Piezoelectric detectors coated with liquid-crystal materials.
The usefulness of liquid crystals as coating materials for quartz resonators in piezoelectric detectors of air-pollution has been tested. The concentration characteristics of the detector with respect to benzene, toluene, chlorobenzene, o- and m-dichlorobenzene, nitrobenzene, and o-, m- and p- diethylbenzene have been determined with the use of 4-pentyl-4'-cyanodiphenyl, 4-pentyl-4'-propylazo-benzene, 4-propyl-4'-methylazoxybenzene, and cholesteryl oleylcarbonate as coating materials. The effects of the quantity of coating material and of temperature on the sensitivity of the piezoelectric detector have been tested. The influence of the ordered structure of the liquid-crystal coating materials on the selectivity of the detector is discussed. Experiments have been performed to test the usefulness of the detector with liquid-crystal coating for detecting organophosphorus pesticides (DDVP and Phosdrin).
Mierzwinski
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A
Institute of Chemistry, Military Technical Academy, 01 489 Warsaw 49, Poland.
Witkiewicz
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Z