HIFU vs RF vs microwave: how each energy works

HIFU vs RF vs microwave: the short answer

HIFU, radiofrequency (RF) and microwave all use energy to heat tissue under the skin, but they deliver it differently and reach different targets. HIFU focuses ultrasound into tiny heated points at a set depth, which suits lifting early sagging. RF heats the dermis as an electrical current meets the skin's natural resistance, which suits tightening, texture and, through microneedles, scars. Microwave concentrates heat in the fat layer and its fibrous bands while the surface is cooled, which suits body contouring.

• HIFU (focused ultrasound): precise points at chosen depths, used for the jowls, jawline, brow and under-chin.
• RF (radiofrequency): broader heating of the dermis and the bands that tether it, used for laxity, crepey skin, pores and scars.
• Microwave: heating focused in fat and connective tissue, used for pinchable fat, cellulite and mild laxity on the body.
• HIFEM: not heat at all, but a magnetic field that makes muscles contract, used for muscle tone.

In each heat-based treatment, warmth tightens existing collagen and acts as a controlled injury signal, so most of the change builds over the following weeks rather than on the day. That is also why these treatments are usually planned as a short course with reviews, not judged after one session.

At SkinRev Lab, some of these treatments are non-medical sessions performed by Aesthetic Therapists and others are medical treatments performed by Dr Sin Yong. The devices behind the spa treatments are described on the technology page, and the sections below explain each energy in plain language.

How focused ultrasound (HIFU) works

HIFU, also called microfocused ultrasound, converges ultrasound energy on small points below the surface and heats each one briefly until the tissue coagulates, while the skin surface is spared. A 2015 review described these thermal coagulation points as smaller than a cubic millimetre, placed at depths of up to about 5 mm in the deep dermis and the layer beneath, where the heat contracts collagen and stimulates new collagen. It found the method most suited to mild to moderate laxity, with surgery a better route for severe laxity, and listed discomfort during treatment, transient redness, swelling and occasional bruising as the main side effects.

SkinRev offers two kinds of focused ultrasound:

• Medical HIFU, performed by Dr Sin Yong, uses interchangeable cartridges that commonly focus at 1.5 mm (upper dermis), 3.0 mm (deep dermis) and 4.5 mm, the support layer a surgeon tightens in a facelift. Sessions take about 30 to 60 minutes, downtime is usually mild redness, swelling or tenderness for a few hours to a few days, and it is priced at consultation.
• SKINLIFT®, performed by Aesthetic Therapists, uses N Pulse-Ultrasound to deliver multi-sequential pulses to the deeper support layers without breaking the skin. A session takes about 30 minutes, with no needles and no numbing; it is designed to be comfortable, although bony areas such as the jawline can feel stronger. Face is S$888 (excludes eyes and neck) and Double Chin S$488 per session, before GST.

SKINLIFT® is not the same as medical HIFU. Where laxity is deeper, the medical treatment is the closer fit.

How radiofrequency (RF) works: monopolar, microneedle and microplasma

Radiofrequency heats tissue by passing an alternating electrical current through it, and the tissue's resistance turns that current into heat. Because RF heating does not depend on a pigment target, a review of RF devices noted that melanin in the skin surface is not what absorbs the energy, so RF can be used across skin types. The heat contracts collagen and starts a healing response that remodels it, which is why RF is used for mild to moderate laxity. RF devices differ in how the current reaches the tissue:

• Monopolar RF sends current from a treatment tip to a return pad elsewhere on the body, heating a broad volume of dermis and the fibrous septa beneath. VF Lift (6.78 MHz, water-cooled tip) applies it along planned vertical vectors for early to moderate sagging and jowls, with redness on the day and some jawline tenderness for one to three days.
• Microneedle RF releases RF through fine needles at a set depth. RF microneedling treats pores, scars, stretch marks and crepey skin, with redness and mild swelling for one to three days; 4K Body Lift uses insulated needles for small, stubborn fat pockets and the skin above them.
• Microplasma RF forms a plasma discharge from pins just above the skin. SKINTIGHT® (Alma PrimeX, 40.68 MHz) creates tiny surface channels and warms the dermis for crepey or loose skin, texture and pores, at S$588 per zone before GST.
• RF with ultrasound: Svelte Touch delivers both at once for early jowls and mildly heavy eyelids.

