Accurate control of monodisperse core–shell droplets generated in a microfluidic device has a broad range of applications in research and industry. This paper reports the experimental investigation of flow-focusing microfluidic devices capable of producing size-tuneable and monodisperse core–shell droplets. The dimension of the core–shell droplets was controlled passively by the channel geometry and the flow rate of the liquid phases. The results indicate that microchannel geometry is more significant than flow rates. The highly controllable core–shell droplets could be subsequently employed as a template for generating core–shell microparticles with liquid core. Optical, electron scanning microscopy and X-ray computed microtomography showed that the geometry of the core–shell droplets remains unchanged after solidification, drying and collection. The present study also looks at the thermal stability of core–shell particles depending on the particle size. The larger core–shell particles with a thicker shell provide a higher resistance to heating at elevated temperature. The high degree of control with a flow-focusing microfluidic device makes this a promising approach for the encapsulation, storage, and delivery of lipophilic contents.

精确控制微流体装置中产生的单分散核壳液滴在研究和工业中具有广泛的应用。本文报告了能够产生尺寸可调和单分散核壳液滴的流动聚焦微流体装置的实验研究。核壳液滴的尺寸受通道几何形状和液相流速的被动控制。结果表明微通道几何形状比流速更重要。高度可控的核壳液滴随后可用作模板，用于生成具有液体核的核壳微粒。光学、电子扫描显微镜和 X 射线计算机显微断层扫描显示，核壳液滴的几何形状在凝固、干燥和收集后保持不变。本研究还着眼于取决于粒径的核壳颗粒的热稳定性。具有更厚壳的较大核壳颗粒在高温下提供更高的耐热性。流动聚焦微流体装置的高度控制使其成为封装、储存和递送亲脂性内容物的有前途的方法。