Why Sofwave goes only 1.5 mm deep: the middle of the dermis

Sofwave works at a single depth, 1.5 mm, while Ultherapy PRIME heats at 1.5, 3.0, or 4.5 mm depending on the transducer. This article explains why Sofwave keeps to the shallowest of those three.

1.5 mm is the dermis

The firmness and strength of your skin come from the dermis. In measurements of facial skin, the epidermis was under 0.1 mm thick and the dermis beneath it about 0.8 to 2 mm (Chopra 2015, PMID 26508650). Sofwave's target of 1.5 mm sits in the middle of that dermis (Liao 2026, PMID 41985490).

Sofwave heats that depth to improve fine lines, texture, and firmness. Among 36 people treated at 1.5 mm alone, the nasolabial folds and marionette lines were significantly shallower at 1 month, and the change held at 3 months (Hongcharu 2023, PMID 36757157).

The heat stays inside the dermis

Like other ultrasound devices, Sofwave puts heat only where it is aimed. Cylinders of coagulated tissue form 1.5 mm deep in the dermis. Some warmth spreads below that, but not enough to coagulate tissue. Biopsies in an animal study showed heat injury confined to the dermis (Carruthers 2025, PMID 41405933). That keeps the risk of hollowed cheeks low.

Ultherapy also has a 1.5 mm transducer, but the details differ. Unlike Ultherapy, Sofwave cools the skin surface during treatment (U.S. FDA 510(k) K223237), so it can use more energy and coagulate a wider zone. The volume of dermis heated at once is far larger than with Ultherapy's points of heat (Liao 2026, PMID 41985490).

Monopolar radiofrequency devices such as Thermage differ as well. They heat the dermis and the fibrous septa beneath it together, so the heat is not fixed at one depth (Suh 2020, PMID 32319176).

Fine lines soften and the skin firms up

Fine lines and loss of firmness come with age as collagen and elastin in the dermis decline. Sofwave heats the dermis so both fibers rebuild, and it suits mild to moderate skin laxity (Carruthers 2025, PMID 41405933; Liao 2026, PMID 41985490).

In a study of 60 people treated once for fine lines of the face and neck, 86% improved by 1 to 3 grades on a wrinkle scale at 12 weeks. None had side effects linked to the device (Wang 2021, PMID 34417390).

For how the device works, see How Sofwave tightens skin: parallel ultrasound heat at 1.5 mm. The comparison with Ultherapy is in Sofwave vs. Ultherapy: which layer each one treats. For help choosing between devices, see Ultherapy, Sofwave, or Thermage: which skin tightening treatment is right for you?.

References

1. Chopra K, et al. (2015). A comprehensive examination of topographic thickness of skin in the human face. Aesthet Surg J. PMID 26508650 (opens in new window).
2. Liao D, et al. (2026). Use of ultrasound in face and neck rejuvenation. Facial Plast Surg. PMID 41985490 (opens in new window).
3. Hongcharu W, et al. (2023). The efficacy and safety of the high-intensity parallel beam ultrasound device at the depth of 1.5 mm for skin tightening. J Cosmet Dermatol. PMID 36757157 (opens in new window).
4. Carruthers J, et al. (2025). Synchronous parallel ultrasound induces long-term extracellular matrix remodeling of human skin. Dermatol Surg. PMID 41405933 (opens in new window).
5. Suh DH, et al. (2020). Monopolar radiofrequency treatment for facial laxity: histometric analysis. J Cosmet Dermatol. PMID 32319176 (opens in new window).
6. Wang JV, et al. (2021). Efficacy and safety of high-intensity, high-frequency, parallel ultrasound beams for fine lines and wrinkles. Dermatol Surg. PMID 34417390 (opens in new window).
7. U.S. Food and Drug Administration (2022). 510(k) Summary K223237: SofWave System. accessdata.fda.gov.