Browsing by Author "Wu, Chun-Han"

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Calcium alginate microcapsule generation on a microfluidic system fabricated using the optical disk process
(2007-08-01)
Huang, Keng-Shiang
;
Liu, Ming-Kai
;
Wu, Chun-Han
;
Yen, Yu-Tang
;
Lin, Yu-Cheng
This paper describes the generation of monodisperse calcium alginate (Ca-alginate) microcapsules on a microfluidic platform using the commercial optical disk process. Our strategy is based on combining the rapid injection molding process for a cross-junction microchannel with the sheath focusing effect to form uniform water-in-oil (w/o) emulsions. These emulsions, consisting of 1.5% (w/v) sodium alginate (Na-alginate), are then dripped into a solution containing 20% (w/v) calcium chloride (CaCl2) creating Ca-alginate microparticles in an efficient manner. This paper demonstrates that the size of Ca-alginate microparticles can be controlled from 20 mu m to 50 mu m in diameter with a variation of less than 10%, simply by altering the relative sheath/sample flow rate ratio. Experimental data show that for a given fixed dispersed phase flow (sample flow), the emulsion size decreases as the average flow rate of the continuous phase flow (sheath flow) increases. The proposed microfluidic platform is capable of generating relatively uniform emulsions and has the advantages of active control of the emulsion diameter, a simple and low cost process and a high throughput.
Optimization of an optical disk manufacturing process for polymer microfluidic substrates by using the design of experiment methodology
(2010-07-01)
Wu, Chun-Han
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Hsu, Wen-Syang
;
Fan, Kuo-Wei
;
Lin, Yu-Ling
;
Lin, Yu-Cheng
We present an improved method for manufacturing microfluidic structures on a polymer-based substrate, and the design of experiment (DOE) is used to extract the optimum injection parameters. The long cycle time of the injection molding causes high costs in manufacturing, and this prevents conventional techniques from being widely used for mass production. Therefore, this study adopts a new optical disk process to reduce the cycle time. The cycle time of the new method can be reduced by more than ten-fold compared with that of traditional ones. Also, this new method can prevent damage on the mirror plate of the mold. The mold system is composed of a mold insert (stamper) holder and a vacuum system to join the mold insert with the mold. In this way, the time needed to change the stamper is drastically decreased. Our proposed method has the ability to reduce the time required to insert the mold from several hours to a few minutes, to prevent damage on the mirror plate of the mold, and to decrease the cycle time of molding from several minutes to 4 sec. The DOE is applied to study the effects of molding parameters on replication rate of depth, width deviation, birefringence, tilt and surface roughness of the microfluidic substrates. The experimental results show that the proposed method is suitable for mass production. (c) 2010 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3491363]
Using a CD-like microfluidic platform for uniform calcium alginate drug carrier generation
(2007-01-01)
Liu, Ming-Kai
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Huang, Keng-Shiang
;
Chang, Jia-Yaw
;
Wu, Chun-Han
;
Lin, Yu-Cheng
In this paper the manipulation of monodisperse Ca-alginate microparticles using a polymer'-based CD-like microfluidic platform and a reaction of external gelation is presented. Our strategy was based on associating the rapid injection molding process for cross-junction microchannel with the sheath focusing effect to form uniform water-in-oil (w/o) emulsions. These fine emulsions, consisting of 1.5% w/v Na-alginate, were then dripped into an oil solution containing 20% w/v calcium chloride (CaCl2) to accomplish Ca-alginate microspheres in an efficient manner. We have demonstrated that one can control the size of Ca-alginate microparticles from 20 mu m to 50 mu m in diameter (with a variation less than 10%) by altering the relative sheath/sample flow rate ratio. Experimental data showed that for a given fixed dispersed phase flow (sample flow), the emulsion size decreased as the average velocity of the continuous phase (oil flow) increased. The proposed CD-like microfluidic platform is capable of generating relatively uniform micro-droplets and has the advantages of active control of droplet diameter, simple and low cost process, and high throughput.