Sylfirm X vs Secret RF vs Infini for Acne Scars

Written by Dr Gerard Ee | Medically reviewed by Dr Gerard Ee | Expert opinion by Dr Gerard Ee

Dr Gerard Ee is an aesthetic doctor and the founder and medical director of The Clifford Clinic, which he established 14 years ago. He has treated acne scars for 16 years and more than 2,000 acne-scar patients, and is one of Singapore’s longest-standing users of the Infini RF microneedling system (16 years). He holds a Diploma in Dermatology (Cardiff) and is a Member of the Royal College of Surgeons (MRCS). More on Dr Gerard Ee.

Sylfirm X, Secret RF and Infini are often recommended in the same breath, as though interchangeable. They are not equivalent devices, and the differences between them are mechanical rather than a matter of brand. They sit at different points on the power spectrum and suit different patients, and for depressed acne scars that difference decides the result. The following compares them against their FDA-cleared figures and sets out the decision logic used in clinic. It builds on the opinion of Sylfirm X for scars. Having used Infini for sixteen years, I have found these systems separate on whether the acne is still active and how deep the scars sit.

 

The three devices at a glance

Sylfirm X

Sylfirm X uses non-insulated, dual-wave needles, FDA-cleared under K213612 to a maximum of 16 W at 50 Ω. It is precise and well suited to melasma, redness and pores, but that power ceiling limits it for deep remodelling. Patients often ask for it by name, and for a depressed scar it may not be the appropriate option.

Secret RF

Secret RF uses non-insulated needles, FDA-cleared under K170325 to 25 W at 500 Ω, with depth up to 3.5 mm. Its non-insulated needles pass through and calm the oil gland, the reason it is preferred for acne-prone skin. That advantage applies to skin still breaking out rather than to deep remodelling.

Infini

Infini uses insulated needles, FDA-cleared under K121481, reaching up to around 50 W with its 49-pin handpiece. The insulation concentrates energy deep while sparing the surface, giving high usable energy with a strong safety margin, the preferred choice in darker skin. Insulation counts only where the scar is deep enough to need it.

 

The numbers side by side

Each figure is the manufacturer’s FDA-cleared maximum at its stated reference impedance, so the three are not an identical-conditions measurement, though each remains the device’s official maximum and the fairest basis for comparison. Sylfirm X’s own marketing lists its power as confidential while its FDA filing records 16 W. Of the patients who consult me having already chosen a device, many compared the three on marketing material rather than on the cleared figures.

 

How the choice is made

Specifications set the ceiling, but the selection follows the patient rather than the table. The first question in any scar consultation is whether the acne is still active. Where it is, Secret RF is the appropriate choice because it calms the oil gland, often combined with AGNES on the same day for acne-prone skin. Where the skin is clear but the scars are deep, particularly in a darker skin tone, Infini is favoured for its deep, surface-sparing energy. Where scars are tethered, subcision comes before any RF. Sylfirm X, within this framework, is the device for pigment and pores rather than for deep scars. In my experience that question changes the device more often than the scar type does, because many patients continue to break out while believing the acne has settled.

 

Darker skin and keloid tendency

For Fitzpatrick IV to VI skin, insulated Infini is generally safest because it spares the epidermis. Fractional CO2 remains usable in these patients but is delivered at lower energy. A keloid tendency is not by itself a contraindication to treating atrophic scars, though an established keloid cannot be resurfaced by RF. More detail is in the dark skin guide. Safest of the three is not the same as free of risk, and a minority of darker-skinned patients still develop transient pigmentation after a correctly delivered session.

What the trials say, and the insulated-versus-non-insulated rationale

Beyond the headline power figures, the comparative literature explains the sequencing of these devices. Fractional RF microneedling is supported as effective and well tolerated for acne scars (systematic review), and a randomised trial found microneedle fractional RF improved both acne and acne scars partly by acting on the sebaceous glands, the clinical basis for using non-insulated Secret RF in acne-prone skin (RF mechanism RCT). For darker skin, the safety record of fractional RF even in skin type VI supports the use of insulated Infini (type VI study).

The insulated-versus-non-insulated distinction is therefore physical rather than promotional, since insulated needles concentrate energy deep while sparing the surface, which matters most where the risk of pigmentation is highest. Read alongside the FDA power figures, the trial evidence supports using each device where its design fits. No trial has tested these three systems against one another, so the comparison rests on mechanism and cleared output.

 

What the research shows

A systematic review of 16 studies and 481 patients found fractional RF microneedling effective and well tolerated for acne scars (systematic review), and the category is reported as safe even in Fitzpatrick type VI skin (type VI study), which is why insulated Infini is preferred for darker skin. The recurring finding across the device literature is that adequate energy at adequate depth drives scar remodelling, the reason the FDA power figures above carry weight.

