A direct thermal desorber as a sampling device for application specific sensor system

Electronic Nose: Current Status and Future Trends

“…As these new techniques increase the dimensions of the data set the number of theoretical features becomes large, and hence, selection of the right features becomes challenging. 20 For electronic noses based on a sensor array these are principally transient sensor response, [239][240][241] temperature modulation of metal oxide sensors, [242][243][244][245] partial preseparation of the compounds, 206,223,225,246 or slight differences in the sensors caused by a gradient over temperature, doping concentration, sensitive layer thickness, or membrane thickness (compare Figure 16). 247,248 Modern approaches may also have high-dimensional output data as well, for example, the mass-spectrometerbased Smart Nose with its high amount of mass-to-charge ratios, IMS with the time-dependent measurement, 120 or highdensity optical sensor arrays.…”

“…As these new techniques increase the dimensions of the data set the number of theoretical features becomes large, and hence, selection of the right features becomes challenging . For electronic noses based on a sensor array these are principally transient sensor response, − temperature modulation of metal oxide sensors, − partial preseparation of the compounds, ,,, or slight differences in the sensors caused by a gradient over temperature, doping concentration, sensitive layer thickness, or membrane thickness (compare Figure ). ,

16 Measurement results of the gas sensor microarray KAMINA . The array consists of a single monolithic metal oxide film separated into 38 segments by a parallel electrode structure.

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Higher-Order Chemical Sensing

“…Moreover, sample-to-sample variability, sample deterioration, and the strong influence of the sample preparation and sampling procedure on the sensor results, in particular for natural products, are often underestimated, and the corresponding information is missing in many papers. Information on sampling methods and how these influence sensor array results can be found in dedicated papers. , …”

“…Information on sampling methods and how these influence sensor array results can be found in dedicated papers. 128,129 There are also a number of multitransducer sensor systems, besides the already mentioned MOSES II sytem, 130 commercially available, such as the GDA 2 (electrochemical cells, metal-oxide sensors, ion-mobility spectrometer, and photoionization detector) from Airsense Analytics, 131 the FOX 4000 (metal-oxide sensors and polymer-based sensors: thickness-shear-mode resonators, conducting polymers) and the RQ Box from Alpha M.O.S, 132 the Hazmatcad Plus (surface-acoustic-wave devices and electrochemical cells) and the CW Sentry 3G (surface-acoustic-wave devices and electrochemical sensor array) from Microsensor Systems, 133 or microanalytics-based systems from RAE Systems. 134…”

Sample handling for electronic nose technology: State of the art and future trends

“…Heating and reduced pressure are among the most popular and efficient procedures that promote transition of volatile sample components to gaseous phase (vaporization) [26]. They are successfully used for treatment of such samples as soy beans [27], wheat grains [28,29], tea [30], packaging materials [31] etc.…”