Silicone biocompatibility is critical for medical devices, medical-grade components must have biocompatibility to ensure safety applications. In medical LSR molding fabrication, we must comply with the medical equipment regulations and designs.
What is Biocompatibility
The biocompatibility of medical devices means never cause any adverse responses in the surrounding tissues, such as irritation, swelling, or redness.
The latest international standard of ISO 10993-1-2018 and FDA guidelines determine the critical parameters in medical grade parts. These guidelines cover 4 main types of medical devices: active, non-active, implantable, non-implantable.
According to FDA guidelines, biocompatibility standards includes the effect of devices with different materials in multiple categories. There are some key elements in biocompatibility as following:
- Cytotoxicity: The materials must have no toxic effects on cells
- Irritation or Sensitization: The materials mustn’t create any sensitivity or irritation.
- Acute System Toxicity: Medical devices’ usage mustn’t occur any systemic or short-term toxicity.
- Material-medicated pyrogenicity: Materials cannot cause fever in patients.
- Hemocompatibility: The devices cannot cause adverse reactions with patients’ blood.
- Genotoxicity: Anything impact the human genes has gentoxicity. Medical devices and materials must not have this effect, especially in long-term usage on patients.
- Carcinogenicity: This is the capability to cause cancer. This material is prevented in long-term usage.
- Chronic toxicity: The metric is critical for safety determination in implanted or long-term medical devices.
- Degradation: Once medical materials or devices degrade in contact with tissue, the manufacturer should provide degradation information for biocompatibility evaluation.
- Reproductive or Development Toxicity: Medical products for pregnant women require separate tests for safety.
We need to ensure biocompatibility by materials safe performance. Furthermore, these materials can withstand sterilization and cleaning. In recent years, liquid silicone rubber becomes the most popular material in medical devices’ production.
Liquid Silicone Rubber Biocompatibility
Medical devices with biocompatibility silicone rubber are applied internally and externally for patients. The versatility of liquid silicone rubber materials result in numerous medical products, like rings, cushioning pad, gaskets, catheters, closures, stoppers and bottles. As all these medical products require safety testing and risk assessment to determine final medical applications. There are numerous factors to dictate the final application of LSR medical devices. Such as surface structure and chemical composition. It is crucial to test final products’ biocompatibility for patients’ safety.
Liquid Silicone Rubber Bio-characteristics
Liquid silicone rubber is the most preferable material for medical devices and components. It has several characteristics for biocompatibility.
Thermal Stability
The LSR materials have stability in a wide range of temperature between -65℃ to 250℃. This is wider than normal thermoplastic elastomer materials.
Sterilization Capability
As medical devices and components should be sterilized in normal application, the materials must withstand the sterilization process without any chemical or physical defects. Normally, medical facilities can sterilize LSR components by gamma radiation, autoclave, E-beam, and ethylene oxide (EtO). The autoclave is processing in temperature from 110℃ to 190℃, liquid silicone rubber is able to withstand these temperatures easily. However, in order to maintain silicone biocompatibility, we should avoid sterilization methods of hydrogen peroxide, gamma radiation, or ClO2, these methods can change silicone structure.
Texture
LSR has dry and nonstick surface, this makes topical medical device don’t have tacky feel for patients, and stay compliant with application rules.
Biological Inertness
LSR insert qualities prevent its reaction with tissue in human body, this is a critical requirement for any biocompatible materials in internal application.
Hypoallergenic
Liquid silicone rubber never causes allergic reactions in patients, even for sensitive people. Therefore, this characteristic satisfies the biocompatibility requirement of never irritation or sensitization.
FDA Testing
Although liquid silicone rubber has these properties, there are still three-step FDA testing to prove the biocompatibility of LSR.
Biological Evaluation Plan (BEP)
This BEP outlines how manufacturers will evaluate the risk and safety of the LSR materials and products. The final affection on patients will determine the testing types and potential risks in BEP recommendations.
