Rapid 3D Printing of Electrohydraulic (HASEL) Tentacle Actuators

Abstract

A comprehensive material system is introduced for the additive manufacturing of electrohydraulic (HASEL) tentacle actuators. This material system consists of a photo-curable, elastomeric silicone-urethane with relatively strong dielectric properties (ε r ≈ 8.8 at 1 kHz) in combination with ionically-conductive hydrogel and silver paint electrodes that displace a vegetable-based liquid dielectric under the application of an electric field. The electronic properties of the silicone material as well as the mechanical properties of the constitutive silicone and hydrogel materials are investigated. The hydraulic pressure exerted on the dielectric working fluid in these capacitive actuators is measured in order to characterize their quasi-static behavior. Various design features enabled by 3D printing influence this behavior-decreasing the voltage at which actuation begins or increasing the force density in the system. Using a capacitance change of >35% across the actuators while powered, a demonstration of self-sensing inherent to HASELs is shown. Antagonistic pairs of the 3D printed actuators are shown to exert a blocked force of over 400 mN. An electrohydraulic tentacle actuator is then fabricated to demonstrate the use of this material and actuation system in a synthetic hydrostat. This tentacle actuator is shown to achieve motion in a multi-dimensional space.

Printing Reconfigurable Bundles of Dielectric Elastomer Fibers

“…By contrast, 3D printing of DEAs has recently been used to create 3D DEAs in the form of high-aspect ratio, interdigitated architectures. [29,[33][34][35][36][37] Unlike light-based 3D printing, [37] direct ink writing enables complex architectures to be patterned from single [38] and multiple materials [39][40] via extrusion of viscoelastic inks through nozzle-based printheads. network plays a dominant role in its viscoelastic response and subsequent mechanical losses that arise due to breaking and reforming the particle network.…”

“…By contrast, 3D printing of DEAs has recently been used to create 3D DEAs in the form of high‐aspect ratio, interdigitated architectures. [ 29,33–37 ] Unlike light‐based 3D printing, [ 37 ] direct ink writing enables complex architectures to be patterned from single [ 38 ] and multiple materials [ 39–40 ] via extrusion of viscoelastic inks through nozzle‐based printheads.…”

3D Printing of High Viscosity Reinforced Silicone Elastomers

“…Soft, elastomeric ‘rubbery’ materials are polymers with low elastic moduli and high deformation capability, which make them ideal candidates for various applications, including shock absorption, cushions, seals and gaskets, tires, tubes, and belts. Elastomeric feedstocks are actively being developed for additive manufacturing (AM) [ 1 ] and are being applied to soft robotics [ 2 ], metamaterials [ 3 ], auxetic materials [ 4 ], and prosthetics [ 5 ]. Despite tremendous progress over the past 15–20 years, only a subset of traditionally available materials is 3D-printable, and AM-feedstock development remains a considerable challenge.…”

“…Moreover, in comparison to DIW technologies, SLA enables the design and build of more complex structures, including architectures with unsupported overhangs. Recently, several groups have reported on the SLA of silicones [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ] and/or related polysiloxane-containing materials [ 2 ], using predominately acrylate [ 23 , 24 , 25 , 27 ] and/or thiol-ene [ 17 , 18 , 19 , 20 , 21 , 22 , 26 ] crosslinking as workhorse chemistries. Notably, however, many reported SLA silicone formulations have lacked the addition of reinforcing filler.…”

High‐Output Force Electrohydraulic Actuator Powered by Induced Interfacial Charges

“…In this context, recent work in which 3D printing was used as a fabrication method for an electrohydraulic actuator presents a good example, where a soft material (silicone‐urethane elastomer ≈1 MPa) was used as a substrate. [ 48 ]…”