On the attenuation of ultrasound by pure black tattoo ink

Abstract

Black tattoo ink comprises hydrophobic carbonblack nanoparticles. We hypothesized that black tattoo inkdemonstrates transient dynamic activity in an ultrasound field. Brightness-mode sonography was performed on cylindrical receptacles of different bore diameters, filled with black tattooink, water, saline, or air, using pulsed ultrasound with center frequencies of 13 MHz and 5 MHz. The scattering from black ink itself lasted less than tenminutes. At 13-MHz sonication, a transient drop in sound speed was observed, as well as a transient lessening of scattering from distal phantom tissue. The linear acoustic attenuation coefficient of pure black ink was measured to be 0.15±0.01 dB cm ⁻¹ MHz ⁻¹ , equal to whole blood. Low-intensity ultrasonic tattoo removal would be of interestas an alternative to techniques that damage surrounding tissue.