Home » Choosing the Right Laboratory Stirrer
Stirrers, or shakers, are widely used in laboratories to mix and agitate samples before analysis. ptfe coated magnetic
There are various types of laboratory stirrers (magnetic, vortex, roller, etc.). Although they all allow liquid solutions to be mixed, each one meets different needs, so choosing the right type of stirrer is important.
To do this, the properties of the sample must be taken into account (viscosity, presence of living cells, etc.), which will largely dictate the choice of the type, speed, and range of movement of the stirrer to be used.
Two other criteria to consider are the volume and type of sample container, as certain shakers are better suited to certain containers, such as beakers, Erlenmeyer flasks, microplates, or test tubes.
Magnetic stirrers are the most common laboratory stirrers.
They consist of a base with an electric motor and a plate on which the container with the solution is placed, as well as a magnetic bar that is inserted into the container. In the base, an electric motor rotates a magnet which, in turn, rotates the bar inside the sample, stirring it.
These are the criteria for choosing a magnetic stirrer:
– Aluminum is more resistant to thermal shocks
– Ceramic is not affected by chemicals
– Stainless steel is extremely resistant
Overhead stirrers are designed for stirring, mixing, and homogenizing liquids, even those with a high viscosity. These stirrers a re placed on top of the container to be stirred as opposed to other stirrers that operate from below (such as magnetic stirrers). These stirrers consist of a motor and a stirring tool that is inserted into the solution.
These are the criteria for choosing an overhead stirrer:
Vortex stirrers are widely used, particularly in molecular biology, to rapidly mix solutions directly in test tubes or microtubes.
They consist of a heavy base with a rubber receptacle on top. When the operator presses down on the receptacle with the bottom of a test tube, the electric motor starts up, imparting a low-amplitude, high-speed orbital movement to the test tube and the solution it contains.
It is also possible to stir several tubes simultaneously, or microplates with stirrers whose receptacle is replaced by a specific support.
These are the criteria for choosing a vortex stirrer:
Rotary and roller stirrers are suitable for fragile or viscous samples packed in closed tubes and are frequently used for mixing blood samples.
There are several different configurations for rotary stirrers, but they all work according to the same principle: sample tubes are placed on a support that rotates at a fairly slow speed (less than 50 rpm) in order to gently homogenize the contents of the containers.
In a roller stirrer, test tubes are placed on rollers that are subjected to a double rolling and oscillating movement.
These are the criteria for choosing a rotary or roller stirrer:
These stirrers are equipped with a tray that fits most containers, such as microcentrifuge tubes, Petri dishes, microtiter plates, Erlenmeyer flasks, etc. The tray can be bare, fitted with a non-slip mat, or with specific supports to better hold the container. Several trays can also be stacked to increase the number of containers.
The difference between these stirrers lies in the type of tray movement.
Orbital stirrers move the tray in a flat circular orbit. This creates a swirling movement for the liquid inside the container, which is ideal for promoting sample aeration.
Reciprocating or linear stirrers linearly use an alternating back-and-forth movement. This linear action is more aggressive than orbital movement.
Rocking stirrers offer less aggressive shaking for the samples, as the platform performs a lateral, oscillating movement, generating ripples in the sample. A variant of the rocking stirrer is the 3D stirrer, whose tray moves in a three-dimensional motion around its central point, causing the sample to swirl gently, which is ideal for applications on fragile cells.
These are the criteria for choosing one of these stirrers:
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