Open Access

ARTICLE

Fluid Dynamics of a Micro-Bioreactor for Tissue Engineering

P. Yu¹, T. S. Lee¹, Y. Zeng¹, H. T. Low²

1 Department of Mechanical Engineering, National University of Singapore, Singapore
2 Division of Bioengineering, National University of Singapore, Singapore

Fluid Dynamics & Materials Processing 2005, 1(3), 235-246. https://doi.org/10.3970/fdmp.2005.001.235

Abstract

A numerical model is developed for the investigation of flow field and mass transport in a micro-bioreactor, of working volume below 5 ml, in which medium mixing is generated by a magnetic stirrer-rod rotating on the bottom. The flow-field results show that a recirculation region exists above the stirrer rod and rotates with it; the related fluid mixing is characterized by a circulation coefficient of up to 0.2 which is about five times smaller than that of a one-litre stirred-tank bioreactor. The oxygen transfer coefficient is less than 5 h^-1 which is two orders smaller than that of a 10-litre fermentor with aeration, hence the oxygen transfer rate is insufficient for bacteria culture and bubble aeration is needed as was used in the prototype by Kostov et al. (2001). However, it is shown that for certain animal cell cultures, the oxygen concentration level in the micro-bioreactor can become adequate without using bubble aeration, provided that the magnetic rod is rotated at a high speed (rod Reynolds number of 716). At such high rotation-speed, the micro-bioreactor exhibits a peak shear-stress below 0.5 N m^-2 that is acceptable for animal cell culture. The maximum local-energy dissipation rate is below 18 kW m^-3 which is five times smaller than that in a ten-litre Rushton-impeller bioreactor.

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Keywords

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