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Geoinspired bioreactors : from Earth’s precession to stem cell production
Inspired by the precession of the Earth, a new bladeless mixer has been designed, which consists of a tilted and rotating cylinder. I will first present fundamental studies on the transition to turbulence in such rotating flows. At specific aspect ratios, the resonance of eigen modes creates a strong overturning flow even for small tilt angles. At large enough Reynolds numbers, this base flow exhibits a parametric instability involving a triadic resonance.
I will then describe how this simple set-up is used to build large-scale mixers. The mixing has been found to be as efficient as using a classical Rushton turbine, but with a shear 20 times smaller. This soft mixer is thus particularly interesting for bioreactors which require an efficient mixing of oxygen and carbon dioxide but where a strong shear can damage fragile cells. Preliminary results obtained for the growth of microalgae and stem cells in such photobioreactors suggest that it can be a technological breakthrough in biotechnologies.
