In the fields of precision chemistry, biomedicine, and fine chemical industry, the accuracy of temperature detection impacts significantly on the quality of products, and high-precision temperature detection is the premise of temperature control. Among the available temperature sensing technologies, the sensors must have a built-in battery or be powered by the power circuit, which cannot achieve passive detection.
In addition, there are defects of poor anti-electromagnetic interference capability and large size. In this case, it is urgent to develop a small, energy-saving, portable and high-precision wireless passive temperature detection system, and the surface acoustic wave (SAW) devices have attracted great interest because they feature high sensitivity, fast response, small size, etc.
Researchers from the Institute of Acoustics of the Chinese Academy of Sciences (IACAS) optimized and designed a SAW passive temperature sensor with high signal-to-noise ratio by using the COM theory, and constructed a wireless passive saw temperature sensing system with the transceiver module based on step frequency modulation technology.
Researchers used adaptive LMS algorithm and the combination method of multi-point parabola approximation and moving average algorithm to reduce the peak phase fluctuation and significantly improve the accuracy, which was confirmed by wireless temperature measurement. High temperature sensitivity of 36.5 degrees Celsius and very high accuracy of ±0.2 degrees Celsius in the range of 30～100 degrees Celsius were achieved successfully.
This system has a great application prospect in the field of precision manufacturing.
The research, published online in the international academic journal Applied Sciences, was supported by the project of knowledge at the National Key Research and Development Project (No.2018YFB2002500), and the NSFC Joint Key Fund Project (No.U1837209, 11774381).
Figure. 1 Developed high-precision wireless passive saw temperature sensing system and its processing algorithms. (Image by IACAS)
Figure. 2 (a) The sensitivity evaluation and (b) accuracy measurement of the proposed sensor system. (Image by IACAS)
GAO Xu, CHENG Lina, XUE Xufeng, ZHAI Shoupei, LIANG Yong, WANG Wen, LIU Mengwei. Development of Wireless and Passive SAW Temperature Sensor with Very High Accuracy. Appl. Sci. 2021, 11, 7422. DOI: 10.3390/app11167422.
Institute of Acoustics, Chinese Academy of Sciences, 100190 Beijing, China