Medical 3D printing has gone, in just a few years, from an experimental laboratory technology to a well-established production solution. Custom surgical instruments, orthopaedic guides, personalised prostheses, diagnostic components and single-use devices are today increasingly often made through additive manufacturing.
However, when a component is intended for contact with the patient or the healthcare operator, technical performance alone isn't enough. The material and the device must demonstrate adequate biocompatibility and compliance with a detailed regulatory framework, defined by international standards and sector-specific requirements.
This guide explains what is meant by biocompatibility, what the main reference certifications are (including USP Class VI, ISO 10993 and ISO 13485) and what responsibilities fall on the various players in the supply chain.
Biocompatibility is the ability of a material or a device to perform its function without inducing undesirable biological responses in the organism it comes into contact with. Such responses may include irritation, allergic sensitisation, cytotoxicity, chronic inflammation, rejection or other adverse local and systemic effects. It isn't an absolute property of the material considered in the abstract. Biocompatibility must always be assessed in relation to the context of use: duration of contact, type of tissue involved, sterilisation applied, operating conditions.
According to the approach of ISO 10993-1, the biological evaluation of medical devices takes into account, among other aspects, the nature of the contact with the human body. The main categories are:
For each category, the required tests increase in number and severity depending on the associated biological risk. Consequently, a material suitable for a reusable surgical instrument cannot automatically be considered suitable for a permanent implant. Compliance must always be demonstrated in relation to the specific final application.
The three basic tests, common to almost all applications, are:
For implantable devices or those in prolonged blood contact, systemic toxicity, genotoxicity, haemocompatibility, sub-acute and chronic toxicity, and carcinogenicity are added.
The USP <88> Biological Reactivity Test is the chapter of the United States Pharmacopeia dedicated to assessing the biological reactivity of plastic materials intended for medical and pharmaceutical applications. Materials are classified into six classes, from I to VI, depending on the battery of tests passed. Class VI represents the most stringent level.
The assessment mainly comprises:
A USP Class VI certified material has therefore passed all three tests, conducted on extracts prepared in water, vegetable oil, saline solution and ethanol. It's the standard prerequisite for materials intended for contact with drugs, biological tissues or patients in the pharmaceutical and biomedical field. Many industrial 3D printing materials intended for the medical sector carry this qualification at material-grade level.
The ISO 10993 series "Biological evaluation of medical devices" is the international standard that governs the biological evaluation of medical devices. It comprises more than twenty parts covering every aspect of biological safety, including:
The key difference from USP Class VI is that ISO 10993 doesn't certify a material, but the finished device in its specific context of use. It's the approach adopted by European regulation (MDR 2017/745) and by the FDA for the biological evaluation of medical devices.
ISO 13485 is the international standard that defines the quality management system for the medical device industry. It doesn't certify the product but the organisation: design, production, control, traceability, complaint management and continuous improvement.
An ISO 13485 certified supplier guarantees traceable, documented and repeatable production processes, a requirement demanded by the European MDR for the CE marking of medical devices.
This is one of the most delicate sections of any medical project, and it's also one of the most often misunderstood. Several parties are involved in the production supply chain of a 3D printed medical device, each with a well-defined scope of responsibility.
|
Party |
Certifies |
Typical documents provided |
|
Material manufacturer |
The biocompatibility of the raw material according to USP Class VI, some parts of ISO 10993, RoHS/REACH |
Technical data sheet, composition declaration, USP certificate, MSDS |
|
3D printing service provider |
The use of certified materials, batch traceability, the controlled production process, possibly ISO 13485 |
Use of certified materials, composition declaration, batch traceability |
|
Medical device manufacturer |
The biocompatibility of the finished device in its intended use, CE / FDA marking, clinical evaluation, post-market management |
MDR technical file, ISO 10993-1 biological evaluation, EC declaration of conformity, CE marking |
|
Notified Body / FDA |
Validates the entire chain and issues the authorisations to place on the market |
CE certificate, 510(k) clearance, PMA approval |
The key point to internalise is this: the 3D printing provider cannot certify the medical device. Not even if the material is USP Class VI and the process is ISO 13485. The responsibility for the biological evaluation of the finished device, its sterilisation, its intended use and its CE marking always remains with the device manufacturer (that is, the party who places the product on the market with a specific medical use indication).
A competent supplier supports the client with certified materials, traced batches and composition declarations, which are the necessary inputs to the device's biological evaluation, but they don't replace it.
Not always. ISO 13485 is mandatory for the medical device manufacturer who wants to market it in Europe (MDR). For component or service suppliers, it isn't always mandatory, but it's recommended because it guarantees documented and traceable processes, makes the client's life easier during MDR audits, and represents a factor of trust. Many medical device manufacturers require ISO 13485 of their suppliers as a qualification prerequisite.
The market for biocompatible 3D printing materials is expanding rapidly. Below are two of the most used materials.
Medical-grade ABS is an acrylonitrile-butadiene-styrene formulated for healthcare applications and qualified according to USP <88> Class VI. It's suitable for hospital instrumentation, diagnostic components, functional prototypes for medical devices, electromedical housings and other applications involving non-prolonged surface contact.
Its advantages are the low cost, excellent workability in FDM, a pleasant surface finish, and chemical resistance adequate for hospital detergents.
ECOtech is an engineering polymer with a reduced environmental impact, excellent flexural resistance, low deformation and high-quality surface finish. It combines high mechanical performance with a sustainability profile that makes it suitable for various sensitive applications, from medical devices to FDA-approved food packaging.
Its typical applications are anatomical models and surgical guides with tight tolerances, precision medical devices, containers in contact with drugs and food, components where dimensional stability in hot environments is needed, and products with environmental profile requirements.
Sterilisation is an integral part of a medical device's life cycle and must be considered from the earliest design stages. Not all materials are compatible with all sterilisation processes, and some cycles can degrade their mechanical or dimensional properties. There are five main methods.
The most widespread, economical method, free of toxic residues. However, it has a high operating temperature that excludes polymers with insufficient HDT.
Low-temperature sterilisation (30–60 °C) with ethylene oxide gas. Compatible with almost all polymers. It requires a post-treatment aeration cycle to eliminate toxic residues, and some printing technologies (for example porous materials) can retain the EtO longer than expected.
Sterilisation by irradiation (25–40 kGy typical). Compatible with most materials but can cause progressive yellowing, reduced ductility and molecular weight degradation in some polymers. It's the preferred method for high volumes of single-use devices.
A low-temperature sterilisation method (40–55 °C) without toxic residues, suitable for reusable instrumentation and heat-sensitive components. Compatible with most medical polymers and with the majority of metals.
Immersion in chemical solutions (glutaraldehyde, peracetic acid, hypochlorite). This is more properly a high-level disinfection rather than a terminal sterilisation, and it's used in hospital settings for reusable instruments. It's compatible with the main standard medical polymers, provided the part geometry allows complete cleaning and drainage.
A shared vocabulary is the first defence against technical and regulatory misunderstandings in specifications. Below are the key definitions to use correctly.
Medical 3D printing offers unprecedented design freedom and customisation possibilities, but it operates in a complex regulatory context, in which the biocompatibility of the material and the certification of the finished device are distinct areas, with responsibilities distributed along the entire supply chain.
For the designer or manufacturer of medical devices, the key point is knowing who certifies what. On the one hand, it's essential to choose a supplier able to guarantee qualified biocompatible materials. On the other, the device manufacturer remains responsible for the complete biological evaluation, validated sterilisation, CE marking and post-market surveillance.
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