This thesis presents a spheroid chip for multicellular spheroid formation and extraction using removable cell trapping barriers. The previous chips using fixed trapping barriers have faced difficulties in extracting the spheroids. The present spheroid chip achieves a simple spheroid extraction using removable cell trapping barriers formed by membrane inflation.
The membrane between a top layer and a bottom layer of the spheroid chip is inflated by the membrane pressure to form cell trapping barriers in the bottom layer. The cell trapping barriers hold cells to be filled in the trapping region to form spheroids. At the reduced membrane pressure, the deflated membrane removes the cell trapping barriers, allowing spheroids to exit to the spheroid outlet. A 4 × 1 array of the spheroid chips has been designed, fabricated and characterized.
The cell trapping barriers, formed at the membrane pressure of 50kPa, hold the cells in the trapping region at an initial cell inlet pressure of 200Pa. After 24 hour incubation, the cell-cell interaction makes the trapped cells form the spheroids. The spheroids have been extracted through the spheroid outlet at the cell inlet pressure of 5kPa for the membrane pressure of 0kPa. The spheroids have the diameter of 197.2±11.7 $\mu m$, showing the viable cell percentage of 75.5% after extraction.
It is demonstrated that the spheroid chips perform uniform formation and secure extraction of the spheroid for the next stage of spheroid processing.