Development of low-cost ammonia gas sensors and data analysis algorithms to implement a monitoring grid of urban environmental pollutants

Abstract

The present study is focused on the implementation of a novel, low cost, urban grid of nanostructured chemresistor gas sensors for ammonia concentration ([NH(3)]) monitoring, with NH(3) being one of the main precursors of secondary fine particulate. Low-cost chemresistor gas sensors based on carbon nanotubes have been developed, their response to [NH(3)] in the 0.17-5.0 ppm range has been tested, and the devices have been properly calibrated under different relative humidity conditions in the 33-63% range. In order to improve the chemresistor selectivity towards [NH(3)], an Expert System, based on fuzzy logic and genetic algorithms, has been developed to extract the atmospheric [NH(3)] (with a sensitivity of a few ppb) from the output signal of a model chemresistor gas sensor exposed to an NO(2), NO(X) and O(3) gas mixture. The concentration of these pollutants that are known to be the most significant interfering compounds during ammonia detection with carbon nanotube gas sensors has been tracked by the ARPA monitoring network in the city of Milan and the historical dataset collected over one year has been used to train the Expert System.

Improved recovery time and sensitivity to H2 and NH3 at room temperature with SnOx vertical nanopillars on ITO

“…In the same setup, humidity and temperature sensors are also mounted. Further details can be found in refs 50 , 51 .…”

Room temperature amine sensors enabled by sidewall functionalization of single-walled carbon nanotubes

“…In particular, the detection of amines is important for industrial/environmental monitoring, 11 food quality control 12 and disease diagnosis. 13 For example, in food quality control, the levels of ammonia (NH 3 ), trimethylamine (TMA), dimethylamine and triethylamine can be used to assess the spoilage of fish.…”

Semiconducting Carbon Nanotubes: Properties, Characterization and Selected Applications

“…In spite of this urgency, the detection of ammonia atmospheric concentrations in urban areas has been so far widely overlooked, since its average levels are usually low, i.e. in the 20-30 ppb range [70], while novel ammonia CGS are not usually tested at these low levels. Ammonia is one of the molecules most frequently used to test the capability of these devices to operate as CGS.…”