A bond line is invisible in the finished device, but its failure never is. As medical devices grow smaller and incorporate more dissimilar materials, selecting an adhesive that meets both mechanical and biocompatibility requirements has become one of the most consequential decisions in the assembly process.
Critical Requirements for Medical Bonding
Selecting a bonding solution for medical applications is significantly more involved than general industrial assembly. Whether the application involves catheters, needle assemblies, or diagnostic device housings, the adhesive needs to satisfy three primary requirements.
Biocompatibility. Every adhesive used in a medical device needs to be formulated with patient-contact materials in mind. Incure’s Cyro-Weld™ CM-series and 5000-series adhesives are formulated to meet ISO 10993-5 biocompatibility standards, which cover cytotoxicity testing relevant to short-term device contact.
Sterilization compatibility. Devices frequently need to withstand sterilization before use, and the adhesive must retain mechanical properties afterward. Incure’s Cyro-Weld™ 5000-series UV-curable adhesives are validated for compatibility with ethylene oxide and gamma sterilization processes, which is a meaningful consideration since gamma radiation and EtO exposure can embrittle non-stabilized polymer chemistries over time.
Substrate versatility. Modern devices often join high-surface-energy metals, such as stainless steel, to low-surface-energy plastics like Pebax or nylon. The adhesive needs to act as a bridge that accommodates the differing coefficients of thermal expansion between these materials.
Leading Adhesive Technologies for Device Assembly
UV/visible light curable adhesives are widely used for high-volume device assembly because they cure in seconds under the correct wavelength, supporting full in-line quality inspection. Incure’s Cyro-Weld™ 5002F is formulated for hermetic bonding applications such as needle hub, catheter, and reservoir assembly, where a complete, void-free seal matters as much as bond strength. Cyro-Weld™ 5013 is a wicking-grade formulation suited to micro-catheter connections, where the adhesive needs to flow into a narrow gap by capillary action rather than being applied directly to the joint.
Email Us with your specific substrate pairing and sterilization method — grade selection depends heavily on both.
Medical-grade cyanoacrylates remain the standard for rapid fixturing of small components. Cyro-Weld™ CM-3 is an ultra-low-viscosity formulation suited to fine wicking applications, while CM-9 offers a moderate viscosity for general assembly work. For small-gap bonding where slightly more body is needed, CM-105 and CM-110 provide a higher-viscosity option, and CM-800 and CM-815 are formulated specifically for rubber and multi-material bonding where flexibility at the joint matters.
How Incure Supports Device-Assembly Selection
At Incure, we don’t just provide adhesives — we provide a technical framework for navigating the complexity of device assembly, working alongside engineering teams through a structured selection process.
Substrate and sterilization profiling. We identify the exact grade of polymer or metal involved and match the adhesive’s chemical resistance to the sterilization method your process specifies, since not every formulation performs identically across EtO, gamma, and other common methods.
Documentation support. Incure’s Cyro-Weld™ medical-grade series is formulated to meet ISO 10993-5 biocompatibility standards, and we provide the relevant technical documentation to support your own device validation and testing process — this reduces, though doesn’t eliminate, your internal testing burden.
Curing process integration. To ensure the adhesive performs as specified, Incure offers matched UV/LED curing equipment. By supplying both the chemistry and the curing hardware, we help eliminate the process variables that lead to incomplete polymerization and inconsistent bond quality. For engineers weighing UV cure speed against alternative chemistries for a specific joint, our comparison of UV glue versus epoxy for transparent bonding is a useful reference, and our guide on how CTE mismatch causes adhesive bond failure covers a failure mode that’s especially relevant when bonding stainless steel to flexible polymer components.
A Note on Elongation and Flex Fatigue
Device assemblies involving flexible tubing or repeated bending, such as catheter shafts, put unusual demands on a bond line compared to a rigid industrial joint. An adhesive with high elongation at break resists cracking under repeated flex cycles, but elongation and ultimate tensile strength typically trade off against each other in a given chemistry. Matching the specific Cyro-Weld™ grade to the device’s actual flex profile — rather than defaulting to the highest-strength option available — is usually the more reliable path to a durable bond over the device’s service life.
In device assembly, precision in material selection matters as much as precision in manufacturing. Partnering with Incure gives engineering teams access to formulations built around biocompatibility and sterilization requirements from the start, rather than adhesives adapted after the fact.
Common Selection Mistakes in Device Assembly
A few recurring mistakes account for most adhesive-related issues we see in device assembly programs.
Selecting a viscosity grade before confirming the gap size. A low-viscosity, wicking-grade cyanoacrylate like CM-3 performs very differently from a higher-viscosity grade like CM-105 in a joint with more clearance — using the wrong end of the viscosity range for the actual gap is a common source of incomplete fill and weak bonds.
Assuming one sterilization method is interchangeable with another. A formulation validated for EtO exposure doesn’t automatically perform the same way under gamma radiation, since the two processes affect polymer chemistry differently. Confirming compatibility with your specific, final sterilization method — not just “a” method — avoids late-stage surprises during device validation.
Overlooking flex fatigue in favor of peak bond strength. For components that flex repeatedly in use, prioritizing the single highest tensile-strength grade over one matched to the required elongation often produces a bond that’s strong under a static pull test but prone to cracking after weeks of actual use.
Frequently Asked Questions
Q: How is a Cyro-Weld™ grade matched to a specific device application?
A: Incure’s engineers review the substrate pairing, joint gap, required elongation, and sterilization method together, since each of those factors narrows the recommendation independently before a final grade is confirmed.
Q: Does ISO 10993-5 compliance cover every biocompatibility requirement for a device?
A: ISO 10993-5 specifically addresses cytotoxicity. Depending on your device’s contact duration and body-contact classification, additional testing outside the adhesive supplier’s scope may be required as part of your own device validation.
Ready to discuss adhesive selection for your device assembly? Contact Our Team for a technical consultation on the Cyro-Weld™ formulation best suited to your substrates and sterilization process.
Visit www.incurelab.com for more information.