Material selection can be an integral part of ensuring sustainability for medical devices.
The design of this safety syringe allows healthcare practitioners to operate the device with one hand.
A successful medical product undergoes a significant development cycle during which an OEM takes a concept and design, pairs it with a high-performing material, and produces a device within a reliable, efficient process to secure product integrity. In addition, progressive companies look at the total product life cycle and establish sustainability strategies. Integrating sustainability into the product life cycle requires consideration of the economy, protection for the environment, and social responsibility.
For the medical device industry, building in sustainability means reducing the amount of material or energy used, decreasing waste, and minimizing air emissions. It is more important than ever, therefore, for OEMs to carefully consider the materials that will go into their product. This article looks at materials selection as an integral part of the total product life cycle and the move toward sustainability.
Conceptualizing a Medical Need
Medical devices must generally meet a need, but manufacturers also want to create a functional design that factors in human interaction and is aesthetically pleasing. In doing so, manufacturers must also address market challenges and trends. These trends include the shift of healthcare away from hospitals, the nursing shortage, and the aging population. Trends such as limited product reuse—a medical device that is either disposable or has very limited usage—must be considered during initial concept development. Limited product reuse may need to be considered as a way to mitigate the spread of infectious diseases as well. For instance, there are plastic medical devices that cannot be sterilized more than once, making the device a one-time use product. During concept development, it is important to understand the plastic resins available that can ultimately enhance a product's effectiveness. Understanding resin options ensures that the material selected is appropriate for the product's care settings as well as its manufacturing and sterilization processes.
For example, it is important to review available materials in the earliest stages of developing a device, such as a sleep apnea mask for an aging population. As more and more seniors are diagnosed with sleep disorders, treatment has moved from a hospital-only environment to include home treatment. Although a sleep mask would be used in both treatment settings, the one manufactured for the hospital might be a single-use disposable, whereas a reusable version could be manufactured for use in the home.
OEMs must make sure that products are created to suit each environment, and so firms must examine manufacturing processes, distribution, use, and disposal. In the example mentioned above, then, it is important to know that a more cost-effective polystyrene would be appropriate for the hospital mask whereas a high-performing engineering polymer would best suit the home environment. Material selection is just one decision in the process; however, it demonstrates how concept and design can be translated into a customized medical device that serves the same patient need in two different environments.
Designing for Human Interaction
This IV bag is made from a PVC alternative that is clear, resilient, and autoclavable. The material also reduces medical waste costs and eliminates hazardous emissions.
Effective design takes into account the patient's emotional response and thereby improves the patient experience. In the past decade, material selection was often left up to an engineer responsible for the product manufacturing process, often too late to make adjustments that might yield more-efficient production or better product functionality. The need to innovate and differentiate, however, has changed the landscape for medical product companies; today's medical products need to be more user-friendly to help address problems such as worker training and language barriers, as well as to suit the environment in which the device will be used. OEMs must connect material performance to market need and must identify an appropriate mold method, the optimal sterilization method, and the right regulatory path. Designers need to understand a material's properties as well as its performance attributes and how a given material could be used to address patient issues and market trends.
Optimizing Material Selection
Material selection is driven by performance potential and ease of processing. Now, more than ever, it is also driven by sustainability (see the sidebar, “Creating Sustainability”). With a broad range of medical-grade resins available, there are greater possibilities for medical OEMs to choose from. OEMs must apply the right material to a device or packaging design to enhance human interaction while reducing the development cycle and minimizing scrap or production interruptions.
Test data help confirm the attributes necessary to deliver the appropriate level of design flexibility, strength, clarity, and chemical resistance—key attributes for devices and packages with maximum integrity. Comparing data makes material selection simpler. Material properties are also matched to application performance, secondary operations, and regulatory guidelines. And in the case of a product redesign that leads to material conversion, companies should seek out materials compatible with their existing sterilization and validation processes to contain costs and expedite processing. For instance, frequent breakage prompted a provider of natural collagen vascular grafts to convert its glass culture tube to a stronger, more resilient package.
The grafts are used for hemodialysis grafts and peripheral bypasses, so it was important for the company to select a medical-grade copolyester to ensure that the product would address durability, and thus contribute to the product's sustainability. It also decreased secondary packaging, another step toward sustainability. In addition to being compatible with extrusion blow molding, the copolyester offered high clarity, gloss, toughness, and chemical resistance. It tested successfully after ethylene oxide (EtO) and gamma sterilization. In the end, the package was robust, stable, and safe without compromising surgical readiness or performance of the grafts. The new material also decreased secondary packaging and lowered costs for transport and warehousing.
