Nitinol continues to remain a popular alloy for next-generation medical devices, but it comes with specific complexities that engineers should be aware of before starting their project. A successful Nitinol device depends on understanding the unique behavior of Nitinol and planning for the scalability of your device.
Confluent's Nitinol SMEs provide decades of materials science expertise and hands-on experience with Nitinol projects from concept to commercialization. They have provided the following best practices to assist OEMs in reducing development risk, avoiding costly delays, and positioning your program for long-term success.
1. Design iterations are key!A common misconception in medical device development is that the first design should be close to the final design. In reality, successful Nitinol programs often go through multiple iterations to optimize performance, manufacturability, and cost.
Each design iteration provides valuable information about how a device behaves under real-world conditions. Early prototyping and testing can help identify opportunities to improve fatigue performance, simplify manufacturing, reduce material usage, or enhance deployment characteristics.
Rather than viewing design changes as setbacks, treat them as investments in a more robust final product.
2. Select Materials That Support Design Flexibility
The material you choose can either enable innovation or limit it. Different Nitinol forms, including tubing, sheet, strip, and wire, offer unique advantages depending on the application. Material selection should consider not only current design requirements but also future iterations and potential design changes.
The purity of the material should also be taken into consideration. Medical-grade Nitinol can be manufactured in varying purity levels. Confluent's own SE508 ELI provides one of the highest levels of purity in the industry. A higher purity form of Nitinol offers higher fatigue resistance and lower inclusion rates.
Choosing the right starting material provides flexibility as performance requirements evolve and helps prevent unnecessary redesigns later in development.
3. Understand the Impact of Raw Material Changes
A seemingly small modification to raw material specifications can have significant implications. For example, changes to tubing dimensions, wall thickness, or material grade may require entirely new raw material production runs. This can introduce additional lead times and potentially impact project schedules.
When evaluating design updates, it's important to understand whether the change can be accommodated within existing material inventory or if new material procurement is required.
Early communication with your manufacturing partner can help avoid unexpected delays and keep development timelines on track.
4. Define Critical Thermo-Mechanical Requirements Early
Nitinol's unique performance is driven by its thermo-mechanical properties. Defining these requirements early helps ensure alignment between design intent and manufacturing processes.
Key properties to consider include:
Establishing clear performance targets upfront provides a foundation for material selection, process development, and verification testing.
5. Define Test Methods Alongside Performance Requirements
In addition to defining a target property, teams should also establish how that property will be measured.
Questions to consider include:
Defining test methods early helps eliminate ambiguity and ensures all stakeholders are evaluating performance using the same criteria. This approach can significantly reduce delays during verification and validation activities.
6. Consider the Impact of Downstream Processing on Nitinol Performance
For pulsed field ablation (PFA) and other advanced applications, understanding how subsequent processing affects Nitinol performance is critical.
Nitinol is particularly sensitive to thermal exposure. Post-processing operations such as bonding, welding, heat treatment, sterilization, or assembly processes can alter material properties if not properly controlled.
For example, exposure to elevated temperatures may reduce stiffness, shift transformation temperatures, or affect superelastic performance.
Evaluating the complete manufacturing process early allows teams to identify potential risks before they impact finished-device performance.
7. Avoid Over-Constraining Your Specifications
One of the most common challenges in Nitinol programs is over-specification.
Device performance characteristics are often influenced by multiple variables. For example, radial force may be affected by:
Attempting to tightly control every variable can create unnecessary manufacturing complexity and cost. Instead, focus on the parameters that are truly critical to device performance and allow flexibility where appropriate.
An experienced materials science partner can help identify which specifications matter most and where tolerance relaxation may be possible.
8. Choose a Materials Science Partner with a Strong Supply Chain
A reliable supply chain can be just as important as technical expertise. Material availability, production capacity, and supplier relationships all play a role in project success. Delays in any of these areas can extend development timelines and impact commercialization plans.
When evaluating a manufacturing partner, consider questions such as:
Strong supply chain capabilities help reduce risk and create a more predictable path to market.
9. Design with Cost and Scalability in Mind
A design that works in the early stages of PD may not always be practical for full-scale production.
During development, it is important to assess how design decisions will affect:
Considering these factors early can help prevent costly redesigns later and improve long-term commercial viability.
10. Engage Your CDMO Early and Often
Perhaps the most important tip of all- collaborate early.
The earlier a CDMO is involved, the greater the opportunity to positively influence outcomes. Early engagement allows for design reviews, material selection guidance, manufacturability assessments, and risk identification before significant resources have been invested.
A collaborative development approach can help: