09.03.18
US Patent No. 10,028,897 B2; Ultra Ink has patented a removable tattoo ink, comprising colored micro-particles that contain an internal core, comprising one or more bio-absorbable chromophores that are water-soluble dyes, water-soluble pigments, or water-soluble drugs; and, an outer shell that consists of at least one layer of polystyrene sulfonate and at least one layer of polyallylamine hydrochloride. The micro-particles also comprise a coating over the outer shell, wherein the coating comprises polystyrene. The polystyrene coating and outer shell are rupturable by the application of ultrasonic energy.