'Magic ink' is redefining the tattoo

Harvard and MIT researchers are developing life-saving tattoos

Tattoos aren’t just a fashion statement. Scientists are trying to find life-saving applications for them. Harvard and MIT researchers are developing tattoo inks that react to body chemicals, alerting diabetics to blood sugar fluctuations or athletes to dehydration. Someday, patients may observe their body chemistry with tattoos that change colors.

Tattoos, explained

Tattoos last because immune cells trap ink beneath the skin—but there's more to the story. This overview looks at how ancient cultures used tattoos for status, spirituality and punishment; how technology like the electric tattoo machine transformed the art form, and where innovations like smart tattoos could take it next.

Removal of different color tattoo inks may require multiple lasers

Light needs to be absorbed by ink particles to break them down into small enough pieces for the immune system to eliminate. Color ink reflects, rather than absorbs, lasers of the same color, while black ink absorbs all colored lasers.

Technological breakthroughs are spurring innovations in the industry

What if you could see your tattoos before they’re embedded in your skin? Or take a virtual visit into a local studio to work out your nerves over a first tattoo? The industry is anticipating some big technological changes, from 3D designs to sci-fi upgrades to more precise tattoo guns.

Watch the engineering challenges overcome in turning a 3D printer into a tattoo machine

The DIY project required reprogramming the printer to operate on a curved, 2D surface rather than making flat layers in 3D, editing replacement firmware to bypass temperature safety checks, and developing a rapid system to stop the tattoo in case of an emergency. The final product printed "LEG" on a volunteer's leg.

The immune system fights tattoos

Our skin is a fascinating organ that wants nothing more than to protect our bodies from the outside world. Tattoos penetrate that protective wall to inject ink directly into the sensitive, immunologically rich layer of skin known as the dermis.

Blacklights can illuminate certain biological materials, including blood, teeth, and fingernails, because they contain fluorophores—molecules that visibly glow immediately after exposure to higher-energy light.

The first tattoo gun was based on an electric pen invented by Thomas Edison.

Tattoos are made by injecting pigments into the skin

Tattoo ink is injected under the skin, which can leave the body open to infections and allergic reactions. While many tattoo artists are licensed professionals who follow sanitary guidelines, that’s not always the case.

Tattoo inks are largely unregulated by the FDA

With hundreds of ink manufacturers, all unregulated by the FDA, it’s hard to determine the exact ingredients in tattoo inks. Some pigments may contain carcinogenic chemicals, such as heavy metals and aromatic hydrocarbons, or even bacterial contaminants. Red ink often causes allergic reactions and may even contain lead or mercury.

Tattoo removal breaks apart ink particles

Tattoos place ink below the skin's surface layers in packets too large for white blood cells to clear out. By breaking the ink into smaller pieces, the immune system, which is responsible for removing foreign matter, can process them.

The body can remove tattoos after they are broken down by laser

Tattoos place blobs of ink below the surface layers of the skin in packets too large for white blood cells to clear out. By breaking the ink into smaller pieces, they can be processed by the immune system, which is responsible for removing foreign matter.

Scientists create contact lenses that give you infrared vision

Scientists have created lenses that use nanoparticles to convert infrared light into visible light, allowing human eyes to observe previously invisible parts of the electromagnetic spectrum. This technology may help colorblind individuals by converting colors they cannot see into wavelengths they can.

Laser procedures have made tattoo removal much more common

An increasing number of Americans, including high-profile celebrities, get tattoos removed because laser removal has become more advanced and cost-effective. The tattoo industry is adjusting to this mainstream trend.

Rune Elmqvist forwent practicing medicine to invent the first inkjet printer

The Mingograph recorded real-time physiological signals from a patient's electrocardiogram, helping doctors diagnose heart and brain conditions. Eight years later, in 1958, Elmqvist worked with cardiac surgeon Åke Senning to develop the first fully implantable pacemaker.

A 1974 Science News article proclaimed that within a decade, light therapy would be on par with traditional drugs.

