Getting a tattoo certainly isn't known for being a comfortable process. It can also cause damage to the skin, plus it results in bio-hazardous used needles that need to be properly disposed of. A new needle-free technique, however, gets around all of those problems.

Developed at The Netherlands' University of Twente, the process involves placing ink inside a connected chamber and microchannel on a glass chip, which is held against the skin within a cartridge. A laser beam is then used to rapidly heat the ink in the chamber to above the boiling point. In a phenomenon known as thermocavitation, this causes a vapor bubble to form in the chamber. The pressure from that bubble forces a jet of ink to shoot out of the microchannel, through a tiny nozzle and into the skin.

That jet is roughly the diameter of a human hair, and travels at a speed of up to 100 meters (328 ft) per second. As a result, it is claimed to cause very little discomfort – perhaps comparable to the sensation of getting a mosquito bite.

Additionally, the new process uses much less power than a traditional tattoo machine, plus it doesn't waste any ink. By contrast, in traditional needle-based tattooing, a great deal of the ink that's used simply gets wiped off the skin and discarded.

So far, the micro-jet technique has been tested on agarose gel-based artificial skin, using a variety of commercially-available inks. While it caused no burns or other damage to the skin stand-in, the process does only deliver a small amount of ink with each "shot," so that aspect of the technology still needs to be improved.

Once it's perfected, it is hoped that the system could be used not only for the application of cosmetic or biomedical tattoos, but also for purposes such as the relatively painless injection of medication. In fact, scientists at Seoul National University have already developed a device that utilizes similar technology to achieve the latter.

The U Twente research, which is being led by Asst. Prof. David Fernández Rivas, is described in a paper that was recently published in the Journal of Applied Physics.