Neodymium? Never heard of it. Bipolar? That can?t be good. And what?s a gauss, and why does my magnet have 800 of them?!
If this sounds like you, perhaps we can answer a few questions.
For starters, what is a magnet anyway? To keep things simple, a magnet is basically any material that exerts a magnetic field. Magnets fall into two basic types: permanent magnets and electromagnets. Electromagnets generate magnetic fields using electric currents. Permanent magnets, on the other hand, are materials that generate magnetic fields on their own. The greater majority of magnet therapy products use permanent magnets, although more intense treatments like repetitive transcranial magnetic stimulation (rTMS) make use of electromagnets to generate high magnetic flux densities.
Magnetic flux density is a measure of the strength of the magnetic field produced by a magnet. The tesla (symbol: T) is the most widely used unit of magnetic flux density; however, the gauss (symbol: G) is a more convenient unit to use when talking about the kinds of magnets that the average person is used to. One tesla is equal to 10,000 gauss, and to give you an idea of what a gauss equates to, consider your typical refrigerator magnet, which probably exerts a magnetic field of about 10 gauss. (Needless to say, one tesla would make for a pretty strong magnet!) Magnet therapy products tend to use magnets that range from several hundred to over ten thousand gauss (one tesla). The magnetic flux density of a magnet is largely a function of what the magnet is made of.
Practically speaking, a great number of materials can be made into magnets. Typical permanent magnets include ceramic magnets, plastic magnets, samarium cobalt magnets, alnico magnets, and neodymium magnets. The last of these, neodymium magnets (also known as rare earth magnets), exert extremely powerful magnetic fields ? so strong, in fact, that a neodymium magnet the size of a penny can sometimes lift hundreds of pounds with the force of its magnetic field!
This last example brings up an important point. The size of a magnet also plays a significant role in determining the magnet?s therapeutic strength. The same neodymium magnet that can lift hundreds of pounds with its magnetic field may in fact not even be able to penetrate more than a few inches into the human body due to its small size. It is the combination of magnetic flux density and magnet size that determines the therapeutic strength of a particular magnet.
Finally, there is polarity. Perhaps one of the least understood aspects of magnet therapy is the role, if any, that polarity plays in generating therapeutic effects. Polarity is the term used to describe the alignment of particles within the magnet, i.e. the quality that all magnets have north and south poles, with the magnet?s north pole pointing to Earth?s North Pole and the magnet?s south pole pointing to Earth?s South Pole. (Yes, this technically means that the North Pole is actually Earth?s magnetic south pole ? but never mind that for now.) In any case, one can distinguish between two types of magnets: bipolar magnets and unipolar magnets. Bipolar magnets are those that have both north and south polarity on the same side of the magnet, while unipolar magnets have the north pole on one side and the south pole on the other. One difference between bipolar and unipolar magnets is that unipolar magnets tend to have greater penetration than bipolar ones due to the fact that the polarity is uniform on each side. Any other possible differences between the two types of magnets remain a matter up for investigation.