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Roundtable Q & A: Advanced Material

Mon, 06/27/2011 - 9:49am
Ken Breeding, Prakash Pawar

Question 1: What is the greatest factor to consider when determining a material for a medical device?

Ken Breeding
Platform Technology Manager, Medical Devices, Eastman Chemical Company

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To ensure a functional, reliable device, it is essential to consider material attributes in relation to the intended use and performance requirements of the application. For example, a system of cannulae must be designed for quick identification of tube sizes, provide sterile pathways during surgery, and ensure an unobstructed view of the instruments and any sutures inside them. Given these system needs, a material must be selected that is clear and color stable; able to withstand exposure to solvents, lipids, and blood; and has high durability to the forces applied during insertion and manipulation of surgical instruments.

 

 

Prakash Pawar
Applications Development Engineer, Momentive Performance Materials

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Device manufacturers should consider whether the proposed materials:

- Comply with applicable requirements (e.g., FDA or USP Class VI, ISO10993 guidelines)
- Are capable of withstanding the applicable sterilization methods such as Gamma, E-Beam, ETO, Steam, etc
- Provide enough design flexibility and processability that is critical to enabling better yield for the designer and molder
- Meet end user device performance expectations
- Have been subject to application testing that conforms to industry application

Device manufacturers should consider the following criteria to be of highest priority.

- Clear and articulated definition of device and performance requirements
- Materials knowledge, performance experience, and expertise in part design
- Knowledge and experience in marketing, materials availability, molding expertise, and production requirements in various countries where the device may be used

Aesthetics generally are not as critical as clarity and appropriate and effective design for use. While clarity may provide the perception that parts are clean, it often can allow clear visual inspection (e.g., fluid flow), which may lead to increased cleanliness.
Devices are generally best when moving parts and screwed (or bolted) parts are minimized. This often can be achieved through either overmolding or insert molding via simple adhesion to eliminate screws or movable parts. Proper materials selection and process availability can provide design flexibility as well as improved aesthetics to the device.

Question 2: Are there issues with biocompatibility and plastics that medical device manufacturers neglect to consider?

KB: Original equipment manufacturers (OEMs) in the medical industry are experts in material specification for regulatory compliance. It is critical to the innovation process that materials enable the successful introduction of a new device into the marketplace. Eastman has supplied the medical device industry with clear, tough, and chemically resistant copolyester materials for many years, and facilitates the innovation process by working closely with OEMs to ensure they have the information required to specify a material, and that the final device will be compliant. Eastman’s medical grade copolyester materials, including Eastman Tritan copolyester, have been carefully tested to ensure regulatory compliance with governmental and industry standards for biocompatibility. For medical grade plastics, Eastman offers characterization of its products, which include ISO 10993 Part 1 biocompatibility test reports and USP Class VI test reports.

Question 3: How important have the aesthetics of a plastic become for medical device design?

KB: The aesthetic characteristics of plastics for medical devices have become increasingly important. The medical marketplace continues to value safe, durable, and reliable devices, and is increasingly recognizing that a well-designed device makes a connection with users and enhances patient safety and comfort. Material suppliers and designers can work closely together to use contemporary plastic materials that offer design flexibility to develop devices to meet these needs.

Transparency of materials in applications such as needle hubs or fluid bags is valued in the healthcare field for conveying safety, quality, and peace of mind for both the medical professional and patient. Some polymers exposed to sterilization can shift in color, which may cause concern about the sterility and functionality of a medical device. It is important that manufacturers understand the effect of sterilization methods on the appearance of the final device in order to make educated material choices that will enhance functionality and maintain aesthetic appeal.

Final Word: Any thoughts/comments on materials you would like to share with medical device manufacturers to aid them?

KB: Materials used for medical devices vary widely. Devices can be brought to market more efficiently and faster if there is early and ongoing collaboration with material suppliers, manufacturers, and molders to help design engineers identify the optimum material for a given application. It is important for the product development team to have an understanding of the advantages of specific materials for particular design applications, have an understanding of how the materials are processed, and be aware of recent advances in materials.

Beyond clarity and color stability, other critical factors to consider when determining a plastic for a medical device include durability and chemical resistance, temperature resistance, ease of processing and secondary operations, and sustainability attributes. Another significant trend Eastman has observed by working with OEMs concerns the market’s emerging demand for materials free of bisphenol A (BPA). In this area, Eastman has provided information to OEMs to help them make choices about what material to specify for a given device.

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