Adhesion Matters - Sticking Safely: Medical PSAs, Biocompatibility, and ISO 10993

Episode Date: August 24, 2025

Why must a medical adhesive stick—and then let go—without harming the skin? In this episode of Adhesion Matters, we dig into the science—and the sticky business—behind pressure-sensitive adhesives (PSAs) designed for everything from surgical dressings and wearables to wound care patches. We compare key chemistries—silicones, acrylics, and hydrogels—and show how each serves specific medical purposes like temperature resistance, conformability, or moisture management.We break down the rigorous ISO 10993 standards for biocompatibility, including critical tests for cytotoxicity, sensitization, and irritation. We also spotlight how companies like Dow and Henkel navigate those standards while enabling modern device manufacturing through UV-cure imaging and fast assembly.Finally, we look ahead to what’s next: from bioresorbable adhesives and smart, medication-releasing patches to PFAS- and solvent-free formulations—showing how the next wave of medical adhesives aims to stick safely while innovating boldly.Whether you're a materials engineer, regulatory specialist, or just fascinated by where adhesives intersect with healthcare, this episode reveals how smart chemistry keeps us safer—and more comfortable—on the skin. 

Welcome to the deep dive. Ever stopped to think about the incredible, often invisible technology holding your world together. Adhesives are literally everywhere. I mean from the screens in our pockets to, well, the medical devices that keep us healthy. Today we're really getting into something fascinating, though maybe overlooked. The highly specialized world of adhesives for medical devices. Our mission really is to understand why these tiny sticky bits are so critical. How do they stick to delicate skin without causing harm? What kind of, you know, incredibly tough standards do they have to meet? We'll also uncover some pretty remarkable innovations from big players like Dow and Henkel. They're really pushing the boundaries here. Yeah, it's so easy to just

think glue, right? But what we're discussing is completely different. These materials are absolutely fundamental, not just for sticking parts together, but for safety, for comfort, for making sure things work right in really sensitive situations. We're talking directly on skin or even inside the body. So today is really about that intersection of, let's say, advanced chemistry, human biology, and, of course, the strict regulations around medical tech. That's a really important distinction. So when we talk medical device adhesives, it's definitely not your average super glue for fixing a broken mug. Our skin, specifically. That seems like a uniquely challenging surface for anything sticky.

Why is skin so different, so demanding? Well, that's the core question, isn't it? Skin is incredibly dynamic. It's not static at all. It's elastic. It stretches. It moves with us constantly. Plus, it's a moist environment. You know, oils, sweat. And it's always renewing itself, shedding cells. Now, compare that to something like metal or hard plastic. Those are static predictable. Industrial glues often just go for sheer peel strength on those things. But on skin, that kind of aggressive approach would be, well, harmful. A medical adhesive has to bond securely sure. But it also has to move with the skin and needs to let the skin breathe. And crucially, it must avoid

irritation, allergies, scarring, all of that. So the engineering challenge is huge. It's about adhesion, yes, but adhesion without aggression. Adhesion without aggression. I like that framing. Okay, so what's the playbook then? For these specialized medical pressure sensitive adhesives, PSAs, what are the main chemistries involved? And, you know, where does each one really excel in this tricky environment? Okay. So broadly, you're looking at three main families, silicones, acrylics, and hydrogels. And each one brings something different to the party, making them better suited for specific jobs in medicine. Let's maybe start with silicone PSAs. Dow is a big name here. Silicons have some really standout advantages that, frankly, organic adhesives like acrylics

or natural rubber, just can't match. For one, they perform reliably over a huge temperature range. Think really cold, really hot, they handle it. They're also great at sticking to what engineers call low energy surfaces. Low energy surfaces. What does that mean in practice? tricky plastics. Exactly. Materials that other glues just don't want to grab onto, silicones are good at that. Plus, they're incredibly conformable. They just mold beautifully to, say, the contours of the skin and a huge plus clean removability. They come off without leaving dunk behind or worse damaging the skin. They also resist moisture, UV light. They can dampen sound and shock and even act as electrical insulators. Quite versatile. That is a serious list of

benefits. You mentioned sticking to tricky surfaces. What kinds of materials we talk about inside a medical device. Oh, all sorts. Think about how complex devices are built. Our sources point to things like glass, various plastics, silicone rubber itself, MylarPT film, which is common. Then you have high performance stuff like Teflon, PTFE, FEP advanced polymide films like Capon often use in flexible electronics, but also more standard things like aluminum foil, stainless steel, even specialized fabrics or silicone coated cloths. So silicones aren't just for skin contact.

