Session: IMECE Undergraduate Research and Design Exposition

Paper Number: 114124

114124 - The Effect of Heat Treatment on Physical and Mechanical Properties of Pcl Flow Diverters 

Flow diverters (FDs) have emerged as one of the major and promising endovascular treatments of brain aneurysms. Currently, flow diverters are braided from metallic microwires and stay forever in the body of the patient even after full recovery from aneurysms. Metallic FDs are susceptible to distortion and micromovements and cause low-grade inflammation, late thrombosis, restenosis, and other clinical complications. Recently our group proposed non-braided and fully resorbable FDs as a safer alternative based on Polycaprolactone (PCL). This paper presents the impact of heat treatment on the physical and mechanical properties of PCL FDs. The non-braided PCL FDs with 50%, 60%, and 70% porosities were fabricated from our custom, patent-pending fabrication unit. The thermal treatment setup was developed using a temperature-regulated hotplate, a 1000 mL Erlenmeyer flask, DI water, and temperature sensors. The PCL FDs were dipped into the water in the flask by holding upright through a stand. The water bath was heated to three different temperatures of 50°C ± 1.0ºC, 55°C ± 1.0ºC and 60°C ± 1.0ºC and the FDs were put for 30s, 60s and 90s. The strut thickness, porosities, pore sizes, and shapes were measured using scanning electron microscope (SEM) images and ImageJ software before and after treatment and compared. A macro script was developed to automate the quantification of porosities, pore sizes, and pore densities. The surface quality was evaluated using a 3D profilometer. The radial compression, longitudinal strength, and bending flexibility were measured using the Univert biomaterial testing machine before and after the treatment. The results showed that at 60°C the physical properties i.e., pore sizes, pore shapes, and porosities, were significantly altered. Pore shapes became oval, and the porosities and pore sizes decreased by about 10%. Struts became flatter and completely fused. However, at 50°C, no visual changes in pore sizes and shapes were observed. At 55°C and 30s treatment, no or minimal physical change in FD properties was observed. However, for a longer treatment time at 55°C, strut thickness, pore shape, sizes, and porosity changes were observed but less pronounced than those of the 66°C treatment. No significant differences in surface quality and roughness on the PCL FDs were found regardless of the heat treatment temperature and time. Pore sizes and porosities were reduced by 4%. The overall longitudinal and radial compression strength were increased due to the heat treatment. The heat treatment caused better fusion among the struts. However, heat treatment at 55°C showed optimum results for both longitudinal and radial strength. This study could help to find the optimum heat treatment scheme for developing clinically relevant and feasible PCL FDs.

Presenting Author: Alex Matsayko University of Central Oklahoma

Presenting Author Biography: Undergraduate mechanical engineering student and research assistant

Authors:

Mohammad Hossan Univ Of Central Oklahoma
Alex Matsayko University of Central Oklahoma