Resistive and surface ionisation response of SnO2 gas sensing layers

Miniaturized ionization gas sensors from single metal oxide nanowires

“…Here, it should be pointed out that all these results were obtained at temperatures (T z 280 C) significantly lower than the ones used in macroscopic SI devices (T z 800 C), 12,17 and quite close to those typical for conventional RES devices. In terms of surface temperature requirements, the temperature lowering amounts to more than DT z 500 C (800 C / 280 C).…”

“…14,15 Building on this fact, mixed RES/SI detectors were investigated and it was demonstrated that such detectors are able to detect small concentrations of odorous and toxic amines in front of large concentrations of simple hydrocarbons. 12,16,17 These latter devices employed thin film metal oxide materials deposited on standard ceramic heater substrates and were arranged in a parallel plate capacitor geometry to enable SI read out. Nevertheless, they had a serious technical drawback that made extremely complicated their integration in portable and energy efficient systems; high temperature operation (T z 500-800 C) and the need of large electrostatic potentials (V c z 10 3 V) to activate them.…”

“…Nevertheless, they had a serious technical drawback that made extremely complicated their integration in portable and energy efficient systems; high temperature operation (T z 500-800 C) and the need of large electrostatic potentials (V c z 10 3 V) to activate them. 12,14,16,17 Working into the direction of portable, low power consumption gas sensor systems, [18][19][20] we report here on the fabrication and electrical characterization of surface ionization gas sensors based on individual SnO 2 nanowires (Fig. 1).…”

“…Interestingly, this is the same order of magnitude of ion current responses that were observed in our previous experiments on macroscopic thin films of SnO 2 (area $ z 13 mm 2 ) read out using a parallel plate capacitor arrangement (d ¼ 1 mm, V c ¼ 10 3 V). 17 Dividing the extracted ion currents through the geometrical cross-section of the emitting area, the current density enhancement in the nanowire devices is no less than a factor of 10 7 to 10 8 . We tentatively attribute this huge enhancement to two effects:…”

Room temperature detection of amine vapours using copper phthalocyanine based thin films

“…Because of increasing concern over safety and health hazards presented by exposure to amine vapours, the major challenge is to find an effective and reliable way for monitoring amine levels and to detect the exposure to potentially hazardous amine concentrations in the workplace environment. A number of reports are available on odour sensors using metal oxides (SnO 2 , TiO 2 , WO 2 ) based sensors, but they require relatively high operational temperatures (100–500 °C) 7–9.…”