Laser and light based therapies have the important roles in the aesthetic applications. But they are limited in the penetration depth, and may cause post-inflammatory hyperpigmentation for dark skin types. Radiofrequency penetrates much deeper to dermis and subcutis without injury of superficial skin structure to achieve satisfied facial rejuvenation and can be used for all skin types.

Monopolar radiofrequency (MRF) can reach deep soft tissue, and superior to the bipolar or “multipolar” counterparts. MRF is usually designed with a special capacitive coupled electrode membrane to make the energy disperse across the surface for volumetric bulk heating of deep soft tissue. With this design, RF can prevent the heat just limited on the contact surface and the risk of epidermal injury.

With the thermal effect, MRF can make the collagen contraction immediately and further stimulate more new collagen deposition (neocollagenesis). Edge effect is the nature of RF system which may cause uneven energy spreading of the treated surface. By some patented design, this effect can be adjusted. If we treat with some special techniques, the edge effect can be further minimized to get safer and more predictable therapeutic results.

By analyzing the heat transfer model of MRF, a partial differential equation composed of heat generation, conduction and convection can be obtained from Fourier’s law of heat conduction and Newton’s law of cooling. According to this equation, we can maximize the therapeutical safety and efficacy by controlling the generated heat and superficial skin cooling.

In previous study, multiple-pass, low-fluence settings are able to produce similar collagen contraction as single-pass, high-fluence technique. However, it was also well known that the exposure time should be tenfold for every 5 degree Celsius decrease in temperature to achieve the similar amount of collagen fibril alteration. With the safety monitoring of patient feedback on heat sensation, we can achieve the best results by using multiple-pass, high-fluence parameters with the aid of some concept of thermodynamics, such as “quasistatic” process.

With the analysis of mechanics, the delivered RF energy can be released in some vectors to cause immediate collagen contraction which can facilitate skin tightening right away, and further neocollagenesis will make the therapeutic effect better.

Putting the optimized techniques mentioned above together, the MRF can be much safer and more effective. We can have immediate off-table and long lasting skin tightening results.

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this work was not supported by any direct or non direct funding. it is under the author's own responsability