They're bonding crucial components within the device, too, across a huge range of materials. And, you know, there are subtleties in manufacturing, too. Adhesives need curing, hardening. For silicones, you might use peroxide cure systems or platinum cure systems. Different chemistry lets you fine-tune the final properties, flexibility, bond strength, that sort of thing. Another big deal, especially in clean manufacturing, is managing volatile silicones. Little bits getting into the air. Products like Dow's, Dowsel, 7-06-V-Elo adhesive are made specifically to minimize this to prevent

what's called oven dusting. Alvin dusting sounds messy. It is. Tiny silicone particles can contaminate everything, so low volatility is key for quality control. Okay, now quick word on the others, acrylics and hydrogels. Acrylic PSAs. They're often known for strong, durable bonds.

Good breathability, too. You see them a lot where long wear time is needed, like maybe certain ECG electrodes or surgical drapes. Hydrogels are pretty different. They're usually water-based, highly breathable. Great for wound care because they help maintain a moist healing environment. Extremely gentle on removal, too, though maybe not as sticky initially as the others. And some can even deliver medication right through the gel.

Fascinating. Different tools for different jobs. And speaking of tools, Henkel seems to have a massive toolbox with their locked IT range for medical devices. What's the scope there? Oh, Henkel's portfolio is incredibly broad. Their all-a-T medical adhesives include things like instant adhesives, cyanoacrylates, you know, superglue types, but medical grade. Plus, various UV-curing adhesives, acrylics, sinewacrolates, again, even UV silicones, and then traditional epoxy's hybrids. Basically, they aim to have a solution for almost any bonding task in making a medical device.

Okay, so with that huge range, where do these Henkel-L-C-Ga-A adhesives actually end up? What kind of devices? Gosh, almost everywhere. Simple disposables like needles, syringes, catheters, tubing, connectors, but also complex stuff. Medical wearables, patches, sensors, critical equipment like dializers, blood filters, respiratory. respiratory gear, surgical tools, prosthetics, hearing aids, endoscopes, big imaging machines, a list is long. And they're designed to bond a real mix of materials, common plastics like polycarbonate, PPC, ABS, tougher ones like COC, PPP, PMA, polyurethanes, plus flexible stuff, silicones

again, TPEs, elastomers, and metals like stainless steel. What's really neat about their light cure adhesives, the UV ones, is how fast they cure. Speeds up manufacturing massively. They give strong, reliable bonds, often with flexibility built in for devices that move and bend, and many are serescents. Seems minor, but it allows automated cameras using UV light to check every single bond on the production line. Quality control, basically. Right, quality control is one thing. But safety, that brings us to a huge point. With all these powerful chemicals sticking things to us, or even inside us, how do we know they're safe? Tell us about ISO10993. Oh, yes, ISO 100,993. This is the absolute bedrock of safety assurance. It's the international

standard for the biological evaluation of medical devices. It goes way beyond just does it stick. It looks at how the material interacts with living tissue fundamentally. It assesses key things like cytotoxicity is it toxic to cells. Sensitization could it cause an allergic reaction and irritation will it cause redness, inflammation, that kind of thing. And yes, the sources confirm that essentially all the Henkel-Elfi-T-I-T-I-T-I-T-E medical device adheses undergo rigorous testing to meet these ISO-10993 standards. They often mention specific parts like ISO 1093-5 for cytosity, negus 10 for irritation sensitization, maybe mega-4, negative 6, negative 11, depending on the specific use.

