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Top 10 considerations when molding diagnostic cartridges

Molding diagnostic cartridges, lateral flow components, and intricate microfluidic devices is an art that blends the science of mold design, injection molding, and in-vitro diagnostic (IVD) device manufacturing. This expertise guarantees the seamless creation of top-tier, validated, and easily scalable IVD components. Diagnostic cartridge molding involves several crucial factors that should be integrated into your project plan.

Here's a breakdown of these important considerations:

1. Careful Material Selection Opt for a medical-grade material that suits the diagnostic purpose, such as a medical USP Class VI material or one resistant to lipids. The material should have good dimension stability, chemical resistance, and, if visuals are essential, transparency.


2. Thoughtful Mold Design Design the mold with care and consideration for accurate and consistent replication of the diagnostic cartridge. Make sure you specify uniform cooling and heating channels for dimensional control, carefully select an appropriate gate type and location to minimize shear stress, and provide ample draft angles for easy release and to avoid stress during ejection.


3. Strategic Tooling Decisions Tailor the mold tooling to match the required volume and complexity of the cartridge. Factors like the number of cavities, cooling channels, and mold material play a role in optimizing production efficiency.


4. Smart Parting Line and Gate Design Determine where to position the parting line and gate to minimize excess material, or flash, and guarantee proper mold filling. The gate's positioning should prevent trapped air and interruptions in the flow.


5. Precise Tolerances and Surface Finish Pay attention to the specific tolerances and critical dimensions necessary for proper functionality. You should also focus on achieving the right surface finish for the cartridge's main contact points and flow characteristics.

6. Adequate Venting Incorporate appropriate venting mechanisms to allow air and gasses to escape during the molding process. Inadequate venting can lead to cosmetic defects, voids, or haziness on the surface, potentially affecting the clarity of light transmission during diagnostic testing.


7. Meticulous Processing Ensure scrupulous hygiene and proper machine maintenance during molding to achieve low fluorescence. Regularly clean the screw and barrel, maintain low shear and resistance time, eliminate interruptions, and degas the polymer before processing.


8. Seamless Assembly Compatibility If additional components are needed for cartridge assembly, design the molded parts to simplify integration with elements like sensors, electronics, or membranes.


9. Quality and Regulatory Compliance Validate the molding process for robustness, ensuring repeatability and reproducibility for a reliable and high-quality product. Since diagnostic cartridges are intended for medical or regulated application, they also need to comply with all relevant standards, such as ISO 13485 and FDA guidelines.


10. Efficient Cost Management Evaluate the cost-effectiveness of the molding process based on factors such as tooling costs, material efficiency, cycle time, and potential scalability for large-scale production.


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