German technology company Cosinuss has developed the One, a wearable ear device that captures heart rate, heart rate variability, core body temperature and arterial oxygen saturation of the blood from within the ear canal, continuously during activity.

Developed with the help of German Athlete of the Year, Jan Frodeno and triathlete Anja Beranek, the sensor works with a Cosinuss app used or sport watch (ANT+ compatible).

Cosinuss says that it has created the One device to measure body temperature, which determines and influences physical performance and exercise control in sports.

Its aim is to use body temperature data during activity to monitor dehydration, improve accuracy in calculation of calories burned, detect and prevent heat induced illnesses and bring performance measures and exercise control to the next level.