TPU and TPE are everywhere in medical and consumer devices — soft grips, seals, tubing, masks, wearables, skin-contact pads. They feel right, they bond to rigid housings, and they process cleanly. But the moment a part contacts the body or food, the selection stops being about hardness and abrasion and starts being about proof: documented biocompatibility, sterilization compatibility, and a controlled supply chain.
This guide explains what separates a "medical-grade" compound from an ordinary one, and what to line up before specifying. For the bonding mechanics it leans on, see overmolding with TPU/TPE.
Editorial note: This is an independent educational guide, not regulatory or medical advice and not a compliance statement. Standards, test requirements, and grade qualifications must be verified with the material supplier and the relevant regulatory bodies for your specific device and use.
Why TPU and TPE in medical and skin contact
Elastomers earn their place in devices because they do things rigid plastics cannot: a soft, comfortable grip; a flexible seal; tubing that bends without kinking; a skin-contact surface that feels good and stays put. TPU adds toughness, abrasion resistance, and a wide hardness range; TPE compounds add easy soft-touch over-molding and tunable softness. Both can be made into grades that are pre-qualified for medical use, which is what turns "this feels right" into "this is defensible."
Biocompatibility: what ISO 10993 covers
Biocompatibility is the core requirement for anything contacting the body, and the reference framework is the ISO 10993 family of standards for biological evaluation of medical devices. Medical-grade elastomers are commonly pre-tested against specific parts of it. Three that show up repeatedly:
- In vitro cytotoxicity (ISO 10993 part 5) — whether the material harms cells in culture.
- Irritation (part 10) — whether it irritates tissue.
- Systemic toxicity (part 11) — whether it causes a broader toxic response.
When a compound has been pre-tested against these and the supplier provides a statement of biocompatibility, it gives a device designer a documented starting point for a regulatory submission — a demonstrated "pattern of concern for safety," in the language of the field. That paperwork is a big part of what you are buying with a medical grade.
What a medical-grade compound gives you
A medical-grade TPU or TPE is not just chemistry — it is chemistry plus documentation plus control. Published medical TPE series illustrate the package: compounds offered across a useful softness band (for example, Shore A hardness ranges roughly 40–70 and 45–75 in two published MD series), pre-tested for ISO 10993 biocompatibility, with a biocompatibility statement, and made under controlled conditions so the material you qualify is the material you keep getting.
That last point — consistency and traceability — is easy to undervalue until a lot changes underneath a qualified device. A medical grade is, in part, a promise that the formulation will not quietly drift.
Sterilization: gamma, EtO, and more
A device material usually has to survive being sterilized, sometimes repeatedly, without losing its properties or biocompatibility. Medical-grade elastomers are often formulated with this in mind. Published medical TPE compounds, for instance, are noted as offering both gamma and ethylene oxide (EtO) sterilizability.
The catch is that not every method suits every grade. Gamma irradiation can affect some polymers differently than EtO or steam autoclaving, so the sterilization method has to be matched to the material and confirmed for the actual part. Decide the sterilization route early, because it can eliminate candidate grades before any other property is considered.
Bonding soft to rigid in devices
A huge share of device parts are soft-touch over-moldings: a flexible TPE or TPU bonded to a rigid housing. Bondable medical-grade TPE compounds are formulated to bond to common device substrates — ABS, PC, PC alloys, rigid TPU, and copolyester — using multi-shot or insert molding. That lets a designer build grip, seal, and cushion directly onto the structural part, without adhesives that would themselves need biocompatibility qualification.
The bonding still has to be proven for the specific pair and process — the same discipline as any over-molding, covered in overmolding with TPU/TPE. In a medical part, a peeling soft layer is not just a quality defect; it can be a contamination and safety issue, so the bond verification matters even more.
Food-contact grades
Skin contact's close cousin is food contact, and TPU addresses it with dedicated grades rather than a blanket claim. Published food-contact (FC) TPU portfolios include both ether- and ester-based grades and are formulated to comply with EU food-contact legislation and, for many grades, FDA requirements, produced under good manufacturing practice (GMP).
