To further improve the sensitivity of liquid dielectric constant measurements, a cylindrical container-type dielectric constant sensor is proposed in this paper. The container of the sensor consists of a substrate integrated waveguide (SIW) loaded with complementary split ring resonators (CSRRs) and a microstrip line. In order to solve the problem that the electric field distribution of the traditional container liquid dielectric constant sensor is only in a single plane, which cannot obtain good resonance characteristics, the sidewall of the sensor container is surrounded by a flexible material loaded with CSRR-SIW. Higher sensitivity can be obtained from measuring dielectric constant with more concentrated electric field distribution. The simulation results show that when the permittivity of the liquid under test (LUT) changes from 1 to 10, the resonance frequency of the sensor changes from 4.50 GHz to 2.94 GHz. The resonance frequency shift with unit dielectric constant greater than 150 MHz is realized. Using the relationship between the fitting permittivity and resonance frequency, the measurement of the known liquid permittivity of the standard sample is carried out. The test results show that the relative error is less than 2%, and the test sensitivity is 3.85%.
1. Mohamed, A., R. Amar, and H. Cherif, "Hyper-sensitive microwave sensor based on split ring resonator (SRR) for glucose measurement in water," Sensors and Actuators A: Physical, Vol. 321, 0924-4247, Apr. 2021.
2. Marathe, D. and K. Kulat, "A compact dual, triple band resonators for negative permittivity metamaterial," AEU-International Journal of Electronics and Communications, Vol. 88, 157-165, May 2018.
3. Ilona, P., W. Krzysztof, and G. Slawomir, "Detection of methanol contamination in ethyl alcohol employing a purpose-designed high-sensitivity microwave sensor," Measurement, Vol. 174, 0263-2241, Apr. 2021.
4. Hamed, R., M. Maani, and J. Babak, "Towards a machine-learning-assisted dielectric sensing platform for point-of-care wound monitoring," IEEE Sensors Letters, Vol. 4, No. 6, 1-4, Jun. 2020.
5. Viktorija, M., J. Aaron, and J. Simon, "Passive wireless UHF RFID antenna label for sensing dielectric properties of aqueous and organic liquids," IEEE Sensors Journal, Vol. 19, No. 11, 4299-4307, Jun. 2019. doi:10.1109/JSEN.2019.2896481
6. Li, L., H. Hu, P. Tang, B. Chen, J. Tian, and S. Safavi-Naeini, "A modied open-ended rectangular waveguide based re ection approach for dielectric constant characterization of low-loss slab materials," IEEE Transaction Antennas and Propagation, Vol. 69, No. 11, 8009-8014, May 2021. doi:10.1109/TAP.2021.3076486
7. Rasidian, A., L. Shafai, D. Klymyshyn, and C. Shafai, "A fast and efficient free-space dielectric measurement technique at mm-wave frequencies," IEEE Antennas and Wireless Propagation Letters, Vol. 16, 2630-2633, Aug. 2017. doi:10.1109/LAWP.2017.2737632
8. Peng, Z., J. Hwang, and M. Andriese, "Maximum sample volume for permittivity measurements by cavity perturbation technique," IEEE Transactions on Instrumentation and Measurement, Vol. 63, No. 2, 450-455, Feb. 2014. doi:10.1109/TIM.2013.2279496
9. Koirala, G., R. Dhakal, and E. Kim, "Radio frequency detection and characterization of water- ethanol liquid through spiral-coupled passive micro-resonator sensor," Sensors, Vol. 18, No. 4, Apr. 2018. doi:10.3390/s18041075
10. Amir, E., W. Withawat, and A. Said, "High-sensitivity metamaterial-inspired sensor for microfluidic dielectric characterization," IEEE Sensors Journal, Vol. 14, No. 5, 1345-1351, May 2014. doi:10.1109/JSEN.2013.2295312
11. Abdolrazzaghi, M., D. Mojgan, and K. Ashwin, "Strongly enhanced sensitivity in planar microwave sensors based on metamaterial coupling," IEEE Transactions on Microwave Theory and Techniques, Vol. 66, No. 4, 1843-1855, Apr. 2018. doi:10.1109/TMTT.2018.2791942
12. Sadat, J. F and A. S. Javad, "Reconfigurable microwave SIW sensor based on PBG structure for high accuracy permittivity characterization of industrial liquids," Sensors & Actuators A Physical, Vol. 283, 386-395, Jun. 2018.
13. Nilesh, K., P. Surya, and A. Jaleel, "Novel improved sensitivity planar microwave probe for adulteration detection in edible oils," IEEE Microwave and Wireless Components Letters, Vol. 29, No. 2, 164-166, Feb. 2019. doi:10.1109/LMWC.2018.2886062
14. Reyes-Vera, E., G. Acevedo-Osorio, M. Arias-Correa, and D. E. Senior, "A submersible printed sensor based on a monopole-coupled split ring resonator for permittivity characterization," Sensors, Vol. 19, No. 8, 1936-1936, Apr. 2019. doi:10.3390/s19081936
15. Arani, A. and K. Mrinal, "Miniaturized substrate integrated waveguide (SIW) power dividers," IEEE Microwave and Wireless Components Letters, Vol. 26, No. 11, 888-890, Nov. 2016.
16. Feng, X. and K. Wu, "Guided-wave and leakage characteristics of substrate integrated waveguide," IEEE Transactions on Microwave Theory and Techniques, Vol. 53, No. 1, 66-73, Jan. 2005. doi:10.1109/TMTT.2004.839303
17. Salim, A. and S. Lim, "Complementary split-ring resonator-loaded microfluidic ethanol chemical sensor," Sensors, Vol. 16, No. 11, 1802-1802, Nov. 2016. doi:10.3390/s16111802
18. Humberto, L., C. Alonso, L. Jose, A. Ricardo, P. Chavez, and L. Jose, "Wireless sensing of complex dielectric permittivity of liquids based on the RFID," IEEE Transactions on Microwave Theory and Techniques, Vol. 62, No. 9, 2160-2167, Sep. 2014. doi:10.1109/TMTT.2014.2333711
19. Sadat, J. F. and A. S. Javad, "Reconfigurable microwave SIW sensor based on PBG structure for high accuracy permittivity characterization of industrial liquids," Sensors & Actuators A Physical, Vol. 283, 386-395, Jun. 2018.
20. Galindo, R., M. Herraiz, and V. Segovia, "Submersible printed split-ring resonator-based sensor for thin-film detection and permittivity characterization," IEEE Sensor Journal, Vol. 16, No. 10, 3587-3596, May 2016. doi:10.1109/JSEN.2016.2538086