While a few of the following technologies may be out of the scope of licensing for the aesthetician, it is worthwhile to understand their effects on skin tissue since the skin care field has expanded into more advanced methodologies in cosmetic enhancements for the face and body. It is important for professionals to gain clarity about what actually occurs during the controlled thermal wounding process of collagen, as well as the less-invasive modalities of iontophoresis, microcurrent, and LED. Because the skin care professional may be involved with pre- and post-care, they should be mindful of how to make correct treatment choices for skin that has been temporarily compromised through a thermal or chemical treatment.

Advanced methodologies for the use of modern technology begin with an all-encompassing, innovative education. An in-depth study of skin sciences, morphology and underlying cause of skin conditions, intrinsic and extrinsic aging, immune and inflammatory responses, wound healing, cellular electrical pathways (signaling and communications), and barrier function collectively build the scaffolding required for critical thinking that supports the process of creating a pathway for correction. Moreover, the application of heat, chemicals, or any electrical devices also require an understanding of proper use and potential skin responses.

Professionals should become familiar with how each device affects the skin tissue because there is a difference between skin reactions with non-invasive therapies (non-laser), LED, and microcurrent in comparison to the thermal effect (high destructive heat – thermolysis) of laser/IPL, which creates controlled-tissue destruction – such as in hair reduction or the treatment of vascular lesions.

THE CELL ELECTRIC
The topical application of electrical and thermal devices influence the physiology and biology of the skin, no matter how minimum the treatment. Moreover, cells create their own fluctuating electrical fields for cellular activities. Topical procedures may cause an immune and/or wound-healing response, including interference with the barrier function, even if it is only temporary.

The body's microcurrent allows for the precise regulation of the opening and closing of membrane channels that influence cell function under normal and pathological conditions.2 The harmonious flow of these electrical signals is essential to the healthy function of each cell, including cell-to-cell communication. The professional can equate cells to miniature batteries that are conductors of electricity, create energy fields, and are powered by a very low level of electrical current or microcurrent.3 They conduct electricity for the purpose of cell-to-cell communication and intercellular activities. Cells polarize and depolarize through a unique electrochemical process in order to perform numerous functions. The nervous system, muscles, and cell membranes are activated and operated by an internal voltage.

A unique bipolar membrane surrounds each cell and serves as a medium that separates intracellular and extracellular fluids. Imbedded in this membrane are protein channels that allow for the movement of nutrients and cellular wastes in and out of the cell. The opening and closing of these channels are carefully regulated in order to influence cell function under normal and pathological conditions. Single molecules, or complexes of molecules, within the channels allow for the passage of positively- and negatively-charged atoms (ions), such as sodium, potassium, chloride, and calcium. The voltage difference in electrical potential across cell membranes is called the membrane potential and arises from the interaction of ion channels and ion pumps that are embedded in the membrane.3 These channels and pumps maintain different ion concentrations on the intracellular and extracellular sides of a cell membrane.

AESTHETIC TECHNOLOGY
Most devices that are applied in the world of aesthetic improvement began in the field of medicine. However, the discoveries and study of electrical phenomena have been in existence for many centuries. Thermal devices, such as ablative lasers, have been used in surgical settings since the 1970s. Cosmetic lasers were also pioneered in the United States and Russia during the 1970s, with Kumar Patel inventing the CO2 laser with flexible wavelength technology. Since the 1990s, the use of thermal devices (photodynamic therapy), CO2, IPL, and fractional laser continue to evolve into modern times. Known as thermolysis, they create a controlled wound effect within the tissue – denaturing of collagen – in order to combat the effects of photoaging, wrinkles, and other anomalies. Photodynamic therapies create cosmetic improvements for wrinkles, pigmentation, vascular lesions, and port wine stains and are also used in hair reduction. They are classified as medical devices and are used by qualified, licensed medical personnel.

UNDERSTANDING THE SKIN BARRIER
It is essential to become familiar with the mechanisms of the lipid-water bilayers within the intercellular space between the stratum corneum layers. The fundamental functions of the bilayers are to protect internal water from evaporating and act as a barrier against bacteria, viruses, and other foreign interlopers. The acid mantle and the stratum corneum layers remain a principle line of barrier defense, ultimately protecting both epidermal layers and the dermis. The barrier bilayers are vital to normal skin function and protection. The delivery of cosmetic actives requires increased skin permeability. The use of iontophoresis or sonophoresis can enhance this process.

ULTRASOUND
Ultrasound technology uses sound waves at specific frequencies to create physical changes in the skin by temporarily reducing the density of lipids within the intercellular spaces. This occurrence is achieved by generating micromechanical oscillations that generate acoustic waves, heat, and cavitation (microchannels).5 Known as Lacunae, cavitations are produced through generating low frequency sound waves that create alternating regions of compression and expansion, forming aqueous channels that are about 100 microns in diameter. The bubbles instantly implode, causing a heating effect.6 Ultrasound helps to improve the metabolism of cells, promotes the synthesis of protein within cells, supports regeneration of wounded tissue, and assists in the reduction of inflammation.