The important nuance: suitability for a particular food-contact use still requires evaluation — the compliant grade is the enabler, not an automatic pass for every application. And a standard, non-FC grade should never be assumed food safe just because the family has FC options.
Selection quick reference
| Requirement | What to look for | Confirm with |
|---|---|---|
| Skin / body contact | ISO 10993 pre-testing, biocompatibility statement | Supplier documentation + device-level evaluation |
| Sterilizable part | Gamma / EtO (or steam) compatibility | Grade data + test on the actual part |
| Soft-touch on rigid housing | Bondable grade for ABS/PC/PC alloy/rigid TPU/copolyester | Over-molding bond trial |
| Defined softness / feel | Shore A in the needed range (e.g., ~40–75) | Durometer spec with delay time |
| Food contact | Dedicated FC grade (EU / FDA, GMP) | Supplier compliance docs + use evaluation |
| Consistency over time | Controlled, traceable manufacturing | Supplier quality system |
Compliance pitfalls to avoid
- Assuming base chemistry equals medical grade. "TPU is biocompatible" is not a qualification; the tested, documented compound is.
- Choosing the grade before the sterilization method. The method can disqualify grades, so decide it first.
- Treating a material biocompatibility statement as device approval. The finished device must be evaluated as a whole, including processing.
- Using a standard grade for food contact. Only dedicated FC grades carry the compliance basis.
- Skipping the bond trial. In a device, a failed soft-to-rigid bond is a safety problem, not just cosmetic.
- Allowing uncontrolled formulation changes. Lock the grade and supplier once qualified.
Bottom line
Medical-grade TPU and TPE are defined less by chemistry than by proof: documented ISO 10993 biocompatibility with a supplier statement, sterilization compatibility (commonly gamma and EtO), bondability to rigid device substrates, and controlled manufacturing — with dedicated food-contact grades for the food side. Specify by lining up that evidence: confirm biocompatibility, fix the sterilization method early, prove the over-molding bond, and remember that the material documentation supports — but does not replace — evaluation of the finished device.
For an example of biocompatible, bondable medical elastomer compounds and the testing behind them, RTP Company's biocompatible and bondable medical TPE overview is a useful reference.
FAQ
What makes a TPU or TPE medical grade?
A medical-grade elastomer is a specific compound that has been tested and documented for biocompatibility, typically against ISO 10993 standards, with a statement of biocompatibility and controlled, traceable manufacturing. The base chemistry alone does not make a material medical grade — the testing and documentation do.
What is ISO 10993?
ISO 10993 is a family of standards for the biological evaluation of medical devices. Common parts include in vitro cytotoxicity, irritation, and systemic toxicity. Medical-grade TPE and TPU compounds are often pre-tested against these parts to support a device's regulatory submission.
Can medical TPU and TPE be sterilized?
Many medical-grade compounds are formulated to withstand common sterilization methods such as gamma irradiation and ethylene oxide (EtO). The right method depends on the grade and the part, and sterilization compatibility should be confirmed for the specific material and process.
Can medical TPE be over-molded onto rigid plastics?
Yes. Bondable medical-grade TPE compounds are formulated to bond to substrates such as ABS, PC, PC alloys, rigid TPU, and copolyester using multi-shot or insert molding, which is how soft-touch grips and seals are built onto rigid device housings.
Is TPU safe for food contact?
Specific food-contact TPU grades exist and are formulated to comply with food-contact regulations such as EU legislation and FDA requirements, and are made under good manufacturing practice. Suitability for a particular use still requires evaluation, and standard grades should not be assumed to be food safe.
Does a biocompatibility statement guarantee my device is safe?
No. A material biocompatibility statement supports the evaluation but does not certify the finished device. The device, its processing, and its final use must be assessed as a whole, because manufacturing and design can affect the result.
Related: Overmolding with TPU/TPE → · TPU Applications →