Controlled Ag release from electrically conductive coating systems

• Published in: Surface & coatings technology Vol. 336; pp. 29 - 33
• Main Authors: Amberg, Martin, Vandenbossche, Marianne, Hegemann, Dirk
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 25.02.2018; Elsevier BV
• Subjects: Biocompatibility; Coated fibers; Coatings; Continuous coating; Continuous fiber composites; Continuous fibers; Diffusion; Diffusion barrier; Diffusion barriers; Electrical properties; Electrical resistivity; Electrocardiography; Functional fibers; Hydrophobicity; Medical devices; Medical electronics; Medical materials; Plasma; Plasma coating; Polymer films; Polymers; Silver; Silver release; Surgical implants; Textiles; Titanium oxides; Toxicity; Silver release; Diffusion barrier; Functional fibers; Electrical properties; Plasma coating
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2017.10.021

Nowadays, silver (Ag) coatings find widespread use in medical textiles, e.g. wound bandages, mainly due to their antibacterial properties related to the Ag ion release in aqueous media. Moreover, Ag-coated fibers offer excellent electrical properties, allowing their use for sensing applications such as electrocardiography (ECG) belts. Due to the potential cytotoxicity of Ag, electrically conductive coating systems need to be developed with reduced and time-controlled Ag release. In this study, pure silver was continuously deposited onto a polyester (PET) fiber to optimize electrical conductivity for ECG application. The pure silver coated fibers, however, showed the typical initial burst release of Ag ions when immersed in an aqueous environment locally yielding cytotoxic conditions, i.e. high Ag ion concentrations. While the ion release can be favourable for antibacterial properties, it needs to be limited for medical devices. A diffusion barrier is thus required, while maintaining the electrical conductivity. Thus, different plasma polymer top coatings were applied onto the Ag-coated fibers using a continuous deposition process. The functional plasma polymerized films (a-C:H and a-C:H:O) were compared with an ultrathin titanium oxide layer (as recently investigated) regarding electrical properties and silver release. Ag release measurements demonstrated that an efficient control over the release properties (initial burst and long-term release) was achieved depending on the hydrophobicity and thickness of the plasma polymer films. •Functional plasma polymer films are deposited on silver-metallized fibers to control release properties in aqueous environments•Silver ion release can be effectively diminished depending on the distribution of Ag, the plasma polymer layer thickness and its hydrophobicity•Initial burst release conditions are avoided while contact resistance is maintained