Which elastic material should I choose for my medical devices and products? What is medical-grade liquid silicone rubber, and is it safe? If you have these questions, follow this guide to learn more about medical-grade liquid silicone rubber, giving you more confidence when making your decision.
What Is Liquid Silicone Rubber
Liquid silicone rubber (LSR) is mainly composed of polysiloxane. This composition makes it decisively different from rubber, as it is more stable because its main skeleton consists of silicon and oxygen atoms.
When you get liquid silicone rubber, you’ll understand why it’s called “liquid”. Unlike the usual silicone products, it is two viscous liquids before curing. It is only when these two liquids are mixed and processed that they become a soft, elastic material. Medical-grade liquid silicone rubber is an upgraded version of regular liquid silicone rubber that has passed a series of safety approvals and is widely used in the medical field.
Why Medical Devices Choose Medical Grade LSR
No Harmful Ingredients
After curing, Medical-grade liquid silicone rubber has a high level of purity. Whether it’s the raw materials, the production environment, the catalysts, additives, and fillers added, every effort is made to ensure that medical-grade liquid silicone rubber is free of harmful chemicals.
The initial raw material for medical-grade liquid silicone rubber is high-purity quartz sand. This refined, virtually clean material controls the mixing of impurities at the source. Not only that, but the chemicals added during subsequent heating, hydrolysis, cracking, and polymerization are also strictly limited by USP Class VI or other international standards.
The primary filler for medical-grade liquid silicone rubber is fumed silica, which is of higher purity and quality, rather than precipitated silica, which would be used in industrial-grade silicone rubber.
Additives that are harmful to the human body and may be released are absolutely prohibited. Certified medical-grade liquid silicone rubber is free of harmful additives such as BPA, Phthalates, and PFAS. Heavy metal ions, D4, D5, and D6, are also limited to very low levels.
In order to cure into a silicone product that can be used, a safer platinum vulcanization system has been chosen for medical-grade liquid silicone rubber. This vulcanization system produces no toxic by-products and uses a catalyst that is not harmful to humans.
All the raw materials used should be traceable, so you don’t have to worry that qualified medical-grade liquid silicone rubber will make your medical equipment a safety hazard because of different batches.
If you want to know more about the composition of silicone rubber to confirm safety, you can read What Is Silicone Made Of? How Compositions Affect Safety and Performance.
Clean Production Environment
Silicone products made with medical-grade liquid silicone rubber are subjected to molding steps in an environment that meets ISO Class 7 or cleaner. This environment not only ensures that no foreign impurities are mixed in but also ensures that the critical production process is hygienic and prevents bacterial pollute the product.
Biocompatibility
Silicone is widely used in the medical field for its high biocompatibility. Certified medical-grade liquid silicone rubber doesn’t cause irritation and is virtually immune to allergic reactions.
Unlike latex, medical-grade liquid silicone rubber is a hypoallergenic material after curing and is often even used as an alternative to latex. Most “silicone allergies” you hear about are caused by patients who are allergic to other ingredients in substandard silicone products.
When human tissue comes into contact with a foreign chemical, it can cause a rejection or inflammatory reaction. Such reactions caused by medical-grade liquid silicone rubber are within manageable limits, so safety is guaranteed even when implanted as a graft inside the body.
Chemical Compatibility
As mentioned earlier, silicone rubber is stable because of its unique main chain structure. This stability is demonstrated by the fact that when it comes into contact with other chemicals, it rarely reacts with them.
You don’t need to worry about medical-grade liquid silicone rubber reacting with common materials such as metals, PP, and glass in your medical devices and products. They also remain stable over time when in contact with human tissues or bodily fluids, not releasing toxic substances to the outside world or reacting with them to cause harmful effects.
Extractable content is tested as an important indicator in safety standards to ensure that medical-grade liquid silicone rubber is safe for humans.
