Growing Demand for Home Care MedicalDevices Requires Miniaturized Molded Rubber

Molded rubber parts for medical devices must be manufactured to withstand a wide range of operating temperatures, fluids, gasses and pressures. Many assemblies include rubber bonded to metal or plastic parts.

As electronic components have become smaller, more medical devices operate with a combination of electronics and magnetics, which may be used to open and close a valve to dispense a metered amount of oxygen. These devices, such as oxygen concentrators and ventilators, which employ miniature pneumatics, are expected to cycle millions of times without fail. The rubber molding often serves as an insulator in electronic devices.

The rubber molding firm should be experienced with addressing issues involving “sticktion” - the rubber’s properties of stickiness and friction that will allow a valve to open and close quickly and safely. Another concern is the molder’s ability to bond rubber to inserts made of specialty metals with magnetic properties. In miniature pneumatics, such components require extremely complex geometries and tight tolerances, as well as the ability to withstand operating temperatures ranging from -80F to 500F.

Not all rubber materials are suited for home medical devices. Depending on the application, the materials may need to be USP VI tested for biocompatibility and FDA compliance. If the rubber part does not come in direct contact with the body, the same level of testing may not be required.

When selecting the right elastomer for the application, the molder’s chemists and engineers will consider such factors as the part’s operating conditions and the material’s ability to resist such environmental hazards as contact with fluids, abrasion, and temperature fluctuations, as well as the material’s cost.

The rubber elastomers most frequently used in medical device components include:

• Fluorocarbon (FKM or Viton®)
• EP/ EPDM (Ethylene-propylene-diene)
• Silicone rubber (gum and liquid)

In order to produce molded rubber parts, the molder will develop a custom rubber compound for the specific application, which is a recipe of the proper elastomer plus a mix of specialized additives to address such issues as resistance to UV, ozone or oil, bonding, and electrical conductivity. The custom formulation is tested before production with material batch testing to ensure that the compound and the part will perform as specified. Quality also should be assured through careful material sourcing and 100% material tracking.

As medical device manufacturers continue to innovate, growing market demand is supporting the introduction of new products that are less expensive, easy to use and effective in home settings.