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Hydrogels are unique polymer materials that possess hydrophilic chains, allowing them to effectively retain a considerable amount of water within their interstitial structures. The first hydrogel, developed in 1955 by Professor Lim and Wichterle from Prague, was specifically designed for manufacturing contact lenses. Hydrogel has the unique ability to absorb and retain a significant amount of water without dissolving. These gels consist of a three-dimensional (3D) network structure composed of cross-linked polymers. Hydrogels can undergo changes in their properties or behavior in response to different stimuli. There are two main problems addressed when using hydrogels: Firstly, it is imperative to conduct more in vivo research and how they behave after being implanted in humans. Secondly, it's crucial to create new, effective, and ecologically responsible ways to make hydrogels. Hydrogels have emerged as unparalleled vehicles for drug delivery, particularly in the context of brain or spinal cord lesions, heavy metal removal, tissue engineering, biosensor, regeneration, cancer, bioprinting, soft robots, biosensor, photonics, perfumery and food industry. In the future, it will be profitable to focus on the development of more sophisticated biopolymer-based hydrogels, combining natural polymers with elastin-cellulose and elastin-alginate mixes. Such developments would be very helpful in tissue regeneration. [ABSTRACT FROM AUTHOR]

Dielectric elastomer actuators (DEAs) face an acknowledged challenge: On the one hand, the majority of elastomers only achieve small electroactive deformation (<20%) in the absence of prestretch; on the other hand, rare elastomers capable of showing large electroactive deformation require relatively complicated processing and chemistry. This work addresses this challenge by fabricating an elastomer with a network of large side groups, which achieves a very large electroactive deformation (218%) without pre‐stretch. This elastomer can be rapidly and massively fabricated within a few min, by polymerizing a commercial monomer with a large alkyl side group. The large side groups in the polymer network repel each other and extend the load‐bearing strands, which results in a pronounced strain‐hardening behavior. This behavior helps the elastomer to get rid of electromechanical instability during actuation and hence to exhibit a large electro‐active deformation, a high energy density (>> human muscle), and a large output force (≈500 times self‐weight). the elastomer capable of manufacturing a soft electroactive gripper is demonstrated with large deformation, large force, and rapid response, which enables grasping fragile objects of various complex shapes in an agile away. [ABSTRACT FROM AUTHOR]

Reconfigurable soft robots exhibit superior flexibility and adaptability when coping with complex environments and variable tasks. However, conventional modular design strategy based on soft actuator modules with specific structure and actuation mode as the basic constructing element for reconfigurable soft robots always has limited reprogrammability or scalability. Here, a hierarchical reconfigurable strategy is reported that not only offers conventional module reconfiguration as the first level to build different robot prototypes, but also provides the elastically‐guided multimodal actuation (contraction, bend, and twist) as the second level which can be reprogrammed to construct different actuator modules. This strategy deepens the modularity to a higher dimensionality and provides more choices for robots to adjust various conformations and functions as needed, for example, a peristalsis robot, an omnidirectional crawling robot, and a soft manipulator can be easily constructed using the module‐level reconfiguration. Moreover, soft manipulators with various preprogrammed deformation trajectories based on the mode reconfiguration are proven to dramatically reduce the operation difficulty and cost in potential applications such as environment detection and human‐robot interaction. This work provides a hierarchical framework for reconfigurable soft robots and may open up a new way for modular design. [ABSTRACT FROM AUTHOR]

Recently, soft actuators with the capabilities of stimuli response have attracted great attention and shown potential application prospects in soft robots. The critical factor of soft actuators to realize practical applications is the programmable shape deformations. However, it remains a challenge to develop a simple and versatile method to design a soft actuator with programmable deformations. Herein, we report a programmable graphene oxide (GO)/wax moisture-responsive actuator through water-shaping and heat-welding methods. Diverse actuators with different initial shapes can be achieved by the water-shaping method, which provides the possibility for preparing actuators with various desired shapes. Additionally, more complex 3D configurations of actuators can be programmed by the heat-welding method. As proof-of-concept demonstrations, several soft robots, such as a bionic walking robot, a grasping robot, and a weight-bearing robot, are demonstrated. Certainly, the versatile and simple programming methods of soft actuators hold great potential for intelligent robotics. [ABSTRACT FROM AUTHOR]

