PEMF Butterfly coil

PEMF butterfly coil

What is a Butterfly coil and what is its use?










The name Butterfly coil is derived from the form for this type of coil. Alternatively this coil is also called a “Figure 8 coil”, the name being self-explanatory. 








The main reason why this kind of coil has been developed is for applications where deep and very local electromagnetic stimulation fields are required.










An example for use of it is for deep penetration into the brain by so called repetitive Transcranial Magnetic Stimulation or in short rTMS, also called Deep TMS.


Various neurological disorders, including Depression

AlzheimerParkinson's disease, and Migraine are effectively treated by application of this coil type because this technology allows for deep penetration into the brain when placing a butterfly coil directly to the head. 











This picture shows that the maximum peak intensity is perpendicular to the center of the butterfly coil and as such has superior ability [compared to a regular PEMF coil] for reaching the locations deep inside the head or body.

Butterfly pemf coil
Butterfly pemf coil on head
Butterfly coil pemf field distribution
PEMF configuration butterfly coil
Butterfly coil intensity plot pemf field

The PEMF intensity is clearly shown in this actual electromagnetic intensity distribution plot.


The peak value for this butterfly coil is 160 milli Tesla 

(= 1600 Gauss) measured directly at the center of the coil surface. The further away from the coil => the field intensity decreases.

When measured at a distance of one inch (2.5 cm) from the coil surface the field intensity is now 50 milli Tesla (= 500 Gauss) and at a distance of 2" (5 cm) we still measure a field intensity of 30 milli Tesla (= 300 Gauss) and at a distance of 3" (7.5 cm) the value still exceeds 10 milli Tesla (= 100 Gauss)!


These values show that deep concentrated bone and cell penetration with pulsed electromagnetic fields is indeed possible.


There is evidence that this technology can reduce chronic pain and change pain-related brain and nerve activity. The high intensity in combination with the focused PEMF can be applied very locally to obtain fast pain relief.


The type of copper wire and geometry of the coil configuration, together with the biophysical characteristics of the PEMF pulses, determine the form and the intensity of the magnetic field of the coil. 


When generating very high intensity in coils for continuous use with a high power generator, temperature inside the coil increases substantially because of the strong electrical currents fed into the copper wires of the coil. This makes continuous application of butterfly coils for pain relief very difficult, if not impossible.


Solid core coil design results in a more efficient transfer of electrical energy into a magnetic field with a substantially reduced amount of energy dissipated as heat. However, if used continuously the coil still accumulates heat over time, requiring cooling and making it unsuitable for practical applications. 


However an open air PEMF coil can however be used for extensive periods of time without substantial temperature increase and can also be used for local pain relief.