Medical thermoplastic polyurethane offers biocompatibility, durability, processing flexibility, and long-term stability for implantable medical devices.
Implantable medical devices must balance biocompatibility, durability, processing flexibility, and long-term stability within the body. With medical thermoplastic polyurethane (TPU), material scientists and device engineers can create customised device components that offer a balance between the characteristics of rigid polymers and elastomers. These device components may be designed to be implantable, or alternatively made appropriate for shorter-term body contact.
Lubrizol has long specialised in medical-grade TPU and offers polymers suited to a wide range of medical device needs.
What Makes TPU So Adaptable?
TPUs are segmented block copolymers that comprise hard segments (containing isocyanates) and soft segments (containing long-chain alcohols (polyols)). TPU properties can be tuned to fit end-product needs in two ways:
- By choosing different isocyanate and polyol chemistries;
- By adjusting the ratio of hard to soft segments.
These characteristics allow manufacturers to create materials nearly as soft as silicone, or stiff and rigid.
What Makes TPU the Right Material for Implantable Medical Devices?
Medical-grade TPU offers this segmented block copolymer architecture in a form that also maintains excellent biocompatibility, durability in the body, and processing versatility.
Many TPUs soften at body temperature, so that components which are rather rigid during insertion will become more flexible in use, enhancing patient comfort. Moreover, medical thermoplastic polyurethane is particularly well suited for catheter applications where thin walls, robust mechanical strength, and radiopacity are essential.
What Framework Should Guide Medical-Grade TPU Selection?
When choosing a medical-grade TPU, manufacturers must carefully consider the specific use cases in order to select appropriate soft and hard chemistries. Factors include:
- Application requirements: Define device functionality and specific performance objectives that the material must fulfil;
- Comparative materials: Benchmark TPU performance and compatibility against alternative polymer options;
- Biological contact: Determine whether the device interfaces with blood, tissue, or other body fluids;
- Exposure duration: Establish the required timeline for the material in its intended environment, and ensure it will perform safely for the duration;
- Mechanical requirements: Specify strength, compliance, and durability thresholds necessary for device function;
- Chemical resistance: Evaluate material stability against the body fluids, pharmaceutical agents, and cleaning solutions it will contact;
- Thermal performance: Consider temperature exposure ranges during clinical use, sterilisation protocols, and distribution conditions;
- Sterilisation compatibility: Determine whether the device will be single-use or must withstand reprocessing cycles;
- Processing alignment: Verify material compatibility with planned fabrication methodologies and equipment;
- Visual characteristics: Identify transparency or colour requirements;
- Radiopacity: Assess whether radiopacity is necessary for imaging, procedures, or diagnostic applications;
- Regulatory compliance: Confirm material conformance with applicable industry standards and medical device regulations;
- Supply chain and efficiency: Validate supplier capacity to deliver material volumes aligned with project scale and budgetary constraints.
IMCD provides a line of medical-grade TPUs from Lubrizol to support medical device design.
Want to Discuss Your Medical Polymer Selection? Meet us at COMPAMED 2026, Hall 8B, Booth D01, 16 to 19 November, Düsseldorf. |
Designing Devices With the Right Medical Thermoplastic Polyurethane
Understanding the Soft Segment
The application site and duration of use dictate the optimal soft segment chemistry for biostability, as this chemistry directly influences the durability of a polymer.
For example:
- For permanent blood-contacting applications, material selection must address both long-term mechanical durability and biological stability. Polycarbonate-based TPUs are generally preferred in such cases, as they offer strong resistance to both hydrolytic and oxidative degradation;
- In devices that must operate in low-pH environments, such as gastric implants, polyether-based TPUs prove to be the most robust option. Polycarbonate TPUs are susceptible to hydrolysis in acidic conditions.
Understanding the Hard Segment
When selecting isocyanates for the hard sections of medical-grade TPU, it is critical to consider the benefits and drawbacks of both aromatic and aliphatic TPUs, and determine what is most needed for a given application. Chemical resistance, strength and durability requirements, processing methods, and visual criteria must all be considered.
Aromatic TPUs are well suited to applications requiring strength and durability, especially if long-term visual clarity is not a concern. These provide roughly 20% greater tensile strength, fatigue resistance, and abrasion resistance compared to their aliphatic counterparts.
Aliphatic TPUs resist yellowing and are well suited to medical devices that require long-term transparency and patient comfort. These clear, visually appealing TPUs also offer ease of processing over aromatic TPUs, making it simple for manufacturers to add fillers, including radiopaque materials.
There can be trade-offs between the properties of various TPUs, so clients should work closely with their IMCD representatives to determine the right choice for each device.
How Can Medical-Grade TPU Be Processed?
TPUs can be designed for a range of manufacturing techniques, including:
- Extrusion;
- Injection moulding;
- Thermal bonding;
- 3D printing;
- Solvent-based methods.
These techniques can be combined to produce complex, multi-component medical devices.
How Can We Support You?
Medical-grade TPUs are an adaptable solution for a wide range of implantable medical devices.
Selecting medical-grade polymers is complex, and the regulatory landscape keeps evolving. Involving IMCD’s medical experts at the earliest stages of development helps you choose the right solution for your medical device.
We offer a range of medical-grade TPUs from Lubrizol. For more information or to request samples, please reach out to your IMCD representative today.
