Manta Ray Inspired Soft Robot Fish with Tough Hydrogels as Structural Elements

Abstract

The design of soft robots capable of navigation underwater has received tremendous research interest due to the robots' versatile applications in marine explorations. Inspired by marine animals such as jellyfish, scientists have developed various soft robotic fishes by using elastomers as the major material. However, elastomers have a hydrophobic network without embedded water, which is different from the gel-state body of the prototypes and results in high contrast to the surrounding environment and thus poor acoustic stealth. Here, we demonstrate a manta ray-inspired soft robot fish with tailored swimming motions by using tough and stiff hydrogels as the structural elements, as well as a dielectric elastomer as the actuating unit. The switching between actuated and relaxed states of this unit under wired power leads to the flapping of the pectoral fins and swimming of the gel fish. This robot fish has good stability and swims with a fast speed (∼10 cm/s) in freshwater and seawater over a wide temperature range (4−50 °C). The high water content (i.e., ∼70 wt %) of the robot fish affords good optical and acoustic stealth properties under water. The excellent mechanical properties of the gels also enable easy integration of other functional units/systems with the robot fish. As proof-of-concept examples, a temperature sensing system and a soft gripper are assembled, allowing the robot fish to monitor the local temperature, raise warning signals by lighting, and grab and transport an object on demand. Such a robot fish should find applications in environmental detection and execution tasks under water. This work should also be informative for the design of other soft actuators and robots with tough hydrogels as the building blocks.

Advancements in Prelithiation Technology: Transforming Batteries from Li‐Shortage to Li‐Rich Systems

“…Reproduced with permission. [ 111 ] Copyright 2022, American Chemical Society. c) Schematic illustrations of lithium deposition and fixation process.…”

“…prepared stable Li 2 O 2 ‐based pre‐lithiated reagents (P‐Li 2 O 2 ) utilizing electrospinning techniques, with poly(methyl methacrylate) (PMMA) serving as a protective matrix. [ 111 ] The presence of PMMA not only prevented the reaction of Li 2 O 2 with CO 2 and H 2 O but also facilitated dissolution in the electrolyte, exposing Li 2 O 2 for effective de‐lithiation (Figure 11b). P‐Li 2 O 2 could deliver an initial capacity of up to 1148 mAh g −1 (normalized to the Li 2 O 2 mass) and is stable for 8 h at 40% relative humidity.…”

Gradients of properties increase the morphing and stiffening performance of bioinspired synthetic fin rays

“…Fish fins have inspired numerous synthetic materials and structures, for example, 3D printed resin based segmented composite beams [26], propulsion systems for autonomous underwater vehicles (AUVs) [27][28][29][30], and soft robotic grippers [31][32][33][34]. In addition, fish-like robotic systems based on different types of fish [35][36][37][38] and aquatic-aerial vehicles [39][40][41] have been developed. We have recently designed, fabricated and tested fin ray-like morphing beams with polymethyl methacrylate (PMMA) hemitrichs connected with elastomeric ligaments [42] which duplicated the morphing and stiffening mechanisms of natural rays, and which showed the importance of the fibrillar structure of the core region.…”

A Highly Robust Amphibious Soft Robot with Imperceptibility Based on a Water‐Stable and Self‐Healing Ionic Conductor

“…However, the requirement of environment water makes robots lose onland functionalities. [14][15][16]19] A robust DEAdriven soft robot with underwater and on-land functionalities without complex encapsulation remains undeveloped. Therefore, we started from developing a soft, allenvironment stable ionic electrode material and adopted this material to achieve a robust DEA-driven soft robot capable of functioning both underwater and on-land (Figure 1a).…”