Medical-grade silicone: a buyer's reading guide
Medical-grade silicone is not one thing. USP Class VI, ISO 10993, FDA 21 CFR 211 and ISO 13485 each answer a different question — biological safety, biocompatibility testing, manufacturing quality and QMS registration. A part can pass one and fail another. This page lays the standards side by side so you can read a certificate of compliance with confidence.
The four standards, at a glance
USP Class VI is the U.S. Pharmacopeia biological reactivity test for plastics. It grades plastic materials by how the extracted chemicals react with rabbit tissue (intracutaneous, systemic, intramuscular). The "Class VI" grade is the toughest of the six USP plastic classes and is widely cited in medical device specs even outside the U.S.
ISO 10993 is the international standard for biocompatibility evaluation. It splits into a series of sub-tests (10993-5 cytotoxicity, 10993-10 sensitization and irritation, 10993-4 blood interaction, 10993-11 systemic toxicity). A 510(k) submission to the FDA usually requires ISO 10993 panel testing selected by contact duration and tissue type.
FDA 21 CFR 211 is the FDA current Good Manufacturing Practice regulation for finished pharmaceuticals. It is the regulation the FDA inspector applies when auditing a contract manufacturer of medical devices or device components. It defines what your supplier's production floor, QC station, document retention and change-control procedures must look like.
ISO 13485 is the international QMS standard for medical device manufacturers. Most large medical OEMs (Medtronic, Stryker, Becton Dickinson) require their suppliers to hold ISO 13485 certification. The certificate has a scope statement that names the device categories it covers; a generic "ISO 13485" certificate that does not name the part family is not adequate.
Which standard applies to your part
Surface contact, intact skin only (e.g. an external monitoring cuff, a wearable sensor strap): USP Class VI is sufficient; ISO 10993-10 sensitization and irritation testing is the minimum.
Surface contact, mucosal membrane (e.g. a respiratory mask cushion, a baby soother): USP Class VI plus ISO 10993-5 (cytotoxicity) and 10993-10 (sensitization and irritation). Most U.S. OEMs add 10993-18 (chemical characterisation).
External communicating device, tissue / bone / dentin (e.g. a catheter, a long-term implant coating): full ISO 10993 panel, including 10993-4 (blood interaction if the device contacts circulating blood), 10993-6 (implant effects), 10993-11 (systemic toxicity) and 10993-12 (sample preparation). A 510(k) submission usually carries all of these.
Implant (>30 day contact) (e.g. a long-term implantable sensor housing): full panel plus 10993-6 implantation study, 10993-13 (genotoxicity), 10993-14 (carcinogenicity). Few silicone parts clear this; platinum-cured LSR over a wide hardness range is the default candidate.
Standard matrix
| Test / standard | USP Class VI | ISO 10993 | FDA 21 CFR 211 | ISO 13485 |
|---|---|---|---|---|
| What it tests | Biological reactivity of extracts | Biocompatibility per contact type | Manufacturing process & QMS | QMS registration scope |
| Scope | Material | Material + finished device | Manufacturing facility | Manufacturing facility + QMS |
| Who issues it | Test lab (e.g. NAMSA, WuXi) | Test lab | FDA audit | Notified Body (TÜV SÜD, BSI) |
| Required for 510(k)? | Often yes | Yes | Yes (if US supplier) | Yes (if global) |
| Renewal cycle | Per compound change | Per compound change | Annual audit | Annual audit (3 yr cycle) |
| What a buyer asks for | Test report on this compound | Test report + rationale per ISO 10993-1 | Audit report / 483 response | Certificate + scope statement |
| Silicraft reference | On file (platinum-cured LSR) | On file (full panel for MG-002) | Suzhou plant, Class 8 cleanroom | TÜV SÜD, 2024 |
What we mold
Our medical-grade silicone production runs in the Suzhou Class 8 cleanroom (ISO 14644-1). We mold parts on dedicated LSR injection cells that never see food-grade or industrial-grade material. Each batch carries a full traceability record from the raw compound lot to the finished, packaged, lot-marked part.
If you need a regulatory package, ask for it explicitly: we will provide the ISO 13485 certificate (with scope), the compound TDS, the relevant ISO 10993 test reports (for the specific compound you are buying, not a generic data sheet), and a written statement on the platinum-curing process. We sign NDAs as a routine part of medical-device quoting.
FAQ — medical-grade silicone
Is USP Class VI enough for a Class II medical device?
Usually no. USP Class VI tests the material's biological reactivity; it does not certify the manufacturing process. Class II 510(k) submissions usually also require ISO 10993 testing on the finished device and a QMS reference (ISO 13485 or FDA 21 CFR 820).
How long does ISO 10993 testing take?
A typical 10993 panel (cytotoxicity + sensitization + irritation + systemic toxicity) runs 12–16 weeks at a qualified test lab. Adding 10993-6 implantation studies or 10993-13 genotoxicity extends this by another 12 weeks. Plan the regulatory timeline accordingly.
Can the same silicone compound be used across multiple devices?
Yes, if the contact type is the same. A platinum-cured LSR compound that has cleared ISO 10993 for surface contact on intact skin can be reused across multiple devices with the same contact type, without re-testing. Different contact types (e.g. mucosal vs. implant) require separate testing.
Does medical-grade silicone need post-baking?
Platinum-cured LSR does not — there are no volatiles to drive off. Peroxide-cured HTV does, even for medical use, and a post-bake cycle should appear in the supplier's process documentation.