| Summary: | 碩士 === 國立暨南國際大學 === 電機工程學系 === 103 === Based on the finding of our research group that using a mixture of silicate nanoparticles and 3-Aminopropyltriethoxysilane (γ-APTES) as the sensing membrane can enhance the sensitivity of poly-silicon wire sensor, the purpose of this work is to investigate the feasibility of using mixtures of metal oxide nanoparticles and γ-APTES (3-Aminopropyltriethoxysilane) as the sensing membrane for poly-silicon wire and apply it for pH sensing. Solution phase deposition (SPD) method was adopted to deposit the individual mixture onto the PSW surface. Various ratios of dispersant/γ-APTES and nanoparticles/γ-APTES as well as different dispersants were tested when prepared the mixtures. The purpose of adding dispersant in the suspension of nanoparticles is to separate and avoid the conglomeration of nanoparticles. Dispersant for the best performance of PSW pH sensor as well as the optimum dispersant/γ-APTES ratio and nanoparticles/γ-APTES ratio for highest sensitivity of the PSW pH sensor were determined.
Two different metal oxide nanoparticles, Al2O3 and TiO2, were used in this work. Dispersant 2566, 2760 for Al2O3 nanoparticles, and 1186, 1142, 2145 for TiO2 nanoparticles were tested in this work, all of which were purchased directly from the Marvel Chemical, Taiwan. From the experimental results, best pH sensing performance performance of the poly-silicon wire sensor can be obtained when the dispersant 2566 is used for Al2O3 and γ-APTES mixture, and 1186 for TiO2 and γ-APTES mixture. For Al2O3, it is found that a SPD deposition time of 5 min gives the highest PSW channel current, and a dispersant/γ-APTES ratio of 0.3% and nanoparticles/γ-APTES ratio of 2% is the best for PSW pH sensor performance. For TiO2, the best performance of the PSW pH sensor is found at a SPD deposition time of 10 min and with a dispersant/γ-APTES ratio of 0.3% and nanoparticles/γ-APTES ratio of 0.5%. Among other nanoparticles, it is found that the using the mixture of Al2O3 nanoparticles and γ-APTES as the sensing membrane has the best sensitivity. Our result also confirms that dispersant is absolutely necessary for preparing the nanoparticles suspension.
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