Quantification and prediction of jet macro-mixing times in static microwell plates

Nealon, Anthony J.; O’Kennedy, Ronan; Titchener‐Hooker, Nigel J.; Lye, Gary J.

doi:10.1016/j.ces.2006.02.001

Cited by 17 publications

(12 citation statements)

References 37 publications

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“…Flow structures such as toroidal vortices have been experimentally studied and visualized by Gardner and Tatterson (1992), who addressed the hydrodynamic aspects effects of stirring due to a submerged mechanical device. Others, like Suh and Kim (1996), Nealon et al (2006), Peter et al (2006), and Micheletti et al (2006), performed theoretical, numerical, and experimental analyses using a shaker table. In the theoretical and numerical analysis, the studies used potential flow and boundary layer theory and examined the fluid flow with free surface applications.…”

Section: Introductionmentioning

confidence: 99%

Stirring Free Surface Flows Due to Horizontal Circulatory Oscillation of a Partially Filled Container

Kim

Kizito

2009

Chemical Engineering Communications

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Mixing in a partially filled beaker or conical flask using oscillator shaker tables is routinely used for cultivation of biological cells. The present study seeks to gain a better understanding of fluid flow inside a beaker on a shaker table and the fluid motion influence on the mixing of cells within the fluid medium used for their cultivation. The imposed oscillatory motion on the beaker induces free surface deformations, which may cause laminar and low shear flow environments thus uniformly mixing the fluid medium. The low shear and uniformly mixed cell culture medium are requirements necessary for optimum cellular growth. In this study, fluid flow due to periodic and horizontal circulatory oscillations at a beaker boundary has been analyzed both numerically and experimentally. A partially filled beaker was modeled as a circular cylinder, and the cell culture medium was modeled as an incompressible fluid with a free and deformable liquid interface. The three-dimensional numerical model that can resolve the free surface deformation was based on finite difference scheme based on the ''Marker-and-Cell'' method. The method was used to determine the free surface deformation, its coupling to the flow dynamics within the beaker, and the resulting stirring effects. To verify the numerical model and validate the results, a simple flow visualization experiment was performed using an ion laser sheet to optically section flow chamber and reveal the flow pattern. The flow patterns obtained using numerical simulations were similar to those obtained experimentally through flow visualization. This study provides useful information that can be used to optimize the operation of a shaker table necessary to mix uniformly the cell culture, ensuring cell growth. In addition, this model can be extended to study the mixing processes in any chemical reactions within a partially filled container subjected to oscillatory forces.

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Section: Introductionmentioning

confidence: 99%

Stirring Free Surface Flows Due to Horizontal Circulatory Oscillation of a Partially Filled Container

Kim

Kizito

2009

Chemical Engineering Communications

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“…Recently, Nealon et al 127 (36) where d n is the nozzle diameter, D is the well or vessel diameter, h is the liquid height and u 0 is the nozzle velocity.…”

Section: Constant Mixing Timementioning

confidence: 99%

Bioprocess scale‐up: quest for the parameters to be used as criterion to move from microreactors to lab‐scale

Marques

Cabral

Fernandes

2010

J of Chemical Tech & Biotech

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Advances in high-throughput process development and optimization involve the rational use of miniaturized stirred bioreactors, instrumented shaken flasks and microtiter plates. As expected, each one provides different levels of control and monitoring, requiring a compromise between data quantity and quality. Despite recent advances, traditional shaken flasks with nominal volumes below 250 mL and microtiter plates are still widely used to assemble wide arrays of biotransformation/bioconversion data, because of their simplicity and low cost. These tools are key assets for faster process development and optimization, provided data are representative. Nonetheless, the design, development and implementation of bioprocesses can present variations depending on intrinsic characteristics of the overall process. For each particular process, an adequate and comprehensive approach has to be established, which includes pinpointing key issues required to ensure proper scaleup. Recently, focus has been given to engineering characterization of systems in terms of mass transfer and hydrodynamics (through gaining insight into parameters such as k L a and P/V at shaken and microreactor scale), due to the widespread use of small-scale reactors in the early developmental stages of bioconversion/biotransfomation processes. Within this review, engineering parameters used as criteria for scaling-up fermentation/bioconversion processes are discussed. Particular focus is on the feasibility of the application of such parameters to small-scale devices and concomitant use for scale-up.

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“…To initially visualize the mixing of a small liquid addition into the liquid contents of a well, 1% (v/v) inert blue food dye (Supercook, Leeds, UK) was injected into water. This dye has previously been shown not to significantly alter the physical properties of the fluid (Nealon et al, 2006). Each flow visualization experiment was performed in triplicate.…”

Section: Liquid Phase Mixing Time Characterizationmentioning

confidence: 99%

“…Studies have also focused on understanding the engineering environment in microwells for quantification of gas-liquid mass transfer (Doig et al, 2005;Duetz and Witholt, 2004;Hermann et al, 2003) and mixing (Nealon et al, 2006;Weiss et al, 2002). In contrast, studies looking to use shaken microwells for the development of suspension adapted mammalian cell cultures are very few.…”

Section: Introductionmentioning

confidence: 97%

Microwell engineering characterization for mammalian cell culture process development

Barrett

Zhang

et al. 2009

Biotech & Bioengineering

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Experimentation in shaken microplate formats offers a potential platform technology for the rapid evaluation and optimization of cell culture conditions. Provided that cell growth and antibody production kinetics are comparable to those found in currently used shake flask systems then the microwell approach offers the possibility to obtain early process design data more cost effectively and with reduced material requirements. This work describes a detailed engineering characterization of liquid mixing and gas-liquid mass transfer in microwell systems and their impact on suspension cell cultures. For growth of murine hybridoma cells producing IgG1, 24-well plates have been characterized in terms of energy dissipation (P/V) (via Computational Fluid Dynamics, CFD), fluid flow, mixing and oxygen transfer rate as a function of shaking frequency and liquid fill volume. Predicted k(L)a values varied between 1.3 and 29 h(-1); liquid-phase mixing time, quantified using iodine decolorization experiments, varied from 1.7 s to 3.5 h; while the predicted P/V ranged from 5 to 35 W m(-3). CFD simulations of the shear rate predicted hydrodynamic forces will not be detrimental to cells. For hybridoma cultures however, high shaking speeds (>250 rpm) were shown to have a negative impact on cell growth, while a combination of low shaking speed and high well fill volume (120 rpm, 2,000 microL) resulted in oxygen limited conditions. Based on these findings a first engineering comparison of cell culture kinetics in microwell and shake flask formats was made at matched average energy dissipation rates. Cell growth kinetics and antibody titer were found to be similar in 24-well microtiter plates and 250 mL shake flasks. Overall this work has demonstrated that cell culture performed in shaken microwell plates can provide data that is both reproducible and comparable to currently used shake flask systems while offering at least a 30-fold decrease in scale of operation and material requirements. Linked with automation this provides a route towards the high throughput evaluation of robust cell lines under realistic suspension culture conditions.

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Quantification and prediction of jet macro-mixing times in static microwell plates

Cited by 17 publications

References 37 publications

Stirring Free Surface Flows Due to Horizontal Circulatory Oscillation of a Partially Filled Container

Stirring Free Surface Flows Due to Horizontal Circulatory Oscillation of a Partially Filled Container

Bioprocess scale‐up: quest for the parameters to be used as criterion to move from microreactors to lab‐scale

Microwell engineering characterization for mammalian cell culture process development

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