Mechanical and Electrical Design for Shape-Morphing Soft Actuators

Abstract

The need for soft, flexible devices capable of large deformations is evident in a variety of areas including soft robotics, haptics, and wearable devices. Although numerous approaches exist for creating these soft devices, considerable interest has surrounded dielectric elastomer actuators (DEAs). DEAs are electrically controlled actuators with quick, reversible deformation. DEAs are often referred to as “artificial muscles” because their energy density and achievable strains are comparable to mammalian muscles. This thesis focuses on advancing DEAs and DEA technology to improve their capabilities and explore further shape-morphing applications. An optically reconfigurable electrode structure is proposed for use in DEAs and other similar soft actuators. As opposed to a traditional parallel plate capacitor electrode structure, two sets of non-overlapping conductive carbon nanotube stripes are connected to sheets of photoconductive zinc oxide in order to create light-responsive actuators. Precise, reconfigurable control over DEA actuation through UV illumination is demonstrated. A variation of this design is explored to create a dynamic surface for object manipulation via electroadhesion, in which UV illumination is used to activate electrode stripes off-centered from a cylinder to produce rotary motion and translation of the cylinder. An entirely soft pump system is fabricated using a shape-morphing DEA design and a soft Tesla valve structure. The system is used to pump air and water, with potential utility in a range of applications including wearable pneumatic and hydraulic actuators. Finally, an array of shape-morphing DEAs is used to create a bioinspired squid fin.