The combination of fluidity and metallic conductivity has attracted considerable attention to liquid metal (LM), but its development remains challenging due to enormous surface tension. Here, vinyl‐terminated silicone oil and platinum catalyst are added to LM to reduce its surface tension, which develops a special type of liquid‐metal‐silicone (LMS) ink with a catalyst diffusion effect. Combined with an embedded three‐dimentional (3D) printing method, the LMS ink is printed on the support matrix, and the catalyst diffuses outward along the print path to cure the silicone around it, directly constructing self‐encapsulated conductive composites with excellent conductivity and self‐encapsulated flexible tactile sensors based on triboelectric nanogenerator (TENG). The sensor exhibits excellent sensitivity (0.308 V kPa−1), high linearity (≈0.99), and good durability (over 10 000 cycles). Furthermore, when used in flexible wearable electronics, the sensor demonstrates a good performance with an accuracy of ≈96% in classifying different human postures using a convolutional neural network. Finally, through embedded 3D printing with LMS ink and silicone ink, a somatosensory soft robotic gripper with complex cavity structures is designed and manufactured in one step, achieving the all‐in‐one integration of sensors and actuators. This study shows great application potential in flexible electronics and soft robotic systems. [ABSTRACT FROM AUTHOR]

The precise control of soft and continuum robots requires knowledge of their shape, which has, in contrast to classical rigid robots, infinite degrees of freedom. To partially reconstruct the shape, proprioceptive techniques use built‐in sensors, resulting in inaccurate results and increased fabrication complexity. Exteroceptive methods so far rely on expensive tracking systems with reflective markers placed on all components, which are infeasible for deformable robots interacting with the environment due to marker occlusion and damage. Here, a regression approach is presented for three‐dimensional key point estimation using a convolutional neural network. The proposed approach uses data‐driven supervised learning and is capable of online markerless estimation during inference. Two images of a robotic system are captured simultaneously at 25 Hz from different perspectives and fed to the network, which returns for each pair the parameterized key point or piecewise constant curvature shape representations. The proposed approach outperforms markerless state‐of‐the‐art methods by a maximum of 4.5% in estimation accuracy while being more robust and requiring no prior knowledge of the shape. Online evaluations on two types of soft robotic arms and a soft robotic fish demonstrate the method's accuracy and versatility on highly deformable systems. [ABSTRACT FROM AUTHOR]

Origami, the art of paper folding, has emerged as a versatile technique for crafting intricate 3D structures from 2D sheets. Combined with the magnetic actuation, origami paper becomes the building blocks for cost‐effective, wirelessly controllable magnetic robots. Herein, a biodegradable magnetic paper with excellent formability and recyclability is developed, facilitating its convenient utilization and disposal. The programable magnetic paper, fabricated with specific magnetization and crease patterns, enables the transformation of 2D sheets into predetermined 3D structures. Leveraging the lightweight and pliable nature of paper‐based materials, exceptional control of origami robots with fast response is demonstrated, enabling a wide range of locomotion. Furthermore, the paper‐based approach enables the incorporation of electronic functionality into magnetic actuators. By introducing conductive nanoparticles into magnetic paper, an electrically conductive substance is created. Constructing electronic circuits and integrating electronic components onto the paper‐based printed circuit board platform enables the repairing of broken circuits inside complicated equipment and optical sensing of surrounding environments in conjunction with locomotive robots. The origami robots have a huge potential to be facilitated in diverse fields with various functions, demonstrating complex locomotion, and integrating chemical, optical, thermal, and mechanical sensors for monitoring environmental conditions in hard‐to‐reach locations. The array of possibilities holds significant promise for the widespread application of these origami magnetic robots across a diverse spectrum of research fields in soft robotics. [ABSTRACT FROM AUTHOR]

As a new class of robots, soft continuum manipulators have attracted attention due to their flexibility and compliance. However, these characteristics create challenges for precise modeling and control. This study proposes a hybrid offline and online data‐driven scheme to achieve high‐precision tracking control of a soft continuum manipulator. First, a novel multiscale deep neural network learns the manipulator model offline. Specifically, the feature fusion module extracts highly discriminative features and captures long‐term dependencies from the temporal trajectory data. The self‐attention module strengthens the ability to represent fusion features and enhances the model prediction accuracy. Then, the learnt model is updated using multisensor data online, and the proposed controller further compensates for the updated model and enhances the tracking accuracy in the movement stage. Finally, the experimental results demonstrate a significant improvement in motion accuracy under different trajectory‐tracking scenarios (i.e., deviations of <1 mm in position and <0.8° in orientation). The example of the multiwire cable sorting proves the feasibility of the proposed scheme in high‐precision industrial applications. [ABSTRACT FROM AUTHOR]

Endowing tactile feedback for prosthetic hands is profound for upper‐limb amputees. However, existing prosthetic hands are generally not in possession of the embedded sensory feedback. Herein, a flexible tactile sensor array which can be integrated into an untethered soft prosthetic hand to achieve static and dynamic discrimination tasks is presented. The flexible piezoresistive sensory arrays with 25 sensor units which can be arranged on five fingers of the soft prosthetic hand are fabricated. According to the collected large‐scale tactile dataset (including pressure distribution and pressure magnitude) during different grasping tasks, a learning‐based classification model that can reveal the correspondences between tactile information and object attributes while interacting with touched objects is developed. To transfer tactile information extracted from tactile sensor arrays, a wearable vibrotactile feedback band with a spatial coding feedback strategy is implemented by selectively activating vibrotactile motors located on the skin of the upper arm. In a set of tests performed by an individual with transradial amputation and eight able‐bodied subjects, the soft prosthetic hand integrated with tactile sensor arrays can help the users regain finger tactile sensation, discriminate grasped objects, and achieve real‐time dynamic rolling detection. [ABSTRACT FROM AUTHOR]

