Reconfigurable, multi-functional, and robust soft actuators

Date of Award

Spring 1-1-2025

Document Type

Dissertation

Degree Name

Doctor of Engineering (DEng)

Department

Mechanical Engineering & Materials Science (ENAS)

First Advisor

Kramer-Bottiglio, Rebecca

Abstract

Soft robotics is an emerging field that addresses key limitations of traditional rigid robots, offering advantages such as enhanced safety in human-machine interactions, morphability, and adaptive behaviors. Inspired by biological organisms, soft robots rely on artificial muscles -- soft actuators -- to enable flexibility while generating functional mechanical forces. Soft actuation has largely been driven by two main approaches: fluidic actuators, known for their strength and speed, and stimuli-responsive actuators, which offer untethered operation. However, existing designs often lack bulk reconfigurability, multi-functionality, or robust actuation sequences. This means that soft actuators are typically limited to one specific use-case scenario, may not have other useful properties, such as load-bearing properties, or cannot actuate past one sequence. In this dissertation, I explore how granular media, with its ability to transition between critical states and adjust mechanical properties dynamically through shear or jamming, can enhance soft actuators. I present my work on functional, particle-based soft actuators, demonstrating how granular materials can improve performance in soft robotic applications by introducing new functionality using jamming and 3D-printing. My research further refines soft granular actuators to achieve robust and repeatable actuation. Additionally, I investigate how granular phase-changing media can enhance existing soft actuators, introducing load-bearing capabilities and tunable mechanical properties. By embedding Field's metal low-melting-point alloy particles within a liquid crystal elastomer matrix, I achieve variable stiffness properties, increased actuation stress, and electro-responsivity. Ultimately, this dissertation integrates materials with complementary properties to create multi-functional, reconfigurable, and durable soft actuators, paving the way for more adaptable and capable soft robotic systems.

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