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capacitive resistive monopolar radiofrequency: different frequencies?

Some concerns I have with the CRET therapy I would like to buy. I was able to analyze some recent research and I wanted to ask for clarification regarding my curiosity. All the research on this modality is based on a devices that work at a frequency of 448 khz, but there are several devices on the market that share the same technology that produce stimulation on several different frequencies (500 Khz 1000 khz etc.) Putting all the marketing statements aside, I could not find any scientific work concerning the effect of radiofrequencies up to 2 mhz on human tissues. the only article I found is this: In this article it is stated that with increasing frequency the permittivity decreases and the conductivity increases (except in the fat tissue that seems to have the opposite behaviour). How can we analyse this data using radiofrequency? can we say that as the frequency increases, the depth of stimulation penetration increases? or does the opposite happen? Are there any other scientific evidence regarding stimulation at 1 MHz? Thank you in advance for your attention Giovanni

8 months ago

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Prof Tim Watson
Prof Tim Watson

Hi. I have replied to another question on this topic - but your emphasis is a bit different to theirs - so I will add what I can. Essentially, there is a (theoretical) relationship between the frequency of the applied current and the (pure) penetration depth - standard stuff - BUT it is more complex than just resistance or impedance - so one starts looking at permitivity, admittance, conductivity, tissue dielectrics and associated issues. With the application of an RF current in the range up to 1MHz, and using a monopolar application method (where the is one active electrode and a grounding (or reference) electrode, there will be a current which passes through the tissues from one electrode to the other (certainly in resistive mode where the active electrode is bare metal). My personal view, based on the work that we have done, is that the resistive mode of application is likely to be the more important in terms of therapy effects/benefits

The current must travel through the tissues one way or another in order to get from electrode A to electrode B. The current will effectively disperse as it travels through the tissue - and will therefore be less concentrated the further away from the smaller active electrode one goes

I make no claims with regards my medical physics (I have some - but maybe not enough) so I will take the liberty of consulting with some of my colleagues and see if I can come up with a decent answer which fits the facts - whatever they might be

From our experimental work (at 448kHz), there is no doubt that the current does pass through the tissues and brings about significant physiological responses as it does so. From the experimental work of some of my colleagues, we are pretty sure that the effects at a cellular level do vary with the applied frequency (in the lab, in a petri dish). There is nothing in the evidence that I know of that fills the gap between these 2 factual positions at the present time

I will see what I can come up with



thank you for your answer, I already saw that article, but the system used in that report is a bipolar radiofrequency used for aesthetic purposes, I don't know if it shares the same mechanism that can be found on monopolar radiofrequency.

There are some questions that I can't answer 1) HOW HUMAN TISSUES RESPOND TO DIFFERENT FREQUENCIES? I found other sources that states that human tissue impendance (a measure of the opposition to electric current in an electric circuit) drops at high frequency (Electrotherapeutic Devices: Principles, Design, and Applications Artech House Author: George D. O'Clock) SOURCE: You can find it on this link, pages 51-55

On the other hand, we do have the famous skin effect SOURCE:

that causes the effective resistance of the conductor to increase at higher frequencies where the skin depth is smaller. The problem is that skin effect was studied on conductors, but the human body is not a copper wire, it's a resistor (at least in my point of view) and when electrical current passes through resistor THEORETICALLY This leads to the impedance dropping with increasing frequency. This is called the Boella Effect.

2)Does monopolar radiofrequency produce electrical current inside the body? monopolar radiofrequency is ,electrically speaking, a capacitor so it produces an inducted current inside the body so how does this circuit responds to different frequencies? This should question could be answered with the Capacitive Reactance phenomenon: the behaviour of a capacitor in a variable frequency circuit as being a sort of frequency controlled resistor that has a high capacitive reactance valuet very low frequencies and low capacitive reactance value at very high frequencies SOURCE:

So my conclusion is that the higher the frequency the deeper you stimulate, but, again this is just my theory, I would like to be proved wrong or right with real evidence

Thanks in advance


most studies till date have been performed with 448 kHz; there are a few studies using other treatment parameters;in my clinical experience frequency modulation might offer better therapeutical results. However this hypothesis also has to be studied. maybe this article can give you more insight : COREā„¢ Technology: Understanding Penetration Depths of Different RF Modes.

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