Research Showing Slew Rate is the Key Therapeutic Component of a PEMF Signal.
So the place I saw slew rate mentioned was in a patent by Thomas Goodwin. His patent mentions that rise time and fall time should be tuned. I reached out to him to see if I could pay him to consult on the ideal slew rates. He put a lot of effort into it at NASA and it would be great if the ideal slew rate didn't have to be re-discovered. I also asked NASA directly about it but they wanted $2500 for the additional information, then royalties on sales afterwards
https://ppubs.uspto.gov/dirsearch-public/print/downloadPdf/8795147
Another study that lists rise and fall time
https://journals.plos.org/plosone/article/figures?id=10.1371/journal.pone.0061414
High Slew Rate but not too high.
https://www.sciencedirect.com/science/article/abs/pii/S8756328220305494
Another study that mentions slew rate
BOB DENNIS RABBIT STUDY-- Conclusion
The key parameter for biological effectiveness of PEMF was determined to be magnetic slew rate (dB/dt), and the minimum threshold of this parameter for clinical effectiveness for regeneration of bone tissue after orthopedic injury was found to be ~ 100 kG/s. This magnetic slew rate, when sustained for 100 μs at a pulse rate of 10 Hz, was found to be effective both for pain reduction as well as to induce bone regeneration in a critical defect gap
https://www.josam.org/josam/article/view/27/25#:~:text=The%20optimal%20magnetic%20waveform%20slew,%3D%3E%20100%20kG%2Fs
Summarizing the results listed it sounds like rise times of 30t/s are more effective than 100t/s, and 2t/s are better than 1t/s
Here is another that specifically mentions dB/dT:
https://pubmed.ncbi.nlm.nih.gov/28238117/
and more support for slew rate importance if your viewers want more:
https://pubmed.ncbi.nlm.nih.gov/35834942/
And another for slew
https://pubmed.ncbi.nlm.nih.gov/34872332/
Area of Usefulness
I've been doing a lot of calculations, and if the ideal rise time is between 2 and 30 t/s, then a coil design that keeps that range is fairly difficult to design. Next to the coil there will be a rise time faster than 30t/s and 8" away the rise time will be below 2t/s. This makes every coil have an "area of usefulness" where the rise time is between the two extremes (this is obviously something where more research would be helpful). It almost make sense to make the "area of usefulness" tunable so that people can set it close to the coil for surface wounds, and far from the coil for deeper treatments
At the surface of the mat, the field goes from 0mT to let's say 5mT In let's say 100uS. This represents a 50T/S rate of change. On the same mat, 8" above the surface, the field goes from 0mT to 0.5mT in the same amount of time, so the rate of change is only 5T/S. The best coil design will spread the rate of change out as evenly as possible
----
Here is a paper that says the Nasa PEMF Studies showed that high rise time is critical:
https://onlinelibrary.wiley.com/doi/full/10.1002/jcp.21025
Pulsed therapeutic fields are usually more effective if less than 30 gauss (see Curie's Law and dipole saturation), and frequencies are commonly less than 100 Hz, below which they are referred to as extremely low frequency (ELF). Cell phones are several magnitudes of order larger in both considerations.
Both studies indicate rise time (dB/dt) as a critical determinant of efficacy, a characteristic not previously cited in a literature dominated by field strength, frequency, and duration.
----
Too much slew rate makes permeable
https://www.researchgate.net/figure/The-waveform-of-the-high-dB-dt-magnetic-field-pulse-Each-magnetic-pulse-was-15-s-wide%C2%A7fig1%C2%A7316490221
this one shows the waveform used and the measured electrical signal near a neuron:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7689717/
Here is an article showing that a low slew rate PEMF device used in a clinical trial was not effective:
https://www.sciencedirect.com/science/article/abs/pii/S0031938417303876
Obviously these are much higher voltages than you would want to have in your body, but it demonstrates the effect well and here is a study that shoes its better for bones to have the higher slew rate
https://boneandjoint.org.uk/Article/10.1302/2046-3758.1012.BJR-2021-0274.R1/pdf
Summarizing the results listed it sounds like rise times of 30t/s are more effective than 100t/s, and 2t/s are better than 1t/s
Avoiding Higher Frequency Carrier Waves?
