Design Of High-precision Human Skin Temperature Distribution Measuring Device

In clinical medicine,body surface temperature is one of the key physiological parameters,and the patient’s body surface temperature can provide important physiological state information for doctors.At present,the equipment used for human body temperature measurement is mainly used in routine medical examination,and the temperature measurement accuracy is low,which is not better than 0.100℃,besides,it is hard to realize the measurement of temperature distribution.However,in some cases such as pathological analysis and TCM(Traditional Chinese Medicine)cold-heat syndrome differentiation,it is necessary not only to measure human body temperature with high precision,but also to detect the temperature distribution of human skin as the basis for disease diagnosis.Therefore,designing a device that can realize high-precision temperature distribution measurement of human skin has significant application values for the development and the research of detection and diagnosis in the medical field.In order to meet the needs of high-precision temperature distribution measurement in the field of clinical medicine,a 128-channel high-precision human skin temperature distribution measurement device is designed,which realizes a temperature measurement accuracy that is better than ±0.010°C in the temperature measurement range of 30.000°C to 42.000°C.The main work and research of this thesis are as follows:(1)The overall scheme of the temperature measuring device is designed.According to the requirements of measurement accuracy,the high-precision temperature sampling method of NTC(Negative Temperature Coefficient)thermistor temperature sensor and Σ-ΔADC(Analog-to-Digital Converter)is selected.The method of temperature measuring bridge driven by constant voltage source and multi-channel temperature measuring method based on temperature measuring bridge and analog switch array are given.(2)Based on the method of constant voltage source driving the temperature measuring bridge,the high-precision constant voltage source circuit with voltage fluctuation less than 10μV is designed to drive the temperature measuring bridge and supply the reference voltage to the ADC.Aiming at the acquisition of high-precision temperature signals,a 24-bit highprecision ADC chip AD7714 is used to design a sampling conversion circuit,which also completes the common-mode and differential-mode filtering processing of the signals in hardware and the Kalman filtering algorithm for eliminating random interference in software.At the end,the ADC sampling accuracy is better than ±5μV.(3)In terms of the temperature signal calibration processing of the temperature measuring device,the temperature look-up table method based on arithmetic sequence processing is designed and implemented,which solves the nonlinear problem of NTC thermistor temperature sensor and the consistency calibration problem of multiple sensors.(4)By using a high-precision constant temperature oil tank,the designed high-precision temperature measuring device is calibrated and the temperature measurement performance is experimentally verified.The results show that the temperature measurement accuracy index of the this device is better than ±0.010℃ in the temperature range of30.000℃～42.000℃,which can meet the demand of high precision temperature measuring in the field of clinical medical diagnosis.