Achieving Effective Production
Efficient manufacturing requires optimization of part design, mold design, and processing parameters. Having a comprehensive production strategy in place becomes an OEM's insurance against costly production mistakes. Moreover, efficient processing coupled with good quality control can decrease energy use, minimize waste, and improve sustainability.
OEMs must indicate to their supplier early on whether a medical product is to be injection molded, thermoformed, or extruded, and whether there are multiple parts that must be factored into the design. For example, a specialized medical plastics team might review the initial part design for uniform wall thickness to improve part strength and joint design and to maximize product performance.
An OEM would also benefit from a tooling review that analyzes mold design features such as the type of feed system (hot or cold runner), gate design (hot or cold gates), cooling line arrangement, venting, and ejection system to correctly match the material to the process. As part of this process, a mold simulation would pinpoint gate location, the fill pattern, and fill pressure of the proposed part.
To maximize performance while minimizing risk in rigid packaging applications, OEMs must have a combination of clarity for easy product identification and product protection.
To ensure bond integrity and viable device operation of a multiple-component part, OEMs need to understand how to choose a part-joining method that best suits the selected material. Bonding options include adhesive bonding, solvent bonding, welding (ultrasonic, laser, hot plate, vibration, etc.), mechanical fastening, snap fit, press fit, and cold forming. For example, solvent bonding could be used on flexible copolyester tubing to minimize crazing, stress cracks, and bond failure. To join two clear parts, laser welding might be suggested.
Sterilizing for Product Integrity
Medical products must not be compromised after sterilization. Key to achieving this goal is matching the resin to a cost-effective sterilization process that reduces bioburdens without negative effects such as a color shift or physical degradation. Medical-grade polymers used for devices such as syringes, tubing, pump housings, caps, and dialysis components are typically sterilized via EtO, gamma radiation, autoclave, low-temperature hydrogen peroxide gas plasma, or electron beam (E-beam). Most high-volume medical products are sterilized via gamma or EtO, the latter being more expensive and requiring a time-consuming quarantine.
Recent improvements in efficiency have increased the popularity of E-beam sterilization, making it a safe, reliable source of energy that is gaining popularity due to its lower cost. Additionally, E-beam sterilization can be conducted in-house during the packaging process. It is not regulated like gamma radiation because radioactivity is not present.
Companies choosing E-beam sterilization for their transparent medical devices should be aware of the potential for color shift after sterilization. Thorough testing data are a good indicator of how the physical and optical material properties of a particular polymer are maintained after certain sterilization processes.
Packaging for Distribution and Use
Available technical data helped a surgical instrument maker reverse engineer a package design that resulted in a 16% reduction in material costs and a 15% increase in manufacturing capacity.
Whether a company is looking for rigid or flexible packaging, the material must provide a microbial barrier and lasting protection throughout the supply chain and during storage—product must retain its integrity and fitness for use. OEMs need to take a holistic approach to a package's distribution and use. It is important to choose packaging that provides the necessary physical, thermal, and optical performance. Important material attributes for packaging run the gamut from clarity and good melt strength to ease of thermoforming and the ability to be sterilization stable. To adequately meet these performance demands, it is essential for OEMs to tap into available technical data to efficiently produce packaging that diminishes medical waste and environmental impact. Such data are readily available on supplier Web sites.
For example, when a large medical company was looking to create a durable, flexible IV container that was also environmentally friendly, it chose an elastomer as an alternative to PVC. As a result, the company minimized a secondary overwrap while reducing punctures and decreasing medical-waste costs and hazardous air pollutants.
For another company, material data helped them consolidate five current package designs into one. The new robust design reduced material costs by 16%, increased manufacturing capacity by 15%, and created a package that was 25% smaller, providing additional shipping and storage savings.
Understanding materials can help OEMs optimize each stage of the product development cycle and deliver safe, easy-to-use product that poses the least environmental risk. Reviewing performance data enables companies to develop sound, effective medical products and packaging.
Glenda Eilo is global industry leader for the medical market segment of Eastman Chemical Co.'s (Kingsport, TN) specialty plastics business. She can be contacted at email@example.com.