Critical agitation for microcarrier suspension in orbital shaken bioreactors: Experimental study and dimensional analysis

Abstract

Experimental characterization of particle suspension in orbital shakers. New correlation predicting critical agitation conditions for complete particle suspension. Larger orbital diameters promote smaller power dissipations at complete particle suspension. a b s t r a c tOrbital shaken bioreactors are widely used at the laboratory scale for the culture of animal cells in suspension mode. In the case of adherent-dependent cell lines, the choice of agitation conditions at which all particles are just-suspended (or attain complete suspension) has often to be determined. Indeed, with orbital shaken bioreactors, this choice results from the combination of two parameters: the orbital diameter and the agitation rate. That is why, a new experimental protocol for the determination of critical agitation conditions for microcarrier complete suspension has been developed in this paper. It consisted in a side-view visualization of blue-stained particles in shaken Erlenmeyer flasks and cylindrical flasks. 220 experiments representative of animal cell culture conditions have been carried out to study the effect of various operating conditions (bioreactor size and geometry, particle type, density and diameter, liquid viscosity, shaking diameter, filling ratio). Furthermore, a dimensional analysis has been performed, leading to a correlation relating a Froude number (in which the critical agitation N c for complete particle suspension is embedded) to four other dimensionless numbers. Then, the critical agitation conditions determined in this paper were analyzed and discussed with respect to the data available in the literature on the flow structure occurring inside the flask. Our findings revealed that high orbital shaking diameters and large cylindrical vessels should be promoted to get microcarriers into suspension at a minimized power dissipation per unit of volume.

Mixing Time in Intermediate‐Sized Orbitally Shaken Reactors with Small Orbital Diameters

“… for larger reactors ( d i = 10–125 cm) indicated that the Froude number ratio, Fr / Fr cr , is an effective scaling parameter for mixing time measurements in shaken cylinders under a wide range of operating conditions. The flow transition identified by the Froude number ratio was also found to accurately predict the full suspension speed of microcarriers across different bioreactor geometries (cylindrical vessels and flasks) and scales , . The two‐phase PIV study of Pieralisi et al.…”

Impact of hydrodynamics on iPSC-derived cardiomyocyte differentiation processes

“…They were selected based on the EB sedimentation characteristics and sizes (iBET group, unpublished data). Microcarriers were stained using 0.4 % Trypan Blue (Sigma-Aldrich, USA) to aid in visualization (Olmos et al, 2015), and experiments were conducted at a concentration of 1 g/L. Concentrations closer to those employed in cell culture experiments (0.0375 g/L at the start of differentiation and 0.2 g/L at the end) could not be detected by the camera.…”

“…Suspension should therefore be characterized to quantify the minimum speed required for off-bottom suspension and homogeneity, but also to characterize the degree of settling during intermittent agitation modes. Off-bottom suspension has been studied in-depth (Ibrahim and Nienow, 2004;Nienow et al, 2016), however objective techniques and reproducible protocols should be used to quantify suspension (Olmos et al, 2015;Pieralisi et al, 2016).…”

Microcarriers’ suspension and flow dynamics in orbitally shaken bioreactors

“…while the suspended to critical Froude number ratio tends to drift further away from the dashed reference line at F r s /F r cr = 1.1 as h/d i/ √ do/d i increases above 1. It is interesting to note that the suspension speed data obtained by Olmos et al (2015) in Erlenmeyer flasks showed a good scaling with the critical speed, N cr , also for…”