A stannic dioxide sensor array system for organophosphorus insecticides detection

This paper reports on a study using the doped SnO/sub 2/ thin films array as sensor to detect Organophosphorus insecticides. In this paper, the sensor array consisted of six different Sn O/sub 2/ sensing elements doped with HO/sub 2/, PbO, CuO, CoO, NiO and Fe/sub 2/O/sub 3/ respectively. All of the sensing elements and electrode thin films of the sensor array were deposited by using the electron beam evaporation technique. The sensing elements were all deposited in the sandwich structure (SnO/sub 2/-dopant-Sn O/sub 2/) on the Si/SiO/sub 2/ substrate. The thickness of the respective layers were fixed to 1500 - 100 - 1500 . Then, these sensing element thin films were subjected to annealing process at 500 C in the oxygen environment for 5 hours to induce the homogenization of the thin films and also the crystallization process. After that, the Al electrodes were deposited. Electric current response was measured for all of these sensing elements when the sensor array was exposed to the vapour of three different commercial Organophosphorus insecticides at the operating temperature of 250 C. It was found that the sensor array showed reasonable repeatability and selectivity towards the Organophosphorus insecticides.