A novel creation of thread-based ammonia gas sensors for wearable wireless security system
The purpose of this work is a novel design and fabrication of wearable amine sensor embroidered into fabric substrates based on polymer/SWNT-COOH nanocomposite and applied as electronic nose (e-nose) system. The wearable amine sensors were fabricated by drop coating and embroidery processes. Various polymers, namely, polyvinyl chloride (PVC), cumene terminated polystyrene-co-maleic anhydride (cumene-PSMA), poly (styrenecomaleic acid) partial isobutyl/methyl mixed ester (PSE), and polyvinylpyrrolidon (PVP) were blended with SWNT-COOH to produce 4 kinds of polymer/SWNT-COOH nanocomposites, then deposited onto the interdigitate electrodes previously prepared by embroidering conductive yarn on the fabric substrate. The prepared fabric sensors can be fully integrated into wearable surface of shirts. The connection to external electronic circuit can be done conveniently to obtain the sensing data. Wearable amine sensors for e-nose were used to distinguish odor of ammonium hydroxide and triethlyamine, which are usually found in the emission from the human body. These wearable sensors will be very useful for monitoring malodors that have volatile amine in its content. This study can solve wearable sensors' drawbacks, including uncomfortable wearing and washing problems. Therefore, the embroidered sensors with the capability of detecting volatile compounds can be detached before washing the clothes and the variety of gas sensing makes it highly suitable for applications as wearable electronic nose for body odor detection and using a simple pattern recognition based on the principal component analysis (PCA) for discriminating between the responses of wearable amine sensor array to gas odors.