Medical-grade TPU vs industrial TPU: what actually differs
Medical grade is not a purer industrial grade with a markup. It is a different evidence package: ISO 10993 evaluation, extractables control, medical QMS traceability, and a master-file route that saves the device maker registration time.
The definition that matters
Medical-grade TPU is a thermoplastic polyurethane that has completed a biological evaluation and is qualified for body contact or implantation. It is not defined by purity alone, and it is not defined by mechanical performance.
Industrial TPU is specified on mechanics, processing and cost — hardness, tensile strength, tear, melt flow, colour. Medical TPU is specified on a fourth axis: what the material does to tissue, and what it releases into it.
Four differences that decide a project
| Dimension | Industrial TPU | Medical-grade TPU |
|---|---|---|
| Biological evaluation | Not performed | ISO 10993 series — cytotoxicity, sensitisation, irritation, acute systemic toxicity; longer contact adds implantation and subchronic testing |
| Extractables and leachables | Not controlled | Limits on extractable species, residual monomer and catalyst residues |
| Quality system and traceability | Batch tolerance is wide | Medical QMS, retained samples, controlled change notification |
| Registration support | None | Master file (MAF) filing that a device submission can reference |
Why the master file is the commercial difference
A device maker filing for registration has to demonstrate the safety of the whole device, including every material in it. Without a master file, that means obtaining formulation and toxicology detail from the compounder and putting it in the submission — which most compounders will not release.
With a filed master file, the material dossier sits in a separate filing that the regulator can review, and the device submission simply references it. This shortens the review path and keeps the formulation confidential at the same time.
Three common misjudgements
- Treating food-contact approval as medical grade. Food-contact regulation covers oral intake of migrants; it says nothing about implantation or blood contact.
- Treating one passing in-vitro test as qualification. A cytotoxicity pass is the entry test, not the conclusion — sensitisation, irritation and, for long contact, implantation still follow.
- Treating USP Class VI as sufficient for an implant. USP Class VI is a useful baseline, but a long-term implant device needs a full ISO 10993 evaluation, which goes considerably further.
How to specify it in practice
Start from contact category, not from hardness. Skin contact, mucosal contact, indirect blood contact, circulating blood contact and implant each trigger a different testing set, and the same polymer can be acceptable in one and not in another.
Then fix the four specification axes together: hardness range, chemistry type, radiopacity, and contact duration. A supplier who can cover the whole matrix from one platform keeps the biological file reusable as the device design evolves; a supplier who covers one cell of it forces a fresh evaluation at every design change.
Confirm the certification scope and filing status against current documents. A claim of medical-grade status without a scope statement — which grades, which contact category, which filing — is not yet a specification.