An odor sensor based on a fluorescent imaging system was developed to detect the sweat odor of human body. Volatile organic acid substances with low molecular weight were supposed to be one of the key contributors to the odor of a sweat sample collected from the human body. Quinine sulfate, a pH-dependent fluorescent compound that shows fluorescent enhancing in the presence of organic acids, was utilized to prepare an agarose-gel supported fluorescent film. The existence of organic acid components with high abundance in the collected sweat sample was confirmed by the analysis of SPME-GC/MS. Sequence images of the fluorescent film in the absence and presence of odors were recorded by a high-resolution CCD camera. The response of the sensor to typical organic acids in sweat odor, such as acetic acid, isovaleric acid, hexanoic acid and octanoic acid, was evaluated by the analysis of subtraction images as well as the real-time change of mean gray value (MGV). The odor of the sweat sample after incubation was successfully visualized, which indicates the application potential of the developed fluorescent imaging sensor in the detection of human body odor.
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