measurements of ECG (lead II), near-infrared light (810 nm) PPG, and green light (525 nm) PPG from the front of tragus and helix were made at the following treadmill speeds: 0, 2, 4, 6 km/h. The results showed that the PR derived from the green light PPG from the ear significantly related to HR derived from ECG (tragus: r = 0.98, helix: r = 0.97, respectively). In addition, the limit of agreement in Bland-Altman plots between these indices were ± 7.95 (2 SD) bpm and ± 5.96 (2SD) bpm, respectively. In conclusion, these findings suggest that the green light ear PPG might be practical measurement for monitoring HR in a daily life.