Sonophoresis
The penetration of a product by ultrasound is known as sonophoresis. Sonochemistry is the interaction of sound and matter through the process of cavitation.4 Low frequency sonophoresis increases the transpermeability of the skin in order for it to absorb active ingredients. It has been used as a delivery system for medications and as a nonionizable alternative for skin care actives. Sonophoresis may be used in skin tightening aesthetic therapies, the improvement of cellulite, ultrasonic cleaning of the skin, and may also be used in combination with iontophoresis.

Lontophoresis
Iontophoresis requires water-soluble, polarizable ingredients through which charged ingredient molecules are able to transport and penetrate into the skin via a direct current and process of ionization.

Sonophoresis has been shown to be more effective when combined with iontophoresis, showing an increased efficiency of active ingredient absorption by up to 4,000 percent, hence complementing the application of iontophoresis.6

RADIO FREQUENCY
Radio frequency refers to electromagnetic waves within the radio wave portion of the electromagnetic spectrum. In medicine, conventional, continuous radio frequency is a high-frequency, alternating current that creates coagulative necrosis to target tissue.7 Tissue destruction occurs with a probe temperature between 60 and 80 degrees Celsius.7
In aesthetic medicine, radio frequency has been introduced to cause shrinking and tightening of skin tissue through the mechanism of collagen denaturation (controlled wounding). When radio frequency is applied to tissue, the rapid oscillation of electromagnetic energy causes movement of charged particles through the tissue. Known as an endothermic process, this molecular motion is absorbed as heat in the surrounding internal tissue, skin layers act as electrical current resisters, thus heating up to varying degrees.

Newer cosmetic radio frequency devices have been used to remodel several areas of the body and may help create a positive, restorative effect on the lymphatic system and the adipose/connective tissue. These devices are specifically manufactured for aesthetic use on the thighs, arms, and abdominal circumference and for sagging skin, the apparence of cellulite, and the stimulation of
fat metabolism.

LASER
Lasers convert light energy into heat through a process called selective photothermolysis. Unlike radio frequency, the laser must be attracted to a chromophore, such as melanin, blood, or water. For example, the chromophore in a hair follicle is melanin, whereas the chromophore in a vein is blood. When performing laser rejuvenation, the chromophore is water. With laser, the tissue's electrical resistance converts the electric current to electromagnetic thermal energy deeper into the dermis. Because lasers are
chromophore-specific, there is a risk of destroying epidermal melanin, especially in darker skin types, including Asian skin.

THE EFFECTS OF TEMPERATURE ON SKIN TISSUE
Although temperature affects the underlying cells in the dermis, the degree to which it affects those cells is dependent upon the device used and the treatment goals. During a controlled wounding process, temperature influences the level by which collagen becomes denatured.

Collagen molecules are produced in fibroblasts, the cells in the dermis that manufacture collagen, elastin, and ground substance. Fibroblasts make collagen by creating three polypeptide chains that wrap around one another, forming a triple helix. When radio frequency or other thermal devices are applied to the skin, dermal collagen is heated and produces a denaturing of the triple helix. The cross-links become broken, causing them to transform into a gel-like state, also known as denaturation. The cumulative effects of unwinding the links of the triple helix cause a wound response and subsequent tissue remodeling by the formation of new collagen. The exact heat-induced behavior of connective tissue and the result of tissue shrinking are dependent upon several factors, including the degree of temperature created within the tissue, the amount of exposure time, and the hydration level in the tissue.

BIOSTIMULATION WITH MICROCURRENT
As far back as World War II, microcurrent was used by Japanese physicians to fuse non-healing bone fractures.9 Further research with microcurrent during the 1970s and 1980s – in Europe and the United States – demonstrated its clinical effect for the accelerated healing of injured cells. Dr. Reinhold Voll developed the first commercial microcurrent stimulating device, the Dermatron, in the 1960s. It was not only used for electrodiagnostic testing purposes, but also applied therapeutically to stimulate the body. Its effects include relief of smooth muscles spasms of the circulatory, lymphatic, and hollow organ systems; toning of the smooth muscle cells to relieve stasis and spastic constriction; toning of elastin fibers in the lungs of emphysema patients to increase lung capacity; reducing inflammation; reducing the degenerative process by restoring diffusion-osmotic equilibrium; and stimulation of adenosine triphosphate in newly insured striated muscle.10

The presentation of microcurrent supports skin correction by encouraging the reparation process. The principles of microcurrent are similar to those of wound healing. Compromised skin, especially skin with barrier dysfunction and aging, requires a program of restoration that is gradual and progressive for long-term, optimum health. Microcurrent gently urges the repair of the stratum corneum, bilayers, and dermal components to foster the skin into a healthier state. In many ways, this approach is a healthier choice for skin correction and does not add more damage to compromised skin, as opposed to excessive wounding through peels or thermal injury.

