Mixing at the microscale: Power input in shaken microtiter plates

Abstract

Power input and local energy dissipation are crucial parameters for the engineering characterization of mixing and fluid dynamics at the microscale. Since hydrodynamic stress is solely dependent on the maximum power input, we adapted the clay/polymer method to obtain flock destruction kinetics in six-, 24-, and 96-well microtiter plates on orbital shakers. We also determined the specific power input using calorimetry and found that the power input is at the same order of magnitude for the six-and 96-well plates and the laboratory-scale stirred tank reactor, with 40 to 90 W/m 3 (Re' = 180 to 440), 40 to 140 W/m 3 (Re' = 320 to 640), and 30 to 50 W/m 3 (Re = 4000 to 8500), respectively. All of these values are significantly below 450 to 2100 W/m 3 determined for the pilotscale reactor. The hydrodynamic stress differs significantly between the different formats of MTPs, as the 96-well plates showed very low shear stress on the shaker with a shaking amplitude of 3 mm. Thus, the transfer of mixing conditions from the microtiter plate to small-scale and pilot-scale reactors must be undertaken with care. Our findings, especially the power input determined by the calorimetric method, show that the hydrodynamic conditions in laboratory-and pilot-scale reactors cannot be reached.

Reassessing the out‐of‐phase phenomenon in shake flasks by evaluating the angle‐dependent liquid distribution relative to the direction of the centrifugal acceleration

“…To simplify the handling of the OP problem, it has been shown that the system is “in‐phase” at a Ph > 1.26 (Equation ) and an axial Froude number > 0.4 (Equation ), whereas the system is regarded to be “out‐of‐phase” at lower Phase and axial Froude numbers. This concept has proven to be very useful for the design of screening protocols for shake flask experiments (Büchs, Lotter, & Milbradt, ; Gómez‐Pazarín et al, ; Lotter & Büchs, ; Pena, Galindo, & Büchs, ; Pena, Peter, Büchs, & Galindo, ; Peter et al, ) and for mixing investigations in microtiter plates (Dürauer, Hobiger, Walther, & Jungbauer, ). However, the employed digital “black and white” separation is not fully justified.…”

Less Sacrifice, More Insight: Repeated Low‐Volume Sampling of Microbioreactor Cultivations Enables Accelerated Deep Phenotyping of Microbial Strain Libraries

“…Next to microtiter plate (MTP) based systems, microscale bubble‐column and stirred tank reactor‐based MBR technologies with reaction volumes in the mL‐range were developed . In order to ensure a fair comparison of microbial strains among different test conditions, MBR systems have been validated toward controlled environmental conditions, e.g., temperature, mass transfer, power input and, most importantly, scalability of results …”

“…[7][8][9] Next to microtiter plate (MTP) based systems, [10,11] microscale bubble-column and stirred tank reactor-based MBR technologies with reaction volumes in the mL-range were developed. [12,13] In order to ensure a fair comparison of microbial strains among different test conditions, MBR systems have been validated toward controlled environmental conditions, e.g., temperature, mass transfer, power input [11,[14][15][16][17] and, most importantly, scalability of results. [18][19][20] Current MBR technologies enable data acquisition at high temporal resolution by means of non-invasive measurements of various culture parameters.…”

Microbioreactor Systems for Accelerated Bioprocess Development

“…For instance, the discovery of the “out‐of‐phase phenomenon”, which now can be described by the non‐dimensional Phase number ( Ph ), greatly advanced the understanding of fluid dynamics in these devices. In addition, methods were developed to characterize hydrodynamics, mass transfer and power input in MTPs . Results from fundamental research were transferred into application leading, e.g., to the development of MTPs specifically designed for the cultivation of MCFs with high oxygen demand .…”