Selection, Applications, and Biocompatibility of Medical Epoxies
Global investment in medical research continues to rise, surpassing $260 billion in 2013, with the United States accounting for nearly half. As research expands, medical device manufacturing has grown rapidly, reaching $133 billion in the U.S. in 2016 and over $350 billion worldwide. This industry faces strict performance and regulatory requirements, making reliable materials essential. Among these, epoxy adhesives play a critical role in medical device assembly because of their high bond strength, compatibility with many materials, resistance to moisture, and non-toxic formulations that make them suitable for implantable devices.
Adhesive Selection
When designing medical devices, engineers must ask: “What type of epoxy adhesive is best for this application?” There is no universal solution. The ideal epoxy adhesive is the one that meets the application’s performance needs and regulatory requirements. Key factors in adhesive selection include physical properties such as viscosity, thixotropy, cure time, hardness, and density. Biocompatibility certifications like USP Class VI and ISO 10993 may be mandatory. Adhesives must also withstand sterilization processes such as gamma radiation or autoclaving. Most epoxy systems are non-nutrient, which prevents fungus and bacteria from growing on them.
Specialty formulations can further enhance performance. Thermally conductive epoxies use fillers such as boron nitride, aluminum nitride, or aluminum oxide to improve heat transfer. Electrically conductive epoxies, such as silver-filled systems, are widely used in EMI and RFI shielding, solder replacement, and die attach applications. Consulting with epoxy manufacturers such as EpoxySet ensures the best fit for performance, regulatory, and processing requirements.
Application Example: Ultrasound Transducers
Ultrasound transducers are a critical example of epoxy use in medical devices. These probes, used externally or internally, consist of several components. The lens or window material is typically silicone or a urethane adhesive. The piezoelectric element (PZT) is often ceramic for high conversion efficiency. Behind the PZT, engineered epoxy adhesives such as EB-130M-1 are used as backing material, often modified with fillers to meet acoustic requirements. In front of the PZT, acoustic matching layers are applied using epoxy-based systems. EB-106 is a popular lamination epoxy valued for its high strength, low viscosity, and excellent wetting. Together, these materials provide the mechanical strength, acoustic precision, and stability required in sensitive devices.
Biocompatibility
Biocompatible epoxy adhesives are designed to be non-toxic and non-irritating to living tissue, ensuring no harmful physiological or immune reactions. USP Class VI certification confirms that an epoxy is safe for direct or indirect patient contact. Applications include endoscopes, catheters, infusion pumps, transducers, prosthetics, and diagnostic equipment. While USP Class VI certification validates the adhesive itself, it does not guarantee the biocompatibility of the entire device. Engineers must evaluate both materials and design. Not all medical adhesives require certification. Some rely on internal testing or well-established chemistries. Still, USP Class VI and ISO 10993 remain the most widely recognized standards globally.
Conclusion
As medical research and device manufacturing continue to expand, the demand for innovative adhesive solutions grows as well. Epoxy adhesives remain a cornerstone of medical device technology, valued for their high strength, chemical resistance, and reliability in demanding conditions. Whether used in implantable devices, diagnostic equipment, or ultrasound transducers, medical-grade epoxies provide a balance of performance and compliance. Compared with silicones or urethanes, epoxies offer unique advantages in bond strength, processing versatility, and durability, making them indispensable in today’s medical device industry.
