Abstract
The measurement and estimation of human-related senses has become an established technique in sensor research, as well as in the practical design of measurement and control systems. The electronic nose concept is widely used as an analytical tool in industry today. The commercialization of the electronic nose began in 1993 as the concept became widely accepted as an effective instrument for detection and estimation of olfaction. The book describes the general set-up of an electronic nose: it consists of an array of chemical sensors; an air flow system, which switches the reference air and the tested air; a signal analysis technique; and a presentation unit. The main sensor principles presented in the book are also the most frequently used techniques for gas sensors. These are based on two main types of gas sensor: metal-oxide semiconductors and conducting polymer resistive materials. An overview of other gas sensor principles is also given, for example, gas sensors based on the effect of sorbed molecules on the propagation of acoustic waves; field effect semiconductors; electrochemical oxidation and reduction principles; and a catalytic gas sensor. Pellistors are described as well as fibre-optic gas sensors. To increase the complexity of the odour system, an array of mixed sensing principles is often designed, consisting of different types of sensor, in order to create differences in operating temperatures, flow conditions and sensor response times. The analysis technique used, in most cases, is a supervised artificial neural network used in a relative based measurement approach, although other techniques are also mentioned in the book.
The book describes a survey of both chemical properties of odorous molecules as well as biological olfaction from the perspective of human perception. However, many animals have more sophisticated systems, and it would have been interesting to make comparisons.
The applications and three case studies show the direction of the research and development over the last decade. However, the presentation of most of the results as principal component plots indicates that major work is needed to achieve a more human-friendly interface. The next decade should see the development of electronic nose systems into a variety of applications to increase the quality of life as well as for monitoring environmental information. This means that artificial human-related sensor systems could become everyday tools for estimation of your own personal condition as well as that of the environment.
In general, the book presents the state-of-the-art in electronic noses. It can also be considered as an introduction to the subject of electronic noses. This opinion is supported by a sufficiently complete set of references and a good introduction to the chemical, biological and physical background of electronic noses. The book is characterized by a methodical and thorough treatment of the subject matter. The chapters are logically related, and each has its own introduction and bibliography. This approach makes it easy for any reader with only a basic knowledge of related subjects.
However, for researchers, the material and examples feel a little old, since the last three or four years have seen an enormous amount of activity in the field of human-related artificial sensor systems, where the electronic nose is often integrated into more complex systems. By fusing sensor data into a hybrid sensor, or by more complex signal analysis combining data from other sensor modalities such as electronic tongues, we aim to make inferences that may be impossible from a single artificial sensor. Furthermore, a whole electronic head integrates information from all five human-related artificial senses.
However, it remains true that, in a particular area strongly relevant to human-related quality estimation, this book is a valuable and accessible guide and reference. I strongly recommend it as a handbook for users of commercial electronic nose instruments and, particularly for its references to related works.
Peter Wide