Challenges in Designing Medical Device Materials

As the medical device industry advances, plastics used for medical devices must be chemical resistant, able to withstand daily wear and tear, and be optimized for patient safety.

Ellen Turner

Eastman's Tritan material can be used in medical housings.

Today’s material suppliers are challenged to create materials that meet the demands of an evolving medical field. In an increasingly advanced industry, plastics used for medical devices must be able to resist heat, cleaners, and disinfectants, as well as the wear and tear they will experience on a daily basis. Original equipment manufacturers (OEMs) should consider halogen-free plastics, and opaque offerings should be tough, flame retardant, and available in many colors. While all of these qualities must be considered, it is also necessary to keep patient safety top of mind.

Transition to the Hospital

Early plastics that were designed to be heat resistant quickly found a space in the medical world, where there also is a need for devices to be tough and reliable. As more plastics entered the hospital setting, there arose a new requirement for medical plastics: chemical resistance. These materials were being used in devices made to administer harsh drugs, such as those used in oncology treatments. The devices required chemical resistance to maintain durability and structural integrity for the entire time the medicine was being administered. 

The Harsh World of Disinfectants

Another case for chemical resistance came in the form of harsher disinfectants used to combat hospital-acquired infections (HAIs). The strong chemicals in these disinfectants can weaken certain plastics over time, leaving them unsafe and unfit for the medical world. Finding chemical-resistant materials has been an increasingly difficult task for OEMs, as hospitals face more and more regulations to eliminate HAIs. Medical staff also sterilize devices frequently to prepare them for use, which takes a further toll on the durability of medical devices. This cannot be overlooked; patient safety is of utmost importance and clean devices are a necessity, so plastics used in medical settings must be able to withstand constant disinfection.

As disinfectants become increasingly strong and are used more often, the need for improved chemical resistance in materials used to develop medical devices continues to grow. Unfortunately, not all materials have adequate chemical resistance, but they are marketed as if they do. This leads to material specifications that result in poor durability and reliability in the final device.

In addition, device designers need to better scrutinize the chemical resistance data they are presented. A limited-time immersion test does not accurately reflect the frequent sterilizations carried out while in service. Therefore, it is important for material suppliers to maintain focus on all device essentials when they create a material that can withstand disinfectants. 

Halogenated Materials in Recycling

In an age where consumers are concerned about what goes into their products—and hospital patients are becoming increasingly aware of the plastics used during medical procedures—OEMs need to consider with what their materials are made. One example is bisphenol A (BPA). Just as there is a market for BPA-free plastics in the medical industry, there also is a growing need for non-halogenated plastics.

Halogens such as bromine, fluorine, and chlorine are very reactive and can lead to negative environmental consequences. When medical devices made with plastic materials that contain these elements are not recycled or properly disposed of, there is a risk of halogens being released into the environment and reacting with other substances. There is a concern that halogenated plastic materials will release corrosive and toxic gases in a fire. These elements need to be avoided in medical plastics, to reduce risk of fire and negative environmental consequences.

A Rainbow of Materials

In the past, BPA-free plastics have been mostly clear, and a dye was simply added to tint the material when branding or coloring as requested by an OEM. Now, there is an increasing need for opaque plastics, such as those designed to house electrical wires. Material suppliers working with wire-housing cases need to make sure they are flame retardant, in order to prevent electrical fires in the case of faulty wiring.

On another note, OEMs that create these devices have different color preferences that can be assigned to specific brands or for aesthetic purposes. Because of this, material suppliers need to ensure they are creating materials that can be used to develop medical devices in the exact colors brands want, while also considering the previously mentioned flame retardant component, and chemical and sterilization resistance.

Material suppliers have a number of considerations to keep in mind when creating a new offering that will withstand harsh disinfectants and sterilization methods. They need to provide a material that will meet OEM standards, whether it is with chemicals that are or are not added, or the color of the device. While these are important aspects to consider, above all, material suppliers must make a choice that will keep hospital patients safe.

Ellen Turner is market development manager, medical devices at Eastman Chemical Company.

[Image courtesy of EASTMAN CHEMICAL COMPANY]