Development of a technical approach to modify the internal surface of biomedical tubes and other elongated small lumen macrodevices with parylene coating

Abstract

A multitude of differently composed biomedical polymers has been researched for many years for their distinctive ease of production and wide range of applications. New technologies and new material characteristics have always evolved accordingly. The lumina of biomedical polymer tubes such as catheters, intravenous tubes, and biomedical microfluidic channels do not necessarily show the required biocompatibility and desired functionality. In such cases, the products are provided with additional inner liner or coatings to achieve the desired specific properties. Specific adjustments, for example, low friction coefficient, low gas diffusion resistance, wear resistance, and hydrophobicity, are key properties which are in focus for the improvement of biomedical surfaces. In this pilot study, a technical method was developed to deposit parylene-AF4 on the inner surface of silicone tubes with aspect ratios exceeding 78:1. Uncoated and parylene-AF4-coated silicone tubes were investigated in respect to the aforementioned physical properties. Compared to the uncoated tubes, the parylene-coated tubes showed superior quality with respect to friction coefficient, gas diffusivity as well as wear resistance. It could be demonstrated that the new technical approach is suitable to parylene-coat the inner surfaces of tubes with high aspect ratios thereby achieving conformal coatings.