Kirigami-Inspired Programmable Soft Magnetoresponsive Actuators with Versatile Morphing Modes

Wireless Flexible Actuator Photoelectric Synergistically Driven for Environment Adaptability Crawling Robots

Wirelessly driven flexible actuators are crucial to the development of flexible robotic crawling. However, great challenges still remain for the crawling of flexible actuators in complex environments. Herein, we reported a wireless flexible actuator synergistically driven by wireless power transmission (WPT) technology and near-infrared (NIR) light, which consists of a poly(dimethylsiloxane)-graphene oxide (PDMS-GO) composite layer, eutectic gallium-indium alloy (EGaIn), a PDMS layer, and a polyimide (PI) layer. By optimizing the parameters of EGaIn and the concentration of the PDMS-GO composite film, the actuator has excellent bending ability and blocking force under different conditions driven by photoelectronic synergy. In addition, we fabricated a flexible crawling robot with high environmental adaptability by adding crawling structures at both ends of the actuator, which causes a discrepancy in friction between the front and rear feet. The flexible crawling robot has high stability, large deformation, and excellent crawling ability for wirelessly crawling on a plane, slope, and plane with different roughnesses. This work provides an idea for the application of wireless robots in complex environments.

Hydrogel Fibers-Based Biointerfacing

The unique 1D structure of fibers offers intriguing attributes, including a high length-to-diameter ratio, miniatured size, light-weight, and flexibility, making them suitable for various biomedical applications, such as health monitoring, disease treatment, and minimally invasive surgeries. However, traditional fiber devices, typically composed of rigid, dry, and non-living materials, are intrinsically different from the soft, wet, and living essence of biological tissues, thereby posing grand challenges for long-term, reliable, and seamless interfacing with biological systems. Hydrogel fibers have recently emerged as a promising candidate, in light of their similarity to biological tissues in mechanical, chemical and biological aspects, as well as distinct fiber geometry. In this review, a comprehensive overview of recent progress in hydrogel fibers-based biointerfacing technology is provided. It thoroughly summarizes the manufacturing strategy and functional design, especially for hydrogel fibers with distinct optical and electron conductive performance, as well as responsiveness to triggers including thermal, magnetic field and ultrasonic wave, etc. Such unique attributes enable various biomedical applications, which are also examined in detail. Future challenges and potential directions, including biosafety, long-term reliability, sterilization, multi-modalities integration and intelligent therapeutic systems, are raised. This review will serve as a valuable resource for further advancement and implementation as next-generation biointerfacing technology.

Magnetic kirigami dome metasheet with high deformability and stiffness for adaptive dynamic shape-shifting and multimodal manipulation

Soft shape-shifting materials offer enhanced adaptability in shape-governed properties and functionalities. However, once morphed, they struggle to reprogram their shapes and simultaneously bear loads for fulfilling multifunctionalities. Here, we report a dynamic spatiotemporal shape-shifting kirigami dome metasheet with high deformability and stiffness that responds rapidly to dynamically changing magnetic fields. The magnetic kirigami dome exhibits over twice higher doming height and 1.5 times larger bending curvature, as well as sevenfold enhanced structural stiffness compared to its continuous counterpart without cuts. The metasheet achieves omnidirectional doming and multimodal translational and rotational wave-like shape-shifting, quickly responding to changing magnetic fields within 2 milliseconds. Using the dynamic shape-shifting and adaptive interactions with objects, we demonstrate its applications in voxelated dynamic displays and remote magnetic multimodal directional and rotary manipulation of nonmagnetic objects without grasping. It shows high-load transportation ability of over 40 times its own weight, as well as versatility in handling objects of different materials (liquid and solid), sizes, shapes, and weights.

Metainterfaces with mechanical, thermal, and active programming properties based on programmable orientation-distributed biometric architectonics

Interfaces between different materials crucially determine the performance of multi-material systems, impacting a wide range of industries. Currently, precisely programming interfaces with distinct properties at different localized interface positions remains a challenge, leading to limited interface adaptability and unpredictable interface failures, thus hindering the development of next-generation materials and engineering systems with highly customizable multiphysical interface performances. Our research introduces programmable "metainterfaces" for the first time, featuring engineerable biometric architectonics that allows for mechanically, thermally, and actively programmed distribution of interfacial effects by its orientation, driven by artificial intelligence. Enabled by metainterfaces, we showcased improved mechanical properties of future composite metamaterials by programming interface resistance customized to the decoupling modes of distinct lattice topologies. Additionally, we demonstrate enhanced and programmable impact mechanics in fish scale assemblies equipped with pre-programmed metainterface sheets. The proposed metainterface also allows for coolant flow programming in thermal management systems, opening new avenues for development of highly customizable thermos-mechanical systems. Additionally, we introduce digitally controlled "metadisks" enabled by metainterfaces as novel solutions for actively programmable interface systems in robotics, offering real-time adaptive and intelligent interfacial mechanics. This research sets the foundation for next-generation multi-material systems with precisely programmed interfacial effects, offering broad applicability in areas such as smart materials, advanced thermal management, and intelligent robotics.

