The up and down stirring produces no vortex (eddy) and therefore eliminates the need for baffles. This spares costs, simplifies setting up and cleaning of the vessel and allows the creation new types of vessels (because the large vessel opening otherwise necessary for baffle insertion is no more needed).
The very expensive head plates which are heavy, complicated and long to set up and clean are no longer used. Because no special head plates are required anymore, the cost of passing to vessels of different volumes is much lower. For the same reason, it is no more necessary to buy shorter or longer probes and all other parts*). In the MINIFOR system they are all reused and only few, low cost parts need to be changed (see Optimized vessel design).
*) This important costs lead many users to rather buy fermenters with the largest possible vessel volume and to work under more expensive and high volume conditions, even though this was not required by their experiments. With the LAMBDA MINIFOR fermenter-bioreactor system this is now a thing of the past! Clever users always try to work with the lowest possible medium volume as this offers so many benefits.
Almost all laboratory fermenters-bioreactors use circular rotation to agitate the culture medium.
The major technical problem is that the axis of the stirrer (and the motors axis) rotates while the vessel is fixed. Thus, it is a physical necessity that a free space must exist between both, the moving axis and the immobile vessel, otherwise the rotation of the axis would not be possible. This free space allows viruses and microorganisms to get into the vessel. To limit the probability of contamination three ways are used:Almost all laboratory fermenters-bioreactors use circular rotation to agitate the culture medium.
Because of the length of the axis and high transmitted force the magnetic coupling is technically quite complex and very expensive. For this reason, it is never proposed as standard equipment for laboratory fermenters. The client can sometimes buy it as an expensive option. In this way, the initial prices of many laboratory fermenters are kept lower despite of expensive consequences for the client at a later stage, when he is basically forced to buy the magnetic coupling option from the same producer.
LAMBDA has found a very simple, innovative solution for this mixing problem by selecting a non-rotational vertical up and down mixing solution. A simple elastic membrane allows the movement of the stirring axis and serves at the same time as a quality seal between the vessel and its central threaded cap. The membrane separates completely the interior of the vessel from the outside environment and this at low cost for the user.