This paper presents a soft actuator embedded with two types of eutectic alloys which enable sensing, tunable mechanical degrees of freedom (DOF), and variable stiffness properties. To modulate the stiffness of the actuator, we embedded a low melting point alloy (LMPA) in the bottom portion of the soft actuator. Different sections of the LMPA could be selectively melted by the Ni-Cr wires twined underneath. To acquire the curvature information, EGaIn (eutectic gallium indium) was infused into a microchannel surrounding the chambers of the soft actuator. Systematic experiments were performed to characterize the stiffness, tunable DOF, and sensing the bending curvature. We found that the average bending force and elasticity modulus could be increased about 35 and 4000 times, respectively, with the LMPA in a solid state. The entire LMPA could be melted from a solid to a liquid state within 12 s. In particular, up to six different motion patterns could be achieved under each pneumatic pressure of the soft actuator. Furthermore, the kinematics of the actuator under different motion patterns could be obtained by a mathematical model whose input was provided by the EGaIn sensor. For demonstration purposes, a two-fingered gripper was fabricated to grasp various objects by adjusting the DOF and mechanical stiffness.

Many real-world applications for robots—such as long-term aerial and underwater observation, cross-medium operations, and marine life surveys—require robots with the ability to move between the air-water boundary. Here, we describe an aerial-aquatic hitchhiking robot that is self-contained for flying, swimming, and attaching to surfaces in both air and water and that can seamlessly move between the two. We describe this robot’s redundant, hydrostatically enhanced hitchhiking device, inspired by the morphology of a remora ( Echeneis naucrates ) disc, which works in both air and water. As with the biological remora disc, this device has separate lamellar compartments for redundant sealing, which enables the robot to achieve adhesion and hitchhike with only partial disc attachment. The self-contained, rotor-based aerial-aquatic robot, which has passively morphing propellers that unfold in the air and fold underwater, can cross the air-water boundary in 0.35 second. The robot can perform rapid attachment and detachment on challenging surfaces both in air and under water, including curved, rough, incomplete, and biofouling surfaces, and achieve long-duration adhesion with minimal oscillation. We also show that the robot can attach to and hitchhike on moving surfaces. In field tests, we show that the robot can record video in both media and move objects across the air/water boundary in a mountain stream and the ocean. We envision that this study can pave the way for future robots with autonomous biological detection, monitoring, and tracking capabilities in a wide variety of aerial-aquatic environments.

Soft robotics aims at creating systems with improved performance of movement and adaptability in unknown, challenging, environments and with higher level of safety during interactions with humans. This Roadmap on Soft Robotics covers selected aspects for the design of soft robots significantly linked to the area of multifunctional materials, as these are considered a fundamental component in the design of soft robots for an improvement of their peculiar abilities, such as morphing, adaptivity and growth. The roadmap includes different approaches for components and systems design, bioinspired materials, methodologies for building soft robots, strategies for the implementation and control of their functionalities and behaviour, and examples of soft-bodied systems showing abilities across different environments. For each covered topic, the author(s) describe the current status and research directions, current and future challenges, and perspective advances in science and technology to meet the challenges.

No abstract

No abstract