ABSTRACT
High-performance multilayer dielectric elastomer actuators (DEAs) are well-positioned to overcome the insufficient output force and energy density as artificial muscles. However, due to the fabrication process, the multilayer DEAs with nonmodifiable structures often suffer from the limitation of short lifespans and scalable preparation. Herein, reusable multilayer DEAs with the detachable and reconfigurable structure are fabricated. This is achieved by realizing scalable compliant electrodes using the continuous spatial confining forced network assembly (CSNA) method and combining the vacuum lamination (VL) approach to have good attachability and detachability with the VHB dielectric elastomer. The flexible roller-based CSNA method is used to prepare the large area compliant electrodes composed of α, ω-dihydroxy polydimethylsiloxane and electrically conductive nanoparticles. The fabricated electrodes can continuously work over 10 000 cycles at 40% strained stretching and maintain smooth surfaces to construct multilayer DEAs. Moreover, owing to the detachable configuration of the DEAs, the electrodes can also be recovered and reused for building new actuators. The lower limb assistive device is demonstrated by detachable multilayer spring roll DEAs, achieving approximately 3.1 degrees of flexion and extension movement of knee models under a voltage of 7 kV. The detachable and reconfigurable multilayer DEAs shed new light on the applications of wearable assistive devices.
ABSTRACT
With the application of biomimetic shark skin microstructures with hydrophobicity in microfluidics, sensors and self-cleaning materials, microstructure processing methods are increasing. The preparation process has higher requirements for processing cost and efficiency. In this paper, linear low-density polyethylene (LLDPE) hydrophobic films were prepared with the help of melt fracture phenomenon. The equipment is a self-made single screw extruder. By adjusting the process parameters, the biomimetic shark skin structured LLDPE films with good hydrophobic property can be obtained. The surface microstructure shape of the product is related to kinds of additive, die temperature and screw speed. When AC5 was selected as an additive, the optimal processing parameter was found to be 160 °C die temperature and 80 r/min screw speed. A contact angle of 133° was obtained in this situation. In addition, the influences of die temperature and screw speed on the size of shark skin structure were also systematically investigated in this paper. It was found that the microstructure surface with hierarchical roughness had a better hydrophobic property.