Doesn’t Adhere to Wounds or Body Tissues
In addition to not reacting with human tissue, not adhering to human tissue is a major advantage of cured medical-grade liquid silicone rubber. If you put a band-aid on a wound and try to remove it after the wound has scabbed over and recovered, you will find that the skin and the band-aid are stuck together.
The surface of cured medical-grade liquid silicone rubber is smooth, dense, and waterproof, so you can easily separate it from your body after long-term use, which is why it can be used as a dressing. The use of medical-grade liquid silicone rubber for grafts and other products that come into long-term contact with mucous membranes and wounds can help prevent secondary injuries caused by adhesion.
Wide Temperature Adaptation Range
Medical-grade liquid silicone rubber maintains its stability over a wide range and doesn’t easily change its flexibility or other characteristics. Cured medical-grade liquid silicone rubber can withstand temperatures up to 400°F, so it can withstand some heat sterilization.
In addition to its high temperature resistance, medical-grade liquid silicone rubber can also be used for cryo-removal of warts and other procedures at low temperatures. It remains flexible at -85°F and does not become brittle like some materials.
Stability
Cured medical-grade liquid silicone rubber is not easily influenced by the external environment. Whether it’s UV and ozone outdoors orcontact with moisture for a long time, it’s difficult to affect medical-grade liquid silicone rubber that meets standards. It is weather-resistant and has a long service life. When properly maintained, it rarely shows signs of deterioration, even after long periods of use.
Although the properties remain unchanged, medical products that look yellowed and worn will inevitably make patients and customers distrustful, which in turn will affect the sales and reputation of your products. Qualified medical-grade liquid silicone rubber can save you from this problem.
Flexibility
Medical-grade liquid silicone rubber has excellent flexibility. Depending on the application, cured medical-grade liquid silicone rubber can range in hardness from a gummy-soft 20 Shore A to a slightly harder 70 Shore A. If you stretch it, some types can even become seven times their original length.
It’s not just soft, it’s also “stubborn”. Cured medical-grade liquid silicone rubber reverts well to its original shape when squeezed into other shapes.
Tearing is a rare event for medical-grade liquid silicone rubber. Even if the corners to which it adheres move and change shape, its flexibility allows it to change shape within certain limits.
Electrical Insulation and Conductive Silicone Rubber
It also has electrical insulating properties common to the silicone rubber family. This ability makes it possible to block the passage of electrical currents to a certain extent, allowing some precision instruments to be more accurate or preventing electrical power from leaking out and harming patients.
By adding silver fillers, medical-grade liquid silicone rubber, which is otherwise electrically insulating, can also become electrically conductive. Electrocardiogram (ECG) patches are where this specialized medical-grade liquid silicone rubber comes into play.
High Transparency
The high clarity of medical-grade liquid silicone rubber is actually a sign of high purity, because silicone rubber with too many fillers added will whiten. This high transparency allows it to be used in medical devices that require direct visualization of drug delivery or internal conditions. Endoscopes also require this combination of sealing protection and high clarity to obtain a clear image.
Clean Easily
Medical-grade liquid silicone rubber is actually a material that doesn’t harbor bacteria easily. It has a hydrophobic surface and also doesn’t absorb water itself, making it difficult to provide the right moisture conditions for bacterial growth. Grease and medications also tend to just remain on the non-stick surface.
In addition, because medical-grade liquid silicone rubber is resistant to corrosion and high temperatures, it can be thoroughly sterilized using a variety of sterilization methods. In addition to withstanding autoclaving, ethylene oxide sterilization, and gamma irradiation, it can also tolerate repeated rinsing with disinfectants.
All of this makes cleaning medical-grade silicone rubber products after curing much easier, and you don’t need to worry about the ease of cleaning medical-grade liquid silicone rubber after a long period of use.
Liquid Silicone Rubber Injection Molding(LIM) Process and High Fineness
The widespread use of medical-grade liquid silicone rubber in healthcare today is due to its use of the liquid silicone rubber injection molding (LIM) process.
