碩士 / 國立中興大學 / 食品暨應用生物科技學系所 / 100 / Microencapsulation is a technology to embed particle into a microsphere which size ranging from 1 μm to several hundred μm. It can be used to protect and maintain the biological activity of the target material and widely adopted to embed plant or animal pigments, vitamins, peptides and enzymes etc.. The core target can be controlled to release precisely at appropriate time and environment or continuously by delicate coating material design.
Soft lithography and the hydromechanics are integrated in this research to design a microfluidic system for preparing the microcapsules. Microstructure template was fabricated by SU-8 photoresist and lithography process. Polydimethylsiloxane (PDMS) was used for replicating the patterned microstructure and subsequently bonded with glass substrate. The packaged microchip was connected to a continuous fluidic supply system to accomplish a novel microencapsulating platform. The major component of this system is a cross shape microchannel with 0.8 mm width and 66 μm depth. 3% (w/v) alginiate solution and 3% (w/w) calcium acetate in sunflower oil was introduced into the main channel from both side channel and the center channel respectively. In the main channel, the outer fluid (alginate) squeeze the inner fluid (sunflower oil) formed serious oil-in-water droplets according to the laminar flow mode and flow focusing principle. While the droplets formed, the calcium acetate particles suspended in sunflower oil diffuse to the outer aqueous phase and ionized to release of calcium ions which induced gelation of alginate and encapsulated oil droplets. The size of droplets generated by this microfluidic system can be adjusted by carefully control of the flow rate.
When the inner oil phase is set as 0.02 ml/min and the outer water phase is set as 1 ml/min, the formed droplet size was ranged from 61.08 μm (maximum) to 13.46 μm (minimum) and presented an average diameter of 41.98 μm. When the rate of the inner oil phase was maintained constant and the outer water phase was reduced to 0.6 ml/min, the formed droplet was ranged from 276.97 μm (maximum) to 61.07 μm (minimum) and presented an average diameter of 193.77 μm. It can be concluded that the droplet size was reciprocal to the flow rate of outer channel when the flow rate of the inner channel is fixed. This result encourages the future challenge of preparing smaller particles in nano scale by the strategy of increasing the outer fluid flow rate or reducing the channel dimension. The oily core microcapsule with 0.14% astaxanthin was prepared by this developed platform.
Developed microencapsulation platform can be further adopted with various combination of core and wall material to produce high quality microcapsule for researches and commercial applications. The novel system shows advantages on the continuous production, stable particle size distribution, adjustable particle size, processing in mild condition, and is capable to real-time monitoring the production process. Further application can be toward on parallel connection of replicated microfluidic system for increasing productivity or be further integrated with other microfluidic components for dynamics and biochemical reaction study as lab on a chip.
| Identifer | oai:union.ndltd.org:TW/100NCHU5253058 |
| Date | January 2012 |
| Creators | De-Xiong Wang, 王德雄 |
| Contributors | 蔡碩文 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 82 |
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