The Importance of Material Selection in Circular Design of Medical Devices

Circular design considerations
Circularity is gaining importance in medical device design, with jurisdictions imposing regulatory requirements and purchasers adding environmental considerations to procurement criteria. Circularity necessitates a holistic design approach that integrates the business model and regulatory aspects, without compromising device performance and safety. From a business perspective, adopting a circular design can create new revenue streams through refurbishment, reprocessing, and recycling programs. Regulatory considerations are paramount, requiring stringent adherence to standards that ensure the safety and efficacy of reused and recycled materials and components. In some jurisdictions, these aspects extend from performance criteria to traceability and ethical considerations for multiple use cycles. Additional performance criteria may be required for reprocessed or refurbished devices, including aging and conditioning of materials and the device, and how any altered properties affect performance of the device, as well as cleaning and sterilisation properties, microparticle release, and other properties. Indeed, materials must retain key design characteristics throughout the use cycles and thorough testing must evidence the performance criteria are met after reprocessing or refurbishment.

Evaluating Circular Characteristics
Circular characteristics include the cost of sourcing the material, its scarcity, easy of recycling or reuse, the aging properties, and the toxicity of the material after device disposal. These characteristics may be integrated into design using more traditional tools, such as the Ashby plot. Traditionally used to compare different materials based on their mechanical properties, such as strength and weigh, the Ashby plot can equally be applied to select the best material based on 1 or more circular property to visualise trade-offs. Understanding where materials sit in terms of both circularity and performance can guide better multi-criteria decision-making.

Multi-Criteria Decision Making
How can environmental aspects and circularity be integrated into design at development either at the concept of the device or retrospectively? The mechanisms are already in place as design and development of devices has always been based on multi-criteria decision making to balance the benefit-risk ratio is favour of performance and safety. As sustainability becomes more of a focus, additional parameters including reprocessing and end-of-life considerations will need to be considered, along with factors such as cost relating to feedstock and material scarcity. Where these parameters can be objectively measured, either through publicly available data or testing, a comprehensive view of each material’s overall sustainability and how that impacts the device sustainability can be integrated into the design process.

The re-use equation
Reusing medical devices presents both benefits and challenges. On the positive side, reusing some devices can lead to significant cost savings in materials and reduce medical waste, making it an economically and environmentally-friendly option.
The decontamination process, essential for ensuring safety, can be efficient with the right protocols, allowing devices to be safely reused multiple times, subject to tight traceability to ensure that the re-used device is only cycled as many times as the manufacturer recommends. However, the process of decontamination is time-consuming and requires stringent adherence to guidelines to prevent infection risks. Additionally, repeated use and sterilization can alter the material properties of devices, potentially affecting their functionality and durability.
In design for a circular economy, reuse is not always the most logical and cost effective solution; rather intelligent, holistic design of single use device may have an overall benefit.

Separation and Recycling of Materials
An important aspect of circular design is the separation of different materials both during use and at the end of their life cycle. This is crucial for recycling and reprocessing. Different devices, whether multi-use, single-use, or reprocessed, will have varying weightings and criteria in their material selection.
The design process should consider specific criteria of materials and whilst design is often presented linearly, it is inherently cyclic, such that design reconsiderations can be implemented at every stage to optimize both performance and sustainability.

Global Considerations and Regulatory Compliance
Material availability and acceptability can vary globally. Designers must consider these differences when selecting materials for medical devices, particularly where manufacturing across multiple geographic sites. The same applies for methods of manufacturer, most notably ethylene oxide gas sterilization, where local as well as national laws impact implementation. In some cases, upgrading, refurbishing, and reprocessing devices can significantly reduce environmental burden; in other cases, the cost of any process towards reuse is far more expensive than taking a single use approach. Indeed, for some single use devices, reprocessing can have a more significant environmental impact that recycling the components. It is essential to consider how design allows for the recirculation of materials from reprocessing through to remanufacturing and recycling.

The design approach needs to be revisited with new regulations, but also with new technologies. Mechanical recycling often involves simpler processes, but can rely on people to separate materials and therefore medical waste must be decontaminated before recycling begins. In contrast chemical recycling could potentially extract monomers from waste without such steps. Whereas the challenge of chemical recycling to generate recyclable monomers is hampered by the purification steps where mixed waste is used, degradation of biopolymers into fuel stocks creates a cyclic carbon economy with the potential of valorising medical waste into a revenue stream.

Whereas some considerations apply to the device as a whole, there are products composed of different value components. For example, where as the polymers in devices tend to be readily available, metals are more scarce and metal-containing components may have different scores for reuse and recycling compared to other components of the same device. Ranking parts based on their potential for reuse may allow design to focus on multiple decommissioning steps that create an overall benefit.

Final Review and Future Outlook
In conclusion, material selection for medical devices is a key element in a circular economy for medical devices. The current focus is to consider materials that are more aligned with circularity, such as biopolymers and recycled polymers, over traditional options. Medical-grade components will always be required, but the future lies in designing materials that improve performance and safety while facilitating easier decommissioning and recycling.

The future of medical device design will likely see a more holistic approach to materials, incorporating both design and change control. By prioritizing sustainable material selection, the medical device industry can significantly reduce its environmental footprint while continuing to innovate and improve patient care.

Integrating sustainable materials and circular design principles is essential to achieve both environmental responsibility and operational excellence, aligning with the principles of DQS. DQS certificates allow companies to demonstrate that they meet the highest global standards in terms of quality, environmental management and sustainability. Certifications such as ISO 14001 (environmental management) and ISO 13485 (quality management for medical devices) provide a comprehensive framework for the effective implementation of circular design strategies. These standards not only guide companies in minimizing environmental impact, but also ensure compliance with strict regulatory requirements and position them as leaders in sustainable innovation in the medical device industry.