Unlike high-temperature vulcanized silicone rubber, medical-grade liquid silicone rubber is a low-viscosity fluid before it is vulcanized. To achieve overmolding and manufacture precision parts, they need to be mixed and injected into the appropriate mold to heat and cure.
This process allows medical-grade liquid silicone rubber to replicate every minute detail of the mold, including fine structures and complicated textures. Whether it’s the delicate bristles of a silicone brush or a comprehensive structure that incorporates multiple parts, they can be reproduced and mass-produced with medical-grade liquid silicone rubber.
This is certainly good news for medical and healthcare product manufacturers who are looking for finesse and cost savings in production. What‘s more, the process minimizes quality variations between batches and enables automation.
Medical products can also be overmolded using the liquid silicone rubber injection molding process. Wrapping medical-grade liquid silicone rubber around another material, such as metal, provides a better feel, makes it more durable as well as hygienic, and reduces the need for some expensive materials. As a result, medical-grade liquid silicone rubber has become part of medical tool handles and some medical devices.
What You Need to Pay Attention to about Medical-grade Liquid Silicone Rubber
Permeability
The first problem worth noting is that medical-grade liquid silicone rubber is actually breathable or permeable. This doesn’t mean that it will leak when you use it to hold water, but rather that small molecules such as gases and water vapor may pass through its intermolecular spaces, which is more noticeable when used over a long period of time.
This is undoubtedly good news when it is used as a wound dressing or patch, as it is good for recovery and makes the skin more comfortable, but it is not suitable for use in certain barriers that require an absolute seal.
Specialty Chemicals
Although medical-grade liquid silicone rubber has good chemical compatibility, there are still chemicals that it’s not recommended to let it come into direct contact with. It can still corrode when exposed to strong acids and bases for extended periods of time. In addition, it may swell and become completely useless when exposed to hydrocarbon solvents.
Standards That Medical Grade Liquid Silicone Rubber Should Meet
Depending on the application, medical-grade liquid silicone rubber needs to pass different safety standards and testing before it can be compliantly put into production to ensure safety during medical procedures.
- ISO 10993: This is the most important international safety standard for medical-grade liquid silicone rubber and the one you need to be most careful about when making your selection. It requires manufacturers to test materials for allergenicity, cytotoxicity, genotoxicity, carcinogenicity and more. The specific tests vary depending on the use of the medical-grade liquid silicone rubber.
- USP Class VI: North American material safety standards
- FDA 21 CFR 177.2600(If it is a medical device)
- RoHS(EU): Choosing products that have passed RoHS certification guarantees that they don’t contain certain harmful substances
- REACH: EU safety regulations for chemicals
- ISO 9001 and the stricter ISO 13485: Manufacturers of high-quality medical-grade liquid silicone rubber can provide
Medical-grade liquid silicone rubber used for short-term contact generally needs to be tested for cytotoxicity, skin sensitization, irritation or intradermal reactions. Surgical tools and syringe needles are typical examples of such medical-grade liquid silicone rubber applications.
When selecting medical-grade liquid silicone rubber for long-term contact and permanent contact (implantable grade), such as feeding tubes and pacemakers, you also need to be aware of whether the manufacturer has conducted stricter testing for long-term safety.
Medical Applications of Liquid Silicone Rubber
Implants
Medical-grade liquid silicone rubber, which has passed the ISO 10993 requirements for implant-grade materials, has a very high level of safety, so it can be used as implants in the medical and cosmetic fields. Cochlear implants and pacemakers made of silicone rubber are safe and reliable, and can effectively prevent leakage of electrical current.
Silicone artificial nose and breast implants are soft and flexible, and are more easily accepted by the body, thus providing long-term molding effects. Because of the flexibility of the LSR process, doctors can also customize the grafts that are best suited to an individual’s situation, allowing for better implantation results.
