PEMF Waveform Explained

Every PEMF device produces pulses in a distinct shape, known as a waveform. This page explains how the shape of a magnetic pulse, whether square, sine, sawtooth, or triangle, affects how the field rises and falls, how energy is transferred, what slew rate is and how it influences performance, and how these differences impact the overall effectiveness of a PEMF device.
Scientist in lab

What is Waveform?

In PEMF, a waveform is simply the shape of the magnetic pulse over time. It shows how the magnetic field rises, falls, and repeats with each pulse. Every device produces a specific waveform, and the shape of that waveform determines how the field changes as it moves through each cycle. Below are four of the most common waveform types you’ll see used in PEMF devices: square, sine, sawtooth, and triangle waves. However you may see others. 


Each of these shapes can be used to create pulsed magnetic fields, but they behave slightly differently in terms of how quickly the field changes and how energy is transferred. That rate of change, how fast the waveform rises and falls, is what’s known as the slew rate, which we’ll look at in more detail next.

What is Slew Rate?

Slew rate describes how quickly the magnetic field changes during each pulse, in other words, it measures the speed of the rise and fall within the waveform. Two PEMF signals can have the same peak intensity but still behave very differently depending on how fast they reach that peak.


A good example of a waveform has a fast rise time, meaning the pulse reaches its maximum level almost instantly. This creates a steeper slope and a more effective change in the magnetic field. A poor example has a slow rise time, where the signal takes much longer to build up before peaking, resulting in a softer, shallower slope.

How Different Waveforms Affect the Body

When we look back through PEMF research, it becomes clear that not all waveforms behave in the same way when interacting with the body. Even when the frequency and intensity are similar, the shape of the pulse and how quickly it rises and falls, can lead to very different biological responses at the cellular level.


In one of the most well-known studies often discussed in the PEMF field, researchers compared how cells reacted to several waveform types: steady (static) fields, sine waves, triangle waves, delta/ impulse waves, and square waves. The results showed clear differences in how actively the cells responded depending on the signal shape. The static field (no pulsing) produced little to no response. The sine and triangle waves, which change gradually, showed only mild cellular activity. The impulse and especially the square wave, however, produced much stronger responses with the square wave resulting in the most pronounced cellular changes in the experiment.


This suggests that it’s not just the strength of the magnetic field that matters, but the way it changes over time. The sharper rise and fall of a square wave creates a more dynamic electromagnetic environment, which appears to better stimulate cellular processes compared with slower, smoother waveforms. Although the exact mechanisms are still being explored, this finding helps explain why many modern PEMF systems use pulse shapes designed to produce rapid, clean transitions rather than continuous or gently curving ones. In essence, the body seems to respond more actively to signals that switch sharply much like how our nervous and muscular systems naturally rely on quick, pulsed electrical activity.

How Important is Waveform/ Slew Rate?

When comparing PEMF systems, one question that often comes up is just how important slew rate really is and the answer is, very. Slew rate describes how quickly the magnetic field rises and falls with each pulse, and this rate of change directly affects how efficiently energy is transferred. A device with a high slew rate produces a sharper, more dynamic pulse that interacts more effectively with the body, even if the overall intensity is moderate. It’s often a more revealing indicator of engineering quality than simply looking at peak Gauss or Tesla figures.

Summary

Waveform is what gives PEMF its unique character, it shapes how the magnetic field rises, falls, and transfers energy into the body. Even when intensity and frequency are the same, the waveform can dramatically change how effectively those pulses interact with your cells.

 

Research suggests that sharper, cleaner pulse shapes, such as square waves with fast rise times, tend to produce stronger cellular responses than slower, continuous forms like sine or triangle waves. This is because a rapid change in the magnetic field (a high slew rate) induces more efficient microcurrents in the body.

 

In simple terms, intensity tells you how strong the field is, frequency tells you how often it pulses, and waveform shows how well that energy is delivered. A well-engineered waveform with a fast, controlled slew rate remains one of the most important hallmarks of a high-performance PEMF system.

FAQs

Why do PEMF devices use different waveforms?

Different waveforms change the magnetic field at different speeds and in different patterns. Each shape: square, sine, sawtooth or triangle has its own characteristics, and engineers choose them based on the type of pulse behaviour they want to achieve. We see more modern devices use square wave or simular while older devices tend to use sine waves. 

Do you want the fastest slew rate possible?

It might sound logical to assume that if a fast-rising PEMF pulse is good, then an even faster one must be better. But that’s not actually the case. Just like intensity or frequency, slew rate has an optimal range. Too low and the signal becomes weak and inefficient, too high and it can lose its balance or even become counter-productive.


Studies examining PEMF waveforms over the past few decades have shown that there is what engineers often call a “Goldilocks zone” a range that is just right. Research comparing different PEMF systems found that moderate-to-high slew rates, typically between 10 and 120 Tesla per second (T/s), were the most consistently effective at producing strong biological responses without overstimulation.


When the slew rate dropped below around 5 T/s, effects became minimal the pulses simply changed too slowly to create meaningful induction. On the other end of the scale, increasing the slew rate beyond 120 T/s didn’t continue to improve results and, in some studies, actually reduced them. One reason is that the field begins to change so quickly that it no longer couples efficiently with the body’s own bioelectrical processes.


So, when you’re looking at specifications, it’s not about chasing the highest number. What matters is that the device operates within this well-researched window, fast enough to be effective, but not so fast that it becomes inefficient or less stable. Think of it as finding the right rhythm rather than the fastest tempo.

Does a higher slew rate mean higher intensity?

No. Intensity (measured in Gauss or Tesla) refers to the strength of the field, while slew rate (measured in Tesla per second) measures how fast it changes. A device can have moderate intensity but still achieve a high slew rate if it’s designed to switch the field quickly.

Why don’t all companies list their slew rate or rise time?

Accurately measuring these values requires specialist tools such as an oscilloscope and Hall-effect probe. Some manufacturers don’t test or publish this data, focusing only on maximum field strength. Asking for measured slew rate or rise time gives a better idea of how advanced a PEMF system really is.

Explore PEMF Therapy Specifications

Polarity

This page explains what magnetic polarity means in PEMF therapy, the difference between unipolar and bipolar signals, and how the direction of a magnetic field can influence how your cells respond.

Learn more

Frequency

This page explains what frequency means in PEMF therapy, how it relates to the rhythm of pulsing magnetic fields, and why certain repetition rates are used to influence comfort, focus, and relaxation.

Learn more

Intensity

This page explains the different levels of PEMF intensity, what they mean, and how field strength influences depth, comfort, and overall performance.

Learn more
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