Of all of the methods used in the delivery of active ingredients in to the skin, Sonophoresis has much to offer to the contemporary skin treatment therapist.
The technology of using sound or sonic waves as a form of treatment has been around for a number of years, however this has been largely in the area of therapeutic treatment of deeper tissues by Physiotherapists using ultrasound.
The use of Sonophoresis in skin treatment therapy is to provide enhanced permeability of the skin.
This permeabilisation of the skin allows a far higher absorption of the active ingredients the therapist is attempting to infuse. The result will be both a more economical use of the therapeutic agents applied, and a greater response to the agent due to better penetration.
How does it work?
To understand how Sonophoresis works, we must first understand the mechanics of the lipid/water bi-layers in the stratum corneum. They act as one of the principal lines of barrier defense to protect the lower layers of the dermis. It is at this point many of the substances with high molecular weights are repelled.
This is due to the microscopic gaps between the lipid heads of the bilayers being too small to allow them through.
Unfortunately, many of the active ingredients used in skin treatment therapy are complex molecular formulations, and fail to fully pass through this protective layer due to the alternating layers of lipid & water performing their functions correctly.
Sonophoresis acts by temporarily reducing the density of lipids in the intercellular domain of the bi-layers. This disruption occurs due to a combination of micromechanical, thermic and cavitation effects that effectively open up the intracellular pathways, allowing substances with high molecular weights a higher degree of penetration. These openings are known as Lacunae.
With this combination of activity in the intercellular domains, the first question that arises is how safe is this and is there any damage caused? It is true that uncontrolled Sonophoresis can cause excessive thermic reactions, however all modern devices use microprocessor control to limit power output, timing, and set the specific frequencies used, so when used with the correct technique of continual sonicator head movement, there is no side-effect damage to the epidermis.
In this regard, sonophoresis is a safe to use as electrolysis and iontophoresis. However, as with all electromechanical devices used to treat the skin, training in the correct operation and techniques is imperative.
The history of sonophoresis
Ultrasound has been used since the 70s to enhance penetration through the skin, and in the mid 1990s, extensive research was conducted to find attractive alternative delivery systems to injections and oral Medications. A number of these studies focused on facilitating transdermal permeability of various medicinal substances (e.g., insulin) by low frequency (20-25Khz) sonophoresis (LFS).
During clinical evaluation of the effectiveness of sonophoresis, experiments demonstrated that a significant fraction (~30%) of the intercellular lipids of the stratum corneum, were displaced or removed during the application of low-frequency sonophoresis, increasing the skins permeability by up to 800%.
It was this initial research that provided the data for the sonic frequency, safe power output levels and the design of the sonicator heads to develop the devices currently used.
Sonophoresis is a viable and highly effective method to permeabilise the skin. When used alone or in combination with iontophoresis, it is a favorable infusion procedure for the modern skin treatment therapist wishing to achieve maximum results for their clients with a minimum of discomfort.
Many professional skin care companies already have a range of products suitable for use with sonophoresis, with the leading exponents producing their own proprietary sonophoresis devices.
- Sonophoresis has been shown to be effective in the formation of microscopic aqueous channels (Lacunae) through the bilayers of the epidermis.
- The optimum frequency range of the sonic waveform to achieve this is in the region of 20-25Khz with power outputs of less than 125mW/cm2. This waveform is pulsed for very short periods (typically 100ms) usually once per second.
- Sonophoresis has been shown to be even more effective when combined with iontophoresis, with further spectacular increases in the efficiency (up to 4000%) of active ingredient absorption in to the lower levels of the epidermis.
About the Author
Florence Barrett-Hill is an internationally acclaimed dermal science educator, practitioner, researcher and author with a vast experience covering all aspects of professional aesthetic therapy and paramedical skin care. Florence holds over a dozen diplomas and international qualifications covering every aspect of modern skin treatment therapy, and is well respected by her industry peers for her 30+ years of knowledge she loves to share.
Florence is the programme director of Pastiche Resources, an Internationally recognised postgraduate beauty industry education provider.