Low Frequency Ultrasonic Delivery of Active Ingredients to the Skin

Application of ultrasound waves at 20KHz (20,000 cycles per second) has been shown to increase penetration of ingredients up to several thousand fold[i]. The frequencies of ultrasound used in medical treatments at 1-3MHz (1-3 million cycles per second) are largely ineffective. Salicylic acid, amongst other ingredients tested, showed increased penetration by a factor of up to 300 times.

One of the main functions of the skin is to protect us from the environment. The skin is very effective at providing a barrier to the entry of external compounds. The skin barrier is provided mainly through lipids (oils) in between cells in the surface layer of the skin, the stratum corneum. Lipids are impermeable to compounds containing molecular charges.
Think of how water and oil don’t mix. In many cases only a fraction of the ingredients we apply to the skin in cosmetics eventually enters the skin. Part of the art of formulating active skin care products is including technology within the product to enhance penetration. However, penetration rates approaching that provided by low frequency sonophoresis cannot be achieved by penetration enhancers in skincare products.

We are now using low frequency sonophoresis at 20KHz of vitamins C and A as a stand alone treatment and after many of our facial treatments such a light peels and microdermabrasions.
As the frequency of 20KHz is just above the top of the range of hearing occasionally a soft high pitched sound can be experienced during the treatment. The only other sensation is that of warmth.
Treatments take about 30 to 45 minutes. Makeup can be worn afterwards and patients can return straight to work. Application of these vitamins will lighten abnormal skin discolouration and plump up the dermal layer of the skin with new collagen and ground substance to fill out and tighten wrinkles and firm the skin. 

i] Mitragotri S et al, Transdermal drug delivery using low frequency sonophoresis, Pharm Res Mar; 13(3): 411-20, 1996

More information on sonophoresis here