The Fabrication and Applications of Nanocrystalline Particles coated Piezoelectric Crystal Sensors

• Main Authors: Yau-Ching Tsai, 蔡耀慶
• Other Authors: I-Ching Kuan
• Format: Others
• Language: en_US
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/50700269579899238424

碩士 === 大同大學 === 生物工程研究所 === 89 === Abstract The development of sensors is ascending due to the environment pollution and industrial needs. Piezoelectric quartz crystal is known to be a highly sensitive mass-measuring device in gas phase and in aqueous solution and has been extensively used for studies in applied to environmental pollution, biochemical, food, chemical analysis and chemical reaction. Nanocrystalline (NC) materials with particle size smaller than 100 nm have a lot of special properties not found in conventional bulk materials. Because of their small particle size and large specific surface areas, NC materials are potent in sensing applications. The goal of this study is to examine the potential application of adsorbed with the NC materials piezoelectric quartz crystal detector on liquid sensing at the flow system. A flow cell system was designed for the experiment with a constant steady flow speed. Different kinds of acid solution with different concentrations were used to test the response of nanoparticles coated PQC sensors. The nanoparticles of Au, Pt and TiO2 were chosen for this study. These nanoparticles were directly coated on the Au electrode of PQC by gas condensation technique. Nanoparticles coated PQC was then calcinations at 200oC for 1.5 hours in air to bond these nanoparticles on the surface of gold electrode. The vibration frequency of PQC decreased when acid molecules adsorbed onto its crystal surface as a result of increased mass. The frequency changes on various nanoparticles coated PQC exhibited various response curves depending on the acid concentrations and the kinds of acid solution. In this study, TEM was used to analyze the particles size distribution and structure of nanophase Au, Pt and TiO2 particles. SEM was used to examine the surface morphology of nanoparticles coated quartz crystal sensors. The results indicate adsorbed with the nanocrystalline materials a piezoelectric quartz crystal detector can be used to detect different concentrations of formic acid, acetic acid, citric acid, malic acid and gluconic acid. Reversible was observed physical adsorption and a maximum adsorption was obtained. As comparing with different nanoparticles coated PQC in detecting different acids, the stability of NC TiO2 is greater than that of Au and Pt. However, NC Pt has greater adsorption than that of TiO2 and Au at the same acid concentrations.