A great number of butterfly species in the warmer climate have evolved to exhibit fascinating optical properties on their wing scale which can both regulate the wing temperature and exhibit...

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Electroactive hydrogels that exhibit large deformation in response to an electric field have received significant attention as a potential actuating material for soft actuators and artificial muscle. However, their mechanical actuation has been limited in simple bending or folding due to uniform electric field modulation. To implement complex movements, a pre-program, such as a hinge and a multilayer pattern, is usually required for the actuator in advance. Here, we propose a reprogrammable actuating method and sophisticated manipulation by using multipolar three-dimensional electric field modulation without pre-program. Through the multipolar spatial electric field modulator, which controls the polarity/intensity of the electric field in three-dimensions, complex three-dimensional (3D) actuation of single hydrogels are achieved. Also, air bubbles generated during operation in the conventional horizontal configuration are not an issue in the proposed new vertical configuration. We demonstrate soft robotic actuators, including basic bending mechanics in terms of controllability and reliability, and several 3D shapes having positive and negative curvature can easily be achieved in a single sheet, paving the way for continuously reconfigurable materials.Shape transformations are driven by inhomogeneous in-plane deformation of thin elastic sheets provide one of the efficient ways to reconfigurable three-dimensional (3D) structures 1-4 . Thus far, most previous results have focused on sheets that can access only a single trajectory from flat to a programmed shape, which pre-defined on the material 5-9 . Integrating a responsive material 10 or geometric structure design 11 that can be driven independently by two or more stimuli gives access to many pre-programmed shapes, but the difficulty of making and controlling these pattern sheets increases rapidly with the number of orthogonal controllable elements. Alternatively, re-writable hydrogels 12,13 or shape memory polymers [14][15][16] or liquid crystalline polymers 17,18 have been demonstrated to form several shapes from a single sheet. However, these approaches need many times for re-defining patterns. Electroactive materials are of great interest in this respect, as they should allow for continuous reprogramming into an arbitrary number of shapes defined by polarity and intensity of the applied electric field 11,19 . Especially, hydrogel-based actuators can be exchanged chemical components or energy for aqueous mediums and operate by the reaction of gel network response [20][21][22] . Also, the hydrogel network can be pre-patterned for directional operation in response to the environment. Stimulating the movement of the hydrogel using the external electric field is appealing because of reliable control of signal strength and direction. This stimulus requires only ions in the external solution to induce operation. An electric field applied to a polyelectrolyte network locked in an electrolyte solution causes an asymmetrical dispersion of the ions, creating an osmotic ...

Recently, laser scanners have been used for laser processing such as cutting, welding, and grooving, especially in the automotive industry. The laser scanners need a high-speed driving to minimize cracks caused by thermal shock of brittle materials. Therefore, a novel laser processing system that is composed of a laser source and a piezoelectric-driven tilt mirror to control the reflection angle of the laser beam, and a stage equipped with the tilt mirror has been investigated. In this study, a piezoelectric-driven tilt mirror is designed and analyzed for scanning performance to achieve a beam spot of 30 µm, a pattern width of 1 mm, an overlap ratio of 70% of the circle area, and a scanning speed of 1 m/s. Then, structural analysis of the tilt mirror with three piezoelectric actuators is performed to determine the maximum reflection angle and resonance frequency. Finally, a prototype tilt mirror is fabricated and its basic characteristics are experimentally investigated and discussed.

As silver nanowires (Ag NWs) are usually manufactured by chemical synthesis, a patterning process is needed to use them as functional devices. Pulsed laser ablation is a promising Ag NW patterning process because it is a simple and inexpensive procedure. However, this process has a disadvantage in that target materials are wasted owing to the subtractive nature of the process involving the removal of unnecessary materials, and large quantities of raw materials are required. In this study, we report a minimum-waste laser patterning process utilizing silver nanoparticle (Ag NP) debris obtained through laser ablation of Ag NWs in liquid media. Since the generated Ag NPs can be used for several applications, wastage of Ag NWs, which is inevitable in conventional laser patterning processes, is dramatically reduced. In addition, electrophoretic deposition of the recycled Ag NPs onto non-ablated Ag NWs allows easy fabrication of junction-enhanced Ag NWs from the deposited Ag NPs. The unique advantage of this method lies in using recycled Ag NPs as building materials, eliminating the additional cost of junction welding Ag NWs. These fabricated Ag NW substrates could be utilized as transparent heaters and stretchable TCEs, thereby validating the effectiveness of the proposed process.