What makes medical grade skin adhesive patches so sticky, and how are they able to stay in place for weeks at a time?

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What makes medical grade skin adhesive patches so sticky, and how are they able to stay in place for weeks at a time?

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It’s mainly a combination of having the right glue and then the right mechanical properties. The glue part I can’t really help you with, that’s probably a bit of a secret sauce in the adhesives industry so I’m not sure how far you’ll get with the detail chemistry there. But in terms of other properties that are important, usually comes down to water resistance, breathability, and stretch/flexibility. Moisture is pretty detrimental to adhesion. So if your glue doesn’t keep external water (like a shower) out well it’s not going to last very long. Breathability is basically the same issue except the moisture is coming from you (the patient, in the form of sweat). If the patch material doesn’t allow this to wick away and evaporate it is also bad for the adhesion. Stretch/flex is about how well the patch is able to conform to your body and movement. If the patch is too stiff, it’s not going to want to stay curved against your body. It will basically pull itself off trying to straighten back out again or fight against the movement of your skin as you move around.

Really strong glue chemically bonds to the surfaces it’s applied to. Scientists found a glue that chemically mixes with the skin permanently.

But it only reacts with the top layer of skin. As your skin cells die off and shed, the chemically bonded cells are shed too.

So when the patch comes off, it’s not really the glue that wore off, but the skin it bonded to.