Wearable Two-Channel PPG Optical Sensor with Integrated Thermometers for Contact Measurement of Skin Temperature

Abstract

Many factors affect photoplethysmography (PPG) signal quality, one of them being the actual temperature of the skin surface. This paper describes the process of design, realization, and testing of a special wearable PPG sensor prototype with the contact thermometer measuring in detail the skin temperature in the place where the optical part of the PPG sensor touches a finger/wrist. Performed experiments confirm continual increase of temperature at the place of worn PPG sensors during the whole measurement, influencing mainly the PPG signal range. Other parameters seem to be temperature-independent or influenced by other factors—blood pressure, heart rate, etc.

Keywords

• photoplethysmography optical sensor
• wearable sensor
• PPG wave features
• contact skin temperature measurement