CHARACTERIZATION OF OXYGEN-TRANSFER IN A MEMBRANE-AERATED HOLLOW-FIBER BIOREACTOR USING MODIFIED MICROCOAXIAL NEEDLE ELECTRODES

In this work the volumetric O-2 transfer coefficient (OTC) through a m embrane of a miniaturized hollow-fibre bioreactor was measured by the use of modified O-2 microcoaxial needle electrodes. Before measurement , available electrodes were modified by inserting and glueing them in thin glass capillaries to avoid damage. No differences in the behaviou r of the electrodes occurred in comparison to the non-modified electro des. These modified electrodes allowed O-2 partial pressure measuremen t in the 0.8-mm-high extracapillary space (ECS) of the bioreactor with high sensitivity and reliability. O-2, measurements were carried out at the two ports of the ECS at different insertion depths. The results of the measurements showed a homogeneous O-2 supply during variation of the radial co-ordinate of the electrode. In addition to these resul ts, an increase in the local supply in the direction of medium flow wa s observed. The calculated mean OTC (47-63 h(-1)) gave extremely impro ved O-2 transfer due to membrane aeration compared to conventional hol low-fibre systems and other bioreactors used in animal-cell culture te chnology. The improved OTC and the small ECS volume (4.3 ml) makes thi s culture system suitable for the cultivation of primary cells with ti ssue-like densities.