Criteria for an effective device for PEMF (pulsed electromagnetic field) therapy
"Everything in life is vibration" - Albert Einstein
Variables of PEMF therapy devices
PEMF therapy devices produce time-varying* electromagnetic waves with a specific shape. E.g. triangle, rectangular (includes square waves), or saw-tooth. Each wave shape is determined by a specific waveform generator in the device (consisting of circuitry components such as inductors, capacitors, switches, diodes, transistors etc). *Time-varying means that the electric field has a changing voltage amplitude, achieved by changing the current.
Each wave shape has 3 variable parameters:
(1) Pulse Rate. How often the EMF pulses are turned on per second. In this diagram, the pulse rate is 1 / T. E.g. if T=1/10 second, then the pulse rate = 1 / (1/10) = 10Hz. The fundamental frequency of the wave is its pulse rate.
(2) Duty cycle. The amount of time the pulse is active (t) compared to the time between each pulse (T). t / T in diagram. E.g. if T = 1/10 sec. and t = 1/40 sec., then duty cycle = (1/40) / (1/10) = 10/40 = 0.25 or 25%. A square wave has a duty cycle of 50%. (since t is half of T)
(3) Strength /Amplitude of Magnetic field (B) (Tesla is
its larger unit of measurement, or Gauss for
smaller field amplitudes, such as the earth's geomagnetic field of 0.5 Gauss)
and Electric Field (E)
(measured in volts /meter). Amplitudes are determined by coil shapes /sizes and current flowing through them. Maxwell's equations describe how a current in a closed loop
produces an electromagnetic field (originally Ampere's law). The
electromagnetic field is a physical field, an interdependent relationship
between the electric and magnetic fields, which are 90 degrees out of phase (i.e. when E is max,
B=0, when B=max, E=0) .
Each of the pulsed wave shapes generates a unique set of
FREQUENCIES (called harmonics)
as described by the wave's fundamental frequency and the
transforms of the wave shape (set by
device circuitry). The wave's fundamental frequency is the
same as the pulse rate.
Each of the pulsed wave shapes generates a unique set of FREQUENCIES (called harmonics) as described by the wave's fundamental frequency and the Fourier transforms of the wave shape (set by device circuitry). The wave's fundamental frequency is the same as the pulse rate.
• Frequency (measured in Hertz) simply refers to the number of oscillations that pass by a fixed point in one second: e.g. the musical note 'A' vibrates at 440 Hz - 440 wave cycles per second.
How the therapy is applied to the body E.g. via a wand, pad, mat, probe for general body treatment or specific target areas. Different application areas require appropriate treatment field strengths.
• Device's required treatment duration times. Needs to be able to fit comfortably into daily life.
• Cost of device
For effective therapy, electromagnetic wave energy must be absorbed by the body
An electromagnetic wave transmits ENERGY from its source.
Energy carried by EM wave is proportional to the following 3 factors:
1. Its electric or magnetic field amplitude squared (E2 or B2).
2. Its frequency .
3. Its duty cycle
For therapy, the body must be able to absorb the energy carried by an electromagnetic wave, HOWEVER, the energy level does not necessarily need to be HIGH to have a therapeutic effect. E.g. Earth's Schumann field has a strength of only ~ 1 picotesla, which has numerous beneficial effects on the body's electrical functions; also the Sun's electromagnetic spectrum has a field strength of ~4000 picotesla at the Earth's surface, and 7-dehydrocholesterol (7-DHC) in the lower epidermis and dermis layers of the skin absorbs the energy of the sun's UV-B frequency to produce health-essential vitamin D.
NASA study provides some criteria for effective PEMF therapy
A 4 year, multi-million dollar NASA study published in 2003 provided some conclusive criteria for effective energy medicine using time-varying EMFs. This well-conducted and thorough study investigated the effectiveness of "the use of a time-varying electromagnetic field for potentiation of the growth of mammalian cells and tissues" - in particular, this study examined the growth and regeneration of human neural stem cells. The study was not limited to PEMFs, but also included sine waves, and other "energy medicines", including LED's, lasers and static magnetic fields.
The NASA study found PEMFs to be the most effective form of energy medicine. The NASA scientists found that slow (millisecond) pulses or sine waves, and static magnetic fields (even with field strengths of ~12000 Gauss i.e. ~1.2 Tesla) were not as effective as low field strength PEMFs. Finding that these other electrotherapies were not as efficacious as PEMF therapy, the NASA study moved its focus to PEMFs.
