Formaldehyde gas sensor based on quartz crystal microbalance modified with aniline-doped polyvinyl acetate nanofibers

Real-time detection of formaldehyde in the atmosphere remains challenging. The available gaseous formaldehyde sensing methods offer limited sensitivity, selectivity, and robustness. We have modified a quartz crystal microbalance (QCM) system for selective detection of formaldehyde in the air. The QCM surface was functionalized with polyvinyl acetate (PVAc) nanofibers and doped with 2, 4, and 6 wt% aniline to improve the selectivity and sensitivity of the sensor. The chemical content and morphological structure of PVAc nanofibers doped with aniline were confirmed by Fourier-transform infrared (FTIR) spectroscopy, energy-dispersive X-ray (EDX) spectroscopy, and scanning electron microscope (SEM). The results showed that the modified QCM sensor had a sensitivity of 0.056 Hz·ppm-1 with a response and recovery time of 200 s and 90 s, respectively. It gave limits of detection (LOD) and quantitation of 28 ppm and 96 ppm, respectively for formaldehyde. Moreover, compared to the other gases or vapors, the modified QCM was selective towards formaldehyde. The current workplace exposure limit (WEL) for formaldehyde is 2 ppm, with a time-weighted average over eight hours. Future work will focus on improving the reported QCM sensor to meet the required LOD for formaldehyde detection in the environment and industrial sites.