Plasma polymerization of TEOS for QCM-based VOC vapor sensing

Plasma polymerized tetraethoxysilane (ppTEOS) thin films deposited on quartz crystal microbalance (QCM) electrode were used as sensitive layer for the detection of a number of volatile organic compounds (VOCs) such as methanol, ethanol, acetone and chloroform molecules. Their sensing properties were examined by measuring the resonance frequency shifts (Delta f) of QCM which are due to additional mass loading. The results showed that Delta f of QCM were found to be linearly correlated with different vapor pressure of analyte. The sensor showed good reproducibility and reversibility. The ppTEOS film is found to be highly sensitive to methanol vapor than other vapors. Fourier transform infrared spectroscopy (FTIR) analysis showed the presence of CH(x) peaks around 2962 cm(-1) making the elaborated layer more porous and low dense, resulting in the promotion of VOC vapor diffusion into the film.