Oh, my.
I am about to open a can of worms with a bunch of rabbinic scholars.
Because the Tora prohibits humans from tattooing their body, from putting a brand anywhere on their person. (The only exception is when a bondsman or bondswoman refuses to leave one’s employ after the debt is paid. Then, they get their ears pierced. [Yes, this does mean Orthodox women use clip-ons—no pierced earrings for them].)
And, why would I be bringing up tattoos all of a sudden?
Because wearable biosensors may be about to become a thing. And, that information will be vitally important for folks who have compromised health.
Drs. Ali Yeltisen (primary author), Sarah Seifi, Xingchen Dong, Jie Dong, Martin Jakobi, Martin Elsner, and Alexander Koch off the Technical University of Munich (along with Drs. R Moreddu [ChemE U Birmingham UK], Nan Jiang [Harvard], Katia Vega [UC Davis], and Haider Butt [Khalifa University of Abu Dhabi]) jave developed tattoos that respond to changes in our body’s glucose, pH, and albumin levels. Changes these tattoos make readily discernable by our eyes- with no other special equipment needed. The results were reported in Angewandte Chemie.
These tattoos are not responding to the actual blood concentrations, but to those of the extracellular fluid (including some interstitial fluid, which closely matches the levels that obtain in our blood) that abounds in our dermis (skin cells).
Moreover, the tattoos are applied to our bodies using conventional tattoo equipment- only the ink is changed. The inks contain the biosensing chemicals necessary. For example, to discern the pH, the researchers used stuff like methyl red (an indicator that turns red in acidic situations), bromothymol blue (which is greenish blue when the pH is neutral), and phenolphthalein (the standard indicator kids use to discern acids and bases; it’s red in basic solutions and colorless in acids).
Glucose detection ink was a little trickier to develop. To monitor these levels, the researchers employed glucose oxidase, 3,3′,5,5′-tetramethylbenzidine (aka, TMB), and peroxidase (POD). The color change here is manifested because the glucose oxidase oxidizes the glucose in the interstitial fluid, liberating hydrogen peroxide, which then reacts (oxidizes) the TMB, as long as peroxidase (POD) is present. The glucose levels are manifested by a color change from yellow to dark green (as glucose rises from levels of 2 to 50 millimolar [18 to 900 mg/100 mL]).
The concentration of albumin is manifested by the reactions of 3′,3″,5′,5″-tetrachlorophenol and 3,4,5,6-tetra-bromosulfophthalein. When the concentration level reaches 5 g/L of albumin, the tattoo changes from a yellow to blue-green.
Of course, folks would be interested in the actual levels of these compounds, so the team developed color gradients that could manifest the concentrations clearly. This system also has a 20 second delay before the ink and interstitial fluid react with one another, so results are not instantaneous.
And, while the tattoos have about a six month shelf life, once the tattoos change color (for example, indicating the rise in glucose concentrations) , the color will disappear if the glucose level drops- but won’t change back again should the glucose level rise anew.
That’s the next step in the development.
If they weren’t just a one time use thing, I could see it. If there weren’t easier ways, sure. (Reminds me of the Jewish man who nearly panicked after learning his heart valve replacement would come from a pig. Fortunately, the rabbi okayed this, and he had the surgery and did just fine. I’m thinking they might NOT agree with this tattoo, though.)
Holly recently posted..That Which We Tolerate, and That Which We Don’t
Right now, these only have use in the hospital to help monitor the patient, ensuring a “crash condition” is not imminent. Or, for marathon runners to ensure they stay hydrated.
But, yeah, I don’t see rabbinical approval coming anytime soon, Holly. Even with that “pikuach nefesh’ (saving of a life) exception.
Whoa! This is a really creative and cool approach to thinking about this stuff. Sure, they have a long way to go, but what a wonderful display of human ingenuity and ever-expanding ideas. Thanks for sharing!
I think this will make it easier for nurses (the folks who monitor patients most often) to more easily recognize when a patient needs intervention.
Just curious, What is the thought about tattoos used on patients about to receive radiation treatment for cancer, to mark out where radiation is to go-are they permitted? The tattoos you write about are interesting, if they can be further developed.
Those marks that patients receive for cancer treatment are not usually accepted. The desire is to use a marker pen, where the mark lasts less than 14 days.