Comparison Of Air-Wheel Bioreactor Against The Traditional Stirred-Tank Bioreactor in Microcarrier Applications

The novel single-use bioreactor from PBS Biotech® is the first with a pneumatic mixing device powered solely by gas buoyancy, eliminating the need for an external mechanical agitator. It is also the first volumetric (non-fixed bed type) bioreactor whose geometry was designed specifically to optimize mixing. The result is a bioreactor that offers both gentler mixing and lower shear than stirred tanks with traditional geometries. This both reduces the scale up problem over traditional systems and offers better performance for bioprocesses using shear-sensitive cell lines and applications such as microcarriers and transient transfections.

A recent series of experiments comparing the performance of PBS Air-WheelTM bioreactors to that of traditional stirred-tank bioreactors are presented here, with the goal of evaluating how low-shear mixing may improve performance in shear-sensitive applications such as microcarriers. This superior and commercially available bioreactor system holds promise to be the enabling technology for new biological and vaccine products.

The patented design of the Air-Wheel mixing device consists of two critical features: the air cups and the vanes. The air cups, located on the periphery of the Air-Wheel device, capture the gas bubbles from the sparging element, powering its rotation and creating high tangential fluid flow around it. The vanes positioned inside the Air-Wheel device help create bidirectional, axial fluid flow as the wheel rotates. The combination of these flows results in highly efficient, three-dimensional fluid motion.

By applying the buoyant force of the rising gas bubbles on the periphery, we are able to scale the size of the Air-Wheel proportionally with the bioreactor size, to maintain gentle fluid mixing with low wall shear stress across a full range of bioreactor scales.