Key facts
- Circuit
- Current passes from one active tip through the body to a return pad; bipolar devices keep the circuit between two electrodes on the handpiece
- Frequency
- 6.78 MHz on Thermage FLX and on the CLASSYS Volnewmer
- Heating
- Volumetric bulk heating of the dermis and subdermal fibrous septa, with surface cooling
- Response
- Immediate contraction of existing collagen fibres, then remodelling as fibroblasts lay down new collagen over months
- Not
- Focused ultrasound, which places discrete thermal points at set depths down to the SMAS
What is monopolar radiofrequency?
Radiofrequency is electrical energy that warms the deeper skin through resistance in the tissue rather than through light. Monopolar describes the circuit: a single active electrode in the treatment tip delivers the current, which travels through the body to a grounding or return pad, usually on the back or abdomen. Because the current must pass through the tissue beneath the tip to complete the circuit, the heat is generated in depth, through the dermis and the fibrous septa below it, rather than only at the surface.
The result is volumetric heating: a broad, bulk warming of the dermis and the tissue immediately beneath it, reported as effective to roughly 4.3 mm depending on the treatment tip and technique, while cryogen or contact cooling protects the epidermis. Collagen fibres contract when heated, and over the following months fibroblasts respond by laying down new collagen. Nothing is focused, because the target is the layer as a whole.
How is it used in aesthetic medicine?
Its natural territory is dermal laxity: skin that is thinning, crepey or loosely draped, where the problem is distributed through the layer rather than concentrated at a structural plane. Thermage FLX, a monopolar, capacitively coupled 6.78 MHz device, is used for mild to moderate laxity of the face, eyelids, neck and body, and Dr Sin Yong's approach to it is set out on the Thermage page. Most people describe deep heat during each pulse, with transient redness and warmth afterwards.
VF Lift – Vertical Facelift is his own protocol on the CLASSYS Volnewmer, also 6.78 MHz monopolar radiofrequency, planned zone by zone along vertical vectors and calibrated per zone toward laxity, excess puffiness or hollowing. It is radiofrequency only and does not use focused ultrasound. Monopolar radiofrequency and focused ultrasound pair logically rather than compete: one conditions the dermal envelope as a volume, the other places points of heat at a structural depth.
“HIFU or radiofrequency is the wrong question. They do not do the same job.”
Dr Sin YongOn why the two energies are not rivals
What is it often confused with?
The commonest confusion is with HIFU and Ultherapy. High-intensity focused ultrasound converges acoustic energy to discrete points at set depths, down to the SMAS layer a facelift tightens, leaving the tissue between points unheated. Monopolar radiofrequency spreads heat broadly through the dermis. One is an awl, the other an iron; they are different jobs, which is why asking which is better is the wrong question.
It is also distinct from other radiofrequency formats. Bipolar radiofrequency keeps the circuit between two electrodes on the handpiece, so the current travels a shorter, shallower path and no return pad is needed. RF microneedling delivers radiofrequency from needle tips placed in the dermis at a set depth, with limited surface involvement. Each reaches a different depth in a different way; the word radiofrequency alone does not say which is meant.
When is it not the answer?
Monopolar radiofrequency does not remove excess skin, and a face whose real issue is volume loss is not helped by heating it harder; deflation is refilled, not lifted. Laxity concentrated at the structural layer argues for depth rather than volumetric heating, and established descent with skin excess is a surgical problem referred to a plastic surgery specialist. Thermage in particular does not address fat distribution or volume, which is where protocols built on different mechanisms come in.
Because the current passes through the body to a return pad, monopolar radiofrequency is not used in anyone with a cardiac pacemaker, implantable defibrillator or other implanted electronic device. It is postponed during pregnancy and over skin that is infected, broken or inflamed, including an active cold sore or an eczema flare in the treatment area. Metal implants in or near the area and recent filler or threads are reviewed individually before any plan is made.