Design and build of small-scale magnetic soft-bodied robots with multimodal locomotion

Small-scale magnetic soft-bodied robots can be designed to operate based on different locomotion modes to navigate and function inside unstructured, confined and varying environments. These soft millirobots may be useful for medical applications where the robots are tasked with moving inside the human body. Here we cover the entire process of developing small-scale magnetic soft-bodied millirobots with multimodal locomotion capability, including robot design, material preparation, robot fabrication, locomotion control and locomotion optimization. We describe in detail the design, fabrication and control of a sheet-shaped soft millirobot with 12 different locomotion modes for traversing different terrains, an ephyra jellyfish-inspired soft millirobot that can manipulate objects in liquids through various swimming modes, a larval zebrafish-inspired soft millirobot that can adjust its body stiffness for efficient propulsion in different swimming speeds and a dual stimuli-responsive sheet-shaped soft millirobot that can switch its locomotion modes automatically by responding to changes in the environmental temperature. The procedure is aimed at users with basic expertise in soft robot development. The procedure requires from a few days to several weeks to complete, depending on the degree of characterization required.

Physics-aware differentiable design of magnetically actuated kirigami for shape morphing

Shape morphing that transforms morphologies in response to stimuli is crucial for future multifunctional systems. While kirigami holds great promise in enhancing shape-morphing, existing designs primarily focus on kinematics and overlook the underlying physics. This study introduces a differentiable inverse design framework that considers the physical interplay between geometry, materials, and stimuli of active kirigami, made by soft material embedded with magnetic particles, to realize target shape-morphing upon magnetic excitation. We achieve this by combining differentiable kinematics and energy models into a constrained optimization, simultaneously designing the cuts and magnetization orientations to ensure kinematic and physical feasibility. Complex kirigami designs are obtained automatically with unparalleled efficiency, which can be remotely controlled to morph into intricate target shapes and even multiple states. The proposed framework can be extended to accommodate various active systems, bridging geometry and physics to push the frontiers in shape-morphing applications, like flexible electronics and minimally invasive surgery.

Kirigami Makes a Soft Magnetic Sheet Crawl

Limbless crawling on land requires breaking symmetry of the friction with the ground and exploiting an actuation mechanism to generate propulsive forces. Here, kirigami cuts are introduced into a soft magnetic sheet that allow to achieve effective crawling of untethered soft robots upon application of a rotating magnetic field. Bidirectional locomotion is achieved under clockwise and counterclockwise rotating magnetic fields with distinct locomotion patterns and crawling speed in forward and backward propulsions. The crawling and deformation profiles of the robot are experimentally characterized and combined with detailed multiphysics numerical simulations to extract locomotion mechanisms in both directions. It is shown that by changing the shape of the cuts and orientation of the magnet the robot can be steered, and if combined with translational motion of the magnet, complex crawling paths are programed. The proposed magnetic kirigami robot offers a simple approach to developing untethered soft robots with programmable motion.

Locally Addressable Energy Efficient Actuation of Magnetic Soft Actuator Array Systems

Advances in magnetoresponsive composites and (electro-)magnetic actuators have led to development of magnetic soft machines (MSMs) as building blocks for small-scale robotic devices. Near-field MSMs offer energy efficiency and compactness by bringing the field source and effectors in close proximity. Current challenges of near-field MSM are limited programmability of effector motion, dimensionality, ability to perform collaborative tasks, and structural flexibility. Herein, a new class of near-field MSMs is demonstrated that combines microscale thickness flexible planar coils with magnetoresponsive polymer effectors. Ultrathin manufacturing and magnetic programming of effectors is used to tailor their response to the nonhomogeneous near-field distribution on the coil surface. The MSMs are demonstrated to lift, tilt, pull, or grasp in close proximity to each other. These ultrathin (80 µm) and lightweight (100 gm-2 ) MSMs can operate at high frequency (25 Hz) and low energy consumption (0.5 W), required for the use of MSMs in portable electronics.

Design of a Bistable Artificial Venus Flytrap Actuated by Low Pressure with Larger Capture Range and Faster Responsiveness

The rapid closure of the Venus flytrap (Dionaea muscipula) can be completed within 0.1-0.5 s due to the bistability of hyperbolic leaves and the curvature change of midrib. Inspired by its bistable behavior, this paper presents a novel bioinspired pneumatic artificial Venus flytrap (AVFT), which can achieve a larger capture range and faster closure action at low working pressure and low energy consumption. Soft fiber-reinforced bending actuators are inflated to move artificial leaves and artificial midrib fabricated from bistable antisymmetric laminated carbon fiber-reinforced prepreg (CFRP) structures, and then the AVFT is rapidly closed. A two-parameter theoretical model is used to prove the bistability of the selected antisymmetric laminated CFRP structure, and analyze the factors affecting the curvature in the second stable state. Two physical quantities, critical trigger force and tip force, are introduced to associate the artificial leaf/midrib with the soft actuator. A dimension optimization framework for soft actuators is developed to reduce their working pressures. The results show that the closure range of the AVFT is extended to 180°, and the snap time is shortened to 52 ms by introducing the artificial midrib. The potential application of the AVFT for grasping objects is also shown. This research can provide a new paradigm for the study of biomimetic structures.