Shapes and frequencies of effective PEMF therapy waves
Wave shape
PEMF therapy devices produce time-varying* electromagnetic waves with a specific shape
A large NASA study determined that rapidly varying PEMF waveforms provided the most effective therapy. E.g. triangle, rectangular (includes square waves), saw-tooth or impulse. 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.
E.g. The SOTA magnetic pulser outputs an impulse wave, and its companion Silver Pulser outputs a square wave. IMRS mat outputs a sawtooth wave, and a square wave on the pad and probe. The OMI mat outputs a sinusoidal waveform, the Bemer 3000 has a complex, patented sinusoidal waveform.
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, where T is the time between pulses.
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.
Note: The impulse wave produced by SOTA magnetic pulser does not produce a constant frequency, but disperses a spray of different frequencies for each pulse averaging ~ 4 Hz.
(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) AND ELECTRIC FIELD (E)
Magnetic field strength (B) is measured in Tesla for large amplitude fields, and Gauss is used for smaller field amplitudes (such as the earth’s geomagnetic field of 0.5 Gauss). 1 Tesla = 10,000 Gauss; 1 Gauss = 100 microtesla (μT)
Electric Field (E) is 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)
Frequencies
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.
