CARBON NANOTUBE-CHITOSAN THIN FILM ON QCM (QUARTZ CRYSTAL MICROBALANCE) FOR DETECTION OF IPA (ISOPROPYL ALCOHOL)

This study presents the development of a quartz crystal microbalance (QCM) sensor coated with a multi-walled carbon nanotube–chitosan (MWCNT-COOH/CS) composite for the detection of isopropyl (IPA) vapor, a common volatile organic compound (VOC). The composite was synthesized via glutaraldehyde crosslinking to enhance bonding between carboxyl-functionalized MWCNTs and chitosan, followed by sonication and stirring to ensure uniform dispersion. Material characterization was carried out using Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and field-emission scanning electron microscopy (FESEM), confirming successful integration and interaction between MWCNTs and CS. Static QCM analysis showed that the MWCNT-COOH/CS composite achieved a balanced frequency shift of approximately 106 Hz with a response time of ~40 seconds, outperforming standalone CS and MWCNT layers in terms of response speed and signal stability. Dynamic measurements across IPA concentrations from 300 to 700 ppm revealed a linear frequency shift trend with a correlation coefficient (R²) of 0.9713. Compared with similar sensors reported in the literature, the developed composite exhibits promising sensitivity, faster response time, and ease of fabrication, suggesting strong potential for real-time VOC monitoring applications.