Tattoos are notoriously painful. They require large needles, blood is typical, and they can take hours to complete. The healing process can be long and a bit painful as well.
But tattoos aren’t just for decoration—they can also cover up scars, guide cancer radiation treatments, or restore nipples after breast surgery. Tattoos can also act as medical alerts instead of bracelets for patients with diabetes, epilepsy, or serious allergies.
So a group of scientists at the Georgia Institute of Technology set out to find an easier way to administer them.
How Does A Painless Tattoo Work?
Modern tattoo machines use electromagnetic force that moves needles at a high frequency—up to several thousand times per minute—in and out of the skin as they deposit liquid ink. The needles penetrate into the skin from a few hundred micrometers up to two millimeters.
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In addition to pain, adverse effects of tattooing can include skin reactions and infection.
Doctors were already using microneedle patch technology for minimally invasive drug delivery that eliminates biohazardous sharps waste and causes little or no pain or bleeding. The patches are inexpensive and require minimal training to administer.
So the Georgia Tech researchers took that microneedle patch concept and made it into a tiny tattoo machine. Each microneedle on the patch represents a dot or pixel in an image. They used single-color, multi-color, changing-color, and ultraviolet-visible tattoo inks to create tattoo symbols, numbers, letters, and other medical/decorative images applied to the skin.
After applying the patch to the skin for just a few minutes, microneedles deliver their ink and then dissolve.
“We’ve miniaturized the needle so that it’s painless, but still effectively deposits tattoo ink in the skin,” wrote researcher Mark Prausnitz, principal investigator on the paper which was published in the open source journal iScience. “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.”
They tested the tattoos on rats and followed up after a year. The tattoos remained intact with minimal distortion—similar to the changes that happen with tattoos as humans age and bodies change.
The Potential Uses Of Microneedle Ink
The tattoos could be useful in human medicine, for example, in vaccine delivery that displays the year of the injection. The researchers tested the concept by tattooing the number 20 on a rat. They also created hearts, stars, and QR codes.
They also tested tattoos that were visible only when exposed to light and heat, and the scientists wrote that they could create similar tattoos that respond to glucose levels or other stimuli that would be useful to people with diabetes or other health issues.
The technology could also encode information in the skin of animals in place of clipping the ear or applying an ear tag.
The art of the microneedle tattoo process may not yet be at a level that would satisfy most tattoo enthusiasts, and the scientists acknowledge they may never emulate the artistry of skilled tattooists.
“The goal isn’t to replace all tattoos, which are often works of beauty created by tattoo artists,” Prausnitz wrote. “Our goal is to create new opportunities for patients, pets, and people who want a painless tattoo that can be easily administered.”