Conduct Test
The materials testing is based on the categories of ISO 10993-2018 appendix A. In order to determine whether LSR products provide adequate biocompatibility. Professional researchers will conduct several assessment types to prove safety and risk factors. These tests include toxicology risk and chemical risk evaluation, in vivo or vitro biological studies, literature analysis on clinical studies and scientific experiments.
Biological Evaluation Report (BER)
The final biological evaluation report will summarize the tests and analysis. The FDA will receive a copy of the report with test results, then make the final decision on devices’ biocompatibility.
Why Biocompatibility is Important
Medical devices without risk level will increase adverse reaction rate for patients. In some case, untested biocompatible devices could result in worse conditions. Therefore, in order to prevent these situations, the FDA requires all test results of medical devices’ biocompatibility. All these tests depend on contact level of devices, but even brief contact items must prove safety. Patients will suffer harm from medical treatment without such proof.
Biocompatibility testing of LSR products is crucial. The manufacturing process will introduce structures and chemicals with safety issues in materials. Therefore, biochemical assessment with risk analysis and testing will ensure no injury or danger to patients with the finished LSR parts.
Implants Testing Importance
Implants biocompatibility testing of medical devices can prevent serious complications in patients. Although the same LSR materials of implants won’t cause problems in external applications, the internal applications for an extended time will lead to complications, in reason of interaction with blood and tissues. Such as, the insulation materials in implantable electronics will contact tissues directly. These inert materials’ composition will cause thrombosis, fibrosis, or bacterial growth from different surface structure. Therefore, risk evaluation and testing can prevent dangerous application of these materials.
The long-term implants have potential risks like carcinogenicity. As growing knowledge of carcinogens and increased longevity of implants devices, the FDA and ISO add the new testing category to implants. Even the materials prove safety in a few months, carcinogenicity examination can determine the danger over years’ application in human body.
External Testing Importance
Biocompatible devices for external application must not cause sensitivity in any patients, even patients with high sensitivity levels. Therefore, hypoallergenic and nonactive medical devices ensure all patients can benefit from these products. This allows faster applications of medical devices without testing at first.
Furthermore, LSR has pleasing texture for external applications, LSR medical devices don’t have sticky and tacky feeling. This encourages patients more compliant with treatment. Although texture testing of LSR products is not a required part of bioccompatibility, it does ensure the comfort of medical devices.
Biocompatible LSR Benefits in Medical Industry
Biocompatibility testing is crucial to ensure safety for patients. The criteria in FDA and ISO 10993 conform to the safety standard of all medical devices. Once materials or devices don’t conform to the stands, modifications are required to achieve the ISO or FDA standards. For example, LSR may cause problems for implants usage. However, surface alternation will make this material less prone to harboring bacteria.
Graft Polymerization
Grafting hydrogel can avoid platelets gathering on LSR surface, and also reduce the absorption of proteins. However, graft polymerization cannot suffice all medical device applications. In reason of hydrogel will affect the mechanical properties of LSR surface.
Ion Implantation
Ion implantation can increase the interaction between LSR materials and area cells, in order to prevent bacteria growth. The implanting carbon into LSR materials will not affect the mechanical structure. Otherwise, it can improve cyto-compatibility of LSR.
Long-term application of medical will give rise to physical or chemical changes in human body, which is not apparent with short-term use. Therefore, biocompatibility testing is not only ensuring the safety of medical devices, but also understanding the risk for use and taking steps to mitigation.
Furthermore, biocompatibility testing can also examine human body affection on medical devices operations. In order to guarantee no reaction between the patients’ tissues and medical parts, and promote the safe operation of devices. Although materials are biological inert, they also have potential to affect the implants function. Biocompatibility plays vital roles in medical industry, it protects patients and ensure devices operation. Without professional testing, there are always doubt about the safety and reliability of medical devices.
Contact Miwo
All in all, Liquid silicone rubber (LSR) biocompatibility provides a wide application in numerous medical parts and components. Our experts can give you the guidance in LSR-based medical devices. We have produced millions of LSR parts since 2015. Our professional knowledge, expertise, tools and experience will assist you to improve your medical devices.
Contact our engineering team now for more information about LSR biocompatibility.
