A Sampling Bag-Based Dehumidification System for Electronic Nose Analysis

Most of chemical gas sensors exhibit crosssensitivity to humidity. In this study, we explored the potential of using water vapor permeability of polymeric materials to reduce the water content in gas samples for sensor analysis. We developed a dehumidification system using a disposable Nalophan TM bag flushed with dry air to accelerate water vapor diffusion. Our method was able to accelerate the sample humidity removal compared to passive storage of Nalophan TM bags from >2h to <1h (from 80% to 20% RH). We validated the system using human urine headspace samples (pooled and spiked with disease-related volatile compounds) to simulate a disease condition. Photoionization detector (PID) measurements before and after drying indicate minimal volatile compounds loss. An electronic nose (E-Nose) classified pooled vs. spiked urine with 83% accuracy after Nalophan TM drying, compared to 86% obtained with a Nafion TM membrane dryer. Results demonstrated that the disposable bag-based dehumidification method can mitigate humidity interference while preserving most diagnostic information and avoiding cross-contamination risks.