Scientists develop tattoos that are pain-free, blood-free, and self-administered

Transforming the ancient art of tattooing

Tattoo artists use hypodermic needles to inject ink into the deeper layer of the skin. This can damage the skin and causes blood clots to form, which creates bruising. To prevent infections, the person must take care of the area after the tattoo is complete.

The new tattoo patch has tiny microneedles that penetrate the skin's surface.

"We've miniaturized the needle so that it's painless, but still effectively deposits tattoo ink in the skin. 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," said Mark Prausnitz, principal investigator on the paper.

To create the patch, researchers started with a mold on which microneedles are arranged in a specific pattern. Each microneedle acts like a pixel to create a tattoo image in any shape or design. Then the microneedles are filled with tattoo ink, and a patch backing is added for convenient handling. The resulting patch can be applied to the skin. The microneedles penetrate the skin's surface, dissolve, and release the tattoo ink within a few minutes.

Inks of various colors can be incorporated into the microneedles, including black-light ink that can only be seen when illuminated with ultraviolet light. These microneedles are designed to disrupt only the most superficial layers of the skin to avoid nerve endings and blood vessels, making them painless and safer than hypodermic needles.

The study showed that the tattoos could last for at least a year and are likely to be permanent, making them viable cosmetic options for people without the risk of infection or the pain associated with traditional tattoos.

"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," said Mark Prausnitz.

Addressing privacy in medical alert devices

The tattoo patches can be used as a medical alert device and are designed with privacy in mind. The patches are either light or temperature sensitive so that the tattoo only appears under ultraviolet light or at high temperatures. This provides patients with privacy, revealing their tattoos only when desired. The microneedles can also be filled with temporary inks for short-term medical purposes.

Additionally, the tattoo patches could be used as a means to cover burns and scars. This could help to improve a patient's appearance and restore their self-esteem after a traumatic experience

Encoding information on the skin of animals can also benefit from the new tattoos. Rather than clipping the ear or applying an ear tag to animals to indicate, say, sterilization status, a painless and discreet tattoo can be offered as an alternative.