Author ORCID Identifier

https://orcid.org/0000-0003-1191-5321

Semester

Spring

Date of Graduation

2025

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

Konstantinos A. Sierros

Committee Co-Chair

Jennifer M. Jones

Committee Member

Jennifer M. Jones

Committee Member

Edward M. Sabolsky

Abstract

Highly stretchable strain sensors are essential components in soft electronics, enabling integration of sensing and signal transmission into deformable systems. This thesis explores the fabrication and characterization of coaxial core–shell fibers composed of a conductive carbon grease core and an elastomeric silicone shell. These fibers were produced using coaxial direct ink writing (DIW), a versatile additive manufacturing technique that allows continuous deposition of multi-material filaments. The goal was to achieve mechanically compliant yet electrically stable fibers capable of withstanding large deformations, suitable for applications in wearable electronics and soft robotics.
The printed fibers were systematically examined through mechanical tensile testing, cyclic loading, and electromechanical measurements to understand their deformation behavior and conductivity response under strain. Cross-sectional imaging was used to evaluate the structural integrity of the core–shell geometry, and potential failure mechanisms were investigated. Emphasis was placed on analyzing the interplay between material properties, printing architecture, and interface dynamics in determining overall performance. To enable coaxial printing, custom coaxial nozzles were designed and fabricated, allowing for stable co-flow of the inks and consistent formation of the core-shell structure.
This work demonstrates that coaxial DIW is a viable method for producing stretchable, fiber shaped strain sensors with tailored mechanical and electrical properties. The findings contribute to a growing body of research on soft, deformable materials and offer practical insights for engineering robust and reliable components for future soft electronic and sensing systems.

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