What to Consider When Designing Silicone Hemostasis Seals
Before designing a hemostasis seal, it’s important to understand why they are so important. Silicone hemostasis sealing needs to minimize blood loss during percutaneous procedures as much as possible. Guide wires and other device components require these to aid in the closure process and to create a fluid-tight seal around the medical device.
When designing a silicone hemostasis seal for a specific device, there are a few imperative requirements to take into consideration: desired sealing range, pressure required, insertion force, volumetric constraints, and manufacturing assembly costs. Once these logistics are determined, material selection can occur. There are two main categories: HCR/ETR (Gum Stock) and LSR (Liquid Silicone Rubber.) HCR/ETR has greater elongation, more variation of material lots, higher part costs, and 20-70 Durometer. LSR offers faster processing times, lower part costs, 30-70 Durometer, but less material lot variation. There are also several loading options to think about as well, including colorants, self-lube, and PTFE. When it comes to coating options, silicone oil or parylene can be chosen.
The size of the instrument passing through the device determines the seal and slit geometry. Single slit symmetric seals, duckbill designs, multi-slit with retention, single slit with wiper seal, and interfaces slits with retention are all options in design and depend on your specific sealing requirements. Symmetry reduces manufacturing and assembly costs. The assembly process involves the relationship of all components and their effect on the seal’s performance. Static compression, radial compression, seal retention, tolerances, and symmetry will all have an effect on how your seal is manufactured. Lastly, after your hemostasis seal is assembled, you must determine how it will be sterilized, its shelf life, and how it will be lubricated for use.