The zNose, a new electronic nose using acoustic technology

Abstract

An array of sensors simulating the human olfactory response has become known as an electronic nose, or eNose. An eNose provides a vectorial image in N-dimensional space (where N equals the number of sensors) of specific vapor mixtures containing possibly hundreds of different chemical species. Typically, eNoses have only a few sensors, produce responses that are not correlated, and have poor sensitivity. A new type of electronic nose, based upon fast chromatography and a single high-Q acoustic sensor, solves these problems by stimulating a virtual sensor array containing hundreds of orthogonal sensors. Analysis of any odor is accomplished by serially polling this virtual sensor array or a spectrum of retention times. This paper will describe the acoustic technology as well as present results for applications involving important vapors associated with several commercial foods and beverages. Part per billion sensitivity has been achieved with volatile compounds and part per trillion sensitivity for semi-volatile compounds. Because the new acoustic technology is quantitative it is the only electronic nose technology to be validated by the US EPA. The commercial expression of this technology, the zNose, is now providing an on-line quantitative measure of quality for food, beverages, cosmetics, and other aromatic products.