A Novel E-Nose Chamber Design for VOCs Detection in Automobiles

To detect parts per billion (ppb)-level volatile organic compounds (VOCs) in automobiles, a pre-concentrator is generally needed for electronic noses (e-noses), which can enrich ppb-level concentration to parts per million (ppm) level. However, the current e-nose chamber structure could dilute the pre-concentrated gases and then the detection performance is reduced. To solve this problem, a novel chamber design was proposed in this paper. The core design idea was to reduce the space for the gas flow in the chamber, taking into account the shape and size of the gas sensors. Specially, for the pin-type gas sensors, a series of cylindrical structure design was adopted, and for the micro-electro-mechanical system (MEMS) patch-type sensors, the headspace was compressed. The results of computational fluid dynamics (CFD) based simulation showed that the concentration of pre-concentrated gases in the novel chamber was higher than that of the traditional chamber. The designed chambers were manufactured using polylactic acid (PLA) material by 3D printing. Experimental gases were prepared from polyurethane (PU) leather and polyvinyl chloride (PVC) leather to verify the performance of the chambers, and the results demonstrated that the proposed new e-nose chamber was superior to the traditional one in terms of the pre-concentration effect, repeatability and classification performance.