Assembling a disposable diagnostic cartridge or an external fluid-connector set means joining small plastic and metal parts that have to seal, survive sterilization, and pass cytotoxicity testing. The adhesive choice sets how fast the line runs and how well the joint holds.

What Sets These Adhesives Apart

Adhesives used in device-component assembly are formulated and tested against biocompatibility standards, most commonly ISO 10993-5 for cytotoxicity. Beyond that, they need consistent bond strength on engineering plastics, resistance to the fluids the device contacts, and stability through a validated sterilization cycle. Incure Cyro-Weld grades are formulated to meet ISO 10993-5, and selected grades are validated for ethylene oxide and gamma sterilization; the specific route must be confirmed against each grade’s datasheet. These are device-component bonding materials for external and disposable assemblies, not implant adhesives, and no grade here is offered for implanted or long-term tissue-contact use.

Chemistry Options

• UV and visible light-cure acrylates (Cyro-Weld 5000-series): cure in one to several seconds under a spot or flood lamp, cure water-clear, and many grades fluoresce for automated inspection. Grades such as 5002F, 5004F, 5013F, and 5017F cover a viscosity range from wicking to gel. Suited to joints where a light path reaches the bond and cycle time matters.
• Cyanoacrylate (Cyro-Weld CM-series): single-part instant adhesives that fixture in seconds on elastomers and plastics. Low-viscosity grades such as CM-3 and CM-9 wick into tight joints; higher-viscosity grades such as CM-500 and CM-2500 fill gaps. Good for fast fixture without cure equipment.
• Two-part epoxy: slower cure but strong, gap-filling bonds across dissimilar materials and shadowed joints a light cannot reach. Used where structural strength and chemical resistance outweigh cycle time. A room-temperature or mild heat cure is chosen based on the temperature limit of the plastics in the assembly.
• Light-plus-secondary dual-cure grades: a light cure fixtures the part in seconds while a secondary heat or moisture mechanism completes the bond in any shadowed region, useful for opaque housings and blind joints.

Email Us with your substrates, joint geometry, and sterilization method, and our team will recommend a grade.

Matching Viscosity to the Joint

Wicking grades below about 50 cP flow into press-fit and annular gaps by capillary action and cure fast, but drain from open or wide joints. Medium grades hold a bead for positioning. Gel and thixotropic grades fill gaps up to roughly half a millimeter and stay on vertical surfaces. Dispense the minimum volume that completes the joint, since excess adhesive cures slower and can wick where it is not wanted.

Substrate Compatibility

Common device plastics behave differently. Polycarbonate and ABS bond readily with UV acrylates and CA. Cyclic olefin polymers and polypropylene are lower energy and may need surface treatment or a grade tuned for them. Verify that the cured adhesive resists the specific fluids and cleaning agents the assembly contacts. When the joint pairs a rigid engineering plastic with another part, the Incure Uni-Weld plastic bonder selection guide covers matching a grade to that substrate.

Documentation and Change Control

Adhesive selection for device-component assembly carries a paper trail. Keep the biocompatibility test reports, the sterilization validation data for the exact grade and cycle, and the material certifications on file, and reference them in the device master record. Lock the process parameters, dispense volume, cure dose, fixture, and cure equipment, in a controlled work instruction. Treat an adhesive lot change, a lamp change, or a supplier reformulation as a change-control event that may require bond-strength requalification, since even a minor formulation adjustment can shift adhesion to a given plastic. Retain production samples so a field question can be investigated against material from the same lot. Where a contract manufacturer does the bonding, the same controls and records should be specified in the supplier agreement rather than left to their discretion.

Cure and Inspection

Light-cure grades need the right wavelength and dose at the bond line; an L9000 UV LED spot lamp matched to a light guide delivers a repeatable, low-heat cure, and understanding what a light guide does in a spot system helps set working distance. Use adhesive fluorescence for 100 percent coverage inspection. Build the validation package around pull or burst testing before and after the sterilization cycle and after accelerated aging, since some chemistries change modulus after gamma exposure. For clarity-critical joints, UV glue versus epoxy for transparent bonding compares the options.

Closing

Reliable device-component bonding comes from matching chemistry and viscosity to the joint, confirming substrate and fluid compatibility, and validating the bond through the real sterilization and aging conditions. Grade selection should always rest on the current biocompatibility and sterilization test data for that grade. Contact Our Team to review your assembly.

Visit www.incurelab.com for more information.