Selecting Filter Materials for Medical Devices: Key Regulatory Considerations

The term “medical grade material” is widely used in medical device development but it is not a regulatory classification, nor does it guarantee that a material is suitable for every medical application.

In practice, “medical grade” is often used as a blanket term to suggest that a material has some history of use in healthcare or life science applications. What it does not clearly define is:

• What type of biological or chemical testing has been performed
• The contact conditions that were evaluated
• Whether that data applies to your specific device, use case, and exposure profile

Two materials described as “medical grade” may have very different regulatory profiles depending on:

• Direct vs. indirect patient contact
• Exposure duration
• Chemical environment
• Sterilization method

For engineers, the more useful question is not “Is this material medical grade?” but rather:

“What validation data exists for this material and does it align with my application?”

This mindset is essential when navigating regulatory expectations for medical filtration.

A thoughtful material selection process starts with understanding the regulatory questions that shape how a filter interacts with the device, the patient, and the manufacturing process.  Those considerations often emerge through contact conditions, safety requirements, performance expectations, and downstream process impacts.

Define Contact & Exposure: The Foundation of Biological Safety

Every regulatory evaluation begins with understanding how the filter is used:

• Does the filter have direct patient contact, indirect fluid contact, or no patient exposure?
• What type of fluid passes through the filter (air, liquid, blood)?
• Is exposure short term, long term, or repeated?

These factors drive biological safety evaluation under the ISO 10993 risk based framework, which is the global standard for assessing biocompatibility of medical devices.

A common starting point is:

• Cytotoxicity testing (ISO 10993 5, MEM Elution)

Additional biological endpoints may be required depending on contact type and duration.

Blood Contact Potential: Hemocompatibility

If there is any possibility that a filter could contact blood, directly or indirectly, hemocompatibility must be considered.

This often includes:

• Hemolysis testing (ASTM F756, direct contact)

Blood contact risk should be evaluated conservatively, especially when abnormal operating conditions or failure modes could introduce exposure.

Microbial Control: Bacterial Retention Performance

When microbial retention contributes to device safety or function, validated performance data is essential.

Typical considerations include:

• Bacterial Challenge Testing (BCT)
• ASTM F838 sterilizing grade validation
• Diminutive organism testing to represent worst case retention performance

Pore size alone does not define microbial performance validated retention testing does.

Endotoxin Risk: USP <85>

Endotoxins can present patient risk even in non sterile devices.

Engineers should assess:

• Whether endotoxin limits apply to the application
• Risk of endotoxin introduction via materials or manufacturing

Relevant testing commonly includes:

• USP <85> Bacterial Endotoxins Test (BET)

Particulate Sensitivity: USP <788>

For particulate sensitive applications such as infusion, diagnostics, or fluid delivery, considerations often include:

• USP <788> particulate performance
• Cleanliness of materials and assemblies
• Manufacturing and handling controls that minimize particle generation

Chemical Exposure Risk: Extractables & Leachables

Filters can present elevated extractables and leachables (E&L) risk due to:

• Large surface areas
• Long contact times
• Challenging chemical environments

A risk based E&L assessment considers material composition, exposure conditions, and sterilization effects.

ADCF & Restricted Substance Expectations

Many OEMs require confirmation of:

• Animal Derived Component Free (ADCF) status
• Alignment with expectations such as EMA 410
• Clear supplier documentation and traceability

Some high performance filter materials fall under broad PFAS definitions. Engineers should evaluate:

• Whether PFAS are intentionally present
• How PFAS content is disclosed and documented
• Whether customer or regional restrictions apply

The key is transparency and application specific risk assessment, not generalized assumptions.

Filter materials must maintain integrity and performance across sterilization methods such as:

• Ethylene Oxide (EtO)
• Gamma
• Steam or autoclave

Sterilization compatibility data is often included in validation guides, but application specific testing may still be required.

USP Class VI and the Industry’s Move Toward Risk Based Frameworks

Historically, USP Class VI has been widely referenced as a material safety benchmark and is often cited in customer specifications. However, USP has published substantial updates to USP <87> and <88>, that formally move away from the traditional Class I–VI plastics classification system.

These updates reflect a broader regulatory shift toward:

• Risk based, application specific evaluation
• Greater use of in vitro biological testing
• Reduced reliance on legacy, generic material classifications

This evolution closely aligns with the ISO 10993 framework, which evaluates biological safety based on intended use, contact type, and exposure, not on a single material designation.

For engineers, the implication is clear: while legacy specifications may still reference USP Class VI today, future looking material selection strategies should be grounded in modern, risk based approaches supported by relevant validation data.

Beyond material selection, regulators and OEMs increasingly evaluate how and where filtration components are manufactured as part of overall risk management.

Selecting a filter material for a medical device is not about choosing a generic “medical grade” component or checking a legacy box. It is about aligning validated material data, regulatory expectations, manufacturing controls, and application specific risk.

By approaching material selection through a modern, risk based lens, engineers can reduce development risk, streamline regulatory submissions, and build more robust medical devices.