Non-invasive and wearable thermometer for continuous monitoring of core body temperature under various convective conditions.

We describe the design of a thermometer that can be worn during everyday activities for monitoring core body temperature (CBT) at the skin surface. This sensor estimates the CBT by measuring the heat flux from the body core based on a thermal conductive model. The heat flux is usually affected by the ambient convective conditions (e.g. air conditioner or posture), which in turn affects the model's accuracy. Thus, we analytically investigated heat conduction and designed a sensor interface that would be robust to convection changes. We performed an in vitro experiment and a preliminary in vivo experiment. The accuracy of CBT in an in vitro experiments was 0.1°C for convective values ranging from 0 to 1.2 m/s. The wearable thermometer has high potential as non-invasive CBT monitor.