Laboratory Magnetic Stirrer

November 2, 2021

In simple terms a Laboratory Magnetic Stirrer or stir bar is a small magnetic bar usually covered in plastic and a plate underneath. This plate has a rotating magnet or a series of electromagnets.

History of the Laboratory Magnetic Stirrer

To begin with, we must know that it was Arthur Rosinger (Newark, New Jersey, United States) who acquired the patent 2,350,534 whose name is Magnetic Stirrer. This happened on June 6, 1944, but its first application had already been registered two years earlier.

In said patent, the detailed description of this laboratory instrument was found. It indicates that this is a coated magnetic bar placed inside a container, being the same activated by the magnetic influence of another magnet. The other magnet is placed below the support base.

As for the coating on this bar, the creation was independently created by Edward McLaughlin . Being this employee in the Torpedo Experimental Establishment (TEE) laboratories, located in Greenock, Scotland. It is important to mention that he gave the name to this stirring bar as “flea”, because it jumped quickly when the rotation speed was very high.

To all this we must mention that there is a patent dated October 9, 1917, number 1,242,493, in the name of Richard H. Stringham of Bountiful Utah, United States. In this case, the bar used stationary electromagnets at the base, something very different from the original model.

If we go back to the first multi-point magnetic stirrer, it was developed by Salvador Bonet of the SBS company in 1977. It is important to mention that he introduced the rotation with the necessary power to stir “liters of water”. This application was essential to find the standard we have today.

What is the Laboratory Magnetic Stirrer?

We know as a Laboratory Magnetic Stirrer an electronic instrument, which makes use of a magnetic field to achieve mixing one or more solutes with a solvent . This process is achieved in an automated way.

But this instrument also has the ability to heat chemical solutions. As well as minimizing the risk that the solutions end up altering. We must bear in mind that in most cases when the stirring process is done manually, the solutions can become contaminated.

Laboratory Magnetic Stirrer Features

To begin we must know that this laboratory instrument contains a small stirring bar. The latter being used to stir the mixture, other characteristics of this device would be;

  • Its shape is elongated, with an octagonal section and a circular frequency.
  • In most cases these rods are a few millimeters long, although larger stirrer rods can be found that reach a few centimeters in length.
  • Stirring bars have a rim around the center that they rest on when rotating.
  • In the magnetic stirrer bar we can find a Teflon coating in most cases. But you can also find a glass coating in some cases.
  • In most cases magnetic stirrers rotate their magnets using an electric motor.
  • In general, this bar is usually used with small amounts of liquids or very viscous, this way it will work better.

Finally, we must add that the shaker image retriever is usually formed by a magnet attached to the end of the rod . This must be coated with Teflon and is used for the recovery of the stir bar inside the container. Furthermore, such a stirrer can be just a magnet rotating under the container.

Types of Laboratory Magnetic Stirrer

There are two types of magnetic stirrers that we can find. The first is the motorized magnetic stirrer and the second is the multi-position magnetic stirrer. To better understand these we will talk in more detail about these magnetic stirrers;

  • Magnetic motor stirrer ; In this case we find that it is designed to withstand long working hours. In fact, after such a long time of work, the motor can be replaced. Which are generally very inexpensive, as well as the other spare parts you may need.
  • Multi-position magnetic stirrer ; As we can imagine from its name, it is designed to stir several solutions at the same time. On the other hand, you can set a different speed for each solution if you need it. It is important to note that the latter is one of the most functional in laboratories, since they are very efficient and can save space.

Magnetic Stirrer Parts

As with other laboratory materials , these have several parts. Which we must know well if we want to use this instrument correctly. Specifically, we can say that its parts are the following;

  • Switch to turn the unit on and off.
  • It has a connection cable to the electrical network.
  • It has an electronic control for the regulation of the stirring speed.
  • It has a magnetic stirring bar covered with Teflon, which is immersed in the substance to be stirred.
  • It has an electronic motor provided with additional high-grip magnetic fields, the latter being in charge of transferring said magnetic field or bar.

What is a Laboratory Magnetic Stirrer for?

A Laboratory Magnetic Stirrer is basically used to mix liquids with each other or with some powder. This is done in order to produce solutions, for fluid or viscous dispersions , and for suspensions.

It is a very useful device, especially in biology or chemistry laboratories . We must bear in mind that in these fields, this apparatus is needed to carry out various types of mixtures.

It is important to mention that many scientists prefer to use this type of device since it is much quieter. But that is not the only advantage that it presents, since apart it turns out to be very resistant , so it does not usually break easily.

The latter is due to the fact that it has no moving parts that can break. It is also very easy to clean, which is very popular with many scientists.

Continuing with the uses of the Laboratory Magnetic Stirrer, we have to considerably reduce the contamination of the reagents . Keep in mind that in the case of motorized agitators, they contain lubricants, so there is a risk that the solution will be contaminated. Due to this, it is widely used in various fields of science, especially in chemistry and biology.

On the other hand, it should be added that some Laboratory Magnetic Stirrers are specially designed to stir thick and viscous liquids . In these cases we find specialized magnets for this type of work, since they are easier to carry out this type of action.

What are the uses of the Laboratory Magnetic Stirrer?

The Laboratory Magnetic Stirrer is used mostly in chemistry and biological laboratories, since they are the places where most liquids and solutions are worked. As we have been mentioning, this instrument is usually used for mixing, but it can also be used for heating.

In the latter case, we are talking about a type of Laboratory Magnetic Stirrer that has a heating system. Thanks to this system it is possible to heat the mixtures, while stirring it.

How to use a Laboratory Magnetic Stirrer?

The use of a Laboratory Magnetic Stirrer is not complicated at all, as long as you have some knowledge about it. To begin we must take the flask or beaker. Then add the content, which is the solution that we are going to stir. It is important that the beaker or flask is on the stir plate.

When we have done this, we must take the magnetic bar and insert it into the container. Then we must turn on the device and adjust the speed . The ideal is to start with a slow speed, and then increase to obtain the result we want.

It is important to be careful that the liquid is not going to spill during the stirring process. Also when we are done, we must bring the device to its initial speed. Then turn off the equipment and remove the Laboratory Magnetic Stirrer from the container.

Advantages of the Magnetic Stirrer

Many scientists decide to opt for this mechanism since it is much more silent , efficient and has no moving parts that can break. On the other hand, it has a small size, so it is much easier to clean. Other advantages of this laboratory equipment are;

  • They are much cheaper .
  • They do not contaminate the reagents, because no lubricants are used.
  • It does not present problems at the moment of hermetically sealing the rotary mechanical connection.

Disadvantages of the Magnetic Stirrer

Just as this instrument has its advantages, it also has its disadvantages. A clear example is its limitation due to its small size, since being small they can only be used in experiments at the laboratory level . It basically only works at low scales or in chemical analysis.

At the same time we must indicate that when treating viscous liquids or thick suspensions, they can be difficult to stir.

Dr. Loony Davis5
 | Website

Born and raised in Brussels in an English family, I have always lived in a multicultural environment. After several work experiences in marketing and communication, I came to Smart Water Magazine, which I describe as the most exciting challenge of my career.
I am a person with great restlessness and curiosity to learn, discover what I do not know, as well as reinvent myself daily, someone who is curious about life and wants to know. I enjoy sharing knowledge.
This is my personal project but I also collaborate in other blogs, it is the case, the most important web on water currently exists in the US, if you are interested you can read my articles here.

Leave a Reply

Your email address will not be published. Required fields are marked *