Abstract
Electronic nose applications in environmental monitoring are nowadays of great interest, because of the instruments' proven capability of recognizing and discriminating between a variety of different gases and odors using just a small number of sensors. Such applications in the environmental field include analysis of parameters relating to environmental quality, process control, and verification of efficiency of odor control systems. This article reviews the findings of recent scientific studies in this field, with particular focus on the abovementioned applications. In general, these studies prove that electronic noses are mostly suitable for the different applications reported, especially if the instruments are specifically developed and fine-tuned. As a general rule, literature studies also discuss the critical aspects connected with the different possible uses, as well as research regarding the development of effective solutions. However, currently the main limit to the diffusion of electronic noses as environmental monitoring tools is their complexity and the lack of specific regulation for their standardization, as their use entails a large number of degrees of freedom, regarding for instance the training and the data processing procedures.
Highlights
The concept of the electronic nose as a tool made up of sensors used to classify odors was introduced for the first time by Persaud and Dodd in 1982 [1]
In the course of their experiments, these two researchers set themselves the goal of creating a tool capable of emulating the mammalian olfactory system by recognizing different odors and giving repeatable responses. The electronic nose they developed comprised: (I) a matrix of sensors to simulate the receptors of the human olfactory system; (II) a data processing unit that would perform the same function as the olfactory bulb; (III) a pattern recognition system that would recognize the olfactory patterns of the substance being tested, a function performed by the brain in the human olfactory system [2]
Because of the electronic nose’s capability to discriminate and recognize a variety of different gases and odors using just a small number of sensors, and the first promising results obtained from research in this field, there was huge interest in the subject in the science community and over the course of time this led to a host of research projects focusing on electronic nose applications in various different areas, including, for instance, the medical and diagnostic [3,4,5], food [6,7,8] and cosmetics [9] sectors
Summary
The concept of the electronic nose as a tool made up of sensors used to classify odors was introduced for the first time by Persaud and Dodd in 1982 [1]. The drawback of sensorial analyses is that they are generally complex, costly and difficult to execute in real time For these reasons, in some cases it may be preferable to use electronic noses to replace other analytical methods in the environmental field. They may be the only currently available method of simultaneously both evaluating the odor concentration of the analyzed air and classifying it, by attributing to it a specific olfactory class and thereby recognizing the provenance of the odor [35] For all these reasons, several different studies have been conducted in recent times with the aim of evaluating the possibility of applying electronic nose technology to environmental applications. This article reviews the findings of those studies with particular focus on the proposed applications
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