In this paper, we propose a humidity sensor based on a negative resistance oscillator using conducting polymer (CP) PEDOT:PSS film at room temperature. The proposed humidity sensor basically consists of a microstrip line and a negative resistance circuit, which creates a negative resistance for high-frequency oscillation. The microstrip line has a circuit structure that is connected through a via hole between the ground plane and the signal line with a CP thin film. From our experimental results, we find that the oscillation frequency of the sensor gradually decreases as the relative humidity (RH) increases. Owing to the conductivity variation of the CP film with the RH value, the oscillation frequency of the sensor sensitively changes in real time. Therefore, we suggest that our microwave-oscillator-based sensor scheme is a good candidate for the design of a robust and stable humidity sensor.
Bibliographical noteFunding Information:
This research was supported by the MSIP (Ministry of Science, ICT and Future Planning), Korea, under the ITRC (Information Technology Research Center) support programme ( IITP-2017-2013-0-00680 ) supervised by the IITP (Institute for Information & Communications Technology Promotion). This research was also supported by the Basic Science Research Program through the National Research Foundation (NRF) of Korea funded by the Ministry of Science, ICT & Future Planning ( NRF-2015R1C1A1A02037804 ) and by the Mid-career Researcher Program through the NRF of South Korea under funding for Science and Engineering ( NRF-2017R1A2B4012051 ).
© 2018 Elsevier B.V.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Surfaces, Coatings and Films
- Metals and Alloys
- Electrical and Electronic Engineering
- Materials Chemistry