The art of tattooing may have found a diagnostic twist.
A team of scientists in Germany have developed permanent dermal sensors that can be applied as artistic tattoos.
As detailed in the journal Angewandte Chemie, a colorimetric analytic formulation was injected into the skin instead of tattoo ink.
The pigmented skin areas varied their color when blood pH or other health indicators changed.
A tattooist places ink directly in the dermis, a roughly one-millimeter-thick layer of tissue that hosts nerves, blood vessels, and hair follicles.
The tattoo needle punctures the epidermis, the uppermost layer of skin, and releases the pigments into the dermis below, where the pigments stain the skin permanently.
Using tattoos for diagnostic rather than cosmetic purposes is a new concept.
Researcher Ali K. Yetisen, who works at the Technical University of Munich, Germany, and his colleagues thought the technique could be helpful to place sensor formulations at spots in the body where they can record changes in metabolic substances directly, without any spatial distance or time delay, and perhaps for a very long period of time.
The researchers then identified and adapted three colorimetric chemical sensors that produce a color change in response to biomarkers.
The first sensor was a rather simple pH indicator consisting of the dyes methyl red, bromothymol blue, and phenolphthalein.
If injected into a model skin patch – a piece of pig skin – the resulting tattoo turned from yellow to blue if the pH was adjusted from five to nine.
The other two sensors probed the levels of glucose and albumin.
Albumin is a carrier and transport protein in the blood.
High glucose levels in the body may indicate diabetic dysfunction, whereas falling albumin levels can indicate liver or kidney failure.
The glucose sensor consisted of the enzymatic reactions of glucose oxidase and peroxidase, which, depending on the glucose concentration, led to a structural change of an organic pigment, and a yellow to dark green color change.
The albumin sensor was based on a yellow dye that, upon association with the albumin protein, turned green.
The scientists then applied several sensor tattoos onto patches of pig skin.
When they changed the pH or the glucose or albumin concentrations, the colors of the decorated areas changed accordingly.
They quantified these visible effects by evaluating the colors with a simple smartphone camera and an app.
The authors claim that such sensor tattoos could allow permanent monitoring of patients using a simple, low-cost technique.
With the development of suitable colorimetric sensors, the technique could also extend to recording electrolyte and pathogen concentrations or the level of dehydration of a patient.
Further studies will explore whether tattoo artwork can be applied in a diagnostic setting.
Researchers have developed a new colour-changing tattoo ink that responds to changes in the body, such as blood sugar and sodium levels.
Using a liquid with biosensors instead of traditional ink, scientists want to turn the surface of the human skin into an “interactive display” – an idea that makes this proof-of-concept an exciting one to watch. Technology like this could become a revolutionary new way to monitor health.
So far, the team has developed three different inks that shift colour in response to changes in interstitial fluid – the stuff that sloshes around between our cells, comprising some 16 percent of the human body weight.
Of the three sensor inks, the most intriguing is the one that can measure glucose levels. The sensor changes its colour from blue to brown as blood sugar rises.
Having a glucose-sensing tattoo could conceivably make life easier to people with diabetes, who have to rely on pin-prick blood tests throughout the day to monitor their glucose.
The team has also created an ink that shifts from pink to purple in relation to pH levels, and a third sensor that can detect sodium, shining a vibrant green hue under UV light in the presence of rising salt levels.
Xin LIU, Katia Vega
“The Dermal Abyss creates a direct access to the compartments in the body and reflects inner metabolic processes in a shape of a tattoo,” the team writes on the project website.
“It could be used for applications in continuously monitoring such as medical diagnostics, quantified self, and data encoding in the body.”
For someone who has a health condition that requires careful dietary monitoring, or even if you’re just a data nerd and like the idea of tracking bodily changes with a cool-looking tattoo, it’s an alluring concept.
“People with diabetes email us and say, ‘I want to try it out,'” one of the team, Xin Liu from MIT told CBS News.
But if you’re ready to be signed up for one of these biosensing tattoos, unfortunately we have to disappoint you for now. So far, DermalAbyss is only in the proof-of-concept stage, and there’s no indication of when it might become a real product.
The researchers have tested the inks on patches of pig skin, using injections to change the levels of the fluids to be detected.
In the video below, you can see these test patches in action, as well as a digital rendering of what such a colour-changing tattoo might look like on a human arm:
Before this amazing tech can be approved in humans, it will need to go through several stages of rigorous tests, probably in animals first and then eventually in people. Things to look out for are adverse reactions to the ink and possible allergies.
There’s also the question of how to make sure the tattoo indicators are as accurate as possible. In a medical situation, you’d want that colour-changing ‘interface’ to be as reliable as a blood test, and we’re definitely not there yet.
“It will take a long time for anything practical to go to market, but it [the technology] evokes imaginations and opens up possibilities,” Liu told CBS News.
More information: Ali K. Yetisen et al. Dermal Tattoo Biosensors for Colorimetric Metabolite Detection, Angewandte Chemie International Edition (2019). DOI: 10.1002/anie.201904416
Journal information: Angewandte Chemie , Angewandte Chemie International Edition
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