Humidity Monitoring Using Flexible RF Sensors

Radiofrequency gas sensors offer many advantages compared to other types of sensors especially due to their low cost, energy efficiency and ability for wireless readout. Furthermore, they can be deployed for air quality monitoring, industrial and transportation activities. However, humidity is the major environmental interferent. In this paper, a flexible RF sensor associated to a polymer sensitive material was proposed for real time pollutant detection. Before testing in realistic conditions, the sensor was characterized under different relative humidity in order to estimate the sensor’s performance. A climatic chamber was used to generate humidity at 25 °C. Results showed a low hysteresis, reversible and repeatable response in exposition to humidity over a range from 35 to 75 %RH with a sensitivity of -1.325 MHz/%RH and -0.05 dB/%RH.