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Abstract The design and fabrication of advanced soft actuators with programmable actuation are highly desirable in constructing intelligent soft robots. In this work, a programmable light‐driven liquid crystalline network (LCN)‐based soft actuator was judiciously designed and prepared by constructing structural anisotropy across the thickness of the film. A three‐dimensional (3D) deformable LCN actuator was realized by polymerization‐induced phase separation of small‐molar‐weight monomers and polymer networks. The resultant anisotropic LCN displays anisotropic microscale nanoporous architecture across the thickness in addition to uniform alignment at the molecular scale. The actuation behaviors of LCN film are tunable by adjusting the size and distribution of nanopores in LCN bulk via changing polymerization conditions and monomer components. More importantly, the nanoporous LCN film can be harnessed as a promising template to achieve diverse light responsiveness by changing the photothermal dyes via a feasible washing and refilling process, demonstrating a reprogrammable light‐driven soft actuator.

Abstract The human muscle bundle generates versatile movements with synchronous neurosensory, enabling human to undertake complex tasks, which inspires researches into functional integration of motions and sensing in actuators for robots. Although soft actuators have developed diverse motion capabilities utilizing the inherent compliance, the simultaneous‐sensing approaches typically involve adding sensing components or embedding certain‐signal‐field substrates, resulting in structural complexity and discrepant deformations between the actuation parts with high‐dimensional motions and the sensing parts with heterogeneous stiffnesses. Inspired by the muscle‐bundle multifiber mechanism, a multicavity functional integration (McFI) approach is proposed for soft pneumatic actuators to simultaneously realize multidimensional motions and sensing by separating and coordinating active and passive cavities. A bio‐inspired interweaving foldable endomysium (BIFE) is introduced to construct and reinforce the multicavity chamber with optimized purposive foldability, enabling 3D printing single‐material fabrication. Performing elongation, contraction, and bidirectional bending, the McFI actuator senses its spatial position, orientation, and axial force, based on the kinematic and sensing models built on multi‐cavity pressures. Two McFI‐actuator‐driven robots are built: a soft crawling robot with path reconstruction and a narrow‐maneuverable soft gripper with object exteroception, validating the practicality in stand‐alone use of the actuator and the potential for intelligent soft robotic innovation of the McFI approach.

Actuators based on soft elastomers offer significant advantages to the field of robotics, providing greater adaptability, improving collision resilience, and enabling shape‐morphing. Thus, soft fluidic actuators have seen an expansion in their fields of application. Closed‐cycle hydraulic systems are pressure agnostic, enabling their deployment in extremely high‐pressure conditions, such as deep‐sea environments. However, soft actuators have not been widely adopted on unmanned underwater vehicle control surfaces for deep‐sea exploration due to their unpredictable hydrodynamic behavior when camber‐morphing is applied. This study presents the design and characterization of a soft wing and investigates its feasibility for integration into an underwater glider. It is found that the morphing wing enables the glider to adjust the lift‐to‐drag ratio to adapt to different flow conditions. At the operational angle of attack of 12.5°, the lift‐to‐drag ratio ranges from −70% to +10% compared to a rigid version. Furthermore, it reduces the need for internal moving parts and increases maneuverability. The findings lay the groundwork for the real‐world deployment of soft robotic principles capable of outperforming existing rigid systems. With the herein‐described methods, soft morphing capabilities can be enabled on other vehicles.

Abstract Actuators utilizing snap‐through instabilities are widely investigated for high‐performance fast actuators and shape reconfigurable structures owing to their rapid response and limited reliance on continuous energy input. However, prevailing approaches typically involve a combination of multiple bistable actuator units and achieving multistability within a single actuator unit still remains an open challenge. Here, a soft actuator is presented that uses shape memory alloy (SMA) and mixed‐mode elastic instabilities to achieve intrinsically multistable shape reconfiguration. The multistable actuator unit consists of six stable states, including two pure bending states and four bend‐twist states. The actuator is composed of a pre‐stretched elastic membrane placed between two elastomeric frames embedded with SMA coils. By controlling the sequence and duration of SMA activation, the actuator is capable of rapid transition between all six stable states within hundreds of milliseconds. Principles of energy minimization are used to identify actuation sequences for various types of stable state transitions. Bending and twisting angles corresponding to various prestretch ratios are recorded based on parameterizations of the actuator's geometry. To demonstrate its application in practical conditions, the multistable actuator is used to perform visual inspection in a confined space, light source tracking during photovoltaic energy harvesting, and agile crawling.