This is one of the reasons I'm leary of kilohertz or megahertz carrier waves for PEMF. Low frequency electrical stimulation of nerves has a regenerative effect, whereas high frequency can make nerve damage worse
I have a preliminary product designed and as well as the coil. I get a field of about 200ut about 12" above a 12" coil so the depth of field is really good
3mT limit ?
This article makes it look like I should limit the field strength to under 3mt for maximum effectiveness. Have you heard that before?
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6902701/
Here is the specific quote "Of relevance, it has been recently shown that applied low-frequency magnetic fields in the range of 1 mT are capable of radical-pair amplification generated by flavin-tryptophan moieties, whereas amplitudes exceeding the hyperfine nuclear interactions limit (∼3 mT) are inefficient at doing so (62), perhaps giving insight as to the origin of the myogenic efficacy amplitude ceiling of the pulsing magnetic fields described in this report (Supplemental Fig. S3)"
So the place I saw slew rate mentioned was in a patent by Thomas Goodwin. His patent mentions that rise time and fall time should be tuned. I reached out to him to see if I could pay him to consult on the ideal slew rates. He put a lot of effort into it at NASA and it would be great if the ideal slew rate didn't have to be re-discovered. I also asked NASA directly about it but they wanted $2500 for the additional information, then royalties on sales afterwards
https://ppubs.uspto.gov/dirsearch-public/print/downloadPdf/8795147
Another study that lists rise and fall time
https://journals.plos.org/plosone/article/figures?id=10.1371/journal.pone.0061414
High Slew Rate but not too high.
https://www.sciencedirect.com/science/article/abs/pii/S8756328220305494
Another study that mentions slew rate
BOB DENNIS RABBIT STUDY-- Conclusion
The key parameter for biological effectiveness of PEMF was determined to be magnetic slew rate (dB/dt), and the minimum threshold of this parameter for clinical effectiveness for regeneration of bone tissue after orthopedic injury was found to be ~ 100 kG/s. This magnetic slew rate, when sustained for 100 μs at a pulse rate of 10 Hz, was found to be effective both for pain reduction as well as to induce bone regeneration in a critical defect gap
https://www.josam.org/josam/article/view/27/25#:~:text=The%20optimal%20magnetic%20waveform%20slew,%3D%3E%20100%20kG%2Fs
Summarizing the results listed it sounds like rise times of 30t/s are more effective than 100t/s, and 2t/s are better than 1t/s
Here is another that specifically mentions dB/dT:
https://pubmed.ncbi.nlm.nih.gov/28238117/
and more support for slew rate importance if your viewers want more:
https://pubmed.ncbi.nlm.nih.gov/35834942/
And another for slew
https://pubmed.ncbi.nlm.nih.gov/34872332/
Area of Usefulness
I've been doing a lot of calculations, and if the ideal rise time is between 2 and 30 t/s, then a coil design that keeps that range is fairly difficult to design. Next to the coil there will be a rise time faster than 30t/s and 8" away the rise time will be below 2t/s. This makes every coil have an "area of usefulness" where the rise time is between the two extremes (this is obviously something where more research would be helpful). It almost make sense to make the "area of usefulness" tunable so that people can set it close to the coil for surface wounds, and far from the coil for deeper treatments
At the surface of the mat, the field goes from 0mT to let's say 5mT In let's say 100uS. This represents a 50T/S rate of change. On the same mat, 8" above the surface, the field goes from 0mT to 0.5mT in the same amount of time, so the rate of change is only 5T/S. The best coil design will spread the rate of change out as evenly as possible
----
Here is a paper that says the Nasa PEMF Studies showed that high rise time is critical:
https://onlinelibrary.wiley.com/doi/full/10.1002/jcp.21025
Pulsed therapeutic fields are usually more effective if less than 30 gauss (see Curie's Law and dipole saturation), and frequencies are commonly less than 100 Hz, below which they are referred to as extremely low frequency (ELF). Cell phones are several magnitudes of order larger in both considerations.
Both studies indicate rise time (dB/dt) as a critical determinant of efficacy, a characteristic not previously cited in a literature dominated by field strength, frequency, and duration.