SKINTIGHT® is performed by Aesthetic Therapists; the other RF treatments are performed by Dr Sin Yong.

How microwave body contouring works

Microwave contouring uses electromagnetic waves at a far higher frequency than RF, measured in gigahertz rather than megahertz, to concentrate heat in the fat layer and its fibrous bands while cooling keeps the skin surface comfortable. Heat-damaged fat cells are cleared by the body over the following weeks, and the warmed connective tissue responds too, which is why microwave is used for pinchable fat, cellulite and mild laxity. It is neither a laser nor radiofrequency.

• SKINSHAPE® uses Miglou UHF microwave technology and is performed by Aesthetic Therapists. A session takes about 30 minutes per area, with cooling and no needles, at S$288 per 15 × 15 cm area per session, before GST; a full tummy is usually two areas. There is no planned downtime, and people usually carry on with their day.
• Onda Pro uses 2.45 GHz microwaves with contact cooling and is performed by Dr Sin Yong within a medical assessment, which makes more sense when fat, cellulite and laxity overlap or medical factors need checking. Skin is usually pink and warm for a few hours, with tenderness for a few days, and it is priced at consultation.

Microwave contouring is not a weight-loss treatment and does not treat visceral fat, the fat around the organs. It suits people near a stable weight with pinchable areas. The evidence is still developing: SkinRev's own treatment pages note that published microwave body-contouring studies are small, used other 2.45 GHz devices and had short follow-up. For Onda Pro, progress is reviewed with photos and measurements over the course.

Muscle stimulation (HIFEM and EMS): muscle, not heat

High-intensity focused electromagnetic (HIFEM) treatment does not heat tissue: a rapidly changing magnetic field triggers repeated, involuntary muscle contractions. It is used for muscle tone, not for fat loss or skin tightening. A small MRI study of 22 adults measured a thicker abdominal muscle layer and a thinner fat layer after four HIFEM sessions, with no adverse events reported; as a single-group study, its authors called for further research.

• SKINSCULPT® uses HIFEM through a 36 cm applicator for the buttocks, tummy, thighs, underarms and pelvic floor. Sessions take about 30 minutes per region, fully clothed, at S$288 per region before GST. Mild muscle soreness the next day is common. It is performed by Aesthetic Therapists.
• SKINGLIFT® combines external radiofrequency warmth with electrical muscle stimulation (EMS) to support pelvic floor muscle tone and intimate comfort. Daily activities resume the same day, avoiding intercourse and strenuous exercise for 24 to 48 hours. It is performed by Aesthetic Therapists, with the price given on WhatsApp, and it is not a treatment for urinary incontinence.

Not every device in this family uses heat or muscle stimulation. SKINLDM® uses alternating ultrasound frequencies as a micro-massage rather than as heat, for sensitive, redness-prone or reactive skin, and most clients return to their day with little visible reaction. It shows that “ultrasound” on a treatment menu can mean very different things, from deep focused heating to a gentle surface massage, so it is worth asking what a device actually does.

Laser heat and cold: Time Freeze Laser LCLR® and fat freezing

Two other energy treatments work on similar targets with different physics: laser light used as deep, even heat, and controlled cooling.

