Now go for painless tattoos that can be self-administered, say Researchers

Instead of sitting in a tattoo chair for hours enduring painful punctures, imagine getting tattooed by a skin patch containing microscopic needles. Researchers at the Georgia Institute of Technology have developed low-cost, painless, and bloodless tattoos that can be self-administered and have many applications, from medical alerts to tracking neutered animals to cosmetics.

“We’ve miniaturized the needle so that it’s painless, but still effectively deposits tattoo ink in the skin,” said Mark Prausnitz, principal investigator on the paper. “This could be a way not only to make medical tattoos more accessible, but also to create new opportunities for cosmetic tattoos because of the ease of administration.”

Tattoos are used in medicine to cover up scars, guide repeated cancer radiation treatments, or restore nipples after breast surgery. Tattoos also can be used instead of bracelets as medical alerts to communicate serious medical conditions such as diabetes, epilepsy, or allergies.

Various cosmetic products using microneedles are already on the market — mostly for anti-aging — but developing microneedle technology for tattoos is new. Prausnitz, a veteran in this area, has studied microneedle patches for years to painlessly administer drugs and vaccines to the skin without the need for hypodermic needles.

tattoo/en.wikipedia.org

“We saw this as an opportunity to leverage our work on microneedle technology to make tattoos more accessible,” Prausnitz said. “While some people are willing to accept the pain and time required for a tattoo, we thought others might prefer a tattoo that is simply pressed onto the skin and does not hurt.”

Transforming Tattooing

Tattoos typically use large needles to puncture repeatedly into the skin to get a good image, a time-consuming and painful process. The Georgia Tech team has developed microneedles that are smaller than a grain of sand and are made of tattoo ink encased in a dissolvable matrix.

“Because the microneedles are made of tattoo ink, they deposit the ink in the skin very efficiently,” said Li, the lead author of the study.

In this way, the microneedles can be pressed into the skin just once and then dissolve, leaving the ink in the skin after a few minutes without bleeding.

Tattooing Technique

Although most microneedle patches for pharmaceuticals or cosmetics have dozens or hundreds of microneedles arranged in a square or circle, microneedle patch tattoos imprint a design that can include letters, numbers, symbols, and images. By arranging the microneedles in a specific pattern, each microneedle acts like a pixel to create a tattoo image in any shape or pattern.

The researchers start with a mold containing microneedles in a pattern that forms an image. They fill the microneedles in the mold with tattoo ink and add a patch backing for convenient handling. The resulting patch is then applied to the skin for a few minutes, during which time the microneedles dissolve and release the tattoo ink. Tattoo inks of various colors can be incorporated into the microneedles, including black-light ink that can only be seen when illuminated with ultraviolet light.

Prausnitz’s lab has been researching microneedles for vaccine delivery for years and realized they could be equally applicable to tattoos. With support from the Alliance for Contraception in Cats and Dogs, Prausnitz’s team started working on tattoos to identify spayed and neutered pets, but then realized the technology could be effective for people, too.

The tattoos were also designed with privacy in mind. The researchers even created patches sensitive to environmental factors such as light or temperature changes, where the tattoo will only appear with ultraviolet light or higher temperatures. This provides patients with privacy, revealing the tattoo only when desired.

A magnified view of a microneedle patch with green tattoo ink/photo:Georgia Tech

The study showed that the tattoos could last for at least a year and are likely to be permanent, which also makes them viable cosmetic options for people who want an aesthetic tattoo without risk of infection or the pain associated with traditional tattoos. Microneedle tattoos could alternatively be loaded with temporary tattoo ink to address short-term needs in medicine and cosmetics.

Microneedle patch tattoos can also be used to encode information in the skin of animals. Rather than clipping the ear or applying an ear tag to animals to indicate sterilization status, a painless and discreet tattoo can be applied instead.

“The goal isn’t to replace all tattoos, which are often works of beauty created by tattoo artists,” Prausnitz said. “Our goal is to create new opportunities for patients, pets, and people who want a painless tattoo that can be easily administered.”

 

All tattoos are not same, what’s harmful in ink matters

Although people have decorated their bodies for millennia with tattoo images as a form of self-expression but the inks used remained unregulated, resulting in products whose components are largely a mystery.

Now, researchers have analyzed almost 100 inks and report that even when these products include an ingredient label, the lists often aren’t accurate. The team also detected small particles that could be harmful to cells.

To be presented today at the fall meeting of the American Chemical Society (ACS) Fall 2022, the team from Binghamton University (State University of New York), the study probed the particle size and molecular composition of tattoo pigments using a variety of techniques, such as Raman spectroscopy, nuclear magnetic resonance spectroscopy and electron microscopy.

“The idea for this project initially came about because I was interested in what happens when laser light is used to remove tattoos,” says John Swierk, the project’s principal investigator. “But then I realized that very little is actually known about the composition of tattoo inks, so we started analyzing popular brands.”

Swierk and undergraduates in his laboratory interviewed tattoo artists to see what they knew about the inks they use on their customers. The artists could quickly identify a brand they preferred, but they didn’t know much about its contents. “Surprisingly, no dye shop makes pigment specific for tattoo ink,” Swierk explains.

“Big companies manufacture pigments for everything, such as paint and textiles. These same pigments are used in tattoo inks,” he said and noted that tattoo artists must be licensed in the locales where they operate for safety reasons, yet no federal or local agency regulates the contents of the inks themselves.

Tattoo inks contain two parts

Tattoo contains a pigment and a carrier solution. The pigment could be a molecular compound such as a blue pigment; a solid compound such as titanium dioxide, which is white; or a combination of the two compound types such as light blue ink, which contains both the molecular blue pigment and titanium dioxide.

The carrier solution transports the pigment to the middle layer of skin and typically helps make the pigment more soluble. It can also control the viscosity of the ink solution and sometimes includes an anti-inflammatory ingredient.

Swierk’s team has confirmed the presence of ingredients that aren’t listed on some labels. For example, in one case ethanol was not listed, but the chemical analysis showed it was present in the ink. The team has also been able to identify what specific pigments are present in some inks.

“Every time we looked at one of the inks, we found something that gave me pause,” Swierk says. “For example, 23 of 56 different inks analyzed to date suggest an azo-containing dye is present.” Although many azo pigments do not cause health concerns when they are chemically intact, bacteria or ultraviolet light can degrade them into another nitrogen-based compound that is a potential carcinogen, according to the Joint Research Centre, which provides independent scientific advice to the European Union.

In addition, the team has analyzed 16 inks using electron microscopy, and about half contained particles smaller than 100 nm. “That’s a concerning size range,” says Swierk. “Particles of this size can get through the cell membrane and potentially cause harm.”