FAQ

listbutton hover What is the shaking diameter?

The shaking table of an orbital shaker moves in a circle. The diameter of this circle is called the “shaking diameter”.

Most commonly used diameters are

  • 12.5 mm (ca ½ inch)
  • 25 mm (ca. 1 inch)
  • 50 mm (ca. 2 inch).

On all Kuhner shakers the orbital movement can be changed at any time.

listbutton hover Do different diameters affect the cultivation?

Yes. The shaking diameter is a
key factor for the cultivating conditions in a shaken bioreactor. Given the same speed; the bigger the shaking diameter, the better the oxygen transfer rate inside
the culture. This also applies to microtiter plates.

listbutton hover Do you need a smaller shaking diameter when working with microtiter plates (e.g. 3mm)?

No. Microtiter plates can also be shaken with a larger diameter; the smaller the diameter, the faster the speed required (e.g. 700 rpm with 3mm). When choosing a larger diameter such as 50mm, a speed of 250 rpm may be enough to guarantee proper mixing and oxygen transfer.

listbutton hover What is the sheer sensitivity in a shaken bioreactor?

In a shaken bioreactor the mechanical stress on the cells is usually considerably less than in a stirred system. In a stirred bioreactor there are two stress effects: on the one hand you have small eddies near the impeller blades and on the other hand, small bubbles burst on the liquid surface because the vessel is sparged from the bottom. In a shaken bioreactor there is surface aeration and the shaking movement gives uniform mixing without any local power inputs.

listbutton hover Does the shaker motor heat the shaking table?

No. Kuhner shakers have a unique drive system emitting less than 10 watts of heat.

listbutton hover Is the speed of the motor the same as the speed indicated on the display?

Yes. All Kuhner shakers have a direct drive. On a Kuhner drive there is no belt or friction wheel and therefore no slip. Slippage is the cause of any speed difference between the shaking table and the speed indicator.

listbutton hover Do you need a special kit for stacking incubator shakers?

No. Kuhner machines do not need any kits or special tools for stacking.

listbutton hover How about shaking light sensitive medium?

Kuhner has the option of blackened windows to prevent light affecting your medium.

listbutton hover How do I reduce evaporation from flasks/MTP?

The smaller the volume and the longer the fermentation time, the more the evaporation rate affects your cultivation. Evaporation can be reduced by using special lids, stoppers, adhesive foils etc. One example is the Duetz system for microtiter plates. It is also necessary to humidify the incubator chamber.

listbutton hover How do I stop the condensation on the inside of the window?

All new Kuhner incubator shakers fitted with the humidity option have heated door windows and frames to prevent condensation.