An earbud-based photoplethysmography and its application

This paper presents an earbud-based photoplethysmography (PPG) and its application. This PPG recording system permits long-term continuous monitoring of cardiovascular function since it can be worn comfortably on ears. Experimental investigations showed that stress and drowsiness could be estimated by analyzing measured PPG signals. Furthermore, noise suppression techniques for motion noises and ambient light interferences are introduced to make a recorded signal more acceptable.