Are temporary tattoos the future of wearable technology? / by Karen Frances Eng

Using your skin as the interface, LogicInk’s programmable tattoos use biological and chemical sensors to monitor everything from sun exposure to hydration levels to air pollution.

Temporary tattoos are a fun way to express yourself. But what if they could also tell you when you’re getting too much sun, or exposed to environmental pollutants, or have had one too many margaritas? LogicInk, a new wearable health-monitoring platform, promises to use biochemical sensors to help you keep tabs on your body’s well-being, while liberating you from bulky electronics.

We asked LogicInk co-founder and TED Fellow Skylar Tibbits — who develops programmable materials at MIT’s Self-Assembly Lab — and CEO Carlos Olguin to tell us more.

Programmed with chemistry and biology,  LogicInk ’s “tattoos” give you live visual feedback about your body and environment.

Programmed with chemistry and biology, LogicInk’s “tattoos” give you live visual feedback about your body and environment.

How does LogicInk work?

Carlos: LogicInk is a very thin stick-on tattoo, kind of like a temporary tattoo except that it doesn’t require water to apply. You just flip the card attached to the tattoo, press it to your skin and remove the card. Once it’s on, the tattoo’s design changes visually to alert you of a condition of interest in your body. Our first product, LogicInk UV, tells you when you’ve had enough sun for the day, for example.

Skylar: The UV application is just the beginning. It actually makes more sense to think of LogicInk as a platform, for which we’re now developing other functions — such as monitoring your body’s hydration level, blood alcohol level and so on. The possibilities are endless. The long-term vision for LogicInk is to have many tattoos that have many different sensors, so you can mix and match design and sensing capabilities.

What’s the idea behind LogicInk?

Carlos: We’re taking wearables to the next level technically — using chemistry and biology rather than electronics. We’re also thinking about the kind of people who adopt wearables. Right now, they’re bulky, and they tend to be difficult to understand and expensive. They also invariably require other devices, like smartphones. For a lot of people, that creates a multisensory wearable experience that’s frankly impractical or unaffordable or just ugly.

We also keep hearing that people want to be untethered from their electronics to go on a hike, swim and so on — they don’t want or need to have the phone with them at all times. Yet many still want to keep an eye on what’s going on in their body or environment so that they can live a healthier and longer life. We created LogicInk with all these folks in mind.

Tell us about how LogicInk UV works. And who is it for?

Skylar: LogicInk UV targets the 89 million Americans that are concerned about UV overexposure. According to the Skin Cancer Foundation, one in five Americans will develop skin cancer in their lifetime.

The tattoo uses a chemical system with a photocatalytic component that reacts when exposed to UV radiation. The component changes color gradually and spatially, and is printed in such a way on the sticker that it creates a living display. It’s programmed with chemistry to be able to create an animated gradient that changes color in response to UV exposure.

The device has two visual indicators: one tells you the intensity of UV you’re being exposed to in the moment, and the second indicator is cumulative — the graphic moves clockwise to tell you when you’ve had enough sun for the day.

Does it work with sunblock?

Skylar: Yes. The device senses UV radiation, so after you’ve applied the tattoo, if you put a sunblock over it, it will naturally block UV. It’ll also give you an idea when you need to reapply—say, after a swim. We used a metric from the World Health Organization to determine what the safe limit for UV exposure is for somebody with sensitive skin.

Carlos: Every sunblock is different, so we want to make sure that the sunblock at least gets removed faster on the device than on your skin, so that you never get a false reading that you’re being protected when you’re not. Ultimately, LogicInk will tell you to reapply earlier than you normally would.

One of the key things we’re learning from moms is that it’s helping them have peace of mind in the sun — so they don’t need to be on top of their kids at all times to see if they’re putting sunblock on or not. At the end of the day, they can then have a conversation about the rings — did they get full exposure? Did they stay within safe limits? It can be a tool for raising awareness about sun safety.

The outer circle turns fully pink when you’ve had enough sun for the day, based on WHO data for sensitive skin. The inner circle moves from white to dark pink (and back) depending on the amount of exposure you’re receiving at any given time.

The outer circle turns fully pink when you’ve had enough sun for the day, based on WHO data for sensitive skin. The inner circle moves from white to dark pink (and back) depending on the amount of exposure you’re receiving at any given time.

For people who are used to using apps to track progress over time, is there a way to collect data from LogicInk products despite the lack of electronics involved?

Carlos: We’re working on a mobile app exactly for this purpose. While we want people to be able to opt out of electronics technology—the tattoo is the user interface — they will also have the option to scan the tattoo at the end of the day or whenever they want, upload the information to the app and track the results over time.

How long can you wear the tattoo?

Carlos: It will vary depending on the purpose of the sensors. We designed LogicInk UV for single-day use because that’s the unit of time we want to measure for cumulative UV exposure. The device itself can last several days—even weeks—on your skin, and it’s repositionable, too. So future products on this platform could be reusable over time.

As LogicInk is meant to be used daily, is there a safe way to recycle or dispose of it?

Carlos: Safe disposal is very important to us. The only thing missing in LogicInk is a biodegradable film, and we’re working with different suppliers to change that. Everything else in the sticker is not just biodegradable, but most of it is edible as well: the photoreactive sensors are made up of food-grade elements. We’re very happy about that. Regardless, none of the chemical sensors come into contact with your skin, and the part that does is medically graded.

For the alcohol sensor, we’re working with a biomolecule already in your body that metabolizes alcohol, embedding it into the LogicInk system to create the colorimetric change. That said, it wouldn’t be a consumer product that you’d just buy off the shelf without any kind of regulation process in place.

Various sensors LogicInk is currently working on.

Various sensors LogicInk is currently working on.