Design and Implementation of a Novel Interferometric Microwave Radiometer for Human Body Temperature Measurement

Abstract

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.

High-Precision Temperature Inversion Algorithm for Correlative Microwave Radiometer

“…In Figure 10b, the comparison of MSE values during the convergence of the other three algorithms except for the PSO algorithm shows that by combining the advantages of PSO and LM algorithms, the PSO-LM-BP algorithm improves the iteration efficiency and accuracy, makes it difficult for the network to converge to the local minimum, and reduces the fluctuation of temperature prediction of the broadband correlative microwave radiometer compared with the traditional BP neural network. The inversion algorithm of the correlative microwave temperature measuring system in this paper is compared with the paper on temperature measurement by a microwave radiometer published by Sun et al [24]; the results are shown in Table 5. The inversion algorithm of the correlative microwave temperature measuring system in this paper is compared with the paper on temperature measurement by a microwave radiometer published by Sun et al [24]; the results are shown in Table 5.…”

“…The inversion algorithm of the correlative microwave temperature measuring system in this paper is compared with the paper on temperature measurement by a microwave radiometer published by Sun et al [24]; the results are shown in Table 5. The inversion algorithm of the correlative microwave temperature measuring system in this paper is compared with the paper on temperature measurement by a microwave radiometer published by Sun et al [24]; the results are shown in Table 5. The PSO algorithm is used to determine the initial network weight parameters due to its global search property, and then, the second derivative information of the LM algorithm is combined to accelerate the convergence speed and improve the iteration efficiency; finally, an innovative PSO-LM-BP high-precision inversion algorithm is proposed in this paper.…”

“…The inversion algorithm of the correlative microwave temperature measuring system in this paper is compared with the paper on temperature measurement by a microwave radiometer published by Sun et al [ 24 ]; the results are shown in Table 5 .…”

“…In 2021, Sun et al used a BP neural network inversion algorithm to predict the temperature; the average error is 0.575 °C and the maximum error is 1.358 °C [ 24 ]. This result did not meet the accuracy standard of medical temperature measurement (±0.2 °C) [ 25 ].…”

Design of Wet Media Digital Thermometer Calibrator Based on ATmega328p

“…Handayani, in her research in 2019, made a thermometer calibration media using the DS1820 sensor as the temperature sensor and a dry heater as the heating medium with a humidity sensor. The drawback of this study is that the media used still has an error value between the display of the device and the thermometer compared [10]. Ardelina in 2019 also calibrated a thermometer using the LM35 sensor as the temperature sensor and a dry heater as the heating medium.…”