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 (CaCl 2) creating Ca-alginate microparticles in an efficient manner. This paper demonstrates that the size of Ca-alginate microparticles can be controlled from 20 µm to 50 µm 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.
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 (CaCl 2 ) to accomplish Ca-alginate microspheres in an efficient manner. We have demonstrated that one can control the size of Ca-alginate microparticles from 20 µm to 50 µm 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 microdroplets and has the advantages of active control of droplet diameter, simple and low cost process, and high throughput.
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