Integrated tin oxide odour sensors

Gardner, Julian W.; Shurmer, H.V.; Corcoran, P.

doi:10.1016/0925-4005(91)80186-n

Cited by 67 publications

(29 citation statements)

References 10 publications

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“…In an initial processing of the data, presented in this paper, the only information used was the maximum amplitude of the Poly(x-methylstyrene) 7 Poly(styrene-co-acrylonitrile) 8 Poly(styrene-co-maleic anhydride) 9 Poly(styrene-co-allyl alcohol) (Table 1). As discussed below, each odorant could be clearly and reproducibly identified from the others by using this sensor apparatus.…”

Section: Resultsmentioning

confidence: 99%

“…Arrays of metal oxide thin film resistors, typically based on SnO2 films that have been coated with various catalysts, yield distinct diagnostic responses for several vapors (7)(8)(9). However, due to the lack of understanding of catalyst function, SnO2 arrays do not allow deliberate chemical control of the response of elements in the arrays nor reproducibility of response from array to array.…”

mentioning

confidence: 99%

“…Prior attempts to produce a broadly responsive sensor array have exploited heated metal oxide thin film resistors (7)(8)(9), polymer sorption layers on the surfaces of acoustic wave resonators (10,11), arrays of electrochemical detectors (12)(13)(14), or conductive polymers (15,16). Arrays of metal oxide thin film resistors, typically based on SnO2 films that have been coated with various catalysts, yield distinct diagnostic responses for several vapors (7)(8)(9).…”

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confidence: 99%

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A chemically diverse conducting polymer-based "electronic nose".

Freund

Lewis

1995

Proc. Natl. Acad. Sci. U.S.A.

310

188

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We describe a method for generating a variety of chemically diverse broadly responsive low-power vapor sen-sors. The chemical polymerization of pyrrole in the presence of plasticizers has yielded conducting organic polymer films whose resistivities are sensitive to the identity and concentration of various vapors in air. An array of such sensing elements produced a chemically reversible diagnostic pattern of electrical resistance changes upon exposure to different odorants. Principal component analysis has demonstrated that such sensors can identify and quantity different airborne organic solvents and can yield information on the components of gas mixtures.There is considerable interest in developing sensors that act as analogs of the mammalian olfactory system (1, 2). This system is thought to utilize probabilistic repertoires of many different receptors to recognize a single odorant (3, 4). In such a configuration, the burden of recognition is not on highly specific receptors, as in the traditional "lock-and-key" molecular recognition approach to chemical sensing, but lies instead on the distributed pattern processing of the olfactory bulb and the brain (5, 6). We describe herein the construction and characterization of a broadly responsive vapor detection array based on conducting polymer "chemiresistor" elements. Such conducting polymer elements are simply prepared and are readily modified chemically to respond to a broad range of analytes. In addition, these sensors yield a fairly rapid lowpower dc electrical signal in response to the vapor of interest, and their signals are readily integrated with software-or hardware-based neural networks for purposes of analyte identification.Prior attempts to produce a broadly responsive sensor array have exploited heated metal oxide thin film resistors (7-9), polymer sorption layers on the surfaces of acoustic wave resonators (10, 11), arrays of electrochemical detectors (12-14), or conductive polymers (15, 16). Arrays of metal oxide thin film resistors, typically based on SnO2 films that have been coated with various catalysts, yield distinct diagnostic responses for several vapors (7-9). However, due to the lack of understanding of catalyst function, SnO2 arrays do not allow deliberate chemical control of the response of elements in the arrays nor reproducibility of response from array to array. Surface acoustic wave resonators are extremely sensitive to both mass and acoustic impedance changes of the coatings in array elements, but the signal transduction mechanism involves somewhat complicated electronics, requiring frequency measurement to 1 Hz while sustaining a 100-MHz Rayleigh wave in the crystal (10, 11). Electrically conductive organic polymer elements are well-suited for such an array, because swelling of the polymer upon exposure to an analyte will induce changes in the resistivity of the polymer film (17,18). This enables a direct low-power electrical signal readout (the film resistance) to be used as the sensing signal. Some prior work has been pe...

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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A chemically diverse conducting polymer-based "electronic nose".

Freund

Lewis

1995

Proc. Natl. Acad. Sci. U.S.A.

310

188

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“…Efforts to provide sufficient variability in sensor technology and operation for proper array optimization include the modeling of reactions in the most popular chemiresistive sensor, the tin oxide sensor [1], manipulation of such design parameters as electrode geometry (in phthalocyanine [2] and metal oxide thin films [3]), use of multiple modes of operation for each sensor to minimize the physical size of a heterogeneous array architecture [4], the use of molecular sieves at the front end of the sensor array to provide prefiltering (by size) of molecules of interest [5], and the development of improved supporting infrastructure in the form of improved headspace samplers [6]. Various (heterogeneous) combinations of metal oxide and conducting polymer sensors have been used to differentiate single analytes such as toluene, n-propanol, n-octane, methanol, ethanol, 2-propanol and 1-butanol [8].…”

Section: Use Of Chemical Sensor Arraysmentioning

confidence: 99%

Array Optimization and Preprocessing Techniques for Chemical Sensing Microsystems

et al. 2002

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Physical sensors, defined by their direct chemical interaction with the sensing environment, are a valuable and often essential contribution to the solution of stringent chemical sensing problems. Methods for conditioning signals from these sensors to optimize their presentation to subsequent decision-making models in the signal processing flow are presented. The assembly of sensors into an array and the preprocessing of these signals are the two primary techniques for conditioning a chemical image for concentration detection, chemical discrimination, and, in some cases, odor localization. Array optimization involves locating the point at which adding additional sensors to an array generates more noise than information and is highly dependent on the application and number of analytes to be sensed or differentiated. Signal preprocessing techniques include noise reduction, feature extraction, the reduction of array inputs, and the scaling of individual sensor signals and provide a means by which to reconstruct an array of chemical sensor signals into a subset of information that enables a decisionmaking model to do its job with greater efficiency and accuracy. In this chapter, surveys of methods are accompanied by representative examples employing a wide variety of sensors including ChemFETs, chemiresistors, acoustic wave devices, and surface plasmon resonance sensors.

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“…These materials with nanoscale structure become one of the main tools in the brand new science of nanotechnologies with promising applications in medicine, energy and communication. Other applications of transparent conductive or semiconductive oxide films (as passive or active layers) have been reported and the most widely known are: transparent contacts for solar cells [2], sensors for several purposes [3], semiconductors in transparent thin-film transistors [4] and other electronic applications. The fundamental properties of these films depend strongly on the deposition technique: spray pyrolysis [5], rf sputtering [6], electron beam [7] and laser methods [8] are some of them.…”

Section: Introductionmentioning

confidence: 99%