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.

Self-healing materials can repair damage caused by mechanical wear, thereby extending lifetime of devices. A transparent, self-healing, highly stretchable ionic conductor is presented that autonomously heals after experiencing severe mechanical damage. The design of this self-healing polymer uses ion-dipole interactions as the dynamic motif. The unique properties of this material when used to electrically activate transparent artificial muscles are demonstrated.

The flash phenomenon occurs when oxide ceramics are heated above a threshold temperature under an applied electric field. It is defined as an abrupt increase in the conductivity of the specimen. The specimen then can be held in this state of high conductivity by switching the power supply from voltage to current control. Here, we report on the emergence of new X-ray diffraction peaks in 3 mol% yttria-stabilized zirconia (3YSZ) when the specimen is held in this current controlled state. These peaks are indexed as a pseudocubic phase of zirconia. The peaks extinguish and reappear when the field is turned off and on. The specimen temperature in the flash state is measured from the thermal expansion of platinum, which is placed as a thin film on a small portion of the specimen surface. Experiments without the electric field, at even higher temperatures than those measured with the platinum standard, do not show any change of phase, thus ruling out Joule heating as the cause of this phenomenon. The time dependency of the growth and dissolution of the pseudo cubic phase is reported. These in situ experiments were carried out at the Advanced Photon

The use of magnesium oxide (MgO) as a filler in an epoxy molding compound (EMC) was considered to identify the maximum thermal conductivity that could be achieved without compromising rheological or processing control and processing flexibility. MgO is an attractive candidate filler for EMCs used in automotive and other applications because MgO is inexpensive, electrically insulative, has relatively high thermal conductivity, is nontoxic, and is a relatively soft filler material meaning it will be less abrasive to surfaces it contacts during its processing and shape molding. A maximum bulk thermal conductivity of 3 W/mK was achieved with a 56% volume fraction of MgO filler. This 56 vol% MgO-filled EMC has a thermal conductivity approximately twice that of traditional silica-filled EMCs with the same volume fraction of filler and has equivalent electrical insulative, thermal expansion, and water absorption characteristics. It is concluded that if a thermal conductivity greater than 3 W/mK is needed in an EMC, then a much more expensive filler material than MgO must be used.Index Terms-Epoxy molding compound (EMC), fillers, magnesium oxide (MgO), original equipment manufacturer, thermal conductivity, thermal management.

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