During catheter and fluid-path device assembly, the adhesive joint is often the weakest link in an otherwise robust design. Bonds between hubs, connectors, strain reliefs, and tubing must survive dispensing, assembly stress, and validated sterilization without leaking or delaminating. Medical-grade adhesives are formulated specifically for this manufacturing challenge. The Bonding Demands in Catheter Assembly Catheter and disposable fluid-connector assemblies stack several hard requirements onto one joint: Flexibility with strength. The bond between a rigid hub and a flexible shaft must flex through repeated handling without cracking. Fluid resistance. Joints contact saline, contrast media, and cleaning agents during manufacturing and function testing. Sterilization survival. The adhesive must retain bond strength and dimensional stability after the validated cycle, whether that is ethylene oxide (EtO) or gamma irradiation. Substrate range. Common materials include nylon, polyurethane, polycarbonate, PVC, and thermoplastic elastomers, each with different surface energy. Biocompatibility of the finished component. Adhesives should be formulated to meet ISO 10993-5 for cytotoxicity so the assembled device-component passes its own testing. General-purpose industrial adhesives usually fall short on at least one of these, most often sterilization stability or substrate wetting on low-energy polymers. Adhesive Chemistries for Fluid-Path Assembly UV and visible-light-curable adhesives. These cure in seconds on demand, which lets an operator seat a hub, verify alignment, and then lock the joint with a light burst. The Incure Cyro-Weld 5000 series, including grades such as 5002F, 5004, 5013, and 5017, is formulated to meet ISO 10993-5 and validated per grade for EtO and gamma sterilization. Light cure suits automated hub bonding, tip forming, and strain-relief attachment where at least one part transmits light. Cyanoacrylates. Fast-wetting instant adhesives reach handling strength in under a minute and wick into tight annular gaps by capillary action. The Incure Cyro-Weld CM series spans viscosities from about 2 cP for capillary needle-to-hub bonding up to roughly 2,500 cP for gap-filling on larger connectors, with grades such as CM-4, CM-50, CM-500, and CM-2500 covering that range. CM-series grades are formulated to meet ISO 10993-5. For curing light-cure joints, a UV LED spot lamp matched to lightguide reach and working distance places energy precisely on small assemblies, while a UV lamp sized for resin curing handles higher-volume trays. Not sure which chemistry fits your joint and sterilization method? Email Us with your substrates, gap size, and validated cycle. Matching the Grade to the Joint Needle or wire into a hub: a low-viscosity capillary grade that wicks the full bond length without pooling. Hub to shaft: a medium-viscosity light-cure grade that holds position on the joint and cures on demand for alignment control. Strain relief or overmold interface: a flexible-cured grade that survives repeated bending. Connector or luer body: a gap-filling grade where tolerances are looser. Substrate compatibility is the gate. Polyurethane and nylon bond well to both families; PVC and TPE often need a light abrasion or plasma treatment first. Always confirm on production substrate lots, since resin formulations shift between suppliers. Process Control for Repeatable Bonds Surface preparation. Solvent-wipe and, for low-energy…