Heart rate estimation using on-nail wearable photoplethysmography.

Heart Rate (HR) measurements in current wearables are mostly derived from photoplethysmography (PPG). PPG signals have been measured at various locations on the body, however, to date, limited studies have investigated wearable, reflective mode, PPG signals from the finger- and toe- nails. Being rigid surfaces, they may provide comparatively motion robust measurements compared to sensors placed on flexible and stretchable skin.