NASA study also found that LOW frequency, LOW field strength, RAPIDLY-VARYING PEMFs provided the most effective therapy compared to alternatives. They found that these criteria promoted better healing and regeneration of damaged or diseased tissue, greater cell longevity, accelerated cell growth, improved cellular transmembrane potentials (mainly observed in nerve cells), and an upregulation of genes (increases creation of certain gene products) related to collagen production, cell restoration and growth.
Specifics of NASA study
Significant growth rate of cells was clearly demonstrated using a square wave, with a current of 1 - 6 mA, having a frequency spectrum with a fundamental frequency of 10 Hz, using a variable duty cycle (which is the fraction of one period the pulse is active, compared to the time between each pulse).
WAVEFORM: Square wave.
"The most effective electromagnetic waveform for repair of trauma was a square wave with a rapid rate of change (dB/dt) which saw cell growth increased up to 4.0 times."
By way of confirmation of their findings, the NASA study references a report by Sandyk et al. of a dramatic improvement in a patient with progressive degenerative multiple sclerosis when subjected to PEMF treatment at a frequency of 2-7 Hz and magnetic field strength of 7.5 picoTesla (much less than the NASA study and closer to the Schumann field intensity of ~1 picoTesla). (Sandyk, 1992; NASA, 2003)
FUNDAMENTAL FREQUENCY (Pulse rate): 10 Hz. This fundamental frequency is in line with the frequency of the life-sustaining Schumann resonance field surrounding the earth, which is also that of the brain's alpha waves when in a calm, relaxed state.
ELECTROMAGNETIC FIELD STRENGTH: 1 - 20 µTesla (10 - 200 mGauss ) Neural cells (excitable cells) were subjected to these extremely low-level electromagnetic field amplitudes --- i.e. less than half of the Earth's average geomagnetic static field strength of about 0.5 Gauss (50 µTesla).
Criteria for effective PEMF therapy
WAVEFORM of EMF should change direction rapidly. E.g. as in a square wave, impulse or saw-tooth wave; NOT slowly as in a sine wave or triangle waveform with a wavelength of milliseconds; the fast rise and fall times of square and saw pulses produce a spread of frequencies, which are multiple higher, odd harmonics of their fundamental frequency. These are mathematically described by "Fourier transforms" - a summation of a sine wave's fundamental frequency and its harmonic frequencies. The fundamental frequency is the pulse rate.
Dr. Bassett, who introduced the saw-tooth wave in 1974, found that a fast-changing EMF induces the maximum current in treated bones for accelerated healing.
Whether any part of the body is affected by EM wave energy depends on whether that body part absorbs its energy --- and that depends on the FREQUENCIES of, or the harmonics generated by, the wave.
If any life form, body cell /part or object resonates at a certain frequency it can absorb energy from an EM wave with that frequency. Resonant processes take place at cellular level (membrane and/or nucleus) Lerner, E.J., 1984, Biological effects of electromagnetic fields, IEEE Spectrum, 21: 57.Google Scholar
Royal Rife discovered that viruses and bacteria could be deactivated by exposing them to their resonant frequencies.
Energy of the Schumann Resonance frequencies in the approx. 8-30 Hz. range were found to be absorbed by the body by scientists W.R. Adey and Zimmerman. Termed the "biological window of frequencies" by W.R. Adey, our body's cells and brain operate / resonate with these frequencies and their higher harmonics.
The brain operates on 4 distinct frequencies throughout the day, viz.:
• ACTIVE. Beta (14-30 Hz): Alert /energized brain state. Brain is aroused and engaged in mental activity
• CALM. Alpha (8-14 Hz). Frequency produced by the brain in a relaxed state (irritability produces higher frequencies); this is in line with the average resonant frequency of the Schummann resonance field surrounding the earth.
• CREATIVE. Theta (4-8 Hz): Creative / Daydreaming state; prone to a flow of ideas.
• SLEEP. Delta (0.5-4 Hz): Deep relaxation / Sleep state
The average of the Fundamental Schumann frequencies of the Schumann resonance field measured around the earth is 7.83 Hertz. (you can think of this as the "heartbeat" of the earth). Its primary harmonics are 14.3, 20.8, 27.3 and 33.8 Hertz.
Specific frequencies in the 0-30 Hz range have demonstrated particular therapeutic effectiveness for different problems. E.g. 2 Hz has been shown to aid nerve regeneration, 7Hz stimulates bone growth, 10 Hz repairs ligaments, and the Schumann frequency (~ 7-8 Hz) has had an overall therapeutic success.