And it's the same for the dousal A materials distributed by specialists like Voto-Miller-Himmy. They ensure everything meets these incredibly strict biocompatibility requirements. This level of biological testing is, well, worlds apart from what's needed for, say, office tape. And it's absolutely crucial for getting regulatory approval from bodies like the FDA in the U.S. or the EMA in Europe. Patient safety is the absolute priority. Okay, so let's make this concrete for you listening. What does all this mean in practice?

Think about medical wearables. Those continuous glucose monitors, ECG patches, fancy fitness trackers. Things people wear for days, even weeks. This tech relies completely on these advanced adhesives. It's not just about sticking. It's enabling life-changing technology. Wearables are such a perfect example. Take a glucose monitor.

It needs to stay put for, what, seven days, 14 days, through showers, exercise, sweating, skin moving, all of that. But then, when it's time to change it, it has to peel off cleanly. No pain, no irritation, no ripping the skin. And sometimes designers even think about reapplication, maybe repositioning it. Achieving that balanced, secure hold and gentle release is a massive material science challenge. And it gets even more interesting when you bring in things like the right to repair movement. You hear about patients trying to, let's say, hack their CGM sensor. Trying to replace a battery or something to make it last longer. Exactly. Now, manufacturers might not designed for that explicitly, but this kind of user behavior puts new pressures on the

adhesive designers. Suddenly, you have to think not just about the initial wear and removal, but maybe potential reuse scenarios, even if unintended. How do you keep it secure, but also skin-friendly if someone tries to reattach it? It's a real-world dilemma that goes beyond the initial specs. It shows how user actions can actually push innovation. That's fascinating. Real-world use pushing the design envelope. It really does sound like engineers are constantly performing this high wire act, balancing opposing needs. What are some of those key design tradeoffs they're always wrestling with? Oh, absolutely. A tightrope walk is a good way to put it. It's all about tradeoffs. You need super strong adhesion, right? So the device doesn't fall off.

But you also need painless, trauma-free removal. Those two are often in direct conflict. Then there's breathability. You want the skin underneath to stay healthy, not get all clammy, like under a cheap bandage. But at the same time, the adhesive probably needs to resist water, sweat, another balancing act. And now there's this growing tension between single-use sterility, historically dominant in health care, and the push for more sustainable, maybe reusable or repairable devices. How does the adhesive fit into that? And to help manage these tricky balances, companies like Dow also develop supporting materials. Things like primers, Dowsells, 749 PSA primer as an example. They help prepare difficult surfaces so the

adhesive sticks better. Or cross-linkers and anchorage additives. These can tweak the atesives properties, boost adhesion to tough stuff, but critically, without messing up that clean removal. It's all part of the toolkit. This is clearly such a dynamic field. Looking forward, then, what's next? What's on the horizon for medical adhesives? Where's the innovation heading? There's some really exciting stuff coming down the pike.

One major area is bioresorbable adhesives. Imagine adhesives used inside the body, maybe to close a wound or hold tissue, that just naturally dissolve and get absorbed by the body once their job is done. No need for removal. Wow, okay. Then there's the whole area of smart adhesives. We're talking materials that could do more than just stick. Maybe they release medication in a controlled way directly from the patch.

Or maybe they incorporate tiny sensors for diagnostics, monitoring things right through the adhesive layer. Integrated health monitoring in the patch itself. Potentially, yeah. And another really significant push is towards greener and healthier formulations, specifically moving away from PFEDS, those forever chemicals, and also reducing or eliminating solvents in the manufacturing process. Dow, for instance, already offers solventless PSAs,

like their Dowzel 210, 2013 series used maybe for protective films and things like that. It all ties back to minimizing environmental impact, and crucially, any potential long-term health concerns for patients. That's becoming more and more central. You know, when you step back, it's just remarkable. The hidden science, the sheer complexity packed into these seemingly simple, sticky materials, they really are the unsung heroes in so much of modern health care. quietly enabling safety, comfort, and a lot of the advanced medical tech we rely on.

Absolutely. Unsung heroes is right. So thinking about the future, as medical technology gets even closer to us, integrating more seamlessly with our bodies, what role do you listening right now think these incredibly clever adhesives will play? How will they help make future devices even more personalized, more patient-friendly? Something to think about. Thanks for joining us on this deep dive.