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Published on August 8th, 2017 | By: April Gocha, PhD

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Graphene temporary tattoos offer potential for mobile health monitoring, human machine interfaces, and more

Published on August 8th, 2017 | By: April Gocha, PhD

[Image above] Credit: Austin DeArmond; Flickr CC BY 2.0

 

 

I’m ready for a shift in healthcare.

 

And I’m not talking about anything happening in Washington, D.C. (although that’s an important story, too).

 

I’m ready for the era of wearable sensors that monitor our health, in sickness and in health—sensors that can not only diagnose and help treat disease, but that can keep us healthy by monitoring vitals, hydration, nutrient levels, and more. Sensors that can collect our biometric data, monitor it, and help us predict problems even before they become problems.

 

Perhaps my desire for a monitored health life is partially because I love data—but it’s not just me that dreams of such a future. Many teams of researchers from all over the world have been researching, testing, and developing wearable sensors that can monitor various aspects of our individual health.

 

And, unlike more widely used wearable devices, such as smart watches and fitness trackers, wearable sensors with constant and intimate contact on the skin have the potential to offer medical-grade data. While wearable devices are great for motivating us to move more and track some basic parameters, they don’t do enough and aren’t accurate enough to really help doctors examine our health.

 

Teams have already developed various flavors and configurations of wearable sensors, like this stick-on sweat sensor or this LCD tattoo, which really isn’t a tattoo at all.

 

But actual tattoos definitely aren’t out of the question, either.

 

We recently reported on the DermalAbyss project, a collaboration between MIT and Harvard researchers that is developing biosensor-containing tattoo inks that can be used to tat skin with medical sensing-designs.

 

To some, however, the idea of injecting your skin with actual tattoo ink—which contains various materials (many ceramics) that can cause adverse immunological reactions—is a little too much.

 

So maybe a sensor fashioned into a temporary tattoo, akin to those paper-backed skin stickers of your youth, are a better fit.

 

A group of researchers recently published a paper in Nature Nanotechnology detailing nanomesh temporary tattoo sensors made from a water soluble polymer and a thin film of gold. Although that development isn’t yet a fully integrated monitoring system, it’s thinness and flexibility are key for developing wearable sensors that look and feel like temporary tattoos.

 

And now, a team at the University of Texas at Austin has developed a wearable electronic sensor that incorporates wonder material graphene, allowing the temporary tattoo-like sensor to measure electrical activity from the heart, muscles, brain, and more.

 

The UT-Austin team’s sensor consists of an ultrathin layer of graphene, just 460 nm thick, coated with a polymer layer of poly(methyl methacrylate) (PMMA), which are together mounted onto transfer paper. The bilayer material, ~85% transparent and with more than 40% stretchability, can be cut into ribbon designs depending on the type of sensor created.

 

And—just like those temporary tattoos from your youth—the graphene sensors are applied by simply placing them on the skin, wetting the backing paper, and slowly peeling it away. No adhesive is needed because van der Waals forces (the same ones that allow geckos to walk up walls) hold the thin sensors in place on the skin.

 

“The graphene tattoo is a dry physiological sensor which, because of its thinness, forms an ultra-conformal contact to skin, resulting in increased signal fidelity,” coauthor Shideh Kabiri Ameri at the University of Texas at Austin says in a Phys.org news story. “Conformability results in less susceptibility to motion artifacts, which is one the biggest drawbacks of conventional dry sensors and electrodes for physiological measurements.”

 

According to the scientists, their graphene tattoos stay attached to skin for several hours “without fracture or delamination,” and applying a liquid bandage on top can prolong the temporary tattoo-tastic experience for several days.

 

So far, the scientists have been able to use their graphene tattoos to measure skin temperature, skin hydration, and electrical activity of the heart, muscles, and brain, according to the paper’s abstract.

 

“Graphene electronic tattoos are most promising for potential applications in mobile health care, assisted technologies, and human machine interfaces,” Kabiri Ameri says in the Phys.org story. “In the area of human machine interfaces, electrophysiological signals recorded from the brain and muscles can be classified and assigned for specific action in a machine. This area of research can have applications for the internet of things, smart houses and cities, human computer interaction, smart wheelchairs, speech assistance technology, monitoring of distracted driving, and human-robot control. Recently we have demonstrated the application of graphene tattoos for sensing human signals to wirelessly control flying objects. That demonstration will be reported in the near future.”

 

The paper, published in ACS Nano, is “Graphene electronic tattoo sensors” (DOI: 10.1021/acsnano.7b02182)

 


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