The body also absorbs other natural, higher frequencies in order to thrive. In particular, we need sunlight, which provides us visible light, near infrared, and UV frequencies when we are out in the sun, which enter and work in our body. These frequencies are extremely high. E.g. visible light has a frequency range of 430-770 THz (a tera Hertz = 1012 Hz).
Electromagnetic field strength
PEMF therapy using LOW electromagnetic field strengths has established its effectiveness.
The NASA study used pulsed electromagnetic fields (PEMFs) at 1-20 µT.
When using PEMF therapy LONG-TERM E.g. for regular maintenance: ELECTROMAGNETIC FIELD STRENGTH (AMPLITUDE) should probably be in line with those of the NATURAL electromagnetic fields we experience every day:
• Earth's Schumann Resonance field. As low as 1 picoTesla (i.e. 1,000,000 times lower than the strength of Earth's DC geomagnetic field!).. Our cells are so sensitive they can pick up signals even at this low intensity.
• The solar spectrum. Provides a field strength of 1 kW/m2 as the integral of the solar frequencies from infrared to ultraviolet that reach earth. This is equivalent to 0.004 µT = ~4000 picoTesla = 4.0 x 10-5 Gauss.
Note that the Earth's geomagnetic field is essentially a static/constant field (frequency of 0 Hz) of ~50 uT or 0.5 gauss This magnetic field stores energy, but can not emit energy. Since it is not changing, it can not induce a current. Some organisms display the ability to sense or navigate by magnetic field (e.g. certain bacteria, insects, birds, molluscs and even some mammals (e.g. cattle prefer to align themselves with the field when standing in a field :) )). Without knowing the "how", Caltech and Univ. of Tokyo researchers found evidence that humans have working sensors able to detect changes in direction of an Earth-strength magnetic field and send signals to the brain, resulting in a reduction of alpha brain waves. "The alpha rhythm is the dominant human brain oscillation in the resting state when a person is not processing any specific stimulus or performing any specific task [...]. When an external stimulus is suddenly introduced and processed by the brain, the alpha rhythm generally decreases in amplitude."
Dr. Ludwig Wolfgang found that Earth's geomagnetic field is actually not competely constant, but vibrates to a small degree, as a result of the modulation of 64 trace elements within the earth's core and crust. The frequency spectrum of these small variations (at the poles) are 11.79 (fundamental frequency, 16.67, 23.58 and 30.8 Hz. Similar to the Schumann Resonance field, Earth's geomagnetic field strength changes due to these frequencies is negligible.
Some applications dealing with acute pain use higher EM field strength PEMFs to yield faster results. E.g. SOTA Magnetic Pulser (6 Gauss (600 µT) at coil face). Since the body is not accustomed to these high EM field strengths, they raise some safety concerns, and it is generally advisable not to use them long-term. From a healing perspective, the idea of using high EM field strengths is counter to the body's inherent much lower healing field-strengths. Work continues, but several studies are indeed revealing that healing, such as bone regeneration, may not take place at EM field strengths that are too high.
Electromagnetic field strengths and body penetration of therapy device EM fields
Dielectric loss as therapeutic EM field enters the body
At frequencies below the MHz range (this is most therapeutic frequencies), field strength reduction due to dielectric losses (i.e. the body's insulating effect) is negligible.
At higher frequencies, such as radio/micro wave frequencies, there may be some field reduction due to thermal loss. RF ranges from 20kHz to 300 GHz, and microwave frequencies range from 300 MHz. to 300 G Hz. Field strength
EM field strength falls with distance from therapy device field source
Both electric and magnetic field strengths reduce with distance away from their source. This includes the EMF-producing coils of therapy devices and the Sun (which is so far away from us that its field strength is essentially constant when it reaches us on Earth). The Schumann resonance field is also near constant strength, but in this case, it is because it is sustained by continual lightning strikes.
EMF strength reduces with distance away from an electromagnetic current loop (a.k.a. a coil) . In order to treat inner organs / tissue, the EM field strength needs to be high enough when it reaches target tissue in the body. For a loop or coil, the magnetic field strength (B) drops according to the Biot-Savart Law:
B (x) = μ0 i R2 / 2 (R2 + x2 ) 3/2
B (x) is the magnetic field strength in Teslas at a distance x meters from face of loop (or coil); R is radius of loop in meters, and i is the current in Amps in the current loop. Î¼0 is the constant 4 π x 10 -7 Henrys / m. The electric field (E) drops off in the same way for a PEMF therapy (i.e. it has an AC current in a coil).
To determine the EM field strength of a PEMF therapy application tool, It is necessary to know the loop (or coil) diameter and the EM field strength at its surface.
