Data about your health: what are these digital tattoos?

Personal health data - right on your skin

Imagine if tattoos on your skin could do more than just decorate your skin—what if you could unlock your phone, open your door, or even monitor your health in real-time? Digital tattoos are slowly becoming a field that promises to turn human skin into an interactive screen and healthcare into an invisible but ubiquitous companion.

Healthcare technologies are connecting and integrating more seamlessly than ever before. In the past, medical devices were used to track health parameters or record data. Today, the aim is precision, simplicity and integration into everyday life. As a result of this trend, wearable devices and sensors are getting closer and closer to the human body^[1].

Digital tattoos promise to revolutionize healthcare by enabling seamless, preventive, and predictable personal healthcare. Unlike traditional methods, these small patches provide continuous monitoring so that users receive real-time alerts when health parameters deviate from the norm.

As technology improves, digital tattoos could replace current wearable devices such as smartwatches, which are powered by electrophysiological processes rather than batteries. They can become more accurate and integrated, offering health monitoring and everyday conveniences such as device management and authentication^[2].

Digital tattoos not only help you control your devices but also call an ambulance in the event of a stroke

Thanks to advances in 3D printing and flexible electronics, digital tattoos are thin, waterproof, and stretchable. They can remain on the skin for days or even weeks without causing irritation. Materials such as gold nanotubes, graphene, and specialized polymers make these tattoos highly customizable. They can already monitor key health indicators and transmit data to connected devices such as smartphones.

Digital tattoos can even replace passwords and keys. For example, in 2014, Motorola introduced a digital tattoo to unlock its Moto X phone.

These tattoos can be used to track vital health indicators such as heart rate, hydration, and electrophysiological parameters. They offer non-invasive solutions for monitoring conditions such as cardiac arrhythmia, sleep disorders, and brain activity. This is particularly useful for patients at high risk of stroke due to the possibility of real-time alerts and even the possibility of calling for medical assistance.

Meanwhile, this type of tattoo, placed on the throat, can detect speech-related muscle movements, allowing sub-vocal commands for hands-free communication. Advanced models can eventually track brain signals and control external devices.

What other functions do modern tattoos provide?

Monitor glucose levels in the body. Researchers at the University of California, San Diego, have developed a temporary tattoo that measures glucose from the skin's intracellular fluid. The device attracts glucose molecules to the surface with a small electric current and offers a painless alternative to diabetes management.

A more advanced device, the 'Lab on Skin', monitors glucose, alcohol and lactate levels using a microparticle patch. The data is transmitted wirelessly to a smartphone app, so insights are real-time and discomfort-free.

Glucose readings from sweat. Researchers at Penn State have developed a sensor that measures glucose in sweat using laser-induced graphene and an alloy of nickel and gold. This cost-effective, enzyme-free device provides reliable measurements and opens the door to routine glucose monitoring without any intervention in the human body.

South Korean researchers have also developed a graphene-based patch that tracks sweat's temperature and pH. Micronuclei in the patch automatically deliver medicines if needed.

Graphene-based tattoos. Researchers at the University of Texas have developed near-transparent graphene tattoos that can monitor brain, heart and muscle activity. These tattoos are lightweight, stretchy and fit naturally to the skin.

In some countries, people are already making widespread use of chips implanted under the skin

While such innovations are both surprising and frightening, in some Western countries, people are already used to not having to carry anything with them, as all the information they need is implanted... under the skin. And now, this method will neither wash off nor peel off.

Patrick Paumen, 37, from the Netherlands, uses a microchip implanted in his hand to make contactless payments without carrying his phone or bank card. The microchip, implanted under his skin in 2019, works via NFC technology, similar to contactless cards and smartphones.

British-Polish company Walletmor became the first vendor of implantable payment chips in 2021. Weighing less than a gram, these chips are made of biopolymer material and do not require a battery. The technology is described as safe, has been approved by regulatory authorities, and has already been adopted by more than 500 users.

However, there are still fears about the security and traceability of the personal information contained in these chips and the rather dark future scenarios in which people will be completely controlled by such devices.