| abstract |
The impeller is usable in variable diameter bioreactors with multiple vessel sections in which the volume continuously increases or decreases. The impeller includes an impeller blade extending along an impeller blade axis between first and second axial ends and having opposing impeller blade faces, an impeller blade leading edge, and an impeller blade trailing edge. Each of the leading and trailing edges forms a helix or spiral between the axial ends of the impeller blades. In a particular arrangement, the impeller blade is one of at least two impeller blades joined together along an impeller shaft extending axially along the impeller blade described above, the helix or spiral having a length between the first and second axial ends has a pitch approximately equal to half of |