A surface acoustic wave passive and wireless sensor for magnetic fields, temperature, and humidity

Abstract
In this paper, we report an integrated single-chip surface acoustic wave sensor with the capability of measuring magnetic field, temperature, and humidity. The sensor is fabricated using a thermally sensitive LiNbO3 substrate, a humidity sensitive hydrogel coating, and a magnetic field sensitive impedance load. The sensor response to individually and simultaneously changing magnetic field, temperature and humidity is characterized by connecting a network analyzer directly to the sensor. Analytical models for each measurand are derived and used to compensate noise due to cross sensitivities. The results show that all three measurands can be monitored in parallel with sensitivities of 75 ppm/°C, 0.13 dB/%R.H. (at 50%R.H.), 0.18 dB/Oe and resolutions of 0.1 °C, 0.4%R.H., 1 Oe for temperature, humidity and magnetic field, respectively. A passive wireless measurement is also conducted on a current line using, which shows the sensors capability to measure both temperature and current signals simultaneously.

Citation
Li, B., Yassine, O., & Kosel, J. (2015). A Surface Acoustic Wave Passive and Wireless Sensor for Magnetic Fields, Temperature, and Humidity. IEEE Sensors Journal, 15(1), 453–462. doi:10.1109/jsen.2014.2335058

Acknowledgements
This work was supported by the King Abdullah University of Science and Technology, Thuwal, Saudi Arabia.

Publisher
Institute of Electrical and Electronics Engineers (IEEE)

Journal
IEEE Sensors Journal

DOI
10.1109/JSEN.2014.2335058

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