 

Where the comparative trials place each device

The comparative trials position these devices within the wider range of scar treatments. Non-insulated RF microneedling matched ablative CO2 laser on efficacy with less pigment and less downtime in a split-face study (radiofrequency versus CO2 trial). A picosecond laser matched CO2 on ECCA scores with far fewer adverse effects (picosecond versus CO2 trial), and the 2022 international consensus positions these energy devices as complementary, selected by scar type and skin type (consensus recommendations). Read against this evidence, the distinction between Sylfirm X, Secret RF and Infini is not one of brand but of position on the power spectrum from gentle precision to deep energy.

 

Insulated versus non-insulated, in depth

The single most important design difference among these devices is insulation. Insulated needles are coated along their length and expose only the tip, concentrating energy deep in the dermis while largely sparing the epidermis. This permits high usable energy at depth with a strong safety margin, valuable in darker skin. Non-insulated needles deliver energy along the whole shaft, producing a broader interaction that includes the upper layers. That is gentler on the deep dermis but passes through and influences the oil gland, the reason non-insulated Secret RF suits acne-prone skin. Neither design is superior in the abstract. Each design is matched to a different clinical goal, and the choice follows the scar rather than the specification sheet. Across sixteen years with the insulated system I have found the difference shows most in deep atrophic scarring, where energy must reach the base of the scar without heating the surface.

Needle configuration and depth

The devices also differ in needle configuration and reach. Infini uses an insulated handpiece, commonly in a 49-pin configuration, delivering energy at depths up to around 3.5 mm. Secret RF uses non-insulated needles that also reach around 3.5 mm. Sylfirm X uses non-insulated needles with an adjustable depth from 0.3 mm to 4.0 mm. Needle number and arrangement balance coverage against precision, but for deep scars adequate depth with adequate power decides the outcome. Depth alone settles nothing, since Sylfirm X reaches the greatest nominal depth while delivering the least power.

 

Why the power figures use different impedances

Radiofrequency power depends on the impedance of the tissue it passes through, so manufacturers state maximum output at a reference impedance. Sylfirm X’s 16 W is cleared at 50 Ω and Secret RF’s 25 W at 500 Ω, so the two were not measured under identical conditions. That is a fair caveat, but each figure remains the device’s official maximum as recorded in its FDA clearance, and together they are the most objective basis available. The caveat limits the precision of the comparison without closing the distance between a 16 W ceiling and one of around 50 W.

 

Frequency and what it means

All three devices operate within the same general range, at around 2 MHz. Operating frequency influences how energy couples with tissue, but within this class of device clinical outcome is driven far more by maximum power, insulation and depth than by frequency. The comparison here therefore rests on those three factors rather than on the frequency specification. Frequency is quoted often in marketing and rarely changes what a patient sees at three months.

 

Pain, downtime and session profiles

In day-to-day use the three devices feel broadly similar to the patient. All are performed under topical numbing, with heat and pressure rather than sharp pain, and all typically leave redness for one to three days. Non-insulated devices may produce slightly more superficial warmth, while insulated devices concentrate their effect deeper. Downtime is comparable, and each is delivered as a course of several sessions spaced roughly four to six weeks apart. The differences that matter for scars lie in depth and energy rather than in the patient experience. When a patient tells me a previous course produced nothing, the explanation is usually an underpowered device or sessions crowded closer together than that interval allows. A minority of patients find the deeper passes uncomfortable even after adequate numbing, and moderating the depth reduces what the session achieves.

 

A practical decision guide

Translating this comparison into a decision is straightforward. Where the acne is still active, Secret RF is the choice because it calms the oil gland, often combined with AGNES on the same day. Where the skin is clear but the scars are deep, especially in a darker skin tone, Infini is favoured for its deep, surface-sparing energy. Where scars are tethered, subcision comes first and no radiofrequency energy substitutes for it. Where the concern is melasma, pigmentation, redness or pores, Sylfirm X is the appropriate device. Most patients receive a combination rather than a single device. The patients least satisfied with a previous course, in my experience, were treated with one device across every scar type on one face.

 

Why compare by mechanism, not brand

Brand prestige and marketing do not determine scar outcomes. The mechanism-level factors determine them, namely maximum power, treatment depth, needle insulation and needle type. A sound comparison therefore maps each device’s design onto the task it is asked to perform, rather than ranking brands. The three devices are instructive because they illustrate the spectrum from gentle, pigment-focused treatment to high-energy, deep structural remodelling, the range a complete scar plan draws on. The same framework places any new device, from its cleared power, depth and needle design.

