By Sean Fenske, Editor-in-Chief
 
Medical devices have a complex array of tasks they must accomplish seamlessly and without fail. First and foremost is the clinical therapy each device is developed to deliver. Alongside this mission, however, are other requirements the designer must achieve through the device’s design. One is providing a reassuring appearance that conveys a safe feeling to patients. Another involves environmental impact and sustainability considerations. Still another could be tied to brand reinforcement.
 
Materials used in the creation of a device can assist with all of the aforementioned goals for a device’s design. Selecting the right option for a product can be the first step in ensuring its successful launch and use in the market. As such, it’s important to work with a supplier familiar with the benefits and disadvantages of a given material to confirm it’s the best choice for a particular device.
 
To assist with this, two representatives from SEKISUI KYDEX shared insights on thermoplastics in the following Q&A. Mark Denning, medical market business manager, and Shawn Gum, business development engineer, respond to a number of questions about the material, addressing critical topics such as design, aesthetics, function, sustainability, and more.
 
Sean Fenske: What applications in the medical device space are ideally suited for injection molded thermoplastics, and where are they most used?
 
Mark Denning: There are multiple reasons injection molding is used for medical devices, including material selection, availability, design, application, and volume considerations. For example, one of the world’s leading producers of syringes made two billion units per year at the height of the pandemic. Injection molding is not only the best process to create that design but also the most effective way to produce that type of volume.
 
At SEKISUI KYDEX, our focus is on producing the material for medical device covers or housings. For these products, injection molding can be used in harmony with other processes, such as thermoforming. For example, thermoforming can be used to produce the larger covers, while injection molding could be used for the smaller and more intricate parts. Alternatively, the device manufacturer can combine the two processes to utilize the most cost-effective solution for the individual parts on the cover set.

 
Fenske: In medical device molding, how important are aesthetics? What’s driving this demand?
 
Denning: Aesthetics lead to our expectations and play an essential role in creating patient comfort and reducing anxiety through the color, shape, and design of a device. According to Don Norman’s book, Emotional Design, “aesthetically pleasing products create positive emotions which can vastly influence our experience of that device.”
 
Aesthetics play an important role in branding, especially color. With so much money spent on color to create brand recognition, it’s essential to ensure the brand’s products represent them effectively. For example, when I say Coca-Cola, do you think of their iconic red can? What about John Deere—does the firm’s green color come to mind before an actual model of a tractor?
 
With this in mind, it’s important for device manufacturers to ask themselves, “How can the design and aesthetics reflect the incredible technology that’s hidden inside while staying on brand?” When patients walk into a caregiver’s office, they expect to feel safe. The equipment in the room has a direct impact on that feeling, and when they are confronted with equipment that is not aesthetically pleasing, instead of feeling safe, they might feel like a lab rat. However, the answer to combating this is much simpler than one might think.
 
Through texture, color, and design considerations, device manufacturers can greatly impact a patient’s perception of a product and the care they are about to receive.
 
Fenske: What material attributes do thermoplastics have that make them a benefit to use for medical devices?
 
Denning: Sustainability has emerged as a pivotal trend in medical device materials and thermoplastics can lead to more sustainably minded device designs. Medical device manufacturers are increasingly mindful of the environmental implications of their devices, whether it’s the materials used or the manufacturing processes involved. KYDEX® thermoplastic sheet is an eco-friendly material made from domestically sourced technology derived from salt and natural gas. The rigid sheet composition of this material eliminates the need for plasticizers in the manufacturing process, which is often associated with negative environmental impacts.
 
Other things to consider about the benefits of KYDEX® Injection Molding resins and KYDEX® thermoplastic sheet include design freedom, light weight, in-mold color (to eliminate paint), dent avoidance, and, in some instances, cleanability and resistance to disinfectants.
 
Fenske: What are the design considerations companies need to keep in mind when planning to injection mold with thermoplastics?
 
Denning: The biggest consideration is the volume and how soon the cost of the tooling will be amortized. When the volumes don’t warrant the cost, injection molding might not be the best course forward, and instead, manufacturers should consider another process, such as thermoforming. Alternatively, it might be best to start the production with thermoforming and then migrate into injection molding if the volumes justify. An important consideration for this is to understand if the resin can remain the same or if it will need to be revalidated.
 
Also, determine if there is a resin capable of meeting the demands of the part for the specific application, such as resistance to disinfectants. Is the biocompatibility rating suitable for the application; what other environmental considerations are needed for the finished part? KYDEX® Injection Molding resins are a specialty formulated thermoplastic alloy with the same physical properties as KYDEX® Thermoplastic sheet. Because of this, KYDEX® Injection Molding materials are chemically resistant, have inherently antifungal and antibacterial properties, are cleanable, and will not be stained by harsh cleaning agents, making them ideal for high-traffic areas such as healthcare furniture and medical devices.
 
Fenske: Are there applications where injection molding thermoplastics should be avoided with medical devices?
 
Shawn Gum: Thermoplastics can be used just about anywhere on medical devices, but designers and engineers should carefully consider what the performance requirements are for each part. Some parts may require more heat resistance, such as internal parts near heat sources, and others may require better chemical resistance, such as external covers. There are some thermoplastic materials that can check off all the boxes for these devices, while others may only check one or two. With careful review, designers and engineers can identify the most appropriate thermoplastics to maximize performance and minimize the number of different materials that need to be ordered.
 
Fenske: What aspect of molding with thermoplastics is surprising to engineers/customers? What are the “hidden gems” of using this material for injection molding?
 
Gum: Engineers and designers may be used to designing medical devices with legacy materials, such as fiberglass or sheet metal, which may require painting for high-quality finishes or secondary processes to attach mounting points. Injection molding thermoplastics allows for parts with very complex geometries to be molded in one step with integral color and little to no secondary finishing required.
 
Thermoplastics allow for devices that are lighter weight, more durable, and provide a lower cost of ownership compared to other materials.
 
Fenske: Do you have any additional comments you’d like to share based on any of the topics we discussed or something you’d like to tell medical device manufacturers?
 
Denning: As sustainability-minded design continues to play a pivotal role in today’s world of medical device manufacturing, designers and engineers must carefully consider this aspect of their development projects. They need to balance the sustainability of their medical devices while also achieving the visual consistency needed.
 
When devices are made of mixed materials, they sometimes require additional steps to make them look seamless, which is not always the most economical or sustainable solution. By using injection molding resins with the same physical properties as thermoformed sheets, medical devices can have seamless aesthetics without compromising on sustainable design.
 
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