title: Investigations of the role of cavitation in low-frequency sonophoresis using acoustic spectroscopy.
abstract: Application of low-frequency ultrasound significantly enhances skin permeability. The enhancement of skin permeability is mediated by cavitation, oscillation, and collapse of gaseous cavities. In this article, we report detailed investigations of the occurrence of cavitation during low-frequency sonophoresis. Cavitation was monitored by recording pressure amplitudes of subharmonic emission and broadband noise at four different ultrasound frequencies in the range of 20-100 kHz and at various intensities in the range of 0-2.6 W/cm(2). Enhancement of skin conductivity, in the presence of sodium lauryl sulfate (SLS), was also measured under the same ultrasound conditions. Enhancement of skin conductivity correlated well with the amplitude of broadband noise, which suggests the role of transient cavitation in low-frequency sonophoresis. No correlation was found between the subharmonic pressure amplitude and conductivity enhancement.
authors.affiliation: Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA.
authors.forename: Ahmet
authors.initials: A
authors.lastname: Tezel
authors.forename: Ashley
authors.initials: A
authors.lastname: Sens
authors.forename: Samir
authors.initials: S
authors.lastname: Mitragotri
mesh_terms: D000818:Animals; D004553:Electric Conductivity; D010539:Permeability; D012869:Skin Absorption; D013057:Spectrum Analysis / Q000379:methods; D013552:Swine; D014465:Ultrasonics