----
Too much slew rate makes permeable
https://www.researchgate.net/figure/The-waveform-of-the-high-dB-dt-magnetic-field-pulse-Each-magnetic-pulse-was-15-s-wide%C2%A7fig1%C2%A7316490221
this one shows the waveform used and the measured electrical signal near a neuron:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7689717/
Here is an article showing that a low slew rate PEMF device used in a clinical trial was not effective:
https://www.sciencedirect.com/science/article/abs/pii/S0031938417303876
Obviously these are much higher voltages than you would want to have in your body, but it demonstrates the effect well and here is a study that shoes its better for bones to have the higher slew rate
https://boneandjoint.org.uk/Article/10.1302/2046-3758.1012.BJR-2021-0274.R1/pdf
Summarizing the results listed it sounds like rise times of 30t/s are more effective than 100t/s, and 2t/s are better than 1t/s
Avoiding Higher Frequency Carrier Waves?
This is one of the reasons I'm leary of kilohertz or megahertz carrier waves for PEMF. Low frequency electrical stimulation of nerves has a regenerative effect, whereas high frequency can make nerve damage worse
I have a preliminary product designed and as well as the coil. I get a field of about 200ut about 12" above a 12" coil so the depth of field is really good
3mT limit ?
This article makes it look like I should limit the field strength to under 3mt for maximum effectiveness. Have you heard that before?
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6902701/
Here is the specific quote "Of relevance, it has been recently shown that applied low-frequency magnetic fields in the range of 1 mT are capable of radical-pair amplification generated by flavin-tryptophan moieties, whereas amplitudes exceeding the hyperfine nuclear interactions limit (∼3 mT) are inefficient at doing so (62), perhaps giving insight as to the origin of the myogenic efficacy amplitude ceiling of the pulsing magnetic fields described in this report (Supplemental Fig. S3)"
Scientists that disagree with Dr. Pawluk
Slew rate more important than intensity
https://www.nature.com/articles/srep33537
Slew rate more important than intensity
https://www.nature.com/articles/srep33537
Here is clear research showing that the db/dt is directly connected to the induced voltage in your body:
https://www.researchgate.net/figure/Distribution-of-the-induced-electric-field-during-highest-dB-dt-of-the-5-5-coil_fig3_277683544
https://www.researchgate.net/figure/Distribution-of-the-induced-electric-field-during-highest-dB-dt-of-the-5-5-coil_fig3_277683544
It has a power supply that keeps it at full power (still trying to source a variable power supply without dirty output).
At full power the coil gets slightly warm, but if you take measurements with the hall probe or your h field probe I am guessing it will reach farther than anything else you have right now. I did a lot of experimenting to try and find the smallest delta (as opposed to devices that are high intensity at the coil but it drops off really fast in a few inches)
At full power the coil gets slightly warm, but if you take measurements with the hall probe or your h field probe I am guessing it will reach farther than anything else you have right now. I did a lot of experimenting to try and find the smallest delta (as opposed to devices that are high intensity at the coil but it drops off really fast in a few inches)
Sawtooth on magnetic magic
My electric square wave is turned into a magnetic sawtooth because of the inductance of the coil and the configuration of the circuit. The magnetic field rises fast and falls slowly
My electric square wave is turned into a magnetic sawtooth because of the inductance of the coil and the configuration of the circuit. The magnetic field rises fast and falls slowly
Spectral content
After watching the video, it seems pretty clear that they are focused specifically on the results of the fourier transform. There are many ways to get the results to have a similar "spectral content", but the results can easily be manipulated depending on how you set up the parameters of the spectrum analyser.
I would want to see biological evidence in vitro that there enhanced "spectral content" is any better than a high slew rate square wave. If Bob Dennis is correct, there is likely not much difference in how the cells react
imagine that these different balls with different frequencies (the lengths being different and the weights assumed to be the same) represented different molecules resonant frequencies. If you hit them all at once each one will swing at its own resonant frequency. This would correspond to the square wave.
Then imagine that you could push each one at exactly the right time to keep them swinging. This would correspond to a high spectral distribution
Each should have an effect, but it would take some testing to see which is better. I personally like the square wave best still because it just lets everything resonate at it's own frequency naturally instead of forcing it
After watching the video, it seems pretty clear that they are focused specifically on the results of the fourier transform. There are many ways to get the results to have a similar "spectral content", but the results can easily be manipulated depending on how you set up the parameters of the spectrum analyser.
I would want to see biological evidence in vitro that there enhanced "spectral content" is any better than a high slew rate square wave. If Bob Dennis is correct, there is likely not much difference in how the cells react
imagine that these different balls with different frequencies (the lengths being different and the weights assumed to be the same) represented different molecules resonant frequencies. If you hit them all at once each one will swing at its own resonant frequency. This would correspond to the square wave.
