title: Entrance and propagation pattern of high-frequency electrical currents in biological tissues as applied to fractional skin rejuvenation using penetrating electrodes.
abstract: BACKGROUND
  Fractional resurfacing of the skin using radiofrequency devices has been used for collagen remodeling and rejuvenation.
  
  
  OBJECTIVE
  To determine how radiofrequency current enters and propagates through tissue, and the pattern of the resulting effect.
  
  
  METHODS
  An electrosurgical device with a 0.4 MHz frequency output was used as the source of radiofrequency current. Current was applied via a metallic needle introduced into a large piece of cow liver, with different amounts of energy delivered at multiple points. Cross-sections of the liver were then studied for tissue effect.
  
  
  RESULTS
  Thermal coagulation of tissue started from the tip of the electrode. With higher energy, a rim of coagulated tissue formed around the entire length of the needle. This rim of coagulated tissue was thicker around the tip of the electrode.
  
  
  CONCLUSIONS
  Radiofrequency currents have a tendency to move toward the center of the bulk of tissue. When an electrode of a fractional radiofrequency device enters the skin, maximum heating effect will be around the tip of the electrode in the dermis. This phenomenon can preserve epidermis from injury during dermal heating, reducing post-procedural skin surface side effects seen with many skin rejuvenation procedures.
authors.affiliation: Department of Dermatology, Center for Dermatology Research, Wake Forest School of Medicine, Winston-Salem, NC, USA.
authors.forename: A
authors.initials: A
authors.lastname: Taheri
authors.forename: P
authors.initials: P
authors.lastname: Mansoori
authors.forename: L F
authors.initials: LF
authors.lastname: Sandoval
authors.forename: S R
authors.initials: SR
authors.lastname: Feldman
authors.forename: P M
authors.initials: PM
authors.lastname: Williford
authors.forename: D
authors.initials: D
authors.lastname: Pearce
mesh_terms: D000818:Animals; D002417:Cattle; D004558:Electric Stimulation / Q000295:instrumentation / Q000379:methods*; D004567:Electrodes, Implanted; D006801:Humans; D066298:In Vitro Techniques; D008099:Liver / Q000166:cytology* / Q000502:physiology* / Q000528:radiation effects; D011829:Radiation Dosage; D011846:Radio Waves; D012060:Rejuvenation / Q000502:physiology*; D012542:Scattering, Radiation; D012879:Skin Physiological Phenomena / Q000528:radiation effects*
keywords: current; electrical; fractional; high-frequency; injury; radiofrequency; rejuvenation; skin; tissue