Researchers have developed tiny sensors that can track real-time health data

Technology |  2 min. read

Could a tattoo save your life?

Well, probably not the one pictured above.  But a new “electronic tattoo?”  That’s a yes.

This tattoo is a heart monitor you can wear.  This bit of wearable tech is made from a light, stretchy polymer, called polyvinylidene fluoride. It’s smaller than a credit card and thinner than a human hair. It gets hooked up to your phone and is on whenever, wherever you are.

It does the work of both an electrocardiogram and a seismocardiogram.  And for someone with a heart problem, real-time knowledge of what’s happening with your heart could be life-saving.  It can create an electrical charge from a squeeze or other physical force like the sort of squeezing your heart does.

Here’s a bit of the back-end science:  the petrochemical building block for this high-tech polymer, acetylene, is different than the usual “enes” (e.g., ethylene, propylene, benzene, etc.).  It’s produced by the same process, but instead of a double bond between the carbon atoms, there is a triple bond, and that makes it very unique (yeah, you might have to take our word for it.  Unless you’re a chemist).

And here’s a look:

You can’t ask your doctor for this tattoo yet, but the engineers at University of Texas, Austin are working to bring it out of the lab and into the clinic.

Meantime the same chemicals that go into that polymer tattoo are being used by engineers at Stanford to create wearable sensors that “read” our skin.

These are more like band-aids than tattoos, but like the tattoos the result is real-time health information that could be illuminating for some of us (say, during a workout), and life-saving for others.

The sensors measure changes in our skin. From how much we are sweating to whether our skin is expanding a little, or contracting, as our muscles move.

One day, the Stanford engineers see a network of these band-aid sensors (they call it “BodyNet”) that will be comfortable to wear, during a routine workout or to watch for signs of something serious.  Comfortable because there are no batteries, no stiff wires.  Instead they use 3D-printed circuitry that can bend and stretch.

And the chemistry that makes that possible — like the chemistry behind that electronic tattoo — is built from petrochemicals. These stretchables are actually laminates of different materials, including novel, stretchable polymer electrodes and electrolytes (fancy battery-speak).

These polymers aren’t simple molecules; rather, they are a complex blend of several different monomers. And what really makes this chemistry complicated is two different polyetheramines are cross-linked with a dicarboxylic acid. That’s just to make the electrodes. To make the stretchable polymer electrolyte, the polyetheramine/dicarboxylic acid comonomer is impregnated with the same lithium salt used in lithium-ion batteries, then they take the impregnated copolymer and impregnate propylene carbonate with that.

Ok, ok, enough chemistry already! Let’s wrap it up this way:  Electronic tattoos.  Wearable sensors.  None of these materials would be possible without petrochemicals.  Behind the polyetheramines is a polypropylene oxide skeleton, which starts with propylene.  The dicarboxylic acid (in this case, adipic acid) starts with benzene.  And the propylene carbonate starts with…more propylene. Even the lithium salt is made possible by a derivative of methane (i.e., natural gas).  Class dismissed!