Methanol poisoning causes blindness, organ failure or even death when recognized too late. Currently, there is no methanol detector for quick diagnosis by breath analysis or for screening of laced beverages. Typically, chemical sensors cannot distinguish methanol from the much higher ethanol background. Here, we present an inexpensive and handheld sensor for highly selective methanol detection. It consists of a separation column (Tenax) separating methanol from interferants like ethanol, acetone or hydrogen, as in gas chromatography, and a chemoresistive gas sensor (Pd-doped SnO₂ nanoparticles) to quantify the methanol concentration. This way, methanol is measured within 2 min from 1 to 1000 ppm without interference of much higher ethanol levels (up to 62,000 ppm). As a proof-of-concept, we reliably measure methanol concentrations in spiked breath samples and liquor. This could enable the realization of highly selective sensors in emerging applications such as breath analysis or air quality monitoring.

Nitrogen dioxide (NO₂) is a major air pollutant resulting in respiratory problems, from wheezing, coughing, to even asthma. Low-cost sensors based on WO₃ nanoparticles are promising due to their distinct selectivity to detect NO₂ at the ppb level. Here, we revealed that controlling the thickness of highly porous (97%) WO₃ films between 0.5 and 12.3 μm altered the NO₂ sensitivity by more than an order of magnitude. Therefore, films of WO₃ nanoparticles (20 nm in diameter by N₂ adsorption) with mixed γ- and ε-phase were deposited by single-step flame spray pyrolysis without affecting crystal size, phase composition, and film porosity. That way, sensitivity and selectivity effects were associated unambiguously to thickness, which was not possible yet with other sensor fabrication methods. At the optimum thickness (3.1 μm) and 125 °C, NO₂ concentrations were detected down to 3 ppb at 50% relative humidity (RH), and outstanding NO₂ selectivity to CO, methanol, ethanol, NH₃ (all > 10⁵), H₂, CH₄, acetone (all > 10⁴), formaldehyde (>10³), and H₂S (835) was achieved. Such thickness-optimized and porous WO₃ films have strong potential for integration into low-power devices for distributed NO₂ air quality monitoring.

Dissolved gas in oil analysis is a key measure to determine the status and the health state of power transformers. Different sensors and devices have been developed in the past for continuous on-line monitoring of these gas concentrations. A critical point for these measurements is a good exchange of the oil at the sensor with the oil in the main circulation of the transformer. Due to the low diffusion of the gasses in oil strong gradients of the gas concentration can occur in the different parts of the transformers. Therefore, a thermal pump will be investigated here for providing a strong oil exchange between the sensor and the main transformer part. The pump will be tested under different installation conditions and its fast response time to concentration changes can be shown under these different installations.