The hygroscopic motion of plants has inspired the development of moisture‐activated soft actuators. These actuators driven by ambient moisture sources are of great research interest in robotics and self‐regulating textiles. However, these actuators often have slow motion and can only perform bending and twisting motions. Herein, a cellulose film‐based fast‐morphing and motion‐programmable soft actuator is presented that can generate caterpillar‐like movement. The cellophane films reported here bend almost instantaneously under changing humidity, with a large bending curvature, high repeatability, and negligible hysteresis. Different actuation modes are studied using both coated and uncoated cellophane films. The uncoated cellophane film can continuously move on a moist substrate through autonomous bending–rolling–flipping (or oscillating) cycles. A facile strategy is used here to control the rolling direction and facilitate the flipping motion by offsetting its center of gravity during deformation by adding appropriate weights on the end of the actuator. The coated cellophane film is used to fabricate motion‐programmable actuators through heat‐laminating. Several actuator structures are designed and fabricated and their diverse moisture‐induced motions are demonstrated.

Pneumatic soft actuators possess relatively fast response, inherent high flexibility, and achieve extraordinary shape morphing under large deformations. Conventionally, the entire body of soft pneumatic robots needs to be designed for specific applications. Herein, a soft pneumatic actuator design with structured fabrics as actuator skins, which has high bending stiffness variation that can accomplish multiple tasks and different deformation modes in a single body, is proposed. By adjusting the structured skin, the developed soft actuator can be tailored to achieve various deformations. It is experimentally shown that the bending stiffness of the actuator can be adjusted from 108 to 5654 N m−1. The blocking force of the actuator in bending is comparable with that of conventional fabric‐reinforced pneumatic actuators, while the actuator skins are reusable and programmable. In application, the actuators are used to construct a bionic soft gripper with multiple degrees of freedom. By switching between three grasping modes, the gripper successfully fulfills a series of tasks including lifting weights up to 1 kg and grasping objects ranging from a grain of grape to a large iron basin. This work opens up an avenue for designing structured skins for pneumatic robots with programmable deformation modes and versatile functions.

Soft pneumatic biomimetic robotic systems excel at the specific application they are designed for, often to interact or navigate unstructured environments safely. However, redeployment to new purposes requires substantial resources, from redesign to revalidation. Despite most pneumatic artificial muscles surpassing the power and contraction performance of natural muscles, natural muscles largely remain unmatched in terms of their versatility and complex performance. This is likely due to artificial muscle's low effective strain and high radial expansion, limiting parallel operating efficiencies. To address these challenges, a class of compact versatile pneumatic actuators, called multilayer artificial muscle (MAM), that are capable of deployment to different applications through configurable modularity, is presented. The MAMs are biomimetically inspired by the sarcomere, the building block for natural muscle architecture. Similarly, MAM can extend and contract as well as be rearranged to mimic muscle‐like actions and functions, such as a caterpillar locomotion robot and an entire robotic arm. The MAMs are fabricated through multilayer, multimaterial, low‐cost additive manufacturing, which offers certain advantages such as higher extension, contraction force, and durability. MAMs have the potential to provide a crucial fundamental building block toward future versatile reconfigurable architecture.

Soft pneumatic gripping strategies are often based on pressurized actuation of structures made of soft elastomeric materials, which limits designs in terms of size, weight, achievable forces, and ease of fabrication. In contrast, fabric‐based inflatable structures offer high stiffness‐to‐weight ratio solutions for soft robotics, but their actuation has been little explored. Herein, a new class of pneumatic soft grippers is presented that exploits the in‐plane overcurvature effect of inextensible fabric flat balloons upon inflation. A star‐shaped gripper contracts radially under pressure producing a gripping force on the object whose intensity can be modulated by the pressure input. First, the kinematics and mechanics of a single V‐shaped actuator are studied through experiments, finite element simulations, and analytical models. Then, these results are leveraged to predict the mechanical response of the entire star, optimize its geometry, and maximize contraction and stiffness. It is shown that the gripping performance can be improved by stacking several stars with silicon‐coated corners. It is expected that the flexibility, robustness, scalability, and ease of fabrication of this methodology will lead to a new generation of lighter and larger actuators capable of developing higher forces and moving delicate and irregularly shaped objects while maintaining reasonable complexity.

