Covering a metal surface with polymeric materials may be quite challenging. The first obstacle is how to establish a bond between the metal surface and the polymer cover, two materials that do not normally bond with each other and do not provide good adhesion.
Figure 1 – Adhesion of a polymeric cover to a metal stent by scanning electron microscopy (SEM)
From left to right: the first 3 images shows the poor adhesion generated after stent covering without surface treatment and the last image shows the good adhesion generated from stent covering after surface treatment
As can be seen in figure1, a metal frame covering without any treatment will lead to a polymeric covering that is merely implemented onto the metal frame application, but is not really connected to it, thus, can delaminate with time or pressure applied to the application.
Since adhesion properties ensure the cover’s long-term attachment to the metal frame-based medical device, Medibrane’s scientists have developed an Adhesion Platform, to improve adhesion.
Surface Treatment
The first step of the adhesion improvement platform, is called Surface Treatment, and is meant to prepare the metal surface for bonding with the polymeric material. Using a variety of techniques, our experts are able to increase adhesion between the metal surface of the stent or implant, and the polymeric covering or coating;
Plasma treatment: When a low-temperature, high-voltage electrical discharge is applied to an electrode with a sharp tip, it causes ionizes molecules, also called plasma, to form at the tip. A linear array of such electrodes, that creates a curtain of plasma, modifies the metal’s surface to improve the polymer adhesion.
Primer: Better adhesion can be formed by adding primers, that act as bonding molecules. These primers adhere to the polymer on one side, and to the coating on the other side, thus increase adhesion.
Encapsulation Coating
Another unique technique Medibrane’s engineers have developed to improve adhesion is called Encapsulation Coating. Encapsulation Coating is a technique in which an ultra-thin polymeric membrane coats the frame-based device’s struts to a full extent, providing mechanical attachment between the polymer and the frame. The encapsulation encircling the frame, profound the bonding between the metal frame and the covering and improves adhesion between the polymer cover and the frame.
Medibrane’s unique Adhesion Platform not only improves adhesion, but also enable a manufacturing process that ensures a highly-repeatable production line that yields high uniformity and flawless products.
