Search

Ionic polymer–metal composites (IPMCs) are a class of ionic actuators considered as potential candidates for future soft electronics that are operable under low voltages (generally <10 V), flexible, lightweight, and can be miniaturized. However, IPMCs can only generate linear bending deformation, but not complex 3D deformation, thus limiting their practical application. Herein, the IPMC actuators with anisotropic stripe microstructures are developed inspired by the botanical systems where microstructural anisotropy of the cell walls can lead to dynamic conformations. The stripe microstructure obtained via one‐way polishing is designed to present a certain angle to the edges of the IPMCs in the longitudinal direction and can be localized. Hence, the IPMCs are subjected to the anisotropic action of the microstructure while bending, yielding a complex 3D deformation. In addition, the large surface area and high ion accessibility area caused by polishing can enhance the actuation performance of IPMCs which is also influenced by the stripe angle, including higher displacement (up to 162%) and larger blocking force (up to 226%). Outstanding electromechanical properties and multimodal deformation model of IPMC actuators with microstructure are demonstrated by applications such as a soft switch, robotic gripper, and imitation of plant organs. This study can open a new vista for making high‐performance actuators and has significant implications for the expansion of the applicability of IPMC actuators. [ABSTRACT FROM AUTHOR]

By changing printing parameters, a serious of hydrogel actuators with high mechanical strength and multiple deformation were successfully prepared through three‐dimensional (3D) printing. Base on the enhancement role of cross‐linking density of hydrogel inks, nanofibrillated cellulose (NFC) was treated as reinforcement phase to realize controllable regulation of rheology characteristics. With the increase of NFC content, stress and strain values of hydrogels increased gradually. Attributed to swelling rate and gel‐sol transition point, hydrogel with 12 mg/mL NFC was treated as 3D printing ink. The 3D printing parameters significantly affected self‐driven deformations. The hydrogel actuators with 0°/90°, 45°/135° and Archimedes chord configurations owned bending, spiral and twist deformations, respectively. The hydrogel actuators with relative larger length‐width ratio exhibited higher spiral degree. The high precise anisotropic swelling property of printed bilayer structure was the self‐driven deformation mechanism of hydrogel actuators. The combination of hydrogels and 3D printing extended the application of intelligent hydrogels. [ABSTRACT FROM AUTHOR]

The poly‐N‐isopropylacrylamide intelligent hydrogel actuators with high mechanical strength and efficient temperature responses were successfully prepared via molding and three‐dimensional (3D) printing. Addition of nanofibrillated cellulose (NFC) effectively improved the crosslinking density and viscosity of hydrogels, enhancing the mechanical strength and 3D printable property. Based on sufficient polymerization on interface, bilayer hydrogel actuator prepared via molding exhibited efficient bending/unbending deformations. Bending degree in poikilothermy temperature ranging from 25°C to 55°C was higher than that in constant temperature of 55°C. Inspired by the rheology regulation of NFC, 3D printing intelligent hydrogel actuators with NFC content of 10 mg/mL were polymerized efficiently by ultraviolet irradiation. Self‐driven deformation characteristics of 3D printed intelligent hydrogels actuators were regulated via printing parameters including angle, width and length ratio and filling rate of the layered network structure model. The prepared hydrogel material system with molding and 3D printing ability provided material candidates for design and preparation of intelligent soft actuator and robot. [ABSTRACT FROM AUTHOR]

A hydrogel material system which was fit for molding and 3D printing was developed to fabricate bilayer hydrogel actuators with controllable temperature and near infrared laser responses. Polymerization on interface boundary of layered structure enhanced the bonding strength of hydrogel actuators. By utilizing anisotropic of microstructure along with thickness direction, bilayer hydrogel actuators fabricated via molding realized intelligent bending/shrinking responses, which guided the preparation of hydrogel ink for 3D printing. In-situ free radical polymerization under vacuum realized the solidification of printed hydrogel actuators with graphene oxide. Based on anisotropic swelling/deswelling behaviors of precise structure fabricated via 3D printing, the printed bilayer hydrogel actuators achieved temperature and near infrared laser responsive deformation. Changes of programmable printing path effectively resulted in corresponding deformation patterns. Combination of advantages of molding and 3D printing can promote the design and fabrication of hydrogel actuators with high mechanical strength, response speed and deformation ability. [ABSTRACT FROM AUTHOR]

