Biological odorant sensors

Ultra high-speed gas chromatography (GC) fitted with an odor sensor is a powerful tool for analyzing the chemical vapors produced by explosives or other chemical or biological weapons. 

The aforementioned theories arc concerned wilh Ihc size and shape of odorant molecules, but differ in certain underlying concepts. For example, accommodating for functional groups, electron donor-acceptor characteristics, as well as Ihc sorptive nature of odorants on sensor sites. The vibration Iheory largely concentrates on the far-infrared and Raman spectral characteristics of odoriferous substances. The remaining theories concentrate on structural and behavior characteristics of odorant molecules, stressing direct interactions physically, chemically, and biologically wilh the olfactory sensor system. 

Insects are the most diverse group animals on earth, with approximately five million species described to date (Novotny et al. 2002). Amidst this great diversity are adaptations common to all insects that maximize inclusive fitness in their respective habitats. One such fundamental adaptation is the ability to respond to cues in the environment, in particular the ability to detect external biological compounds via a chemical sensor. The sophisticated olfactory system of insects is able to sense volatile odorants derived from prey, host plants, and conspecific individuals. These compounds are detected by olfactory receptor neurons (ORNs) housed in the antennae, and these ORNs relay information about food sources, oviposition sites, and mates that leads to behavior based on neural responses mediated by the ORNs. The binding... 

Relating Sensor Responses of Odorants to Their Organoleptic Properties by Means of a Biologically-Inspired Model of Receptor Neuron Convergence onto Olfactory Bulb... 

Alkasab, T.K., White, J., Kauer, J.S. A computational system for simulating and analyzing arrays of biological and artificial chemical sensors. Chemical Senses 27, 261-275 (2002) Amoore, J.E. Molecnlar Basis of Odor. C.C. Thomas, Pnb., Springfield, Illinois (1970) Anderson, S.K., Hansen, P.W., Anderson, H.V. Vibrational Spectroscopy analysis of dairy products and wine. In Chalmers, J.M., Griffiths, P.R. (eds.) Handbook of Vibrational Spectroscopy, vol. 5, pp. 3672-3682. Wiley, Chichester (2002)... 

Recent advances in the design and fabrication of chemical and biological sensors for toxicity evaluation are summarized in Chapter 5. Chapter 6 discusses the applications of electronic noses and tongues in areas such as food, beverage, environmental, clinical, and pharmaceutical applications. Chapter 7 overviews the applications of sensors in food and environmental analysis. Chapter 8 focuses on the medical diagnosis, with particular emphasis on in-vivo measurement where either body or breath odor are collected and analyzed. Chapter 9 outlines the DNA biosensors that hold great promise for the task of environmental control and monitoring. 

An electronic nose is a technical chemical sensor system, which shows the same 10 principal steps of odor recognition (Fig. 3h). However, although general similarities may he seen, any more detailed view illustrates drastic differences between the biological and the technical system (see Refs. [4, 5] and references therein). 

As stated previously, this method of sensor design has been motivated by biological systems, namely the mammalian senses of taste and smell. Both the nose and the tongue contain a variety of receptors that react to varying degrees with odors and tastes, respectively, withont being specific for one single analyte. The response of these receptors creates a pattern unique to the particular species, which is in turn processed by the brain. Many odors and tastes may be comprised of elements that are chemically very similar, but the differential response created by these receptors enables these odors to be identified as different. 

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