Quartz resonator with thin TiO2 for NH3 detection

The sorption properties of TiO2 thin films are investigated, in order to detect ammonium vapor existence. For the purpose mass-sensitive quartz resonators covered by TiO2 film are used. TiO2 thin films are prepared using a new method called liquid phase deposition (LPD). By this method metal oxide layers are deposited on surfaces dipped in solutions. The layers are obtained as a result of a balance reaction, which happens between the metal fluorocomplex and metal oxide in aqueous solution. By this process substances with complex morphology are easily coated using no special equipment. The main advantage of this method is its low synthesis temperature-up to 200 degreesC. The sorption sensitiveness of the created structure is registered by the Quartz Crystal Microbalance (QCM) method. An interval of ammonium concentration (from 100 to 10,000 ppm) is investigated. A dependence is obtained between relative change of resonator frequency (Deltaf/f) and ammonium solution concentration. The obtained initial results show that this sort of systems could be used for creating sensor elements aiming the detection of ammonium contamination in the air. (C) 2004 Elsevier Ltd. All rights reserved.