Abstract The rise of stimuli‐responsive polymers has brought about a wealth of materials for small‐scale, wirelessly controlled soft‐bodied robots. Thinking beyond conventional robotic mobilities already demonstrated in synthetic systems, such as walking, swimming and jumping, flying in air by dispersal, gliding, or even hovering is a frontier yet to be explored by responsive materials. The demanding requirements for actuator's performance, lightweight, and effective aerodynamic design underlie the grand challenges. Here, a soft matter‐based porous structure capable of wind‐assisted dispersal and lift‐off/landing action under the control of a light beam is reported. The design is inspired by the seed of dandelion, resembling several biomimetic features, i.e., high porosity, lightweight, and separated vortex ring generation under a steady wind flow. Superior to its natural counterparts, this artificial seed is equipped with a soft actuator made of light‐responsive liquid crystalline elastomer, which induces reversible opening/closing actions of the bristles upon visible light excitation. This shape‐morphing enables manual tuning of terminal velocity, drag coefficient, and wind threshold for dispersal. Optically controlled wind‐assisted lift‐off and landing actions, and a light‐induced local accumulation in descending structures are demonstrated. The results offer novel approaches for wirelessly controlled, miniatured devices that can passively navigate over a large aerial space.

As a typical behavior of releasing energy in a short time, catapulting is a way for organisms to adapt to complex and changeable environments, such as crossing terrain obstacles and spreading seeds. The essence of catapulting behavior is that plants and animals use their structural characteristics to control elastic strain energy locking, triggering, and releasing under external stimulation. At present, bistable or multistable structures are attractive for optimizing the system energy and improving the performance of liquid crystal elastomer (LCE) soft actuators. However, the overelaborate designation of such structures makes it a great challenge to achieve fast morphing LCE soft actuators. Here, a light‐driven azobenzene liquid crystal elastomer (azo‐LCE) soft actuator mimicking the catapulting behavior of fern sporangia is reported. 2D azo‐LCE monoliths are simply folded to construct V‐shaped structures as 3D catapults, which exhibit higher morphing velocity upon UV light, and the morphing velocity is related to the aspect ratio of films. Furthermore, asymmetric morphing behavior occurs by constructing localized UV irradiation conditions, which greatly improves the morphing velocity. It is envisioned that the origami‐inspired azo‐LCE catapults can be further designed as the throwing component in fast‐morphing soft robots for the remote delivery of microcargoes.

To allow a linear one‐way shape‐memory alloy (SMA) wire to have a deterministic curvilinear two‐way actuation, the SMA wire can be bonded on a curved substrate or prestrained soft materials to create mismatched SMA‐wire composites. These composites have recently been applied to soft robots to achieve rapid periodic untethered locomotion. Herein, by knitting bare SMA wires on scattered holes, it is shown that the substrate‐free knitted SMA wires can periodically ride robots forward, where a deterministic spatial curvilinear actuation can be achieved in which its in‐between heated configuration and the final stable pattern is sensitive to the prescribed hole constraints. By arranging “knitting‐constraints,” the 3D‐printed and origami robots with a pair of SMA wires, respectively, are ridden. The SMA wires have an angle parameter with a variation range of 30° for the 3D‐printed robot and that of 8° for the origami robot, where the angle parameter is defined to indicate the performance of the knitted SMAs. Both the robots can displace up to 5 mm in one motion cycle with an average speed of 20 and 15 mm min−1, respectively. The motion efficiencies of the two robots are close to 1 when taking the possible backward movement in one forward‐moving cycle into consideration.

Background: Although various endoscopic surgery robots developed in previous studies are versatile and have high lesion accessibility, they have limitations in terms of reaching the target lesion through the curved path in the large intestine and providing a stable tasking environment for the operator., Methods: An endoscopic surgery robot was developed for performing surgery in the large intestine. The robot was easily inserted into the target lesion in the curved colon through the mounted soft actuator and demonstrated high structural stiffness through the insertion of the sigmoidal auxiliary tendons., Results: The robot was able to access the target lesion in the curved colon through teleoperation alone. Further, it was confirmed that the high structural stiffness overtube improved the overall task performance in the user test., Conclusions: The proposed robotic system demonstrated the possibility and potential of performing advanced endoscopic surgery in the large intestine., (© 2022 John Wiley & Sons Ltd.)