Author ORCID Identifier

https://orcid.org/0000-0001-7607-2009

Semester

Spring

Date of Graduation

2026

Document Type

Dissertation

Degree Type

PhD

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

Edward M. Sabolsky

Committee Member

Xueyan Song

Committee Member

Oishi Sanyal

Committee Member

Terence Musho

Committee Member

Konstantinos A. Sierr

Abstract

The advancement of soft robotics requires materials and manufacturing methods that combine large deformation, structural stability, and integrated sensing within a single soft system. Conventional fabrication techniques often limit design flexibility and the incorporation of functional materials into soft structures. This dissertation addresses these challenges through the development of UV-curable and dual-curable silicone elastomers for the direct ink writing (DIW) of soft robotic actuators and embedded sensors.

UV-curable elastomers were first synthesized through thiol-ene click chemistry using poly(mercaptopropylmethylsiloxane) (MMPS) and vinyl-terminated polysiloxane (VPS). Their curing behavior, rheological response, printability, and mechanical properties were evaluated for DIW. These materials enabled rapid in situ curing during printing and provided flexible matrices for soft robotic and flexible electronic applications. However, high conductive filler loading reduced UV curing efficiency through light absorption and scattering, limiting the use of UV-only systems for multifunctional soft devices.

To overcome this limitation, dual-curable elastomers were developed by combining the UV-curable thiol-ene network with thermally curable silicone systems, including Ecoflex50, XP-727, and XP-830. This approach enabled sequential UV and thermal curing, promoting the formation of interpenetrating polymer networks (IPNs) and improving curing completeness, as well as compatibility with conductive fillers. The resulting materials were characterized using FT-IR, NMR, DMA, TGA, and nanoindentation, confirming tunable rheological, thermal, and mechanical properties for additive manufacturing.

Conductive dual-curable inks containing silver particles with different morphologies and loadings were formulated for embedded sensing applications. To improve the flexibility of the conductive traces, an additional thermally curable silicone system based on amino- and carboxyl-functional PDMS was used for the sensor lines. These materials were processed using a custom DIW platform based on a modified Ender 3 V2 printer equipped with syringe extrusion and an in-situ UV-curing system. Soft pneumatic hinges with embedded serpentine strain sensors were fabricated and evaluated using pneumatic actuation, synchronized pressure control, electrical resistance measurements, and digital image correlation (DIC). The results demonstrated clear coupling among applied pressure, hinge deformation, and sensor response, while also showing that curing conditions influenced flexibility and mechanical durability.

Overall, this work establishes a materials and manufacturing framework for the additive fabrication of multifunctional soft robotic structures with integrated sensing capability. The combined development of UV-curable elastomers, dual-curable networks, conductive composites, and custom DIW processing provides a practical route toward next-generation soft robotic and flexible electronic systems.

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