Multi-channel chitosan coated quartz crystal microbalance device for continuous detection of isopropyl alcohol

Isopropyl alcohol (IPA) is a widely used volatile organic compound, yet its uncontrolled presence poses health and safety risks. This study presents the evaluation of a multichannel quartz crystal microbalance (QCM) sensor coated with chitosan for the real-time detection of IPA vapor. The sensor integrates three independent sensing units on a single substrate, fabricated using gold. A custom 3D-printed packaging system was also developed to enable gas flow channels for continuous monitoring. The chitosan coating, optimized between 1–10 µL, demonstrated effective interaction with IPA resulting in measurable frequency shifts. Experimental results revealed that sensor response was highly sensitive to IPA concentrations, with a linear detection range between 7.5–15 ppm (R² = 0.9806) and an estimated limit of detection (LOD) of 10.7 ppm. At higher concentrations, a logarithmic calibration model (R² = 0.949) captured saturation effects. The device exhibited rapid response (~10 s), reversibility, and stability, confirming its suitability for continuous air quality monitoring and industrial safety applications.