The weakest form of light that is dangerous to humans is ultraviolet

Unlike radio waves, microwave, infrared, and visible light, UV light can produce chemical changes, such as curing adhesives and resins, causing substances to fluoresce, and destroying the genetic material of microorganisms. This makes UV light useful for sterilization, forensics, and quickly drying nail polish.

'Skin stitching' is an ancient tattoo method that's made a comeback

In the slow method, artists use needles to puncture the skin. Then, pigmented thread is drawn through the punctures to create the tattoo, resembling embroidery in the flesh. The method is experiencing a cultural revival within Canada’s First Nations communities.

How 'the Iceman' got his tattoos remains a mystery

Ötzi the Iceman, discovered in 1991, is one of the oldest human mummies ever found—and his 61 tattoos remain a mystery. This explainer looks at how researchers believe the tattoos were made, what their placement suggests about ancient medicine and culture, and why we’re still piecing together their true purpose today.

High-powered red light therapy—delivered directly to nerve fibers via a fiber optic needle—has been used in recent experimental research to suppress pain.

Chip-based 3D printers can be pocket-sized and involve no moving parts

Researchers have demonstrated a proof-of-concept version of a chip-based 3D printer that emits visible light onto light-sensitive resin to construct solid shapes. The technology may provide a portable, low-cost solution for future, small-scale fabrication needs.

NASA began investigating the healing properties of red light therapy in the 1980s, when researchers studying how LED lights could aid in photosynthesis noticed that their hands seemed to heal faster than normal under the lights.

Fiber lasers used for metal engravings can’t burn your skin

These devices use diodes and mirrors to create pulses of light that vaporize metal in billionths of a second, though at wavelengths that cannot react with organic material. Pulse width, power, and speed adjustments can produce white, black, and even colored patterns through controlled heat reactions.

Tattoos suppressed during colonization are experiencing a revival

A few decades ago, the distinct facial tattoos worn by Maori people were on the brink of disappearing. Then, Maori artists brought the cultural practice back into the spotlight. This TVNZ story follows one reporter’s mother as, at 59 years old, she receives tā moko from a Maori artist.

See photos of ultraviolet light therapy, widely administered in the early 1900s, particularly among children with skin diseases, tuberculosis, rickets, and more.

Microchip fabricators create light by heating tin droplets to over 220,000 Kelvin

Every second, lasers strike 50,000 droplets moving at 250 kilometers (155 miles) per hour, vaporizing the tin in supernova-like miniature explosions that produce ultraviolet light. Knowing this light will spread via diffraction as it passes through a filter during manufacturing, designers reverse-engineer the filter design based on the required final microchip pattern.

Bioluminescent reaction enzymes are often used in biomedical research

Near-infrared luciferase systems allow researchers to image and analyze cellular activity in living animals because they penetrate tissue more deeply than visible light. This provides a means of studying gene expression and protein interactions without harming the animals.

Red light therapy—a treatment harnessing a specific form of energy that penetrates the top layers of skin—is marketed for skincare and wellness, but has its roots in NASA plant growth research.

View a gallery of biofluorescent animals, which contain cells that emit various colors when exposed to ultraviolet light.

Hacking the body for a future that didn't happen

Journalist Adi Robertson experimented with one of the most accessible biohacks: magnets. Having a tiny magnet in their right ring finger meant they could sense magnetic fields, attract small metal objects, and more. But magnets weaken over time, eroding this new sense. Such implants do more than offer a new way of interacting with the world, they also pose new complications, such as the inability to get an MRI.

Light therapy was widely used as a medical treatment for various maladies in the early 1900s before it was replaced by antibiotics.

Photographer captures glowing flowers in ultraviolet light

Debora Lombardi utilizes ultraviolet light to reveal unseen colors in flowers, re-shaping their natural beauty. Beginning during the lockdown of March 2020, Lombardi's experimentation evolved, culminating in a series recognized by the World Photography Organization. Her work highlights vibrant purples, blues, and yellows, transforming flowers into surreal, otherworldly specimens by exposing them to UV light in her Italy-based studio.

'Tattoo' comes from a Polynesian word that means 'to strike'

“Tatatau” roughly translates to “strike,” a reference to the ancient process, which involved tapping ink into the skin with sharpened objects, like the bronze implements used circa 1450 BCE in Egypt, below.

