Abstract:
In this work, several factors to increase the sensitivity of a high precision resistive type sensor able to detect from (10 to 15) ppm de H
2
S (g) in air, are considered. It is accepted that the doping of the material sensor (SnO
2
) increases the dispositive sensibility. Several dopants were proved, concluding that the CuO was the most convenient. Several papers are found in the bibliography presenting different techniques to dope the material sensor but, in this work, an own developed at DEINSO technique was employed, in which the dopant is homogeneously distributed in the SnO
2
crystalline lattice. At first, it was proposed to dope the nanocrystalline SnO
2
with different CuO concentrations (1%wt. 5%wt. and 6%wt.) to choose the most convenient one, which resulted 5% wt. CuO. Under these conditions, a more sensible sensor was built and other factors were studied to increase even more the sensitivity. The 5%wtCuO-SnO
2
was deposited on thin films (or layers) forming a multilayers system (which employed from three to six layers or superimposed thin films). The sensor material was characterized with different techniques, such as: DRX, SEM-EDS and GISAXS, which enabled to determine the mean crystallite size, the multilayer system thickness, the crystallinity, the chemical composition and the layers porosity. With the built sensor, (10 to 15) ppm of H
2
S (g) in air concentration was measured at an operation temperature (To) of 140 0C.This finding enabled to solve the request of an ambiance security sensor for the oil cracking plant of an important Argentine oil company. The following subject is not included in this paper but, it is interesting to inform that higher sensitivity of the same described sensor it was possible to detect concentrations from (4 - 5) ppm of H
2
S (g) in air at To=~ 30 0C, which makes possible to build a medical use sensor to detect H
2
S (g) very low concentrations (minor than 5ppm) which are found in halitosis of hepatic maladies.
Keywords:
High sensitivity sensor to detect sulphide gas, Nanocrystalline SnO
2
, CuO doped SnO
2
, Thin films multilayered system, Sensing mechanisms.
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