Fig. 3.

Laboratory unit operations: (A) gravity driven fluid control that depends on the height of the fluid column. The height of the fluid column can be regulated by controlling the amount of fluid inserted into the tip. (B and C) Cell capture is accomplished by allowing cells in the flow to sediment to the bottom of the central trench structure. Flow velocities at the bottom of the trench structure are 3 orders of magnitude lower than in the rest of the device allowing the cells to be effectively retained. Due to the high capture efficiency the number of loaded cells in the trenches can be controlled with the cell loading time.