Challenge: Protection of electronics and tissue
from the corrosive effectsIn order to ensure that implanted electronic devices can reliably fulfil their function in the longer term, they must be protected from the corrosive effects of the environment in the body. Conversely, the surrounding tissue must not be harmed by compounds released by the electronic device or react with the development of fibrous tissue. Metal or glass housing is currently used which, however, is limited in relation to its potential for miniaturization and cost reduction.
To demonstrate its feasibility, Fraunhofer IGB has produced a barrier coating, which constitutes an effective barrier against metal ions and water, on a circular electronic implant component that contains copper and nickel. The demonstrator remained functional after six months storage in a physiological medium and no copper or nickel ions were released.
Excellent barrier effect and mechanical stability
The new approach to this problem involves multiple layers of inorganic and organic coatings that jointly produce a barrier coating that is mechanically more stable and more effective. The required biocompatibility was considered in the choice of materials. The barrier coatings were produced using PECVD and CVD methods and are composed of SiOx, silicone-like and parylene-C coating, with a total thickness of around 20 micrometers. Factors that are to decisive for good barrier efficacy are high levels of cohesion in the bonding between the layers and a form-fit coating. The coatings that have been developed can be applied to a variety of geometric shapes and will thus facilitate the development of new miniaturized implants.