Emmett McArdle and Xianbo Hu, R&D managers for Avery Dennison Medical, discuss a quartet of adhesive capabilities desired by medical device developers and healthcare providers — and why it’s such a challenge to deliver just the right mix.
For many medical device professionals, the challenge to meet multifaceted healthcare market demands can feel like a modern-day quest for the Holy Grail.
This is certainly true when it comes to medical adhesives. One of the foundational building blocks for medical devices such as wound care dressings and wearables, these materials must deliver diverse performance capabilities. Here is a brief look at four sought-after adhesive qualities.
Repositionability
Repositionability is an important quality in some medical devices. For example, a healthcare provider may need to lift a dressing to examine a wound and then adjust and resecure it. Or a nurse may want to remove a self-adhering N95 respirator during a work break and then don it again to return to duty. Soft silicone adhesives (SSA) are the ideal choice for low-tack applications, such as advanced wound dressings. SSA retain their adhesive properties during repositioning. They do not remove skin cells during removal. If the opposite occurs and skin cells are pulled away, they can mask the adhesive, impacting its ability to reattach. Other repositionable options include soft acrylic adhesives. Device designers might turn to acrylics for applications requiring repositionability combined with stronger grip, longer wear time, single-use disposability or lower cost per unit.
Strong grip and adherence
Strong grip and adherence are necessary for medical devices that must hold relatively heavy weight or stay secure for long periods under demanding conditions. For example, super-absorbent wound dressings contain large amounts of fluid between changes. Some wearables must remain securely attached through showering, exercise and other daily activities. Still, the adhesive’s grip should never cause skin trauma, especially since it will be repeatedly used in many cases around the same body part. Rubber-based adhesives deliver a strong grip but are not breathable and tend to be too aggressive for fragile skin.
It’s important to consider the entire adhesive spectrum relative to the desired end use. Adhesives can be engineered with varying levels of tack, and different carrier materials can be leveraged. For example, acrylic adhesives can be coated into breathable, soft carrier materials to improve comfort while delivering strong hold. Also, SSA can be engineered with high tack. Such SSA might be a good fit for some super-absorbent dressings, but atraumatic, or pain-free, release could be compromised by their higher degree of peel adhesion. However, high-tack SSA could be suitable for wearables with mid-range wear times. In this application, the patient’s skin might not be as vulnerable to trauma as the skin of a patient with a severe wound.
Gentle wear and atraumatic removal
Demand is growing for adhesives that deliver gentle wear and atraumatic removal. These qualities are critical in advance wound care for the elderly, infants and others with fragile, delicate skin. In addition to gentle adhesion, healthcare providers often want repositionability when treating serious or chronic skin trauma so they can remove a dressing temporarily to examine a wound, or to shift its position so that a clean portion of the dressing faces the wound, ready to absorb fluids and exudate. Gentle-wear dressings often must offer a hydrophobic barrier around the wound, keeping liquids away from both the wound and peri-wound area. This helps prevent maceration and wound enlargement. All the while, the dressing should remain comfortable for the patient, with minimal to no discomfort each time it is repositioned or removed. Here again, SSA are the preferred adhesive choice because they deliver the most important performance capabilities required for optimal healing and patient experience.
Extended wear time
Extended wear time is one of the most challenging performance requirements facing today’s medical device developers. For example, some wearable devices now call for 30-day wear times whereas previous applications might have stopped at five, 10 or 14 days. With longer wear comes the need for adhesives to withstand many environmental stressors, from daily showering to exercise. Whether it’s biking, hiking, swimming or any number of activities, patients want and need to maintain active lifestyles, and their medical devices are expected to keep up. At the adhesive level, this means delivering the right mix of sustained grip, breathability and waterproof properties. Acrylic pressure-sensitive adhesives (PSA) can be engineered for strong hold, water-resistance and breathability. The latter quality, closely associated with comfort, is enhanced when the PSA are coated onto highly breathable carrier materials.
The next time a product’s adhesive requirements seem quite demanding, remember you can collaborate with your materials suppliers to find practical and innovative solutions.
