Surface Acoustic Wave Based Nitrogen Dioxide Gas Sensors Using Colloidal Quantum Dot Sensitive Films

In this work, we propose a surface acoustic wave (SAW) based NO2 gas sensor with a colloidal quantum dot (CQD) sensitive film. The PbS CQDs was synthesized through a cation-exchange method, which was then spun onto the surface of a designed SAW delay line with a central frequency of 200MHz. To improve the sensitivity, the CQD films were carried out a ligand exchange treatment. The experimental results show the sensitivity has been enhanced more than three times in the aid of the ligand exchange treatment. The fabricated sensor showed good repeatability, low detect limit down to 105ppb and a sensitivity of 0.91kHz/ppm.