What is a shaking diameter?

What is the shaking diameter?

The shaker table of an orbital shaker describes a circular motion with one revolution. The diameter of this circle is defined as the shaking diameter. Common shaking diameters are 0.5 inch [12.5 mm], 1 inch [25 mm] or 2 inches [50 mm].

The shaking diameter has a major influence on cultivation!

For instance, amongst other factors, the maximum oxygen transfer capacity OTRmax is directly dependent on the shaking diameter. According to a model from Maier and Büchs [Biochem. Eng. Journal (2001), Vol. 7, pp 99 – 106. https://doi.org/10.1016/S1369-703X(00)00107-8], the OTRmax can be increased by 20% by doubling the shaking diameter from 25 mm to 50 mm with all other conditions remaining constant. By changing the shaking diameter from 12.5 mm to 50 mm, the OTRmax is increased by almost 50%. For viscous systems, a shaking diameter greater than 50 mm (i.e. 70 mm) is recommended to ensure sufficient mixing and aeration.

You can find more information on the importance of the shaking diameter for shaken cultivations in our FAQ section: Why is the shaking diameter important?

Determining the shaking diameter

Unfortunately, the shaking diameter is not mentioned in most publications, making the reproduction of published experiments difficult. However the shaking diameter of each shaker can be easily determined using the method below. This is particularly useful if there are several different shakers in your lab or you are not able to reproduce the results of your collaboration partner.

1. Place a ruler underneath the shaking table.
   
2. Manually push the shaking table as far back as possible.
3. Read the length measurement L1 (e.g., 4 cm) on your ruler at a specific reference point e.g., silver front plate (figure 1, red arrow). 
4. Turn the shaking table (180°) by hand to the furthest forward position. 
5. Read the length measurement L2 (e.g., 9 cm) on your ruler at the same reference point e.g., silver front plate (figure 2, red arrow). 
6. The difference between L1 and L2 is the shaking diameter (e.g., L2-L1 = 5cm).