Chemical Selectivity and Sensitivity of a 16-Channel Electronic Nose for Trace Vapour Detection

Abstract

Good chemical selectivity of sensors for detecting vapour traces of targeted molecules is vital to reliable detection systems for explosives and other harmful materials. We present the design, construction and measurements of the electronic response of a 16 channel electronic nose based on 16 differential microcapacitors, which were surface-functionalized by different silanes. The e-nose detects less than 1 molecule of TNT out of 10+12 N2 molecules in a carrier gas in 1 s. Differently silanized sensors give different responses to different molecules. Electronic responses are presented for TNT, RDX, DNT, H2S, HCN, FeS, NH3, propane, methanol, acetone, ethanol, methane, toluene and water. We consider the number density of these molecules and find that silane surfaces show extreme affinity for attracting molecules of TNT, DNT and RDX. The probability to bind these molecules and form a surface-adsorbate is typically 10+7 times larger than the probability to bind water molecules, for example. We present a matrix of responses of differently functionalized microcapacitors and we propose that chemical selectivity of multichannel e-nose could be enhanced by using artificial intelligence deep learning methods.

C-14 powered dye-sensitized betavoltaic cells

“…[15][16][17][18] Binding energy peaks at 286.2 eV, and 288.3 eV in the C 1s spectrum are attributed to C-N, C-O, and C=O bonds, respectively. 19 Nitrogen doping in the nano/quantum carbon dots electrode is established by deconvolution of N 1s XPS spectra, Fig. S4(C).…”

Improving the Chemical Selectivity of an Electronic Nose to TNT, DNT and RDX Using Machine Learning

“…Therefore, research is now shifting towards arrays of an increasing number of sensors that are able to distinguish between a series of different substances in various concentration ranges, as a dog’s nose would. The design of a sensor array depends on the application, for example, [1] industrial chemicals, such as pollutants, volatile organic compounds, or explosives [2], or compounds used in environmental monitoring. Often, the applications are in the food and beverage industry [3,4], for detecting fruit aromas or determining the ripening status [5,6], controlling the quality of vegetable oil [7,8], classifying different types of wines [9] or teas [10] and in detecting spoilage due to microbiological contamination [11].…”

“…The maximum number of different sensors reported in the literature is 18 semiconductor sensors installed in a commercially available e-nose [10] or 34 in an experimental setup [13]. We have built a 16-channel e-nose demonstrator [2] for use in this study. The number of sensors in existing e-noses is small compared to the millions of sensing cells in a dog’s nose.…”

Nanoporous Silica-Dye Microspheres for Enhanced Colorimetric Detection of Cyclohexanone

“…In the past decade, a large number of analytical methods for trace explosive screening have been investigated, including gas chromatography-mass spectrometry (GC-MS) [7][8][9][10], electronic noses [11][12][13][14], ion mobility spectrometry [5,[15][16][17][18], surface acoustic wave devices [19][20][21] and fluorimetry [22][23][24][25]. Some effective approaches, such as solid-phase microextraction (SPME) [26][27][28], have been extensively explored for ultrasensitive gaseous detection of non-volatile explosives at the ppb or ppt level.…”