Adhesive selection for Medical Devices

Ensuring Reliability in Medical Devices: The Role of Certified Adhesives

In the realm of medical device manufacturing, the choice of adhesives is critical, especially when these devices require sterilization. The adhesives must not only bond effectively but also withstand the rigors of sterilization processes without compromising their integrity. This blog post explores the glue selection for Medical Devices that need to be sterilized, the impact of sterilization on bonding strength, and the validation tests necessary to ensure reliability.

Glue Validation Test Autoclave

The Importance of Medical-Certified Adhesives

Medical devices often require adhesives that meet stringent biocompatibility standards. These adhesives must be able to bond various substrates used in medical devices while maintaining their properties after sterilization. The glues selected for such applications include Epotek 353ND, Masterbond EP3HTND-2MED Black, and Loctite EA M-31CL Epoxy. Each of these adhesives is designed to meet the high standards required for medical applications.

Impact of Sterilization on Bonding Strength

Sterilization is a critical process for medical devices, ensuring they are free from harmful microorganisms. However, the process can affect the bonding strength of adhesives. Common sterilization methods include autoclaving (steam sterilization), ethylene oxide (EtO) sterilization, and gamma radiation. Each method can impact the adhesive differently:

  • Autoclaving: This method uses high-pressure steam at elevated temperatures, which can lead to hydrolytic degradation in some adhesives, weakening the bond. When glue is exposed to the heat of autoclaving, its molecular structure may become less stable, causing a reduction in adhesion strength. The heat accelerates breakdown processes in the glue, especially those not designed for extreme thermal cycles, which compromises the long-term durability of the bond.

  • Ethylene Oxide (EtO): While effective at low temperatures, EtO can leave residues that might affect the adhesive’s properties.

  • Gamma Radiation: This method can cause changes in the chemical structure of the adhesive, impacting its mechanical properties.

Validation Testing: Ensuring Confidence and Reliability

To ensure that the selected adhesives maintain their performance post-sterilization, rigorous validation testing is necessary. One approach to validation is using the Bayes Success Run Theorem, which helps in determining the confidence and reliability of the adhesive bonds.

Bayes Success Run Theorem:

  • Confidence Level: This represents the probability that the adhesive will perform as expected under specified conditions.
  • Reliability: This measures the likelihood that the adhesive will maintain its bonding strength over time and through multiple sterilization cycles.

Validation tests typically involve:

  • Initial Bond Strength Testing: Measuring the adhesive’s bond strength before sterilization.
  • Post-Sterilization Testing: Assessing the bond strength after subjecting the adhesive to various sterilization methods.
  • Repeated Cycle Testing: Evaluating the adhesive’s performance over multiple sterilization cycles to ensure long-term reliability. 


Selected Adhesives for Medical Devices:

  • Epotek 353ND + Epotek OD2002: Known for its excellent thermal stability and resistance to sterilization processes.
  • Masterbond EP3HTND-2MED Black: Offers high bond strength and is specifically designed for medical applications requiring sterilization.
  • Loctite EA M-31CL Epoxy: Provides strong adhesion and maintains its properties after sterilization, making it suitable for a variety of medical devices.
 

 Conclusion

The use of medical-certified adhesives in devices that require sterilization is essential for ensuring patient safety and device reliability. At Technobis High Tech Solutions, we understand the impact of sterilization—especially autoclaving—on bonding strength. Heating glue during autoclave sterilization can weaken the bond, making thorough validation testing even more critical. By conducting rigorous testing, manufacturers can select adhesives that meet the highest standards of performance and reliability. The adhesives chosen—Epotek 353ND, Masterbond EP3HTND-2MED Black, and Loctite EA M-31CL Epoxy—demonstrate the commitment to quality and innovation in medical device manufacturing.

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