Analysis of Wear Phenomena Produced by Erosion with Abrasive Particles against Fluoropolymeric Coatings

Development and Experimental Study of a Polytetrafluoroethylene-Tipped Microcatheter Poorly Adhesive to n-Butyl-2-Cyanoacrylate

PURPOSE

We have developed a new microcatheter (designated "NSX") with an outer layer of polytetrafluoroethylene (PTFE) at its tip. We compared the adhesion of the new NSX microcatheter and a conventional microcatheter with n-butyl-2-cyanoacrylate (NBCA) in vitro and in swine blood vessels.

MATERIALS AND METHODS

The 3 cm tip of the NSX microcatheter is composed of PTFE, which can be identified by double platinum markers. The tips of the NSX and conventional microcatheters were inserted into a vascular model filled with porcine blood with no flow, and NBCA mixed with lipiodol (1:2) was injected from the microcatheters. Two minutes after the injection of NBCA, the microcatheter was withdrawn and the degree of its adhesion to NBCA was evaluated by measuring the resistance value (N) during catheter removal with a digital force gauge. These measurements were repeated with 20 catheters of each type. Similarly, 5 injections were performed with both the NSX and conventional microcatheters in swine vessels. The degree of adhesion of the catheter and blood vessel was evaluated by 2 radiologists under X-ray fluoroscopy on a 3-point scale: 1, no adhesion; 2, mild adhesion; 3, strong adhesion.

RESULTS

The mean resistance values (N) for the NSX and conventional microcatheters were 0.503±0.186 and 1.051±0.367 (N), respectively (p<0.001). The NSX adhered negligibly to the NBCA and was easily removed, whereas the conventional microcatheter adhered strongly to the NBCA in the blood vessels and was difficult to remove from the swine vessels (p=0.008).

CONCLUSIONS

The new NSX microcatheter with a PTFE tip exhibits poorer adhesion to NBCA than do conventional microcatheters and allows for safer injection of NBCA than conventional microcatheters, without requiring immediate catheter retrieval.

CLINICAL IMPACT

The NSX microcatheter with a PTFE tip adheres less strongly to NBCA than do conventional microcatheters and allows the safe injection of NBCA. The NSX microcatheter has double platinum markers on its tip, which make it easy to distinguish the PTFE-covered region. As the NSX does not adhere firmly to the arterial wall, it is less likely to cause vascular injury during removal of the catheter compared with conventional microcatheters, so there is no need to remove the NSX immediately after injecting NBCA. Even operators unfamiliar with NBCA can use NBCA safely with this new NSX microcatheter without requiring special training or skill.

Performance and Durability of Non-Stick Coatings Applied to Stainless Steel: Subtractive vs. Additive Manufacturing

This study compares subtractive manufacturing (SM) and additive manufacturing (AM) techniques in the production of stainless-steel parts with non-stick coatings. While subtractive manufacturing involves the machining of rolled products, additive manufacturing employs the FFF (fused filament fabrication) technique with metal filament and sintering. The applied non-stick coatings are commercially available and are manually sprayed with a spray gun, followed by a curing process. They are an FEP (fluorinated ethylene propylene)-based coating and a sol-gel ceramic coating. Key properties such as surface roughness, water droplet sliding angle, adhesion to the substrate and wear resistance were examined using abrasive blasting techniques. In the additive manufacturing process, a higher roughness of the samples was detected. In terms of sliding angle, variations were observed in the FEP-based coatings and no variations were observed in the ceramic coatings, with a slight increase for FEP in AM. In terms of adhesion to the substrate, the ceramic coatings applied in the additive process showed a superior behavior to that of subtractive manufacturing. On the other hand, FEP coatings showed comparable results for both techniques. In the wear resistance test, ceramic coatings outperformed FEP coatings for both techniques. In summary, additive manufacturing of non-stick coatings on stainless steel showed remarkable advantages in terms of roughness, adhesion and wear resistance compared to the conventional manufacturing approach. These results are of relevance in fields such as medicine, food industry, chemical industry and marine applications.