Page 214 - Biomedical Engineering and Design Handbook Volume 2, Applications

STERILE MEDICAL DEVICE PACKAGE DEVELOPMENT 193

low-density polyethylene, which provides the film structure with heat sealability. The variety of film
combinations is virtually unlimited, and the performance properties of the film can be customized to
meet the requirements of the package specifications and the medical device. Other examples of film
constructions are

• Polyester/Pe/EVA
• Polyester/Surlyn
• Polyester/nylon/Pe
• Polyester/nylon/PP
• Polyester/PVDV/Pe
• Metallized polyester/Pe
• Polyester/foil/Pe
• Polyester/foil/polyester/Surlyn
• Oriented PP/Pe
• Polycarbonate/Pe/EVA
There may be other combinations of film structures as new materials with different properties are
continually being developed. Consult with packaging material suppliers to determine the optimum
material for your application.
The thermoplastic films used in flexible applications are suited only for sealing to themselves or to
chemically related materials. The sealing of like materials produces fused bonds that may not be pee-
lable and thus applicable for single-use medical devices. To overcome the limitations of sealing like
materials, adhesives specifically tailored for seal-peel functionality are applied to the film surface,
allowing films to remain unaltered and to retain their performance characteristics. The use of uncoated
or coextruded materials for medical device packages is limited in their application by allowing only a
narrow sealing range, providing limited sealability on high-speed equipment, allowing sealing of chem-
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ically similar materials, and Tyvek materials. On the other hand, materials coated with an adhesive
provide versatility and greater benefits, such as a wider sealing range, easy and consistent sealability to
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porous materials such as Tyvek and paper, barrier properties, lower cost, and versatility in adhesive
properties dependent on the application (e.g., pouch or tray application).
Foils. Foil laminate materials are used in applications where high moisture, gas, and light barriers
are essential. Foil can be used in all forms of packaging and for both medical devices and pharma-
ceuticals. The lamination of the foil with plastic films is required to provide sealability. Foil materi-
als are being used for lidding of thermoform tray packages where high moisture and gas barriers are
required and where the sterilization method allows it (e.g., gamma, e-beam, and steam). Wet devices
such as dressings, solutions, sponges, swabs, and other saturated products requiring high moisture
barrier are particularly suited to foil packages. Foil laminations with high-density polyethylene or
polypropylene are common constructions for these package types. For solutions, a form-fill-seal
application is ideal, as the pouch is formed and filled in a multiphase operation on a single machine.
The trend in medical device packaging, over the past 10 years has been to flexible packages, as
they are less costly, more resistant to shipping damage, easier to handle, and produce less packaging
waste. A foil-laminated package offers many benefits such as strength, high environmental barrier,
peelability, easy opening, temperature resistance, opacity for light-sensitive products, sterilizer resis-
tance, ease of formability, compatibility with many products, and tamper evidence.

Thermoformable Plastics. Thermoformed plastics are among the most widely used package types
due to their aesthetic appeal, medical device delivery applications, and versatility for customized
designs to fit contours of medical devices or several components of procedure kits. The selection of
a material for a specific medical device is dependent on several factors such as barrier requirements,
sterilization method, and cost. There are many thermoformable plastics; however, not all have the
ideal properties that lend themselves to medical device packaging applications. For example, an