Solutions of bioluminescent bacteria can create FOMO-inducing living art

A 2002 exhibition at Montana State University-Bozeman placed the bacteria onto petri dishes that served as macroscopic pixels to create images. Once the bacteria finished eating all the food in the sealed dishes, the light slowly faded away, ending the exhibit.

Some materials can absorb low-energy light and emit high-energy radiation

Through anti-Stokes cooling, incoming energy is combined with vibrations in a material's crystal lattice to produce a net reduction in its temperature. Using this effect, lasers can be directed at microchip hot spots to help keep data centers cool.

The origin of LASIK eye surgery, from a lab incident to federal funding and widespread use

After a University of Michigan engineering student suffered retinal burns from an ultrashort pulse laser, researchers realized it could be used to reshape the cornea and improve a person's vision with greater precision than a scalpel and earlier laser technologies. Agencies, including the National Science Foundation, the National Institutes of Health, and the Department of Energy, provided funding to develop and commercialize the procedure.

Bioluminescence may provide a sustainable alternative to electric lighting

French start-up Glowee is experimenting with lights made from bioluminescent microorganisms in public spaces to reduce energy use. While the technology shows promise, challenges remain with brightness, maintenance, and scaling it for widespread use.

The world’s oldest tattoos belong to 'Iceman' Ötzi

Ötzi is the corpse of "the Iceman" found in the Alps along the Italian and Austrian border in 1991. His mummified body was covered with lines and crosses along the “hard-working” areas of his body, signifying their potential application for therapeutic pain management.

Biofluorescent animals—those that absorb light, such as ultraviolet rays, and re-emit other types of light, such as neon green—include some flying squirrels, scorpions, sea turtles, and platypuses.

View an animation of how certain chemicals fluoresce—that is, emit visible light after having absorbed higher-energy light, such as ultraviolet radiation.

This 1440 Original video dives into what the science says about phototherapy and its various potential applications.

Around 32% of American adults have at least one tattoo

Tattoos have waxed and waned in popularity over the centuries, depending upon the social standing of their wearers. Throughout US history, they were often considered taboo. However, growing acceptance of tattoos means they’re more visible in the public eye.

'Barbie' drug melanotan II purportedly offers tanning without the sun—but it's very risky

The substance is not approved by the FDA and is illegal to sell in settings including the UK and Australia. Published case reports discuss serious side effects, including melanoma, a type of skin cancer.

Lasers have been used to create natural adhesives for paper

German researchers at four Fraunhofer institutes have developed a method to seal paper packaging using a carbon monoxide laser. Without the need for glue or plastic adhesives, the Papure project is expected to improve the recyclability of paper. (Some readers may experience a paywall.)

There are stigmas attached to tattoos

Although tattoos are fairly common in the US, some taboos remain. A 2017 study in the Journal of Social Psychology found discrimination against tattoos is alive and well, and that even individuals with tattoos associate them with negative stereotypes.

View a gallery of plants made to shine using ultraviolet-induced visible fluorescence photography, in which organisms re-emit the ultraviolet light they are exposed to in vibrant, glowing colors.

Objects can be made invisible through refraction, in which light from behind an object is bent around it, making only the background visible.

Wood that changed the color of water was the earliest recorded example of fluorescence

Lignum nephriticum, a tea used to treat kidney and urinary illnesses, was described in the 16th century as derived from white wood that turned water a bluish hue. However, in the 17th century, accounts described the wood as reddish and creating a kaleidoscope of colors in water. In 1915, the sources were identified as two different woods, which absorb UV radiation and emit visible light.

Photolithography etches circuit components into a semiconductor wafer

A high-energy laser is fired at molten tin droplets, turning them into plasma that releases the ultraviolet light needed to burn the wafer's photoresist layer. A mask controls what parts of the wafer are etched for subsequent chemical processing.

How to cook food with lasers

Creative Machines Lab at Columbia Engineering have developed a system of software-controlled lasers to cook food with precision, retain moisture with the final-cooked product, brown food within its original packaging, and create an entirely new meal creation process for a consumer. Watch this three-minute video to see for yourself.