• Time Freeze Laser LCLR® uses long-pulsed 755 nm and 1064 nm laser light, scanned across a zone as bulk heating rather than in fractional dots, so the surface stays intact. The heat tightens existing collagen, and new collagen then forms over about four to eight weeks. It is used most often on the jowls, jawline, neck and double chin, takes about 45 minutes for the full face and neck, and usually has no downtime, though zones where fat was targeted may feel tender for a day or two. Dr Sin Yong performs it, and SkinRev notes that no published study has tested this exact protocol.
• Fat freezing (cryolipolysis) relies on fat cells being more sensitive to cold than the skin, nerves, muscle and vessels around them. A 2015 systematic review of 19 studies found that it reduced localised fat with mostly mild, short-term side effects. Redness, swelling, tenderness and numbness can last from days to a few weeks, the effect of a cycle is judged at about twelve weeks, and normal activity can generally resume the same day. Dr Sin Yong performs it.

Both are priced at consultation, after examination. Because they reach the same areas as HIFU, RF and microwave, Dr Sin Yong will explain at consultation why one is suggested over another for your face or body.

HIFU vs RF vs microwave compared

Each energy reaches a different target, with different downtime. The table compares them, with the SkinRev treatment and who performs it.

Which energy suits which concern?

The energy is matched to the concern and how deep it sits, which is why an assessment comes before any device. As a rough guide:

• Early jowls or a softening jawline: focused ultrasound (SKINLIFT® for mild to moderate jowls, medical HIFU where laxity is deeper) or monopolar RF (VF Lift).
• Crepey skin, texture or enlarged pores: microplasma RF (SKINTIGHT®) or RF microneedling.
• Acne scars or stretch marks: RF microneedling, often within a wider medical plan.
• Double chin: SKINLIFT® Double Chin, SKINSHAPE®, Time Freeze Laser LCLR® or VF Lift, depending on whether fat or loose skin is the main cause.
• Pinchable body fat or cellulite: microwave (SKINSHAPE®, Onda Pro), 4K Body Lift or fat freezing.
• Weak muscle tone: HIFEM (SKINSCULPT®).

Energy treatments do not suit everything. None replaces surgery for heavy, loose skin or a large fold of excess skin, none is a weight-loss treatment, and lost volume is a job for filler rather than energy. Tell the team about pregnancy, implants, skin conditions and medicines before any session so that suitability can be checked.

Many people have more than one cause at once, for example some loose skin and a small pocket of fat under the chin. In that case the plan may combine two energies spread over months, or start with one and review. Sometimes the honest answer is that no treatment is needed yet, and you will be told so.

Spa sessions or doctor-led: how SkinRev splits energy treatments

At SkinRev Lab, energy treatments fall into two groups: non-medical sessions performed by Aesthetic Therapists at the aesthetic centre, and medical treatments performed by Dr Sin Yong after a consultation.

• Performed by Aesthetic Therapists: SKINLIFT®, SKINSHAPE®, SKINTIGHT®, SKINSCULPT®, SKINLDM® and SKINGLIFT®. Prices are published before GST, except SKINGLIFT®, which is priced on WhatsApp enquiry; you pay for the session you book, and a course is estimated at consultation rather than sold as a fixed upfront package.
• Performed by Dr Sin Yong: HIFU, VF Lift, Svelte Touch, RF microneedling, 4K Body Lift, Onda Pro, Time Freeze Laser LCLR® and fat freezing. These are priced at consultation, once he has examined you.

Dr Sin Yong is SkinRev's medical adviser and trains the therapists hands-on with the treatment devices, but he does not perform SKINLIFT® or SKINSHAPE® sessions. If an Aesthetic Therapist sees a concern that belongs with a doctor, you are told at the first visit and offered a consultation with Dr Sin Yong, with no obligation to take it up.

Every plan starts with an assessment, not a package. You will be told which energy suits your concern, how many sessions are likely, what the downtime looks like and what it costs before anything is booked. To start, WhatsApp SkinRev Lab on +65 8266 9585 with a short description of your concern. SkinRev Lab is at #B1-28 CityLink Mall, connected to City Hall MRT by an underground walkway, and open daily from 11am to 8pm, including public holidays.