Contact interactions of aorta against PVC catheters

• Adhesion and friction of aorta against catheters has been modelled and validated.
• Assumption of perfectly hemispherical asperity has been removed.
• The presence of a liquid meniscus has been integrated in the theory.
• The model proposed here can be employed to study the adhesion and friction of any pair of materials.

Catheters are common medical devices routinely employed to deliver or drain fluids and medicines. The insertion of such devices generates friction forces that can lead to patient discomfort and tissue damage. In the development of new materials the evaluation of the friction characteristics is a very important step. However, in the development stage only the raw sheet material can be available but not catheters made of it; consequently in vitro test are often carried out.The multi-asperity adhesion model based on the JKR (Johnson, Kendall and Roberts) theory proposed by Prokopovich and Perni. Langmuir. 26 (2010). p. 17028–17036 has been extended taking into consideration that asperities summits are not perfectly hemispherical; therefore, it is now applicable also to ellipsoidal or paraboloidal asperities. The adhesion between aorta tissue and Polyvinyl chloride (PVC) catheters has been modeled considering also the presence of blood as a lubricant as the capillary forces resulting from a liquid film between surfaces have been also implemented.Aorta surface properties, such as asperity heights and radii of curvature, were obtained and used in the calculations. Through the model the adhesion force and real area of contact were calculated; these were used to predict the static friction coefficient in both dry and lubricated case. A good agreement was found between experimental and simulated values of adhesion force and of friction coefficient.