Evaluation of structural and thermophysical effects on the measurement accuracy of deep body thermometers based on dual-heat-flux method

• The paper serves as guideline for the implementation of a new deep body thermometer.
• The deep body thermometer is noninvasive and passive.
• We discussed the structural and thermophysical factors influencing its accuracy.
• With the insights of this paper, it is feasible for thermometer to be wearable.

To help pave a path toward the practical use of continuous unconstrained noninvasive deep body temperature measurement, this study aims to evaluate the structural and thermophysical effects on measurement accuracy for the dual-heat-flux method (DHFM). By considering the thermometer's height, radius, conductivity, density and specific heat as variables affecting the accuracy of DHFM measurement, we investigated the relationship between those variables and accuracy using 3-D models based on finite element method. The results of our simulation study show that accuracy is proportional to the radius but inversely proportional to the thickness of the thermometer when the radius is less than 30.0 mm, and is also inversely proportional to the heat conductivity of the heat insulator inside the thermometer. The insights from this study would help to build a guideline for design, fabrication and optimization of DHFM-based thermometers, as well as their practical use.