1,721,295 research outputs found
Ti–W–O sputtered thin film as n- or p-type gas sensors
No full textWe present some recent trends about research on gas sensors based on semiconducting thin films together with a discussion on the development of novel nanostructured materials such as TiO, TiO2, and WO3 in single phase or as mixed oxides. The films, deposited by RF reactive sputtering from a composite target of W and Ti at two different abundances, are investigated through scanning and transmission electron microscopy (SEM and TEM) techniques for structural characterisation and by volt-amperometric technique for electrical and gas-sensing properties. All of the layers were capable to sense NO2, no effect of poisoning of the surface was recorded, and recovery of the resistance was complete. A concentration as low as 0.5 ppm was detected with a relative change in the resistance ΔR/R about 1400% and as short a response time as 2 min. A detection limit lower than 100 ppb of NO2 is expected
High-precision neural preprocessing for signal analysis of a sensor array
No full textAn array of semiconducting thin-film sensors is used for high-accuracy determination of gas concentrations in a binary mixture of H2S and NO2. For this purpose we developed a newly conceived pre-processing method for data feeding of a standard neural network. Pre-processing exploits dimension compaction of the vectorial signal of the sensor array. This operation is being accomplished by an auxiliary auto-associative network, separately trained from the main one. Our results present unprecedented accuracy even when applied to a validation-data set and appear to be of widespread application
Identification and quantification of methane and ethyl alcohol in an environment at variable humidity by an hybrid array
No full textAn hybrid array, constituted by five chemically modified tin oxide thin films and a humidity sensor are the input of a feed-forward two layers perceptron net to identify and quantify individual concentrations of methane and ethyl alcohol mixtures in a variable humidity environment. The network always identifies which gas is present, no matter to humidity, and predicts the gas concentration with a percentage full scale error equal to 8%
Cavitands as Selective Materials for QMB Sensors for Nitrobenzene and Other Aromatic Vapors
No full text
TiO2:Mo, MoO3:Ti, TiO+WO3 and TiO:W layer for landfill produced gases sensing
No full textNowadays, monitoring landfill produced gases (LFGs) is a major task for environmental safety of the areas neighboring garbage dumps. The authors have explored a novel approach to this problem. We have tested solid-state chemoresistive gas sensors to detect typical complex organic gases produced by landfill, i.e., carbon sulfide, methyl sulfide and xylene. We have prepared TiO2:Mo, MoO3:Ti, TiO + WO3 and TiO:W mixed-oxides thin films deposited by reactive sputtering and then processed through the selective sublimation technique. The layers gave remarkable response towards carbon disulfide and xylene below the attention level for these gases
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