No abstract

Thick films of humic substances (HS) from peat are evaluated for their electrical and humidity properties for use in humidity sensing. The thickness (10-50 mm) of the films is controlled by the amount of deposited solution on the polyester substrate. The samples exhibit typically two regions in their sensitivity curve when tested in the relative humidity (RH) range of 50-95%. The sensitivity (kW/%RH) ranges from 2.81W/%RH to 19.18 W/%RH for higher to lower thickness.

In this work we propose the use of peat as an alternative material to be used for the development of ammonia sensors. A thorough characterization of the material is carried out in order to ensure its feasibility as a source of an efficient sensor. Humin, which is a subproduct of peat, consists basically of carbon and is extracted through the centrifugation of KOH or NaOH solutions. Initially, the material was characterized by determining its physical and chemical properties such as carboxylic groups, exchangeable hydrogen, organic matter, PH and moisture content. The surface area, pore volume and mean pore radio was also evaluated. A topologic study was also performed by means of AFM experiment in order to access the desired morphology uniformity of the film to be used as a sensor. Finally the sensitivity of the samples to ammonia vapor was measured using the standard two-temperature method. Our results show that peat is an interesting substance to be used in the development of inexpensive ammonia sensors and suggests that it is also a promising material to the development of other gas sensors.