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In this paper some problems concerning work stability of SAW NOz sensors employing copper phthalocyanine (PcCu) as the chemical interface and 128"YX lithium niobate as substrate are presented. The proposed sensing element consists of two delay lines: one of them is covered with a chemical coating (PcCu), the another is covered with AI and then PcCu. In this case a response of the sensor depends only on the conductivity changes of the PcCu layer during NO2 exposure. Other effects are identical and therefore are canceled.

The effect of temperature on the frequency shift of NO, SAW chemosensors has been studied. Copper phthalocyanine was used as the chemical interface. We have investigated the influence of crystalline sttucture of PcCu coating on the temperature frequency stability of SAW delay lines on STX-quartz and 1 2 8 O Y X lithium niobiate.change is much lower for the delay lines covered with It was found that the temperature generated frequency p-PcCu films than for the lines employing the a-PcCu layers of the same mass. This is valid for both used substrates.

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