A ring-type device for the noninvasive measurement of arterial blood pressure

A ring-type device based on photoplethysmogram (PPG) and electrocardiogram (ECG) can be worn by a person at all times for the noninvasive and continuous measurement of arterial blood pressure (BP). A motion-free PPG is very important in order to obtain accurate BP value. In this paper, the optimal finger-ring and circuit designs for stable PPG signal detection and accurate R-wave detection are presented. A series of comparative experiments are conducted on 10 subjects using various ring sensors with different configurations. The experimental results show that the convex-type ring sensor, in which light emitting diode (LED) and infrared (IR) detector are placed at the palm side, and separated by a distance of around 1cm, is the optimal choice for ring-type BP measurement.