Methods and apparatus to facilitate gravitational cell extraction

A microfluidic device for gravimetrically transferring cells from a first medium to an input medium, the microfluidic device comprising:

• a cell transfer region;
• a cell settling channel extending from and in fluid communication with the cell transfer region, the cell settling channel being smaller in cross section than the cell transfer region;
• a waste channel extending from and in fluid communication with the cell transfer region, the waste channel being smaller in cross section than the cell transfer region;
• a cell output channel extending downwardly from and in fluid communication with the cell transfer region such that cells in the cell transfer region fall into the cell output channel via gravity, the cell output channel being smaller in cross section than the cell transfer region and substantially perpendicular to the cell settling channel and to the waste channel;
• an input medium channel extending from and in fluid communication with the cell output channel.