Generating gas phase odor components for artificial olfactory systems

Abstract

Even though recent studies have led to a more refined understanding of the mechanisms related to odorant detection, the vertebrate olfactory system remains the least understood sense of the human senses. The total amount of sensing elements, olfactory receptor proteins, in the human nose is counted in tens or hundreds of millions, thus recreating this kind of complex system artificially is challenging. Human nose cannot be seen as an objective sensor, so creating an artificial olfactory system, often called electronic nose or “e-nose”, which is capable to objectively and reliably classify odors in a wide range is a key research question in the field of artificial olfaction. In addition to the detection system in e-nose instruments, something analogical to human brain is needed to interpret the signals in the detecting sensors. Production of easily controllable and measurable odor stimulus is needed when studying human olfaction, olfaction-related physiology and psychological reactions to odors. Controlled odor producing instruments are called olfactometers. In this Master Thesis, a compact olfactometer able to produce controlled continuous odor stimuli from three individual gaseous components is presented. The main objective was to study and verify if the presented system can produce gas streams with the stable concentrations of different odor components. For measuring the output air stream, the device used is a chemical detector ChemPro 100i, that is based on aspiration ion mobility spectrometry (aIMS) technology. The presented olfactometer was used to produce synthetic jasmine scent using three main odor components from jasmine oil. Experiments were conducted to verify the functionality of our olfactometer and to analyze the capability to distinguish different odor component concentrations using the ChemPro 100i data. Further to test the functionality of our olfactometer, we run a short pilot test in which human participants compared a synthetically created scent of jasmine and the scent of real jasmine oil. Results showed that from the measurement data, different concentration sets of three components were able to be distinguished. Human pilot results showed that human nose was confused when comparing three component synthetic jasmine with real jasmine scent but could distinguish between two component synthetic jasmine and real jasmine scent.