A Comparative Analysis of Unipolar vs. Multipolar 
Magnetic Designs Used in Magnetic Therapeutic Devices

By Vincent Ardizzone, EE

With the recent attention focussed on the use of 
magnetism as a viable modality in the treatment of 
pathological conditions such as chronic pain, the 
distinction between the different magnetic designs 
available should be addressed in an effort to determine 
the most efficacious design for use in therapeutic 
treatments.

In the field of magnetic therapy there are two major 
categories of devices in use today. The first category 
deals with devices which utilize alternating current to 
produce what is commonly referred to as EMF or 
Electromagnetic Fields. These fields operate at certain
frequencies which have been the subject of much 
controversy in recent years due to the question of the 
safety of such fields. 

The second category deals with the most benign 
manifestation of magnetism which is the Static Magnetic 
Field. This type of field is basically what is produced 
by the earth itself and is considered an integral 
component of life on this planet. Since a static field 
operates with no frequency it is considered a very safe 
form of energy. Man has learned to reproduce this type 
of field by utilizing two means: direct current and 
magnetic rare earth material. 

Due to the energy input requirements of the first means,
the use of direct current is a less desirable method of 
static magnetic field production and is used mainly to 
produce fields that are much stronger than any found in 
nature and also for devices that require a pulsating 
action of the field. 

Rare earth material on the other hand, such as 
magnetite, cobalt, and neodynium, are permanently 
magnetized and require no additional input energy to 
produce their magnetic properties once they are in a 
magnetized state. Although their magnetic strength is
limited, permanent magnets have become the material of 
choice not only in therapeutics but in a wide range of 
industries wherever a static magnetic field is needed.

Interestingly, even in the narrow category of static 
magnetic fields used in therapeutic treatments, there 
are distinctions. Some devices use single magnetic 
poles and are known as unipolar devices.  (Actually
the term "unipolar" is a misnomer in magnetics since 
every magnet must have two poles, a north and south, in 
order to complete the magnetic circuit. But in magnetic 
therapeutic treatments, if only one pole of a two pole 
magnet is applied to the body it is considered 
"unipolar" since only one field is acting on the body.) 

Other devices use several magnetic poles arranged in an 
alternating fashion of north and south poles. These are 
called multipolar devices. Proponents of the unipolar
design claim that these devices offer the most 
therapeutic benefits since they are most similar to 
the earth's magnetic field. But their claims don't 
appear to hold up to clinical scrutiny. 

In fact, a study published in 1995 in the journal of 
Bioelectromagnetics shows that an alternating polar 
arrangement had the most pronounced effect on pain
sensation. The study, entitled Blockade of Sensory 
Neuron Action Potentials by a Static Magnetic Field in 
the lOmT Range, tested various magnetic pole 
arrangements for their effects on neural depolarization 
of sensory nerves. 

Neural depolarization basically means a drop in the 
voltage of a nerve. When a sensory nerve is resting 
peacefully in an undisturbed state its resting 
potential (voltage) is approximately 70 mV (millivolts 
or thousandths of a volt). In this state the nerve is 
"resting" and no pain is perceived.  When an external 
stimulus of sufficient intensity acts on the nerve, a 
chain of events takes place which causes the resting 
potential of the nerve to suddenly drop down to 0 volts
(depolarization). 

This sudden drop in voltage is also known as the action 
potential because it causes the nerve to act on each 
nerve it is connected to in dominos-like manner until 
it reaches the brain where it is recorded as pain. So, 
anything that could somehow block the action potential 
would thereby block pain transmission. 

Now getting back to the clinical study.. . The study 
showed an amazing 66% of the stimulated sensory neurons 
failed to elicit action potentials when exposed to an 
array of 4 alternating permanent magnets arranged in a 
checkerboard-like configuration. No statistical effect 
was observed when unipolar, or even bipolar magnets 
were used. 

This was the first study of its kind to show clinically 
what many people have experienced personally using 
multipolar therapeutic magnetic devices. The 
researchers hypothesize that the most probable reason 
that the multipolar design has such a pronounced effect 
is due to the steep field gradient produced by such a 
magnetic arrangement of poles. 

A field gradient indicates the degree that the field 
changes within the area it impinges. If the field 
strengths were plotted on graph paper, one would 
observe a series of peaks and valleys as a function of 
movement across the field. Thus, a steep field gradient 
would show a sharp rise or fall in field strength with 
a relatively small movement in the measuring position.

...'s Magsteps and Relax Pads are the only patented 
magnetic therapeutic devices on the market today which 
utilize a polar arrangement similar to that used in the 
clinical study mentioned. In fact, not only is the polar
arrangement practically the same but the triangular 
shape of the magnetic poles used in the ... products
produce an even steeper field gradient than the circular
poles used in the study. 

Therefore it is reasonable to conclude that the ...
Magsteps and Relax Pads are the most advanced static 
field magnetic therapeutic products on the market today.