An improvement of microfluidic‐assisted internal gelation in the preparation of millimeter‐sized ceramic microspheres

The microspheres prepared by the microfluidic‐assisted internal gelation process are still challenging to reach the millimeter size due to the large gravity. The gravity would affect the sphericity and size uniformity of microspheres. The improved microfluidic‐assisted internal gelation process is designed and optimized to produce large‐sized monodisperse ceramic microspheres with good sphericity. The movement mechanism of millimeter‐sized sol droplets and gel microspheres in the microchannel is summarized and the state of the dispersed phase entering the measuring cylinder is controlled. The friction between the gel microspheres and the tubing wall is reduced as much as possible, and ZrO2 ceramic microspheres of 500 ± 5 μm with good sphericity are prepared with the broth at room temperature. The mechanism of sol droplets entering the oil surface is explored to demonstrate the superiority of the improved microfluidic‐assisted internal gelation process. The improved microfluidic‐assisted internal gelation process could be directly extended to preparing other millimeter‐sized monodisperse ceramic microspheres.