Begin with the biological question, then show exactly how the article represents the final finished device.
A defensible test-article record traces the model, revision, lot, patient-contacting materials, manufacturing, sterilization and any relevant packaging, aging or reprocessing. A whole final-finished device is often the clearest representation, but a portion, component, coupon or pooled set may be appropriate when its scientific relationship to the question is documented.
A laboratory can execute a method correctly and still produce evidence that does not apply to the marketed device. Applicability starts before the protocol—with a controlled description of the device, the biological question and the specimen actually supplied.
What is a biocompatibility test article?
A test article is the physical specimen used for biological testing or chemical characterization. Its value depends on whether it represents the device state relevant to the patient exposure being evaluated. The label “medical grade,” a supplier certificate or a polymer trade name cannot establish that relationship on its own: formulation, additives, processing, cleaning, joining, surface treatment and sterilization can all change the finished-device exposure.
FDA's September 2023 guidance centres the assessment on the final finished form while allowing a scientifically justified representative alternative. That guidance predates ISO 10993-1:2025. FDA now partially recognises the 2025 edition, with stated exclusions and a transition accepting declarations to the prior recognition until July 1, 2029. Check the current recognition record and review-division expectations before fixing a US strategy.
The practical question is therefore not “must every study use the entire device?” It is “what specimen preserves the materials, surfaces, residues and exposure pathways needed to answer this question?”
Freeze the biological question before choosing the specimen
Test-article selection becomes much clearer when the team writes a question-led scope first. Record the intended use, patient population, direct and indirect contact, tissue or fluid pathway, contact duration and frequency, and the biological effect or chemistry question being addressed.
- A specimen for extractables profiling may need to represent every relevant patient-contacting material and process residue.
- A local tissue-response study may depend more heavily on the actual surface, coating, geometry or degradation state.
- A reusable device question may require a justified post-reprocessing condition rather than an unused article.
- A comparison study may require the new device and the supported reference to be documented at the same level of detail.
“Largest,” “maximum cycles,” “sterile,” “aged” or “worst case” is not a complete rationale. State the exact property that makes a configuration challenging for the question under review.
Trace the actual configuration
The protocol and report should let a reviewer reconstruct what was tested. A useful handoff table identifies the marketed device family, model and size, drawing or revision, manufacturing lot, build date, patient-contacting components, formulations and colourants, coatings and adhesives, joining processes, manufacturing aids, cleaning steps and relevant in-process residues.
| Record | Question it closes | Common gap |
|---|---|---|
| Identity | Which model, size, revision, lot and build was supplied? | A generic product name with no controlled identifier. |
| Materials | Are all relevant patient-contacting formulations, additives, coatings and adhesives present? | Base polymer named but formulation or coating omitted. |
| Processing | Does the article include normal moulding, machining, joining, cleaning and surface treatment? | Development coupon used without a bridge to production. |
| Condition | What sterilization, aging, packaging or reprocessing state was represented? | State is asserted but lot records or cycle history are missing. |
Sterilization, packaging, aging and reprocessing
Use the intended sterilization method and relevant processing state when they can affect the biological question. Sterilization may alter residues, degradation products or surfaces; packaging interaction and aging may matter where they can change the exposure; repeated reprocessing may affect cleaning residues, corrosion, coating wear or material condition. None of these states is automatically required for every study, and the highest cycle count is not automatically the most challenging state for every endpoint.
Document the method, site, cycle or dose range, number of cycles and relationship to the marketed condition. If an unsterilized, unaged or simulated article is used, explain why that difference does not undermine the question being answered and identify any remaining uncertainty.
Whole device, representative portion, component or pooled set?
A whole device can preserve the clearest relationship, but size, geometry, test-system capacity or a narrowly defined question may justify another format. A representative portion should preserve relevant surfaces and exposure. If cutting exposes surfaces not normally patient-contacting or could introduce contamination, control and document those effects so the prepared article remains relevant to the question. A component or coupon needs a bridge through material formulation and production processing. Pooling requires traceable quantities and a reason the combination represents, rather than dilutes, the intended challenge.
When family variants differ in formulation, surface treatment, geometry or exposure, one specimen may not cover every question. Use a question-specific worst-case selection and document uncovered variants instead of forcing one universal representative.
Extraction planning and the laboratory handoff
ISO 10993-12 provides the controlled framework for sample preparation and reference materials, but the article should not be converted into a universal recipe. The applicable method, material behaviour, endpoint and laboratory validation determine the extraction vehicle, ratio, time, temperature, agitation, controls and permissible deviations.
The handoff should record how specimen quantity or surface area was calculated, what portions were included or excluded, how the article was cut or pooled, the extraction system and conditions, controls, extract appearance, particulates, deviations and chain of custody. FDA's test-report resources also emphasise clear test-article identification and comparison information.
Biocompatibility test-article protocol-review checklist
- State the biological or analytical question and the relevant contact pathway.
- Identify the exact device family, model, size, revision and manufacturing lot.
- Confirm that relevant formulations, additives, coatings, adhesives and process residues are represented.
- Record manufacturing, cleaning, sterilization and any relevant aging, packaging or reprocessing state.
- Justify whole-device, portion, component, coupon, bracketing or pooling choices.
- Check whether cutting or preparation creates an unrepresentative surface or contamination risk.
- Document the controlled extraction inputs, controls, deviations and chain of custody.
- Define what device variants or biological questions remain outside the evidence.
- Obtain qualified laboratory and biological-safety review before authorising the protocol.
Passing an individual test does not by itself establish overall biological safety, regulatory clearance or the adequacy of the full evidence file. Sterility, bacterial endotoxin control, performance and biocompatibility are related but distinct questions.
Primary sources and standards records
- ISO 10993-1:2025 public record — biological evaluation within risk management
- ISO 10993-12:2021 public record — sample preparation and reference materials
- ISO 10993-12:2021/Amd 1:2025 public record — current amendment record
- FDA guidance on use of ISO 10993-1 — final guidance and FDA-specific considerations
- FDA recognition record for ISO 10993-1:2025 — partial recognition and transition details
- FDA test-article comparison examples
- FDA: What Should I Put in a Test Report?
Source status: checked August 22, 2026. Standards records describe scope; consult controlled standards and current jurisdiction-specific requirements for device decisions.
Why this perspective is practical
Arvind Rathore is the founder of MedDev Advisory, where his work focuses on ISO 10993 biological-evaluation strategy and documentation. Before establishing the practice, he was a Marie Skłodowska-Curie Early Stage Researcher at INSERM U1026 Biotis within the ImplantSens network. His research covered implantable electrochemical biosensors, cytotoxicity, oxidative stress, sterilization effects and biomaterial–cell interactions, with research placements in France, Germany and Sweden. Peer-reviewed work in Bioelectrochemistry and Advanced Sensor Research also informs his evidence-led approach. Read more about Arvind Rathore.
Need a controlled workflow for article selection, preparation and protocol review?
The companion pack structures the decision record and laboratory handoff. It does not prescribe a universal method or replace qualified approval of a device-specific protocol.