I. Medical Background and Challenges of Aseptic Environments
Using magnetic connectors in operating rooms or sterile environments presents the greatest challenge of simultaneously satisfying sterilization performance, electrical reliability, and mechanical functionality. Therefore, the "sterilization environment" must be considered a critical design consideration from the outset.
Relevant standards indicate that sterilization methods such as moist heat/steam sterilization, EO (ethylene oxide), and irradiation have their own validation/limitations. The sterilization process for medical devices must be validated and documented. Engineers should use standards such as ISO 17665 as references and acceptance criteria.
II. Potential Impacts of Common Sterilization Methods on Magnetic Connectors
- High-Temperature, High-Pressure Steam
Advantages--Effective at inactivating most microorganisms and spores; commonly used in industry and hospitals.
Risks-- High temperature and humidity can affect the physical properties of some magnet encapsulations and seals; for permanent magnet materials, demagnetization is usually not immediate in the short term, but prolonged exposure or temperatures exceeding the material's temperature limit can lead to demagnetization.
- Ethylene Oxide (EtO)
Advantages-- Low temperature, suitable for heat-sensitive materials.
Risks-- Requires strict ventilation and residue removal processes; may have chemical compatibility issues with certain packaging materials. Primarily used for medical devices requiring cryogenic sterilization.
- Cryogenic methods such as cryogenic plasma/hydrogen peroxide (H2O2) and gamma irradiation
Advantages-- Suitable for heat-sensitive devices (e.g., some electronic modules).
Risks-- Plasma or irradiation may affect the properties of polymer materials or cause changes to the surface/coating of magnetic materials; irradiation may also alter the mechanical properties of polymers; therefore, material-level verification is required. The review points out that cryogenic methods, irradiation, and EtO each have their own focus in terms of suitability for magnetic devices; engineers must select materials and processes based on the target sterilization method during the initial design phase.
III. Engineering Design Requirements
The following are specific items that should be included in the specification sheet for magnetic connectors in sterilization/surgical environments
- Sterilization Compatibility
Explicitly supported sterilization methods, such as: 121°C/15 min moist heat cycling; or EtO; or H2O2, etc., and unacceptable methods. Manufacturers/developers also need to provide post-sterilization functional reports, such as retained magnetic pull, contact resistance, insertion and extraction force, sealing performance, and absence of surface cracks.
- Materials and Coating Selection
Permanent Magnets--Prioritize materials with high Curie temperatures and good high-temperature retention; use corrosion-resistant and impermeable encapsulation, and ensure the encapsulation material is compatible with the sterilization method.
Seals--Select high-temperature resistant or chemical-resistant medical-grade elastomers, specifying resistance to accelerated aging by steam/sterilizers.
Contacts--Electrical contacts should use corrosion-resistant plating, considering plating stability at high temperatures.
Housing and Insulation: Must withstand specified sterilization cycles without cracking, deformation, or water absorption and swelling.
- Structure and Sealing Design
When designing magnetic connectors, minimize small gaps and blind cavities, and design a flat surface for easy cleaning and sterilization.
- Mechanical Durability
Target mating/removal cycles, e.g., greater than 10,000 cycles. Durability must be re-verified after a specified sterilization cycle, with one sterilization cycle after each mating/removal until the end of the total lifespan.
Magnetic Retention Force and Disconnection Force: Measured on samples after N sterilization/use cycles, with the maximum permissible decrease given.
- Electrical Performance Requirements
Minimum/maximum permissible values for contact resistance and insulation resistance in the post-sterilization environment.
For data and high-speed signal ports, contact integrity and transmission performance must be verified after sterilization.
The potential impact on magnetic fields and nearby sensitive equipment, such as MRI and imaging equipment, must be assessed.
IV. Summary
If your product will use magnetic connectors in sterilization or surgical environments, sterilization methods, cleaning procedures, lifespan targets, and maintenance strategies must be incorporated into the design from the outset; verified through real-world testing; and material and packaging selections must be based on experimental data. Only by doing these things well can magnetic connectors be used safely and reliably in the harsh environment of a surgical procedure.