What is considered a safe EM field strength?
The INTERNATIONAL COMMISSION ON NON-IONIZING RADIATION PROTECTION (ICNIRP) is a world-wide authority on EM energy safety, whose data is relied upon by the U.S. FDA and EU. The ICNIRP state that limiting safety values for time-varying PEMFs depend on both frequency and EM field strength.
ICNIRP reference levels for general public exposure to time-varying magnetic fields. (ICNIRP, 2010) Allowable Limits for exposure to an EM field strength various fundamental frequencies is:
At 1-8 Hz. Allowable Limit calculated as 40,000 / Frequency2
uT. E.g. at 4 Hz, Allowable Limit is 2,500 uT (25 Gauss)
At 10-25 Hz. Allowable
Limit calculated as 5,000 / Frequency uT. E.g. at 10 Hz, Allowable Limit is 500 uT
At 25-300 Hz. 200 uT (2 Gauss)
At 10-25 Hz. Allowable Limit calculated as 5,000 / Frequency uT. E.g. at 10 Hz, Allowable Limit is 500 uT (5 Gauss);
At 25-300 Hz. 200 uT (2 Gauss)
These field strength limits refer to continuous exposure, and therapies typically last only several minutes each day, obviously much reducing exposure time. Also, these Allowable Limits do not take into account higher field strength tolerances of head, torso and limbs.
For therapies to be safe: Lower therapy frequencies allow higher
field strength PEMF therapy, and vice
versa, higher therapy frequencies require lower field strength to be used.
Two types of PEMF applications
Non-invasive PEMF therapy is provided via:
(1) Capacitative coupling. Opposing electrodes are placed in direct contact with the skin on either side of the area of interest.
(2) Inductive coupling. A time-varying magnetic field of a PEMF induces an electric field, which produces an electric current in body tissue without direct skin contact. This is the more common application.
Treatment duration times
Longer term exposures to PEMFs are associated with more successful results. (Persinger, 1974)
Treatment times can vary from ~20 mins to up to 10 hours / day. Depending on condition being treated and parameters being used.
Application methods for PEMF
Full body mat for complete body therapy
A full body mat allows you to relax during therapy. An encouragement for regular sessions.
Field needs to switch polarity about every 2 minutes. Prevents the body becoming immune to just one polarity.
Separate coils should be located at head/neck, torso/hips and legs/feet with EM field strengths increasing from the head towards the feet (Lower field strength coils have a lower number of wire turns). The head is sensitive, but the feet are tolerant of higher field strengths, since they are usually closer to the ground where the earth's geomagnetic field is greater. Wire mesh mats, E.g. on Bemer 3000, Medithera and QRS Quantron, boast a more uniform field via a single oval loop on their mats. However, since this yields the same field strength from head to feet, the electromagnetic field strength used is limited to what the head can tolerate. Mat coils are better when made of tightly wound copper.
Treatment session length. Treatment times on a PEMF therapy full body mat are typically less than 10 mins twice / day.
Wands, probes or pads
Usually have higher electromagnetic field strengths than a mat. This allows deeper penetration into body tissues and the ability to focus therapy on specific areas of need.
PEMF devices available
Adey, W.R. â€˜Frequency and Power Windowing in Tissue Interactions with Weak Electromagnetic Fields, Proceedings of IEEE 68, 119â€“125
Ganesan K, et al (2009) Low frequency pulsed electromagnetic field - A viable alternative therapy for arthritis. Indian J. of Exp. Biol. 47:939-948; Linknk
ICNIRP (2010) GUIDELINES FOR LIMITING EXPOSURE TO TIMEâ€VARYING ELECTRIC AND MAGNETIC FIELDS, P. 827. Table 4. Link
NASA Study (2003) PHYSIOLOGICAL A ND MOLECULAR GENETIC EFFECTS OF TIME-VARYING ELECTROMAGNETIC FIELDS ON HUMAN NEURONAL CELLS Thomas J. Goodwin, Ph.D. Lyndon 8. Johnson Space Center. Link to NASA Study
Persinger MA (1974), ELF electric and magnetic field effects: ELF Electric and Magnetic Field Effects: The Patterns and the Problems. p. 275. Link
PEMF - The Fifth Element of Health (2013) Bryant A. Meyers
Sandyk R (1992a): Clinical Case Report - Successful treatment of multiple sclerosis with Prewett TL, Goodwin TJ, Spaulding GF (1993): Three-dimensional modeling of T-24 human magnetic fields. J Neurosci 66:237-250