Radiofrequency Lifting: Monopolar vs Bipolar — What's the Difference?

Lifting Series ② — Where the current flows decides how deep the heat goes

In the previous article I described radiofrequency (RF) as a lift that builds heat "as a surface" in the dermis. But every RF device description mentions monopolar and bipolar. Why is the same radiofrequency divided in two? Here is the explanation I give in the consultation room.

Heat forms where the current has travelled

Radiofrequency passes current through tissue, and the tissue's resistance to that current produces heat. So where the current enters and where it exits is exactly where the heat forms and how deep it goes. That single point is the entire difference between monopolar and bipolar. It is also why some devices attach a pad to your back and others do not.

Monopolar — deep, through the body

Current leaves the tip, travels through the body, and returns to a grounding pad on the back. Because the current passes deep into the body, heat reaches the deep dermis. It has strong power to remodel collagen and restore firmness, and it produces a correspondingly strong sensation of heat. Thermage works this way, and so does Density's Classic tip.

Bipolar — shallow, only between two electrodes

One tip holds two electrodes side by side, and current flows only between them. There is no grounding pad. The current does not travel deep; it stays roughly half the electrode spacing deep, in the superficial dermis. Heat spreads evenly near the surface, which suits texture, fine lines and surface firmness, and it is more comfortable because there is less stimulation. In exchange, its power to lift deep sagging does not match monopolar.

At a glance

	Monopolar	Bipolar
Current path	Tip → through the body → pad on the back	Only between the two electrodes in the tip
Grounding pad	Required	None
Depth reached	Down to the deep dermis	Superficial dermis (about half the electrode spacing)
Character of heat	Deep and strong	Shallow and even
Best suited to	Sagging, deep firmness, collagen remodelling	Texture, fine lines, surface firmness
Stimulation · heat	Considerable (anaesthesia · cooling needed)	Mild
Examples	Thermage, Density Classic tip	Density Boost tip

Putting both in one tip

Devices that combine monopolar and bipolar to fire in a single pass have been appearing recently. The idea is to treat both the deep and the shallow layers at once. Monopolar is "deep and strong", bipolar is "shallow and even", so delivering both from one tip handles the deep and superficial layers in the same spot in one go. This is why Density offers several kinds of tip, and how those tips are used is the subject of the last article in this series.

At ReYeonK, thicker skin with deep sagging leans toward monopolar; thin, sensitive skin leans toward the option that includes bipolar. Which is right is decided by looking at the skin.