Using Active Microfluidic Components for Synthesizing Nanoparticles

• Main Authors: Chen-Hsun Weng, 翁振勛
• Other Authors: Gwo-Bin Lee
• Format: Others
• Language: en_US
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/52949344288775741168

博士 === 國立成功大學 === 工程科學系碩博士班 === 97 === This study reports a microfluidic system for synthesis magnetic iron oxide nanoparticles (Fe3O4), hexagonal gold (Au), magnetic hollow and solid Fe/Ga-based oxide nanoparticles. First, a new microfluidic system capable of mixing, transporting and reacting was developed for the synthesis of iron oxide nanoparticles. It allowed for a rapid and efficient approach to accelerate and automate the synthesis of the iron oxide nanoparticles as compared with traditional methods. The microfluidic system uses micro-electro-mechanical-system technologies to integrate a new double-loop micro-mixer, two micro-pumps, and a micro-valve on a single chip. When compared with large-scale synthesis systems with commonly-observed particle aggregation issues, successful synthesis of dispersed and uniform iron oxide nanoparticles has been observed within a shorter period of time (15 minutes). It was found that the size distribution of these iron oxide nanoparticles is superior to that of the large-scale systems without requiring any extra additives or heating. The size distribution had a variation of 16%. This is much lower than a comparable large-scale system (34%). The development of this microfluidic system is promising for the synthesis of nanoparticles for many future biomedical applications. Second, a new microfluidic reaction system capable of mixing, transporting and reacting is developed for synthesis of gold nanoparticles. It allows for a rapid and a cost-effective approach to accelerate the synthesis of gold nanoparticles. The microfluidic reaction chip is integrated a micro-mixer, micro-pumps, a micro-valve, micro-heaters, and a micro temperature sensor on a single chip. Successful synthesis of dispersed gold nanoparticles has been demonstrated within a shorter period of time, as compared to traditional methods. It is experimentally found that the precise control of the mixing/heating time for gold salts and reducing agents plays an essential role in the synthesis of gold nanoparticles. The growth process of hexagonal gold nanoparticles by a thermal aqueous approach is also systematically studied by using the same microfluidic reaction system. The development of the microfluidic reaction system could be promising for synthesis of functional nanoparticles for future biomedical applications. Third, it is a new approach to synthesize hollow nanospheres in a microfluidic system by using air bubbles as templates. A new microfluidic system which integrates a micro-mixer, a micro-condenser channel, micro-valves, a micro-heater, and a micro temperature sensor, to form an automatic micro-reactor, is used to generate air bubbles that assist in the synthesis of hollow Fe/Ga-based oxide nanospheres. Experimental data show that Fe/Ga-based oxide nanoparticles with a diameter of 157 ± 26nm can be successfully synthesized. The formation mechanism is that the seed nanoparticles are attaching themselves onto the bubbles to form a solid shell. The magnetic properties of the hollow Fe/Ga-based oxide nanospheres are also measured. This may be a promising platform to synthesize hollow nanoparticles for drug delivery applications. Fourth, using the passive micro-condenser to synthesize the solid-core nanospheres can be observed in the microfluidic system without the bubbles. This method offers a way to synthesis two metal elements in the nanoparticles, which can be very useful in the deterministic synthesis of nanostructured precursors for making chemical composition and phase specific nanocomposites. The growth process of alloy nanoparticle by a thermal aqueous approach was studied by taking samples out of the micro-reactor at different volumes to investigate the intermediate product structures. A different growth mechanism from other known mechanisms in the literature is proposed. From this research, we found that the alloy nanoparticle has magnetic. So the magnetic nanoparticle could be applied to bio-application. Key components including micro-reactor, a PDMS (Polydimethylsiloxane)-based microchannel, a peristaltic micro-pump, micro-valves, micro-condenser and micro-heater were integrated to form a new microfluidic system for synthesis nanoparticles utilizing MEMS (micro-electro-mechanical-systems) technologies. In this study, the device provided a convenient way to synthesize the different types of nanoparticles.