Criteria for an effective device for PEMF (pulsed electromagnetic field) therapy

See information at following link to better understand PEMF waves

Wave shape and frequency of PEMF waves

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.

Conclusions for criteria for effective PEMF therapy

Waveform

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.

Frequencies

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).

Sun's Electromagnetic radiation

Electromagnetic field (EMF) strength

PEMF therapy using LOW electromagnetic field strengths has established its effectiveness.

The NASA study used pulsed electromagnetic fields (PEMFs) at 1-20 µT.  

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. 

When using PEMF therapy LONG-TERM  (E.g. for regular maintenance), EMF strength (AMPLITUDE) should probably be in line with those of the NATURAL EMFs 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 cannot 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.

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 (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.

References

Adey, W.R.  Frequency and Power Windowing in Tissue Interactions with Weak Electromagnetic Fields, Proceedings of IEEE 68, 119-125

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 TIME‐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

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