This paper presents how an array of sensors with different sensitivities to gases can be applied for detection of
hydrogen in the presence of humidity when operated upon various temperature - induced profiles. The sensors
in the array are subject to temperature modulation over the range of 350 – 500°C. Temperature profiles are based
on a cardinal sine as well as Meyer wavelet phi and psi functions. Changes in the sensor operating temperature
lead to distinct resistance patterns of the sensors depending on gas concentration. The sensors responses are
studied as a function of target gas concentration (0 – 3000 ppm) and relative humidity level (0 – 75%Rh). Feedforward back-propagation neural networks are used in order to facilitate gas concentration and humidity level
prediction. The results show reliable hydrogen detection upon temperature modulation and a reduction of the
total power consumption.
This paper presents how an array of sensors with various sensitivities can be used for reliable detection and recognition
of gases. An array of six different thin film metal oxide gas sensors has been constructed and tested. The selected sensors
are based on indium, zinc, tin and titanium thin film oxides deposited by reactive magnetron sputtering. Sensors operate
inside a measuring chamber at elevated temperatures of 250 – 300°C. The sensors responses upon hydrogen and
ammonia exposure (0 – 3000 ppm) at relative humidity (0 – 75%Rh) are studied. The results show that exploiting the
cross sensitivity and different sensing performance of the sensors allows to increase the reliability of gas sensing at
relatively low operating temperatures.
TiO<sub>2</sub>-SnO<sub>2</sub> mixed oxide semiconductors are proposed as candidates for hydrogen gas sensors. The sensor responses in terms of the electrical conductance and the sensitivity to hydrogen partial pressure and temperature are analyzed in order to optimize the sensor performance.
TiO<SUB>2</SUB>-SnO<SUB>2</SUB> polycrystalline ceramics were prepared by precipitation from SnCl<SUB>4</SUB> and impregnation of TiO<SUB>2</SUB> powder. Thin films were produced by rf reactive sputtering from Ti-Sn metallic target in the Ar+15%O<SUB>2</SUB> reactive gas mixture. The influence of the system composition on gas sensing performance was investigated. The electrical resistance was measured as a function of hydrogen and methane activity in air at different temperatures between 600 K and 1200 K.