| Summary: | 碩士 === 國立暨南國際大學 === 應用材料及光電工程學系 === 103 === In this thesis, solution phase deposition (SPD) and microwave-assisted solution phase deposition (MW-SPD) methods were used for growing the large-area sensing membrane of a 3-aminopropyltriethoxysilane (γ-APTES) and dimethyldichlorosilane (DDS)-treated silica nanoparticles mixture (γ-APTES+NPs) on polysilicon wires in the batch fabrication of dopamine biosensors. We compared the characteristics of the γ-APTES+NPs membrane prepared by SPD and MW-SPD at fixed power using a solution contained mixture of γ-APTES+NPs and C2H5OH. We investigated the hotplate and microwave annealing (MWA) effects on the sensitivity of dopamine detection. The effects of ultraviolet (UV) light exposure at different stages during deposition on the film properties were also studied.. In order to prove the DDS-treated silica nanoparticles were incorporated with γ-APTES during SPD and MW-SPD, we conducted the analyses including ellipsometer, dynamic light scattering (DLS) and micro-Raman spectroscopy.
It was found that MW-SPD could reduce the deposition time of γ-APTES+NPs significantly. The best deposition time for SPD at room temperature was 6 hours, but for the MW-SPD was only 15 minutes. The detectable range of the dopamine biosensor using γ-APTES+NPs as sensing membrane could be improved from 1×10-21 M ~ 1×10-3 M to 1×10-25 M ~ 1×10-3 M by MW-SPD process. The lowest detection limit was improved by 4 orders of magnitude. The UV illumination could further improve the biosensor with a detectable range of 1×10-27 M ~ 1×10-3 M. The lowest detection limit for dopamine was improved by 6 orders of magnitude for γ-APTES+NPs with MW-SPD+UV process.
As for the microwave annealing processes, we found that the sensitivity of the lowest detection limit for the γ-APTES+NPs prepared by SPD could be significantly improved by the post-deposition of microwave annealing. For γ-APTES+NPs growing by a 6 hour SPD, a 15 minute microwave anneal could improve the detectable range from 1×10-21 M ~10-3 M to 1×10-27 M ~ 1×10-3 M. The lowest detection limit for dopamine was improved by 6 orders of magnitude. The UV illumination after microwave annealing could further improve the biosensor with a detectable range of 1×10-30 M ~ 1×10-3 M. The lowest detection limit for dopamine was improved by 9 orders of magnitude. From the Raman spectra of the membranes, enhanced absorption peaks of Si-O-Si bond were observed in all the films incorporated with silica NPs, especially for γ-APTES+NPs using MW-SPD process. The number of Si-O-Si bonds increased as the NPs incorporated with the γ-APTES. The absorption peaks of Si-O-Si bond were also enhanced for all the films with ultraviolet (UV) light exposure. The γ-APTES+NPs using SPD+MWA+UV process showed the highest absorption peak of Si-O-Si bond. The sensitivity of lowest detection limit increased with the value of absorption peak of Si-O-Si bond. Because the thicknesses of γ-APTES+NPs membranes were in between 1nm and 3nm, it was reasonable to believe that the diameters of the incorporated silica nanoparticles were in the range of 1nm-3nm, resulting in ultra-high surface to volume ratio for the film and ultra-sensitive lowest detection limit for dopamine.
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