Abstract

Endovascular procedures require devices with widely varying mechanical properties: flexibility for navigating tortuous vessels and rigidity for stable therapeutic delivery. Suction-actuated variable stiffness sheaths address this challenge by incorporating axial wire string arrays that mechanically couple under suction to increase flexural rigidity. However, prototype devices achieve stiffening ratios below theoretical predictions, suggesting that interlayer mechanics and string positioning play a critical role. This study investigates whether interweaving polytetrafluoroethylene (PTFE) tape within the string array enhances flexural rigidity modulation and curvature stability. Prototype devices with varying wrap configurations were fabricated and evaluated using flexural testing, curvature stability testing, and mathematical modeling. Results indicate that while small-deformation rigidity is largely unaffected by wrapping, curvature stability is governed by slip and buckling mechanisms. A model reveals stability limits as functions of wrapping architecture and mechanical properties. These findings establish design principles for intra-catheter wrapping and help bridge the gap between theoretical and observed stiffening performance, contributing to improved endovascular device design.

Committee Chair

Guy Genin

Committee Members

Michelle Connor, Jeff Krampf, Jackson Potter

Degree

Master of Science (MS)

Author's Department

Mechanical Engineering & Materials Science

Author's School

McKelvey School of Engineering

Document Type

Thesis

Date of Award

Spring 5-2026

Language

English (en)

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