Hydrogels have diverse chemical properties and can exhibit reversibly large mechanical deformations in response to external stimuli; these characteristics suggest that hydrogels are promising materials for soft robots. However, reported actuators based on hydrogels generally suffer from slow response speed and/or poor controllability due to intrinsic material limitations and electrode fabrication technologies. Here, we report a hydrogel actuator that operates at low voltages (<3 volts) with high performance (strain > 50%, energy density > 7 × 10 5 joules per cubic meter, and power density > 3 × 10 4 watts per cubic meter), surpassing existing hydrogel actuators and other types of electroactive soft actuators. The enhanced performance of our actuator is due to the formation of wrinkled nanomembrane electrodes that exhibit high conductivity and excellent mechanical deformation through capillary-assisted assembly of metal nanoparticles and deswelling-induced wrinkled structures. By applying an electric potential through the wrinkled nanomembrane electrodes that sandwich the hydrogel, we were able to trigger a reversible and substantial electroosmotic water flow inside a hydrogel film, which drove the controlled swelling of the hydrogel. The high energy efficiency and power density of our wrinkled nanomembrane electrode–induced actuator enabled the fabrication of an untethered insect-scale aquabot integrated with an on-board control unit demonstrating maneuverability with fast locomotion speed (1.02 body length per second), which occupies only 2% of the total mass of the robot.

中文翻译：

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基于褶皱纳米膜电极的高性能电气化水凝胶致动器，用于不受束缚的昆虫级软水上机器人

水凝胶具有多种化学性质，可以响应外部刺激而表现出可逆的大机械变形；这些特性表明水凝胶是用于软机器人的有前途的材料。然而，由于固有的材料限制和电极制造技术，基于水凝胶的致动器通常存在响应速度慢和/或可控性差的问题。在这里，我们报告了一种水凝胶致动器，它在低电压（<3 伏）下运行，具有高性能（应变 > 50%，能量密度 > 7 × 105焦耳每立方米，功率密度 > 3 × 104瓦特每立方米），超过了现有的水凝胶致动器和其他类型的电活性软致动器。我们的致动器性能增强是由于形成了褶皱纳米膜电极，该电极通过金属纳米粒子的毛细管辅助组装和消胀诱导的褶皱结构表现出高导电性和出色的机械变形。通过夹在水凝胶中间的褶皱纳米膜电极施加电位，我们能够在水凝胶膜内触发可逆且大量的电渗水流，从而驱动水凝胶的受控膨胀。