 

Other RF microneedling devices in context

Sylfirm X, Secret RF and Infini are not the only microneedle radiofrequency systems available, and patients regularly ask how the others compare. Devices such as Genius, Morpheus8, Vivace and the combined Secret Duo platform each have their own needle designs, depths and power characteristics. Rather than learn every brand, it is more useful to ask three questions of any of them, which are the cleared maximum power, the depth the needles reach, and whether they are insulated. These mechanical factors, rather than the marketing name, determine whether a device suits gentle pigment work or deep structural remodelling. The purpose is not to rank one brand above the others but to set out a framework of power, depth and insulation applicable to whatever device a clinic uses. The commonest error I see in a previous treatment plan is a device chosen because the clinic already owned it.

 

The bottom line

Where the concern is melasma, redness, pigmentation or pores, Sylfirm X is the most appropriate of the three. Where the goal is to remodel depressed scars, Secret RF or Infini is the starting point, within a combination plan. For patients who have tried Sylfirm X without results, see why you may not be getting results. Stated plainly, Secret RF is the device where the acne is active, Infini where it has settled and the scars are deep, and Sylfirm X where the concern is pigment. None of the three removes depressed scarring completely, and a course on the correct device may improve the scars substantially rather than erase them. Across sixteen years I cannot reliably predict at the first consultation how far a patient will improve.

 

Frequently Asked Questions

Is Sylfirm X or Infini better for acne scars?

For depressed scars, Infini is the better of the two, because its insulated needles deliver deep energy at up to around 50 W (K121481), whereas Sylfirm X is a 16 W device (K213612) better suited to melasma, pigment and pores. Sylfirm X remains more appropriate where the concern is pigmentation rather than scar depth.

Is Secret RF more powerful than Sylfirm X?

Secret RF is the more powerful of the two by FDA clearance. It is rated to 25 W (K170325) against Sylfirm X’s 16 W (K213612). Secret RF also calms oil-gland activity, the reason it is preferred for acne-prone skin. Both sit well below Infini’s ceiling of around 50 W.

Which RF device is safest for dark skin?

Insulated Infini is the safest of the three in dark skin, because the insulation spares the epidermis while delivering deep energy, which lowers the risk of post-inflammatory hyperpigmentation. A lower risk is not an absence of risk, so energy is matched to scar depth and sessions are spaced four to six weeks apart.

How is the choice made between subcision and RF microneedling?

Subcision and RF microneedling are usually combined rather than chosen between. Tethered rolling scars need subcision first to release the bands, after which RF remodels the collagen. Subcision therefore comes before RF wherever the scars are deep and tethered. Where the scars are not tethered, subcision adds nothing.

Key references

• Fractional radiofrequency microneedling as monotherapy in acne scars: systematic review. PubMed.
• Safety and efficacy of fractional radiofrequency facial treatment in skin type VI. PubMed.

Comparative trials cited

• Qu L, Sha S, He C, et al. Non-insulated microneedle fractional radiofrequency versus ablative fractional CO2 laser for facial atrophic acne scars: pilot randomised split-face study. Acta Derm Venereol. 2025. PubMed.
• Yuan Y, He Y, Fang J, et al. Fractionated 1064 nm picosecond laser with holographic optics versus fractional CO2 laser for atrophic acne scars: randomised split-face study. Int J Dermatol. 2025;64:85-91. PubMed.
• Salameh F, Shumaker PR, Goodman GJ, et al. Energy-based devices for the treatment of acne scars: 2022 international consensus recommendations. Lasers Surg Med. 2022;54:10-26. Journal.

Device specifications & sources

• S. FDA 510(k) Summary K213612 (SYLFIRM X, ViOL Co., Ltd.): Output power Max 16 W at 50 Ω. 2 MHz. Bi-polar RF.
• S. FDA 510(k) Summary K170325 (Secret RF, Ilooda Co., Ltd.): Max power Max 25 W at 500 Ω. 2 MHz. Needle depth 0.5-3.5 mm.
• S. FDA 510(k) K121481 (INFINI, Lutronic Inc.): insulated RF microneedling system, 49-pin handpiece, maximum RF generator output approximately 50 W.

 

Written, medically reviewed and expert opinion by Dr Gerard Ee, aesthetic doctor and Founder & Medical Director of The Clifford Clinic. This article reflects my clinical experience treating acne scars in Singapore and is intended for general education, not medical advice. Treatment suitability, results, downtime and cost vary from person to person. Please arrange a consultation for advice specific to your skin.