Medical Devices
Medical device components such as respirator masks, valve diaphragms, and other medical equipment components are also often manufactured with medical-grade liquid silicone rubber. They provide an effective seal and a soft texture for a better patient experience.
Medical-grade liquid silicone rubber material allows for more thorough sterilization of these medical devices, allowing them to remain clean and sterile after repeated use over time, regulating and maintaining medical safety.
Surgical Instruments
Medical-grade liquid silicone rubber is also often found on surgical instruments. Silicone sheaths keep the tips of surgical instruments soft and prevent possible injury. LSR found on handles not only prevents the scalpel from interfering with the surgical procedure due to sweat adhesion, but also isolates the electrical current to prevent electrocution.
Drug Delivery Systems
Catheters, drains, and other parts of drug and fluid delivery systems are where medical-grade liquid silicone rubber shines. The flexible body of silicone catheters allows them to change shape to follow the body’s internal structures or external movements for more flexible fluid delivery.
They are also chemically inert and won’t react with urine, glucose solutions, or other common medications, allowing fluids to reach their destinations in their original form.
Health and Consumer Products
In addition to medical applications, medical-grade liquid silicone rubber is also used in products where the safety of the material is important to consumers. Medical LSR in health bracelet sensors, earplugs, orthotics, and menstrual cups is used as a non-allergenic, non-toxic, odorless, and soft material to give consumers greater peace of mind.
If you are also looking for such a product for your consumers that needs to be in long-term contact with their bodies and can guarantee stability and safety for a long period of time, then medical-grade liquid silicone rubber is a wise choice for you.
FAQ
Is Medical Grade Liquid Silicone Rubber Safe？
Yes. As long as you buy Medical-grade silicone rubber that has passed the standard and use it in the right places, it’s safe. Medical-grade liquid silicone rubber is subject to strict raw material and manufacturing environment restrictions, and after it is made, it is required to pass a series of safety tests to ensure that it is hypoallergenic and free of harmful substances such as BPA. As a result, its safety is guaranteed by standards and regulations.
Medical-grade TPE vs. Medical-grade Liquid Silicone Rubber
Medical-grade TPE is cheaper than medical-grade liquid silicone rubber, seals better, and is more flexible in terms of hardness than liquid silicone rubber. It’s also easier to stick to other materials, which makes making certain parts easier.
But when it comes to safety, medical-grade liquid silicone rubber is far superior to TPE, which has proven biocompatibility and is less likely to cause allergies or adverse reactions. It’s also more resistant to high temperatures, so it can withstand prolonged and repeated sterilization that TPE can’t. In addition, medical and liquid silicone rubber lasts longer and is less prone to aging and yellowing like TPE.
Does Medical-grade Liquid Silicone Rubber Produce Microplastics?
Medical-grade liquid silicone rubber doesn’t produce microplastics. It does produce some small particles when it is damaged, but the hazardousness of these particles is evaluated as early as the testing done to pass safety certification, so you don’t have to worry too much about it.
If you’re comparing silicone to plastic in terms of environmental pollution, these small particles don’t remain in the environment for as long as microplastics do, and will eventually break down. So, silicone is actually more environmentally friendly than plastic.
Can I Customize Medical-grade Liquid Silicone Rubber?
Yes. You can customize the color, transparency, and hardness of medical-grade liquid silicone, which can be achieved by adjusting fillers and additives. Due to safety requirements, some bright colors of medical-grade liquid silicone rubber may not be available for customization. Medical-grade liquid silicone rubber suppliers have a minimum MOQ, so you can ask the manufacturer for details on customization.
Final Thoughts
Medical-grade liquid silicone rubber is synonymous with precision and safety. If you want to know more details about medical-grade liquid silicone rubber or want to buy high-quality LSR products, please click Legensilico. We are a professional silicone product manufacturer and support customized silicone products applied in the industrial field, food field, and medical field. Send an inquiry for your safe LSR products now!
