Sunday, March 25, 2012

Medical Adhesives

Adhesives employed in medical practices are commonly used for surgical procedures and appliance bonding. While medical adhesives encompass a wide range of fabrication materials, they are typically composed of synthetic or biological formulations. Various adhesives are incorporated into medical devices and are either disposable (hot melt and pressure adhesives) or are used multiple times. High strength bonding adhesives are able to withstand high heat ranges; some are compatible with electronic devices. Many adhesives are ideal for bonding a wide variety of substrate surfaces, including metals, plastics and rubbers, while others are suitable for skin and suture applications. Medical adhesives may be categorized as one or two-part component epoxy systems, each featuring different curing reactions. Examples of common applications that require medical adhesives include surgical instruments, biosensors, electrodes labeling, catheters, and implantable devices.

Adhesive Types

There are various medical adhesives that feature different bonding qualities when applied to different substrates, and require different methods of application. Standard adhesives commonly found in the medical field include the following three types: pressure sensitive, dissolvable,and electrical conductive adhesives.

Pressure sensitive adhesives (PSAs) are composed of a number of different materials, including rubbers, acrylate and silicone formulations. Whereas other adhesives may require heat or water to activate or “cure” a surface, this type of adhesive bonds to a surface by being pressed on to the substrate. These adhesives are often fabricated in woven and nonwoven variations. In the medical field, various PSAs are often used for skin bandages. Variants include double-sided tapes, for more bonding control.

Dissolvable adhesive films are designed to react and dissolve when exposed to different variables, such as heat, or liquids (including body liquids).

Electrical conductive adhesives are composed of materials that are compatible with medical sensor devices and electrodes and come in either film form and in gel versions, which include active pharmaceutical ingredients.

Adhesive Composition: Synthetics and Biological

The two primary medical adhesive composition categories generally include synthetic and biological materials. Formulations are tested to meet medical safety criteria. Common variants of these adhesive types include the following: acrylics, silicone, polyurethane, and bio adhesives.

Synthetic Adhesives:

Acrylics, or cynoacrylates (CA), are a common type of adhesive, used for suturing wounds, that reduce infection and scarring. Many acrylic adhesives, such as pressure sensitive tapes, are used for bandages and disposable applications. Specific acrylate formula variations are suitable for use under wet and dry conditions. Various acrylic adhesives are solvent based, though hot melt acrylics are also used for an assortment of applications. In medical applications, curing often occurs by atmospheric moisture or UV light.

Silicone is another common material used for medical bonding. Typically, this material is popular because it is biocompatible, and there are several curing formulations.

Polyurethanes are commonly produced in bandage adhesives and are available in various strengths and are efficient in processes and applications due to their water resistance.

Biological adhesives are often used in surgical applications, such as skin grafting and for suturing wounds. The composition of these adhesives includes variations of proteins. Fibrin is a commonly used natural “clotting” protein material that is used to help mend damaged vessels and for wound applications.

Associated Processes

Curing involves the method and the amount time that the adhesive requires in order to achieve full bonding strength. For instance, an adhesive can be “cured” via heat, UV light, pressure, or by atmospheric temperature, and these processes typically

An epoxy system refers to a class of adhesive chemistry types that are fabricated from two types of chemicals. Some formulations are curable by UV light (for example, one-part systems). Other systems, such as two part variations, are cured by heat or room temperatures.

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