Bioreactor Mixing Modes

There are 4 different mechanical processes for mixing in 3D vessels: 1) agitation by shaking, 2) rocking motion, 3) stirring with an impeller, and 4) convection with gas.

Agitation by shaking is best suited for growing cells in flasks and using shaker plates.

For rocking motion, this is “gentle mixing” for shear-sensitive cells (i.e. mammalian cells and immune-system cells), and the rocking motion generates waves for the gentle mixing.

Stirring with an impeller is more suited for microbial and yeast cells, which are not shear-sensitive cells. Although mixing with a vertical wheel is considered “gentle mixing” for growing shear-sensitive cells.

For convection mixing, the convective bioreactor designs rely on mixing by circulation of the bulk liquid, where the circulation is created by pumping a gas into the bioreactor (oxygen, or air, or nitrogen) and the gas forces a convective motion of the liquid, while feeding the cells oxygen or nitrogen.

The 4 different mechanical processes for mixing in 3D culturing vessels.