Monopolar or bipolar RF machine?
What is best for skin tightening?
A very common question I am asked is what is the difference between unipolar, monopolar, bipolar and multipolar (i.e. tripolar, tetrapolar, octipolar) radiofrequency? Which one is best for skin tightening?
First of all, let's make it clear: there are only two poles in electricity: plus and minus. That's basic Physics from high school. So all these names (tripolar, tetrapolar, octipolar whatever-polar) are a misnomer and a little bit of a gimmick, especially when it comes to eight poles, which is an overkill and unnecessary (more on that later). Let me first explain what is monopolar and bipolar, and then I will move to multipolar and unipolar.
But to answer the question on the title of this paragraph, let me just say that for both deep and superficial skin tightening, monopolar radiofrequency wins hands down.
What is monopolar radiofrequency?
In monopolar RF the (+) and (-) poles are located quite far apart from each other. As a result, the current has no other choice but to traverse through ALL skin layers after entering the skin, travel through the body to the other pole, and exit there.
This means that with monopolar RF, and depending on some other factors too, we can treat not only the skin surface (epidermis) but also the middle skin layer (dermis), the deepest skin layer (hypodermis/subdermis) and even the subcutaneous fat deposits below the skin itself.
As I mentioned above, how deep we treat depends on some other factors too, not just on bipolar/monopolar arrangement. However, in most setups monopolar RF allows us the opportunity to go quite deep. Unfortunately this is not the case with bipolar RF, which is restricted to quite superficial treatment, no matter what gimmicks are used to make the current "go deeper".
This is the reason that we do not use bipolar/multipolar RF at our clinic, even though our machine provides that option. We don't even use bipolar RF for superficial treatment, e.g for acne, as we can fine-tune our monopolar machine to work superficially in a much better way than bipolar can ever do.
What is bipolar radiofrequency?
With bipolar radiofrequency the plus (+) and minus (-) poles are located very close to each other - too close for deep treatment.
Because the poles are close to each other (in most machines they are almost adjacent to each other), the current has no other choice but to briefly and superficially penetrate the skin (as little as one millimetre (i.e. the maximum depth of epidermis) and then exit the skin again from the other pole, not very far from where it entered. Quite often the "trajectory" of the current spans just the epidermis.
This means that if we want to properly treat the dermis (and even more so if we want to treat the hypodermis or subcutaneous fat), we must first literally burn the epidermis, which is in the way and absorbs almost all of the current. Because nobody would even want to burn the epidermis, treatment intensity is adjusted at lower levels. This keeps the epidermis happy but deeper skin layers are not treated properly.
Epidermal heating gives the impression of a very strong treatment, with lots of redness and quite often irritation, and there is some superficial tightening. However, not much collagen/elastin production is stimulated in the dermis/subdermis below and definitely no cellulite fat or deep fat reduction (which is located even deeper) ever occurs.
If intensity is increased, in order to work on deeper skin layers and produce some skin firming/lifting, the epidermis is burned/irritated and/or severe pain is experienced, hence some of these burn pictures and extreme pain stories in review websites.
Indeed there are gimmicks such as numbing creams, surface cooling and vacuum suction, to provide deeper treatment with bipolar RF. However, none of those really work well and they also have their own problems: numbing creams cover the intense pain and increase the likelihood of tissue injury/burning; there really is no point providing superficial cooling to avoid excess superficial heat, as the two negate each other and the whole exercise is just a waste of energy; and vacuum suction causes skin stretching/loosening, thread/spider veins and in addition does not allow for the use of active ingredients, which if used can enhance the skin tightening effects of radiofrequency.
In a few words, bipolar RF is just too superficial. Period.
Tripolar, tetrapolar, octipolar and other multipolar radiofrequency
As I mentioned earlier, there are only two poles in electricity. So how come there exists a tripolar radiofrequency machine?
The answer is simple: with tripolar radiofrequency, there are three electrodes, with the two poles (the plus and the minus), always alternating between the three electrodes. At any given time one of them is a minus, the other is a plus and the other is inactive.
With tetrapolar RF, the two poles alternate between four electrodes, with two being inactive at any given time. With octipolar it is two active and six inactive. And so forth...
In theory, this alternation of poles results to more uniform and/or deeper heating. In practice, all you would need to produce deeper heating would be to move just two pole apart - you don't need all this multipolar gimmick. And in any case, you would still not go as deep as with monopolar. With regard to heating uniformity now, this is also pointless. With almost all RF treatments the therapist continuously moves the handpiece, which provides plenty of uniformity without the need of all those "poles".
All in all, I find multiple poles a marketing gimmick. Of course the manufacturers of these machines would disagree. But Physics is Physics. Monopolar means going through all skin layers, while bipolar/multipolar means staying largely on the surface. In nature, electrical current, or any other energy potential differential, will choose the shortest possible distance to travel. Simple.
Unipolar RF is also another form of bipolar. With bipolar RF the two poles are located next to each other, as in left and right. With unipolar RF one pole is in the centre, while the other pole is around the first pole (this is called a coaxial arrangement).
Whatever I said about bipolar and multipolar RF applies to unipolar too: it is too superficial. The current will seek the shortest possible distance to travel through the skin, and as the poles are so close to each other, no matter what gimmick is employed, the current will travel superficially.
Machines with monopolar and bipolar options
Luckily, the better machines on the market offer two or more choices: monopolar or bipolar (or any of the varieties, mentioned above). If you are a practitioner and bought one of those machines, my advice is to just use monopolar. Focus on it, train on it and use it well, and it will be much better than any bipolar arrangement, even if you wish to offer very superficial treatment.
If you are a client, I would definitely advise you to go for monopolar. Some bipolar machines may work well for some applications, but in three words, "monopolar is king".
If monopolar is so much better, why do bipolar machines exist?
The reason is simple: cost. Monopolar machines need to employ higher intensities, as they heat the skin deeply. This means bulk, heavy weight, almost no portability and cost. You can't find a good monopolar machine for less than £20,000.
On the other hand, you can make a pretty cheap, small, light and portable bipolar machine which is also called "radiofrequency" machine for as little as £700, while useless "home use" bipolar machines can cost as little as £200. Since the public does not know the difference and thinks all radiofrequency machines do the same thing, you get the main idea behind bipolar machines.
Due to just superficial heating, even a cheap bipolar machine, may in some cases appear to be very hot and powerful and impress the client, while in reality it is not so powerful at all, and does not treat the deeper skin layers. Obviously, you should not expect much in the way of results from those, either for your clients, as practitioner, or for yourself, as a client.
How do I know what kind of RF treatment I am receiving?
The answer is very simple. If a metal or self adhesive pad is used to connect you to the machine, then you are having a monopolar RF treatment. If your only contact with the machine is the operator handpiece, then you are having a bipolar-type treatment.
Deep/superficial RF treatment: important, but not the whole picture
Of course, depth of treatment is not the only important thing in radiofrequency, neither it is only affected by the arrangement of poles, and these are subjects that we I am discussing in other parts of this guide.