Research On Technology For Non-invasive Human Core Body Temperature Monitoring Based On Single-Heat-Flux Principle

The human core body temperature is a vital physiological parameter,which is closely related to human metabolism.At present,main measurement methods of human core body temperature include both invasive ways(e.g.insertion of a probe in blood,bladder,etc)and non-invasive ways(e.g.measurement at rectum,tympanic membrane,sublingual,and axilla,etc).Invasive methods would bring certain trauma to the subjects while non-invasive methods have some flaws such as non-continuous monitoring and unsatisfactory accuracy.First of all,a single-heat-flux sensor was designed for the non-invasive measurement of human core body temperature based on the single-heat-flux principle.A 3D model was established and simulated by a FEM software(COMSOL Multiphysics)to evaluate the effects of ambient temperature,human tissue characteristics,structural parameters(height and radius)and thermophysical parameters(thermal conductivity,density and specific heat)on the measurement accuracy of the thermometer.Then,the measurement interface system was designed to acquire temperature data,fulfill analog-to-digital conversion,estimate core temperature and display results.Experiments were carried to verify this measurement system,and the results showed that,the error was within ± 0.1 ℃ for the range of 35-41 ℃ on the hot plate.Finally,to verify the performance of measurement system for estimating the actual human core body temperature,we recorded the core temperature using the proposed single-heat-flux sensor and an infrared ear thermometer.The results were as follows:1)there was no significant difference between the temperatures measured by the two methods when the core body temperature of 22 volunteers were recorded one hour per person;2)The changing trends of these two temperatures were highly correlated and consistent when 2 volunteers were continuously monitored for 24 hours to observe the circadian rhythm of their core temperature.Compared with some previous studies,the proposed measurement system could continuously monitor the human body core temperature with satisfactory accuracy.The results of this thesis lay the foundation for the studies of highly accurate,portable and miniaturized human core body temperature monitoring system.