PEEK in medical technology
Using PEEK selectively in medical technology
In medical technology projects, PEEK is rarely the starting point. The material usually comes into play when standard engineering plastics are not sufficient or when several requirements have to be met at the same time.
Typical examples are handles, rotary controls, housings, insulators or instrument components. What counts here is not only the shape but also the question of whether a part can meet repeated reprocessing, media exposure, mechanical load and functional requirements over the long term.
For applications of this kind, material grade, manufacturer information and the intended type of contact or use are decisive. Industrial-grade PEEK is therefore not automatically suitable for every part used in medical technology.
Reprocessing as the practical test
The real test does not begin with the first use but with repeated cleaning, disinfection or sterilisation. Heat, moisture, chemicals, time and handling place demands on plastic parts across the entire life cycle.
Project-related tests showed that PPSU and PEI can display changes in appearance after repeated cycles under certain STERRAD NX conditions. Mechanically, such parts may remain unaffected; depending on the application, changes in appearance can nevertheless be an exclusion criterion.
Under comparable conditions, PEEK can be the more suitable option and is therefore deliberately considered in such applications. What remains decisive, however, is always the specific reprocessing procedure: steam sterilisation, plasma sterilisation, chemical disinfection or other methods place different demands on the material.
A look at typical PEEK parts for medical technology applications
Producing complex geometries economically
Many parts used in medical technology are geometrically demanding. Large free-form surfaces, small functional contours, thin walls, snap-fit areas or insulating zones have to be reproduced precisely and repeatably.
PEEK is particularly suitable where this design freedom must be combined with load-bearing capacity, resistance and dimensional accuracy. The part still needs to be designed for injection moulding: wall thicknesses, gating, demoulding, tolerances and inspection characteristics have to match the material.
Processing PEEK places particular demands on mould temperature control, material handling and the process window. The article Processing PEEK precisely in injection moulding examines these relationships in more depth.
Typical requirements for PEEK parts in medical technology
- Reprocessing Parts have to withstand cleaning, disinfection or sterilisation without impairment to their function, dimensions or appearance.
- media exposure Cleaning, disinfection and process media or body fluids must not impair the surface, dimensional accuracy or function.
- Mechanical function Guides, bearing points, latching areas, connector areas or handles have to work reliably throughout the intended use.
- Geometry Function-critical contours, tight tolerances, thin walls or complex geometries have to be repeatably mouldable.
- Insulation Electrical insulation is relevant above all where it is combined with temperature, media exposure, reprocessing or mechanical load.
- supporting documentation Depending on the application, material grade, type of contact, biocompatibility, traceability and customer-specific approvals can be decisive.
Considering chemical and mechanical stability together
In medical technology, cleaning, sterilisation, media exposure, handling and service loads do not act separately from one another. A part has to retain its function under all these influences combined.
This applies in particular to jaw parts, handles, rotary controls, housings, guides or connector areas. Concentration, temperature, exposure time, cleaning cycle and mechanical load all help determine whether a plastic remains suitable over its service life.
A single material property value is not enough for this assessment. What counts is whether material, geometry, surface and process work together in later use.
Putting insulation and biocompatibility in context
With bipolar instruments, connector inserts or electrically active functions, insulation can be an integral function of the part. On its own, however, electrical insulation is rarely a sufficient reason for PEEK, because many plastics have insulating properties.
PEEK is particularly suitable when electrical insulation must be combined with further requirements such as temperature resistance, media exposure, reprocessing, mechanical load or tight geometries. The question is not only whether a plastic insulates, but whether that function is retained under actual conditions of use and reprocessing.
Biocompatibility also has to be considered in relation to the application. The type and duration of contact, the material grade used, additives, processing, surface condition and the required evidence are decisive. A PEEK grade specified for medical applications can provide the basis for such an assessment; however, this does not automatically establish the suitability of the finished part.
Examining limits and alternatives early
PEEK is a high-performance polymer, but it is not always the most economical or technically most appropriate solution. Depending on the application, PPSU, PEI, PPS or other engineering plastics may be sufficient or even better suited.
PPSU can be of interest where repeated steam sterilisation, toughness or coloured instrument components are involved. PEI can play a role where stiffness, temperature resistance and insulation are required. PPS or other engineering plastics can be sufficient depending on media exposure, temperature and geometry.
Alternatives should therefore be included in the material assessment at an early stage. A sound assessment considers the application, reprocessing, required documentation, geometry and production together.
Assessment for medical technology applications
In medical technology, PEEK is appropriate above all when it performs a specific function that simpler plastics cannot meet reliably over the required service life.
What is decisive is not the material in isolation but the question of whether a part can be produced so that it remains functional, inspectable and economically viable under real conditions.
Bringing material, application and process together
Material selection alone does not solve a project. A coherent solution only emerges when material grade, application, design, mould and injection moulding process are matched to one another.
PEEK is therefore used selectively for instrument components and demanding plastic parts where several of these requirements come together.