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.

Butterfly coil used with PEMF

Alternatively this coil is also called a “Figure 8 coil”, the name being self-explanatory.

PEMF figure 8 coil

Applications for butterfly coil

Butterfly coil on head

The main reason why this kind of coil has been developed is for applications where deep and very local magnetic stimulation fields are required. An example for use of is for deep penetration into the brain by so called repetitive Transcranial Magnetic Stimulation or in short rTMS or also called Deep TMS.

Various neurological disorders, including Depression, Alzheimer, Parkinson'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 on the head.

Butterfly coil for Curatron

The same principle enabled us to develop a butterfly type coil for the Curatron 3-D device. With the use of the 3-D high power generator together with the Curatron butterfly coil, a maximum intensity of 160 milli Tesla (1600 Gauss) is generated at the center of the butterfly coil, as pictured here under.

PEMF field distribution butterfly coil

At the right side is a picture showing the actual distribution plot with the numbers for the butterfly coil, when set for maximum electromagnetic field intensity.

The peak value of the 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.

E.g. 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).

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 the 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.

The Curatron butterfly coil is of open air design placed inside a small pad and can be used for extensive periods of time without very substantial temperature increase. Because of the longer average time it can be applied, it is also excellent for very local pain relief.

Copyright - Ben Philipson Curatronic Ltd. Parmeds Curamove EMT

Plot of pemf field strength of butterfly coil