Biocompatibility testing evaluates whether a medical device and its materials can interact with the human body without causing unacceptable biological harm. Guided by the ISO 10993 series, it considers risks such as cytotoxicity, sensitization, irritation, systemic toxicity and material degradation.
Testing forms part of a wider biological evaluation. It should be planned according to the device’s materials, manufacturing processes, patient-contact type and contact duration—not treated as a fixed checklist.
What Is Biocompatibility Testing?
Biocompatibility testing examines the biological safety of materials that directly or indirectly contact a patient. This includes the finished device as well as coatings, adhesives, colorants, processing residues, sterilization by-products and substances that may leach during use.
The objective is not to prove that a material has no biological effect. It is to demonstrate, through scientific evidence and risk assessment, that the device’s biological risks are acceptable for its intended use.
Biocompatibility evaluation should consider the complete finished device because manufacturing, cleaning, packaging, storage and sterilization can change its chemical and biological characteristics.
Why Biocompatibility Testing Matters
A material described as “medical grade” is not automatically suitable for every medical device. Biological safety depends on how the material is processed, where it contacts the body and how long that contact continues.
Inadequate evaluation can result in irritation, allergic reactions, toxicity, inflammation or other patient harm. It may also delay an FDA submission or EU MDR conformity assessment.
Biocompatibility evidence commonly supports an FDA 510(k) premarket notification and the device’s EU MDR technical file. Planning it early reduces the risk of expensive retesting after materials and manufacturing processes have been finalized.
Standards for Biocompatibility Evaluation
ISO 10993-1 provides the framework for biological evaluation within a risk-management process. Other parts of the ISO 10993 series address specific activities and endpoints, including:
- ISO 10993-5 for cytotoxicity
- ISO 10993-10 for skin sensitization
- ISO 10993-11 for systemic toxicity
- ISO 10993-12 for sample preparation
- ISO 10993-17 for toxicological risk assessment
- ISO 10993-18 for chemical characterization
- ISO 10993-23 for irritation
The applicable standards and endpoints depend on the device and regulatory market. FDA recommendations may include considerations beyond the general ISO framework.
How Biocompatibility Evaluation Works
1. Define the Device and Patient Contact
Document all patient-contacting materials, components, coatings and manufacturing processes. The assessment should include direct contact and indirect contact, such as fluids delivered through device tubing.
The device is categorized according to the nature of contact:
- Surface-contacting device
- Externally communicating device
- Implant device
Contact duration is generally categorized as:
- Limited: up to 24 hours
- Prolonged: more than 24 hours and up to 30 days
- Long-term or permanent: more than 30 days
These categories help determine which biological endpoints require evaluation.
2. Characterize the Materials
Manufacturers should identify the composition, grade, supplier and processing history of each patient-contacting material. The controlled Bill of Materials can help maintain this traceability.
Material characterization should also address additives, colorants, processing aids, cleaning agents and manufacturing residues. Supplier declarations alone may not provide enough information to establish biological safety.
3. Review Existing Evidence
Existing information may include previous test reports, published literature, supplier data, chemical characterization and documented experience with an equivalent material or device.
Any equivalence rationale must account for material composition, manufacturing, geometry, patient contact, sterilization and exposure. General statements that two materials are “the same” are rarely sufficient without supporting evidence.
4. Conduct Chemical Characterization
Chemical characterization identifies substances that may be released from the finished device. Extractables and leachables data can then support a toxicological risk assessment.
This risk-based approach may reduce unnecessary biological testing when the chemical profile and patient exposure are sufficiently understood.
5. Select Biological Endpoints
Common endpoints include:
- Cytotoxicity
- Sensitization
- Irritation or intracutaneous reactivity
- Acute and subacute toxicity
- Genotoxicity
- Hemocompatibility
- Implantation effects
- Chronic toxicity
- Carcinogenicity
- Reproductive or developmental toxicity
- Degradation
Not every device requires testing for every endpoint. Each relevant endpoint should be addressed using existing evidence, testing or a documented scientific justification.
6. Test Representative Finished Devices
When testing is required, samples should represent the final device configuration. They should incorporate the intended materials, manufacturing processes, cleaning, packaging and sterilization.
For sterile devices, sterilization validation and biological evaluation must be coordinated. Ethylene oxide processing, for example, can leave residual chemicals, while radiation may alter polymer properties.
Devices sterilized using EO may also require consideration of ISO 11135 and the residual limits addressed by ISO 10993-7.
7. Document the Biological Evaluation
The biological evaluation report should explain:
- Device and material characterization
- Patient-contact classification
- Evidence reviewed
- Testing performed
- Results and deviations
- Toxicological assessments
- Unresolved biological risks
- Overall biological-safety conclusion
The findings should connect with the device’s risk-management records and benefit-risk determination.
Biocompatibility and Design Verification
Biocompatibility testing commonly contributes to verification and validation by confirming that biological-safety requirements and associated risk controls have been met.
Biological evaluation should begin during material selection, while formal testing normally occurs once the design and manufacturing process are stable. Testing too early can produce evidence that no longer represents the marketed device.
When Is Re-evaluation Required?
A change does not automatically require repeating every test, but it must undergo a documented biological-risk assessment. Re-evaluation may be needed following changes to:
- Material composition, grade or supplier
- Colorants, coatings or adhesives
- Manufacturing or cleaning processes
- Sterilization method or cycle
- Packaging or shelf life
- Patient-contact duration
- Device geometry or surface area
- Intended use
Existing evidence may remain usable when equivalence is scientifically demonstrated.
Common Biocompatibility Mistakes
Common problems include:
- Treating ISO 10993 as a mandatory testing checklist
- Testing raw materials instead of the finished device
- Using incomplete supplier information
- Ignoring processing and sterilization residues
- Selecting endpoints without a documented rationale
- Testing before the design is stable
- Failing to assess material or supplier changes
- Weak linkage between results and risk management
How SJML Supports Biocompatibility
SJML provides medical device compliance services covering biological-evaluation planning, material documentation, testing strategy, risk assessment and regulatory-file preparation.
Its integrated design and engineering capabilities help teams evaluate materials, manufacturing, sterilization and packaging as connected decisions. This reduces late-stage changes and keeps biological-safety evidence aligned with the finished device.
Contact SJML’s QARA team to discuss biocompatibility planning or biological-evaluation support.
Frequently asked questions
CAD is used to model device parts, assemblies, and enclosures in 2D and 3D before anything is built. Engineers use it to check fit and clearance, run early analysis, generate manufacturing drawings, and produce the documented design outputs that design controls under ISO 13485 and FDA Part 820 require.
CAD models and drawings are design outputs. They are created from design inputs such as user needs, requirements, and applicable standards. Under FDA 21 CFR Part 820.30, design outputs must be documented, reviewed, and traceable to the inputs they satisfy, which is why CAD files and their revision history belong in the design history file.
Teams work in native formats from their CAD system and exchange data using neutral formats like STEP and IGES for geometry, STL for 3D printing, and PDF for released drawings. Manufacturing partners often need native files plus dimensioned drawings with GD&T so tooling and inspection match the design intent.
CAD supports compliance by producing controlled, traceable design outputs. Released models and drawings carry revision history, approvals, and links back to requirements. Kept inside change control and a design history file, they give auditors evidence that the device was designed, reviewed, and transferred to manufacturing in line with ISO 13485 and FDA design control expectations.
