Maximizing Adhesion While Minimizing the “Ouch” Factor
Adhesion to skin has been an ongoing challenge since the mid-1800s when Dr. Horace Day first combined India rubber, pine gum, turpentine, litharge, and cayenne pepper extract, and applied the mixture to strips of cloth to be used as surgical tape. Cayenne pepper?! That sounds like pain in a bottle just from the application if it, never mind the removal!
In balancing the aggressiveness of the adhesive with the potential for pain upon removal, surface energy, compatibility and rheology must all be taken into account, as well as the flexibility and extensibility of the carrier. For example, the hydrophilicity of the adhesive can be adjusted to increase the bond, which may be necessary for rigid carriers such as sensors and drug delivery systems. Where ease of removability may be the dominant factor, such as with bandages or tapes being used on delicate skin, ensuring gentle removal will be a driving factor.
All of this, coupled with a plethora of variations in skin, makes it obvious why the development of skin contact adhesives keeps many scientists employed. If you’re seeking to break into this aspect of the health care market, knowing your Ps and Qs about skin adhesion will be essential to talking the talk with potential customers. It’s a lot more complex than choosing the cheapest product out there. Understanding the properties of each adhesive under consideration is necessary to ensure application success and client satisfaction.
The good news is that there are adhesives available that work. Acrylics tend to be the adhesives of choice because they are generally able to adhere without leaving a lot of residue or causing too much pain upon removal. For delicate or compromised skin, silicone adhesives are much gentler and are often chosen for use on neonatal and elderly patients where a more aggressive adhesive could damage the skin. The challenge is zeroing in on just the right one.
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