Where does the oxygen go? : kLa measurement in bioreactors

Small plastic tubes are available as single-use bioreactors for cell cultivation as a cost effective alternative to larger scale cultivation systems. However, the characteristics of the tubes with regard to oxygen transfer have hardly been investigated. Using a specially adapted shake flask reader (SFR) and chemical optical sensors with rapid response time, the volumetric oxygen mass transfer coefficient (kLa) for tube systems was determined. The characteristics of these cultivation vessels were investigated more closely, which represents an important step towards defined screening processes by monitoring oxygen in bioreactors