Faculty of Information Technology, Beijing University of Technology, Beijing 100124, China.
Sensors (Basel). 2021 Feb 25;21(5):1619. doi: 10.3390/s21051619.
In this paper, the key technology of interferometric microwave thermometer is studied, the research can be applied to the temperature measurement of human body and subcutaneous tissue. This paper proposes a hardware architecture of interferometric microwave thermometer with 2 GHz bandwidth, in which the phase shifter is used to correct phase error and the quadrature demodulator is used to realize autocorrelation detection function. The results show that when input power is 7 dBm, the detection sensitivity can reach 176.54 mV/dBm and the temperature resolution of the microwave radiometer can reach 0.4 K. Correction algorithm is designed to improve the accuracy of temperature measurement. After correction, the phase error is reduced from 40° to 1.4° and when temperature changes 0.1 °C, the voltage value changes obviously. Step-by-step calibration and overall calibration are used to calibrate the device. Inversion algorithm can determine the relationship between physical temperature and output voltage. The mean square error of water temperature inversion by multiple linear regression algorithm is 0.607 and that of BP neural network algorithm is 0.334. The inversion accuracy can be improved by reducing the temperature range. Our work provides a promising realization of accurate, rapid and non-contact detection device of human body temperature.
本文研究了干涉式微波温度计的关键技术，该研究可应用于人体和皮下组织的温度测量。本文提出了一种具有 2GHz 带宽的干涉式微波温度计的硬件架构，其中采用相移器来校正相位误差，采用正交解调器来实现自相关检测功能。结果表明，当输入功率为 7dBm 时，检测灵敏度可达 176.54mV/dBm，微波辐射计的温度分辨率可达 0.4K。设计了校正算法以提高温度测量的精度。校正后，相位误差从 40°降低到 1.4°，当温度变化 0.1°C 时，电压值变化明显。采用逐步校准和整体校准对设备进行校准。反演算法可以确定物理温度与输出电压之间的关系。多元线性回归算法的水温反演均方误差为 0.607，BP 神经网络算法的均方误差为 0.334。通过减小温度范围可以提高反演精度。我们的工作为人体温度的精确、快速和非接触式检测装置提供了一种有前景的实现方式。
