Differential Passive Microwave Planar Resonator- Based Sensor for Chemical Particle Detection in Polluted Environments

This paper presents an inkjet-printed differential passive microwave planar resonator-based sensor for toxic vapor detection at room temperature. Two devices are presented, with 5 (D1) and 50 (D2) layers of composite sensitive film (PEDOT:PSS-MWCNTs). Each one consists of two band-pass resonators with the fundamental modes around 2.5 and 2.7 GHz. Theoretical and experimental results are presented, both devices show sensitivity to ethanol vapor ranging from 500 to 1300 ppm according to the magnitude and resonant frequency shifts of their scattering parameters (S-parameters). Limitations due to a continuous drift on both the reference and the sensitive channels are discussed. Though further improvements are needed, such sensor is a good candidate for integration into real-time multi-sensing platforms adaptable for the Internet of Things.