“Housing” for cells in monodisperse microcages

We present a method to form monodisperse microcages encapsulating cells with poly-L-lysine (PLL) membrane. These microcages were prepared with a monolithic three-dimensional microfluidic axisymmetric flow-focusing device (3D AFFD) using internal gelation method. The production process of microcage is mild enough for cells. The microcages were sufficiently monodisperse and robust to be trapped in a beads-based microfluidic array system for easy observation. We also confirmed that (i) the PLL membrane is semi-permeable, (ii) cells are able to move freely inside the microcages, and (iii) cells can be successfully cultured inside these microcages.