Nanoassembled thin film gas sensors. III. sensitive detection of amine odors using TiO2/ poly(acrylic acid) ultrathin film quartz crystal microbalance sensors

Seung Woo Lee, Naokl Takahara, Sergly Korposh, Do Hyeon Yang, Klyoshl Toko, Toyokl Kunltake

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59 Citations (Scopus)


Quartz crystal microbalance (QCM) gas sensors based on the alternate adsorption of TiO2 and polyacrilic acid (PAA) were developed for the sensitive detection of amine odors. Individual TiO2 gel layers could be regularly assembled with a thickness of ∼0.3 nm by the gas-phase surface sol-gel process (GSSG). The thickness of the poly(acrylic acid) (PAA) layer is dependent on its molecular weight, showing different thicknesses of ∼0.4 nm for PAA25 (Mw 250 000) and 0.6-0.8 nm for PAA400 (Mw 4 000 000). The QCM sensors showed a linear response to ammonia in the concentration range 0.3-15 ppm, depending on the deposition cycle of the alternate TiO 2/PAA layer. The ammonia binding is based on the acid-base interaction to the free carboxylic acid groups of PAA and the limit of detection (LOD) of the 20-cycle TiO2/PAA400 film was estimated to be 0.1 ppm when exposed to ammonia. The sensor response was very fast and stable in a wide relative humidity (rH) range of 30-70%, showing almost the same frequency changes at a given concentration of ammonia. Sensitivity to n-butylamine and ammonia was higher than to pyridine, which is owing to the difference of molecular weight and basicity of the amine analytes. The alternate TiO2/PAA400 films have a highly effective ability to capture amine odors, and the ambient ammonia concentration of 15 ppm could be condensed up to ∼20 000 ppm inside the films.

Original languageEnglish
Pages (from-to)2228-2236
Number of pages9
JournalAnalytical chemistry
Issue number6
Publication statusPublished - Mar 15 2010
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry


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