Broadband Temperature and Airflow Sensing Based on CSSR-Thermistor-Loaded Transmission Line Design

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Abstract
This work presents the design of a compact wireless temperature and airflow sensing method using a complementary split ring resonator (CSRR)-loaded microstrip transmission line integrated with thermistors. The sensing principle relies on the temperature-dependent resistance of the thermistor, where varying airflow temperature modulate the heating and cooling dynamics, resulting in measurable changes in the slope and amplitude of the CSRR-loaded transmission line response. To establish a predictive relationship between these dynamic features and actual air temperature variation, a linear regression model is utilized and validated using experimentally obtained datasets. The model achieves a mean square error (MSE) of less than 0.15 dB and sensitivity of 0.2 dB/°Celcius over 18% frequency bandwidth with less than 0.05 dB sensitivity variation. Further validation confirms that such a sensing mechanism can be utilized to distinctively measure airflow rate by monitoring the time-dependent variation of the transmission response and mapping these dynamic features to actual flow rate measurements. The fabricated prototype is characterized under controlled hot-air flows in the range of 11.3 – 22.1 standard liters per minute (SLPM) at a constant source temperature of 100° C. With its low-profile architecture and compatibility with low-cost fabrication techniques, the proposed sensing mechanism offers a scalable, robust, and easily integrable solution for real-time airflow monitoring in industrial ventilation, distributed sensing, and internet of things (IoT) applications.
Funding Information
  • Rumah Program Organisasi Riset Elektronika dan Informatika (OREI), Internet of Things, National Research and Innovation Agency (BRIN), Indonesia (SK01022025)
  • French Embassy in Indonesia through the Science et Impact 2025 Program

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