Planar electrohydraulic HASEL (hydraulically amplified, self-healing, electrostatic) actuators are soft actuators which display large linear strains and actuation stresses, as well as high specific energies and specific powers. We use the energy minimization approach to derive a nonlinear quasistatic model to describe the actuation behavior of planar HASEL actuators. In the model, we consider the large strains in the shell due to the Maxwell stress, large deflections of the actuator from the electrostatic zipping, and the hydraulic coupling due to the liquid. We apply the model to both linear planar and circular planar HASEL actuators and compare the results with experimental data
Recently developed hydraulically amplified self-healing electrostatic (HASEL) actuators can utilize diverse material systems to create high-performance, muscle-mimetic actuators that can be tailored to specific applications. Initial versions of HASEL required cumbersome high voltage driving electronics and utilized a manual fabrication technique which was not easily adjusted to iterate designs. This presentation will describe a versatile and accessible fabrication technique using a computer numerically controlled (CNC) heat sealing machine to rapidly prototype complex designs of HASEL actuators. With this simple fabrication technique, we can create high performance HASELs which offer a variety of actuation modes. These actuators harness electrostatic zipping mechanisms to reduce operating voltages and facilitate a smooth actuation response to input voltage. Moreover, these HASELs feature linear strains over 100%, specific power of 816 W/kg, and cut-off frequencies of 125 Hz; these metrics enable actuators which are fast and powerful enough to jump. Using these devices, we create a continuum actuator capable of three-dimensional articulation and an active surface with programmable morphology. Additionally, we develop a portable electronics package for untethered operation of these soft robotic devices. This presentation will highlight the diverse design freedom inherent to HASEL actuators in terms of material selection and actuator design.
Soft robotics research has been motivated in part by the versatility and functionality of human muscle. Researchers have tried to mimic the speed and performance of human muscle by using soft fluid actuators; however, these actuators are often slow and bulky. Research conducted in the use of dielectric elastomers has proven to be promising. These dielectric elastomers can produce large strains using high voltage electrical input. However, the development of these dielectric elastomer actuators has been inhibited due to their susceptibility to dielectric breakdown and electrical aging. One recent technology that can solve these issues and advance the field of soft actuators, is that of the hydraulically amplified self-healing electrostatic (HASEL) actuator. Such actuators are comprised of a liquid dielectric enclosed in an elastomer shell with electrodes on either side of the shell. Incorporating a liquid dielectric dramatically reduces the impact of dielectric breakdown on the performance of HASEL actuators and allows for hydraulically-coupled modes of actuation. However, the voltages that are required to operate these actuators are still challenging for commercial applications. Our work uses a simulation-driven approach to determine design parameters for donut HASEL actuators that provide a high actuation strain at a reduced pull-in voltage. We outline a modeling approach that is comprised of calibrating the properties of a multiphysics finite element model using actual HASEL actuator experimental data. The model is validated using a donut-shape HASEL actuator from literature. The model is then applied to determine the optimal electrode size and fluid dielectric permittivity for achieving a low operating voltage. This simulation-driven design assists in the fabrication of soft actuators with potential application to a variety of industries.
The SEMATECH High-NA Actinic Reticle review Project (SHARP) is a synchrotron-based, EUV-wavelength microscope, dedicated to photomask imaging, now being commissioned at Lawrence Berkeley National Laboratory. In terms of throughput, resolution, coherence control, stability and ease of use, SHARP represents a significant advance over its predecessor, the SEMATECH Berkeley Actinic Inspection Tool (AIT), which was decommissioned in September 2012. SHARP utilizes several advanced technologies to achieve its design goals: including the first Fouriersynthesis illuminator on a zoneplate microscope, EUV MEMS mirrors, and high-efficiency freestanding zoneplate lenses
with numerical aperture values up to 0.625 (4×). In its first week of operation, SHARP demonstrated approximately 150 times higher light throughput than AIT and a spatial resolution down to 55-nm half-pitch with 0.42 4×NA (i.e. the smallest feature size on our test mask.) This paper describes the current status of the tool commissioning and the performance metrics available at this early stage.
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