Medical Device Link.

FEATURE

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Different design and process possibilities

Ease of opening and sterilisability are important factors in the packaging of sterile medical devices. Thermoform-fill-seal (TFFS) lines can be equipped with an applicator for inserting a small window of a different material into the top web of the TFFS package. This can involve a combination of an easy-peel material with a gas permeable Tyvek (DuPont, Luxembourg, Luxembourg) strip to create a package that combines ethylene oxide (EtO) sterilisation with the desired opening characteristics and savings in materials costs. The process is described below.

Reducing material consumption

Often, medical products require sterilisation after the packaging operation. In the case of sterilisation with EtO, typical material choices are sterilisation papers or nonwoven fabrics such as Tyvek. In packaging processes such as thermoforming, flow wrapping or tray sealing working from roll fed film, Tyvek would have to be used as the top web, which means that the entire package top, the largest side of the package, would consist of this high value material.

Figure 1: Example of a thermoformed package made from PA/PE film compound with a relatively small Tyvek window in the upper web, suitable for full EtO sterilisation.

In terms of sterilisability, this is not required. Full EtO sterilisation can be accomplished using a far smaller Tyvek window applied to the top web of the thermoformed package. The top web film itself can consist of standard film compounds such as a polyamide–polyethylene (PA/PE) with the desired opening characteristics (Figure 1).

Creating the window

Figure 2: Process of inserting a small window of Tyvek into the top web of a different material in the TFFS package. (click image to enlarge)

Fabrication of the window can be performed automatically on a thermoforming line equipped with a specially designed applicator. The TFFS system first forms a cavity from the lower web film, which can be a rigid or a flexible material (Figure 2). The cavity is then loaded with the product. Because the pack cavity is open at the top, it is simple to load the product from above.

In parallel, the applicator cuts a window of the specified size into the flexible top web, typically a converted multilayer film such as a PA/PE compound. The size and placement of this window depend on the product and its application. A strip of different material, which in this case is Tyvek, is then positioned adjacent to the window and sealed to the top web. Exact positioning of the Tyvek strip is achieved by sensor control and alignment of the strip and the window location. The modified top web is then hermetically and securely sealed to the outer contour of the bottom web of the package cavity. Finally, the sealed package is cut out according to the selected specifications.

This process satisfies the sterilisability requirements while using only a fraction of Tyvek material, and offers the integration of an opening aid. The easy-peel material can be chosen from a range of films and suppliers to achieve the desired opening characteristics. The Tyvek strip can be tightly sealed to the top web to permit full EtO sterilisation. From the perspective of material costs, the savings potential is considerable, depending on the type/design of package.

Cost-effective alternative to bags

This special TFFS system offers an alternative to packaging medical devices in premanufactured vented bags. The vent allows for the sterilisation of the packaged products with EtO. However, these bags normally use large circular pieces of Tyvek that leave as much as 30 per cent of the original material unused. In addition, as a part of the sealing and cutting process, a large area of the film has to be trimmed and discarded in every unit that is packaged. These factors lead to a high amount of waste and incur significant material and disposal costs.

TFFS packaging utilises materials more effectively by creating an exactly formed cavity out of PA/PE films. Thermoformed packages can be customised to nearly every product shape, which allows for more efficient use of the material than is possible with preformed bags, and an increase in the stability of the product within the package. The design of the package itself requires a rectangular shaped piece of Tyvek instead of a circular one, which increases the material yield. Thus, the only material waste is the edge trim that results from the chain guide of the TFFS machine.

In terms of prod-uctivity, the savings are considerable. Packaging products into preformed bags requires several time consuming steps at various machines. Manual filling of the preformed bag is labour
intensive. With the TFFS system, loading of the products into the thermoformed cavity is done inline from above, that is, from the largest side, manually or automatically. Subsequent steps are performed automatically on the same machine. Higher output is achieved with fewer operators required and the process guarantees a higher level of productivity and efficiency.

Another important factor is the savings potential in terms of storage costs and production area. The storage costs for preformed bags are considerable. In comparison, roll fed films used in thermoforming require less storage space and can be used for various products.

Brand specific product design

Figure 3: Most packaging films are printable and allow brand specific designs of the manufacturers’ information to be printed directly on the package.

The wide range of packaging films available today means that the described TFFS system can be customised to meet the requirements of almost any product to be packaged; Tyvek can be applied to practically any flexible film. Because most films are printable, the pack can be given an individual and brand specific design. Equipped with a data printer or even a flexographic printer, the system also permits inline printing of the required manufacturer information directly onto the top web of each package during the packaging process (Figure 3). The integration of printing equipment into the thermoforming machine allows manufacturers to change product markings and codings with little or no idle time. Total production performance is maintained and it becomes unnecessary to stock package inserts or labels in various languages and designs. The end customer can easily locate critical information, rather than relying on a loose paper insert. This technology also increases the level of traceability of the packaging process.

The TTFS system offers more than efficiency. Many medical device packages require increased seal strength to ensure that the package cannot burst when exposed to varying atmospheric pressure. The applicator makes it possible to seal a window with easy opening characteristics to the top, and the web to be tightly sealed to the sealing contour of the bottom web. This creates a robust package with an
integrated opening aid.

Markus Boeck is Manager Medical Packaging at Multivac Sepp Haggenmüller GmbH & Co. KG, Bahnhofstrasse 4, D-87787 Wolfertschwenden, Germany, tel. +49 8334 6010, e-mail: markus.boeck@multivac.de, www.multivac.com.