Hydraulically amplified self-healing electrostatic actuators with muscle-like performance

Abstract

Existing soft actuators have persistent challenges that restrain the potential of soft robotics, highlighting a need for soft transducers that are powerful, high-speed, efficient, and robust. We describe a class of soft actuators, termed hydraulically amplified self-healing electrostatic (HASEL) actuators, which harness a mechanism that couples electrostatic and hydraulic forces to achieve a variety of actuation modes. We introduce prototypical designs of HASEL actuators and demonstrate their robust, muscle-like performance as well as their ability to repeatedly self-heal after dielectric breakdown-all using widely available materials and common fabrication techniques. A soft gripper handling delicate objects and a self-sensing artificial muscle powering a robotic arm illustrate the wide potential of HASEL actuators for next-generation soft robotic devices.

An Easy‐to‐Implement Toolkit to Create Versatile and High‐Performance HASEL Actuators for Untethered Soft Robots

“…[52] While the power supply developed in this work was shown to effectively drive untethered modular units of HASEL actuators through a user input, a closed-loop controller is necessary for autonomous operation of these devices. [23,24,53] Additionally, the use of high-voltage power supplies, switches, and soft logic developed for DEAs [54][55][56] could enable further miniaturization of the driving electronics for integrated actuation, sensing, and control of arrays of modular HASELs. [23,24,53] Additionally, the use of high-voltage power supplies, switches, and soft logic developed for DEAs [54][55][56] could enable further miniaturization of the driving electronics for integrated actuation, sensing, and control of arrays of modular HASELs.…”

“…[30][31][32] Here, we repurposed an inexpensive 3D printer into a three-axis CNC heat sealing machine (Figure 2a) and used it to thermally bond sheets of biaxially oriented polypropylene (BOPP). In this work, we used ionically conductive polyacrylamide (PAM) hydrogels to enable transparent designs of HASELs [23,24] (Figure S1, Supporting Information), as well as off-the-shelf and inexpensive carbon-based conductive paint that was easily applied with a paint brush. A biodegradable vegetable-based transformer oil (Envirotemp FR3, Cargill) was chosen as the liquid dielectric because of its favorable dielectric properties, nontoxicity, and low viscosity.…”

“…The experimental setup is shown in Figure S7 (Supporting Information) and was similar to the technique used by Acome et al [23] The results are summarized in Figure S8 (Supporting Information), which show the efficiency of the actuators as a function of the number of actuators within a stack. The experimental setup is shown in Figure S7 (Supporting Information) and was similar to the technique used by Acome et al [23] The results are summarized in Figure S8 (Supporting Information), which show the efficiency of the actuators as a function of the number of actuators within a stack.…”

“…HASEL actuators use electric fields to locally displace liquid dielectrics enclosed in soft hydraulic architectures, which mitigates losses in speed and efficiency associated with transporting fluid through a system of channels (typically seen in soft fluidic actuators). [24] While initial prototypes of HASELs [23,24] provided muscle-mimetic actuation characteristics, achieving such performance required very high voltages (HVs) (≈20 kV), which severely restricted the options for commercially available miniature high-voltage amplifiers for portable driving electronics. [23] Importantly, the electrohydraulic driving mechanism of HASEL actuators is compatible with a wide range of stretchable and also flexible yet inextensible materials that are not available to DEAs (particularly for electrodes); HASELs have been built using compliant ionic conductors but also flexible metallized layers as electrodes.…”

Bioinspired Soft Robotic Caterpillar with Cardiomyocyte Drivers

“…[1][2][3][4][5][6][7][8][9] With their shape-morphing features, soft robots are more behavioral flexible and adaptable to execute specific tasks. [1][2][3][4][5][6][7][8][9] With their shape-morphing features, soft robots are more behavioral flexible and adaptable to execute specific tasks.…”