#5-2. Tattoo Ink II: Infinitink, Innovative Tattoo Ink

Drs. Bruce Klitzman and Kim Koger of Duke University were the first to start researching new types of tattoo ink. Then, Candela, a successful American laser manufacturer, introduced Infinitink in 2007 in collaboration with Rox Anderson of Massachusetts General Hospitial. Infinitink created quite a sensation and was voted as the ”Invention of the Year in fashion” by Time Magazine in 2007.

The mechanism of action of Infinitink is simple, as shown in <Figure 2>. It was shown to be safe for use in the human body. Water soluble pigments that would be otherwise absorbed and metabolized in the body are microencapsulated to maintain the color. The coating material ruptures and releases water-soluble pigments when it is heated by an external energy source (NIR, UV, or IR). Encapsulation is removed with the Q-switched Nd:YAG laser and the heat generated by the laser dissolves the coating material (carnauba wax). The released pigments are quickly absorbed and degraded by surrounding tissues.

Figure 2. Diagram showing easy removal of Infinitink from the skin.

New tattoo ink technology

Infinitink consists of biologically safe water-soluble chromophores and coating material which are listed in <Tables 1, 2>. The coating processing determines loading, which refers to the stability of pigments and coating materials in the body. When the loading is high, the amount of ink remaining in the skin increases. Coating methods include aerosol collision, emulsion spraying, chamber deposition, and in situ encapsulation, each of which leads to different loading and should be selected appropriately.

Table 1. Candidates of chromophore

Table 2. Candidates of coating material

<Figure 3> shows composition of currently marketed Infinitink. The normal distribution of the particle size is around 100㎛. Most of the particles in the ink are of this size and those that are smaller are absorbed in the body. What is interesting is that the normal distribution shifts toward the left when the particle size is measured after heating. This signifies that larger pigment particles and coat particles have been degraded. Therefore, after heating at a certain temperature, ink particles and coating materials are reduced to smaller particles that are easily absorbed in the body.

Infinitink is innovative in terms of excellent safety and reversibility. The market response is not as explosive as the magnitude of the new concept. This may be due to the strong custom of using conventional ink and lack of awareness. Considering that ink needs to improve before the tattoo industry can grow further, innovative products like Infinitink is a very promising development.