Fluctuation enhanced gas sensing with WO3-based nanoparticle gas sensors modulated by UV light at selected wavelengths

Understanding the Potential of WO3 Based Sensors for Breath Analysis

“…Another interesting method for increasing the sensor response of SMOX-based sensors is fluctuation-enhanced sensing (FES). Irradiation with ultraviolet (UV) light has a photocatalytic effect on resistive gas sensors [56]. Through irradiation of Au-NP decorated WO 3 with two different lasers it is possible to increase the sensor signals to both low (>20 ppm) and higher (>50 ppm) ethanol concentrations [56].…”

“…Irradiation with ultraviolet (UV) light has a photocatalytic effect on resistive gas sensors [56]. Through irradiation of Au-NP decorated WO 3 with two different lasers it is possible to increase the sensor signals to both low (>20 ppm) and higher (>50 ppm) ethanol concentrations [56]. The effect of humidity on the sensor response was not considered in any of the research.…”

Fluctuation-Enhanced Sensing: Review of Practical Issues

“…Resistive gas sensing layer can be made on ceramic or silicon substrates and efficiently irradiated from different distances. Selected wavelengths of the UV light can modulate the physical properties of the gas sensing layer (e.g., DC resistance, lowfrequency resistance fluctuations) [55]. We observed that changes of DC resistance induced by UV irradiation are independent of the changes of the recorded low-frequency noise [56].…”

“…This effect can be easily induced by UV LEDs irradiating the gas sensing layer (Figure 7). Numerous papers are presenting the detailed results of gas sensing modulated by UV light applied to different gas sensing layers [51][52][53][54][55][56][57][58]. A series of low-cost UV LEDs, emitting UV light within wavelet range 250÷355 nm is available on the market.…”

“…The depth of penetration depends on light wavelength, irradiated material and its morphology. We can assume that the depth of UV light penetration does not exceed a few µm only [55]. Thus, the gas sensing layer can be modelled as two parallel resistors: an external one modulated by UV light and the inner one without this effect.…”