Sensitive relative humidity monitoring sensor based on microwave active resonator with PEDOT:PSS

Jin Kwan Park, Chorom Jang, Gi Ho Yun, Hee Jo Lee, Hyang Hee Choi, Jong Gwan Yook

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


In this paper, a relative humidity monitoring sensor based on an active resonator with PEDOT:PSS is studied in the microwave regime. The proposed active resonator is patterned on a printed circuit board and excited by electromagnetic field coupling. The active resonator consists of two parts: a passive core resonator and an active circuit. The passive core resonator senses the humidity via the PEDOT:PSS conducting polymer film, which is located in the area of the passive core resonator with the strongest electric field. The active circuit compensates for the loss of the passive core resonator to enhance the quality factor and thus improve the sensitivity of the relative humidity sensor. By combining the passive core resonator with the active circuit, the active resonator exhibits a high quality factor (2887), which is 90 times that of the passive core resonator alone. Moreover, the sensitivity of the proposed humidity sensor is improved when using the active resonator. To verify the performance of the proposed humidity sensor, a commercial sensor is placed alongside the proposed sensor in a well-controlled environment chamber. According to the experimental results, as the relative humidity increases, the transmission coefficient (S21) increases, while the resonance frequency decreases. As a result, the sensor exhibits an increase in S21 of 3.58 dB and a decrease in the resonance frequency of 8.85 MHz when the relative humidity changes from 30% to 85%.

Original languageEnglish
Pages (from-to)166283-166293
Number of pages11
JournalIEEE Access
Publication statusPublished - 2020

Bibliographical note

Funding Information:
This work was supported by the National Research Foundation of Korea (NRF), through the Basic Science Research Program, funded by the Ministry of Science and ICT under Grant NRF-2017R1A2B2011724.

Publisher Copyright:
© 2020 Institute of Electrical and Electronics Engineers Inc.. All rights reserved.

All Science Journal Classification (ASJC) codes

  • Computer Science(all)
  • Materials Science(all)
  • Engineering(all)


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