Artificial muscle actuator has been devoted to replicate the function of biological muscles, playing an important part of an emerging field at inter-section of bionic, mechanical, and material disciplines. Most of these artificial muscles possess their own unique functionality and irreplaceability, but also have some disadvantages and shortcomings. Among those, phase change type artificial muscles gain particular attentions, owing to the merits of easy processing, convenient controlling, non-toxic and fast-response. Herein, we prepared a silicon/ethanol/(graphene oxide/gold nanoparticles) composite elastic actuator for soft actuation. The functional properties are discussed in terms of microstructure, mechanical properties, thermal imaging and mechanical actuation characteristics, respectively. The added graphene oxide and Au nanoparticles can effectively accelerate the heating rate of material and improve its mechanical properties, thus increasing the vaporization rate of ethanol, which helps to accelerate the deformation rate and enhance the actuation capability. As part of the study, we also tested the performance of composite elastomers containing different concentrations of graphene oxide to identify GO-15 (15 mg of graphene oxide per 7.2 mL of material) flexible actuators as the best composition with a driving force up to 1.68 N. [ABSTRACT FROM AUTHOR]

As promising candidates in the field of artificial muscles, ionic‐polymer–metal composites (IPMCs) still cannot simultaneously provide large deformations and fast responses, which has limited their practical applications. In this study, to overcome this issue, a Nafion‐based IPMC with high‐quality metal electrodes is fabricated via novel isopropanol‐assisted electroless plating. The IPMC exhibits a large tip displacement (35.3 mm, 102.3°) under a low direct‐current driving voltage and ultrafast response (>10 Hz) under an alternating‐current (AC) voltage. Furthermore, the simultaneous integration of a large deformation and fast response can be achieved by the IPMC under a high‐frequency (19 Hz) AC voltage, where the largest bending amplitude is 5.9 mm and the highest bending speed reaches 224.2 mm s−1 (596.2° s−1). Additionally, the lightweight IPMC exhibits a decent load capacity and can lift objects 20 times heavier. The outstanding performances of the Nafion IPMC are demonstrated by mimicking biological motions such as petal opening/closing, tendril coiling/uncoiling, and high‐frequency wing flapping. This study paves the way for the fabrication of lightweight actuators with simultaneous large displacements and fast responses for promising applications in biomedical devices and bioinspired robotics. [ABSTRACT FROM AUTHOR]

• A humidity-driven monolayer film actuator based on agarose are fabricated. • The film actuator can rapidly deform and roll under humidity-driven conditions. • Surface patterning of films can enhance rolling speed and alter the rolling mechanism. • Application potentials in smart bionic devices and soft crawling robots. The widespread availability and easy accessibility of humidity make it essential to explore simple and low-cost methods to prepare structurally and materially efficient humidity-driven actuators with spontaneous and continuous locomotion to facilitate the application of bionic devices, intelligent sensors, and soft robots. Herein, this paper reports a humidity-driven monolayer film actuator. It is self-assembled from agarose (AG) and graphene oxide (GO) modified with polyvinylpyrrolidone (PVP), referred to as PGO, using a simple casting method. The PGO/AG composite film actuator exhibits an ultra-fast humidity response time (124.58° s−1) and recovery time (18.87° s−1), enabling rapid rolling locomotion driven by water evaporation. Notably, the programmable surface patterning of the PGO/AG composite film actuator with graphite results in a shorter single rolling time (0.43 s) and a faster rolling speed (28.73 mm s−1). Based on these advantages, the PGO/AG film actuator can mimic the opening and closing of flowers, mimosas, and fast-crawling robot driven by periodic water vapor (9.9 body length min−1). This finding provides new insights into the design of multifunctional actuators based on humidity-driven films. [ABSTRACT FROM AUTHOR]