Digital aroma technology for chemical sensing: temporal chemical images of complex mixtures

Abstract

The reliability of Electronic nose applications is mainly based on the sensitivity, repeatability and discernment properties of the sensors composing the array. Due to nature of the chosen sensitive layers, the sensors are particularly suitable to classify environments in which compounds with various chemical functionality play a key role. This article is focusing on the novel strategy aimed at the improving the quality and quantity of chemical information from the sensing instruments based on incorporation kinetic aspects of the array response for perfect formation and improved discrimination of chemical images of the probes. We describe a procedure for reducing both time response and number of elements of gas sensor arrays based on principal component analysis. Thus, digital aroma technology may be used not only as background for formation of chemical images using intelligent sensor massifs but also as an effective experimental tool for characterization and selection coatings with desired chemical functionality by using time-resolved pattern recognition.

Thin Films of Tret-Butyl Calixarene as Sensitive Materials for Organic Compound Detectors

“…Response was registered during 10 minutes, however in all cases the maximum response value was taken as informative parameter, that is, the maximum deviation of the resonator oscillation frequency from its initial value. The temperature during the measurement was maintained at 20 î Ñ by means of thermostat [22]. To ensure the equal measurement conditions and eliminate the influence of previous experiments after each measurement the cell was cleaned by blowing with carrier-gas (argon), which always lead to restoration of the sensors working characteristics.…”

“…Kalchenko. The films were obtained by thermal evaporation in vacuum (with the VUP-5M setup, residual pressure of 5×10 -4 Pa) and deposition onto the metal electrodes of piezoelectric transducers [22], or onto the polished silicon substrate 20x20 mm in size for optical transducers [23], in both cases at room temperature (297±2 î K). The average deposition rate was about 10 nm•min -1 .…”

“…In this work for direct experimental evaluation of organic compounds vapor adsorption onto the calixarene coatings, the 5-channel multisensor system based on AT-cut quartz resonators (with resonance frequency of 10 MHz) was used [22]. Upon adsorption of the analyte molecules on sensitive layer the working frequency of quartz resonator decreases.…”

Improvement of sensor response reproducibility and multistage recognition approach for samples with dominant components

“…A fully automated quartz crystal microbalance set designed at ISP, Kyiv (8 channels, 10 MHz AT-cut crystals) with a measurement interval of 1 s was used in our experiments [7]. The measuring procedure involved the following stages: argon circulation; brandy vapor−argon mixture circulation (bubbling, 12 ml of [11]. Thin films (about 100 nm) were prepared by thermal sputtering in vacuum (VUP-5М, pressure of 5×10 -4 Pa, temperature of 297 ± 2 К, deposition rate of 0.1 nm/min).…”

Adsorption–desorption noise can be used for improving selectivity

“…The receptor molecules are attached to an electronic device able to measure the amount of the analyte adsorbed during the bindingreleasing process. The device may be either a MEMS device, such as quartz crystal microbalance [1,2], or vibrating/bending cantilever [3], or field effect transistor [4], or other [5]. The device with the receptor molecules is called chemical sensor or detector.…”