Cosmetic microcurrent has many benefits, including enhancement for aged and photoaged skin, improvement of skin texture, reduction of fine lines and wrinkles, diminishment of the appearance of acne scars, and the reduction of trauma, irritation, and inflammation. It also has pre-surgical benefits and encourages post-surgical skin healing.

PHOTOMODULATION
Cell tissues respond to specific frequencies of light. Several biological functions within the body are dependent upon light energy. For example, UVB is absorbed by photoreceptors within the cells in order to create a cascade of reaction that is required for vitamin D synthesis.
Monochromatic light increases oxygen and blood flow, accelerates wound healing, and facilitates pain reduction and muscular relaxation. LED has been developed for everything from wound healing to cosmetic improvement, including collagen synthesis and reduction of inflammation. Jennifer Brodeur, a leading researcher, skin specialist, and developer of LED, states that use of LED creates a chemical, physiological, and biological responses within the cells.11

Chemical – Mitochondria absorb oxygen and complete the breakdown of glucose to carbon dioxide and water to produce adenosine triphosphate. Photosynthesis and cellular respiration are two examples of chemical reactions within a cell that are created by LED.

Physiological – The absorption of light at the correct wavelengths create a response that alters secretions within the hypothalamus, thus aiding in a more-regulated hormonal activity. The physiological response of LED is beneficial to those with sleeping disorders, jetlag, and mood disorder.

Biological – The body can create its own wound response when it is aided by the correct wavelength, thereby enhancing healing and regeneration; strengthening the capillary system; increasing lymphatic system activity, circulation, RNA and DNA synthesis, and phagocytoses; stimulating fibroblast activity and tissue granulation; and inducing a thermal effect within the heart of the cell.

Skin care professionals are entering a new era of skin correction and care that requires greater insight into the biological processes of cells and systems within the skin. Moreover, building a program of care and management becomes more complex. The philosophy of doing no harm remains a mainstay in order to protect the epidermis at all times during treatment.

References
1 Haltiwanger, S. (n.d.). Use of Electrotherapy for Disease Treatment - Research into the Resonance Therapy and Rife Microscope, Rife Research - Europe. Retrieved from http://www.rife.de/use-of-electrotherapy-for-disease-treatment-.html
2 Neher, & Sakmann. (n.d.). The Nobel Prize in Physiology or Medicine 1991. Retrieved from http://www.nobelprize.org/nobel_prizes/medicine/laureates/1991/
3 Cooper, G. M., & Hausman, R. E. (2013). The Cell: A Molecular Approach (5th ed.). Sunderland, Mas: Sinauer Associates.
4 Medicine Meets Virtual Reality, & Satava, R. M. (1995). Interactive technology and the new paradigm for healthcare: Medicine Meets Virtual Reality III proceedings, San Diego, January 19-22, 1995. Amsterdam: IOS Press.
5 Shah, S. (2012, August 28). Sonophoresis. Retrieved from http://www.slideshare.net/shreeraj9183/sonophoresis-drug-delivery-system
6 Barrett-Hill, F. (n.d.). Sonophoresis. Retrieved from http://www.beautymagonline.com/technology-a-treatments/1166-sonophoresis-2
7 Byrd, D. (n.d.). Pulsed Radiofrequency for Chronic Pain. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2913603/
8 A Nonsurgical Way to Lift, Tighten, and Tone Skin | Ultherapy. (n.d.). Retrieved from http://www.ultherapy.com/Physicians/Science-Behind-Ultrasound-Skin-Lift
9 Retrieved from http://www.fieldsforlife.org/bibliography_microcurrent_files/Microcurrent_Cosmetics_Timeline
10 Davis, P. (1992, December). Retrieved from http://www.medsciencepro.com/images/pdf/Microcurrent-A-Modern-Healthcare-Modality.PDF
11 Brodeur, J. (2012). Effects of LED – Photomodulation.

Alexandra J. Zani is an international educator, researcher, and author with a background in cell biology and medical. Her passion for education resulted in receiving numerous advanced certifications, both in the United States and abroad. Zani earned an instructor license for aesthetics/cosmetology, is National Coalition of Estheticians, Manufacturers/Distributors, & Associations (NCEA) Nationally Certified, certified in Oncology Esthetics®, and the Pastiche Method® of Skin Analysis. She is a member of the International Association for Applied Corneotherapy (IAC). Zani presents education for advanced aesthetic technology, including microcurrents, LED, and non-ablative laser. She is a specialist in the anti-aging sciences, including the effects of nutrition, lifestyle, and the mind/body connection.