Then imagine that you could push each one at exactly the right time to keep them swinging. This would correspond to a high spectral distribution
Each should have an effect, but it would take some testing to see which is better. I personally like the square wave best still because it just lets everything resonate at it's own frequency naturally instead of forcing it
**To Properly Measure Intensity you need a high speed hall effect sensor**
I purchased 10 high speed hall effect sensors from digikey the other day. If you like I can send one to you. They will make very similar lines on your oscilloscope, but they have the advantage of being able to measure the actual strength of the field. It outputs 65mV per millitesla. It would be great to see a video showing which mat has the most uniform field. Based on my calculations the field is going to be well above the "safe" limits at the surface of the mat if they make 500uT 10" above the mat.
I purchased 10 high speed hall effect sensors from digikey the other day. If you like I can send one to you. They will make very similar lines on your oscilloscope, but they have the advantage of being able to measure the actual strength of the field. It outputs 65mV per millitesla. It would be great to see a video showing which mat has the most uniform field. Based on my calculations the field is going to be well above the "safe" limits at the surface of the mat if they make 500uT 10" above the mat.
Dr Pawluk Uses this Study to Determine how much intensity is needed to create 15 gauss in the body using the inverse square law.
https://www.medicalrent24.it/wp-content/uploads/2018/02/44-Effects-of-electrical-physical-stimuli-on-articular.pdf
Watch starting here:
https://youtu.be/XypkgXgbNAQ?si=SEQLq_jRYberD6si&t=1169
file:///Users/bryantmeyers1/Downloads/I-ONE_therapy_in_patients_undergoing_total_knee_ar%20(1).pdf
https://www.medicalrent24.it/wp-content/uploads/2018/02/44-Effects-of-electrical-physical-stimuli-on-articular.pdf
Watch starting here:
https://youtu.be/XypkgXgbNAQ?si=SEQLq_jRYberD6si&t=1169
file:///Users/bryantmeyers1/Downloads/I-ONE_therapy_in_patients_undergoing_total_knee_ar%20(1).pdf
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Slew Rate
One way of measuring the quality of a sensed signal is to look at the slew rate. The slew rate refers to the slope of the intrinsic signal (Figure 8) and is measured in volts/second.
In electronics, slew rate is defined as the change of voltage or current, or any other electrical quantity, per unit of time. This is similar to Faraday's law as it shows how rapidly a signal rises and falls.
In other cases, a maximum slew rate is specified in order to limit the high frequency content present in the signal, thereby preventing such undesirable effects as ringing or radiated EMI.
One way of measuring the quality of a sensed signal is to look at the slew rate. The slew rate refers to the slope of the intrinsic signal (Figure 8) and is measured in volts/second.
In electronics, slew rate is defined as the change of voltage or current, or any other electrical quantity, per unit of time. This is similar to Faraday's law as it shows how rapidly a signal rises and falls.
In other cases, a maximum slew rate is specified in order to limit the high frequency content present in the signal, thereby preventing such undesirable effects as ringing or radiated EMI.
Biphasic shocks are more effective than monophasic shocks and need lesser energy. Typically when 360 Joules are delivered for defibrillation in a monophasic defibrillator, 200 Joules are given in a biphasic defibrillator.
The proposed mechanism is that a single monophasic wave of energy is not able to depolarize all the myocardial cells. Some cells close to the electrode gets too much energy while those away from the electrode gets too little. Reversing the polarity helps to sweep off these cells as well. This response is sometimes called a ‘burping’ response of a biphasic waveform.
A prospective randomized evaluation compared monophasic and biphasic wave forms in 22 survivors of out of hospital cardiac arrest during implantation of a cardioverter defibrillator [1]. Of the patients, 15 (68%) had lower defibrillation threshold with biphasic pulse.
The proposed mechanism is that a single monophasic wave of energy is not able to depolarize all the myocardial cells. Some cells close to the electrode gets too much energy while those away from the electrode gets too little. Reversing the polarity helps to sweep off these cells as well. This response is sometimes called a ‘burping’ response of a biphasic waveform.
A prospective randomized evaluation compared monophasic and biphasic wave forms in 22 survivors of out of hospital cardiac arrest during implantation of a cardioverter defibrillator [1]. Of the patients, 15 (68%) had lower defibrillation threshold with biphasic pulse.