Page 213 - Biomedical Engineering and Design Handbook Volume 2, Applications

192 MEDICAL DEVICE DESIGN

grade papers and are comparable to some grades of spun-bonded olefin. The consistency of the thick-
ness provides less variation in the sealing process; and tear resistance is superior to paper but not as
®
good as spun-bonded olefin. This material may provide an acceptable alternative to Tyvek .
Paper. For many years, paper was the only choice for package types until the introduction of
®
Tyvek as a medical packaging material. However, paper still plays a significant role in the medical
®
device industry. Over the years before the introduction of Tyvek , paper materials compiled a sig-
®
nificant performance record of product protection and patient safety. Although Tyvek has taken a
majority share of the medical device package market, the industry is finding ways to utilize paper in
combination with plastics and foils to provide the needed performance characteristics with favorable
economics.
The significant features of paper materials that enable it to continue as a feasible packaging mate-
rial alternative are
• Sustainability
• Cost
• Disposability
• Sterilization
• Combination with other materials
• Versatility
• Peelability
• Range of grades
Some of the limitations of paper as a medical device packaging material are

• Strength—low tear and puncture resistance
• Dimensional stability
• Moisture sensitivity
• Aging—limited under certain environmental conditions
Paper can be used as lidding material for semirigid and flexible trays, and for peelable pouches.
Adhesive coatings are required to allow sealing.

Films, Laminates, and Coextrusions. Many films are used in medical device packaging applica-
tions. Both flexible formed and nonformed pouches, as well as bags, use films for their manufacture.
These materials offer a high degree of versatility and are available in a countless variety of forms in
monofilms, laminations, and coextrusions. The specific material to be used for a medical device is
dependent on the performance properties required for the device application. For example

• Sterilization method (e.g., the material must tolerate high temperature)
• Protection requirements (e.g., high puncture resistance)
• Peel requirements (e.g., easily peelable)
• Package style (e.g., formable vs. nonformable pouch)
• Barrier properties (e.g., moisture or oxygen barrier)
• Packaging process (e.g., in-line sealing vs. form-fill seal)
• Packaging aesthetics (e.g., visibility of product)

The flexible materials used for medical device packages include a plastic film that is usually a
lamination or extrusion-coated material. The material most commonly used for flexible packaging
applications is oriented polyester (e.g., Mylar ), which is used as a base for properties such as,
TM
dimensional stability, heat resistance, and strength with an adhesively laminated seal layer, such as