Liquid metal (LM) elastomer composites offer promising potential in soft robotics, wearable electronics, and human‐machine interfaces. Direct ink write (DIW) 3D printing offers a versatile manufacturing technique capable of precise control over LM microstructures, yet challenges such as interfilament void formation in multilayer structures impact material performance. Here, a DIW strategy is introduced to control both LM microstructure and material architecture. Investigating three key process parameters–nozzle height, extrusion rate, and nondimensionalized nozzle velocity–it is found that nozzle height and velocity predominantly influence filament geometry. The nozzle height primarily dictates the aspect ratio of the filament and the formation of voids. A threshold print height based on filament geometry is identified; below the height, significant surface roughness occurs, and above the ink fractures, which facilitates the creation of porous structures with tunable stiffness and programmable LM microstructure. These porous architectures exhibit reduced density and enhanced thermal conductivity compared to cast samples. When used as a dielectric in a soft capacitive sensor, they display high sensitivity (gauge factor = 9.0), as permittivity increases with compressive strain. These results demonstrate the capability to simultaneously manipulate LM microstructure and geometric architecture in LM elastomer composites through precise control of print parameters, while maintaining geometric fidelity in the printed design. [ABSTRACT FROM AUTHOR]

Traditional robotic devices are often bulky and rigid, making it difficult for them to adapt to the soft and complex shapes of the human body. In stark contrast, soft robots, as a burgeoning class of robotic technology, showcase exceptional flexibility and adaptability, positioning them as compelling contenders for a diverse array of applications. High-performance electrically responsive artificial muscle materials (ERAMMs), as key driving components of soft robots, can achieve efficient motion and deformation, as well as more flexible and precise robot control, attracting widespread attention. This paper reviews the latest advancements in high-performance ERAMMs and their applications in the field of soft robot actuation, using ionic polymer-metal composites and dielectric elastomers as typical cases. Firstly, the definition, characteristics, and electro-driven working principles of high-performance ERAMMs are introduced. Then, the material design and synthesis, fabrication processes and optimization, as well as characterization and testing methods of the ERAMMs are summarized. Furthermore, various applications of two typical ERAMMs in the field of soft robot actuation are discussed in detail. Finally, the challenges and future directions in current research are analyzed and anticipated. This review paper aims to provide researchers with a reference for understanding the latest research progress in high-performance ERAMMs and to guide the development and application of soft robots. • Inspired by the good performance of natural muscles, extensive attention has been paid to the study of artificial muscles. Based on the structure and properties of artificial muscles, the research progress of high-performance artificial muscle materials is systematically reviewed, the working principle of the device-driven deformation is comprehensively analyzed, and the material design, preparation process and characterization methods are deeply analyzed. • The opportunities and challenges of high-performance artificial muscle materials, especially ionic polymer-metal composites and dielectric elastomers, are discussed, and their future research directions are proposed, laying the foundation for further innovative research on artificial muscle materials and their application development in the field of soft robot actuation. [Display omitted] [ABSTRACT FROM AUTHOR]

Soft robots, as a new type of robots, are highly flexible and deformable, which can adapt to the needs of tasks in complex environments. However, due to the complex nonlinear behaviors of soft materials and the unpredictable motion of actuators, accurate modeling and development of suitable controllers for soft robots are currently the main challenges for real applications. In this paper, we propose and compare two different modeling approaches to estimating the shape deformation of a two-dimensional pneumatic soft robot (2D-PSR): an analytical model based on the motion and air pressure dynamics and a data-driven model using Koopman operator theory and finite-dimensional approximate realization of the extended dynamic mode decomposition algorithm. The Unscented Kalman Filter (UKF) is applied to the two models to estimate the system state and filter the noises from sensors, respectively. Subsequently, based on the established models, the linear quadratic regulator (LQR) is designed to realize the precise trajectory tracking control of the 2D-PSR under two typical input signals. Both simulation and experimental results show that the proposed LQR control schemes with UKF designed based on the analytical model (A-FL-UKF-LQR) and Koopman linear model (K-UKF-LQR) can achieve the expectations in terms of tracking accuracy and robustness, in which the K-UKF-LQR framework outperforms the A-FL-UKF-LQR to a certain degree. [ABSTRACT FROM AUTHOR]

In the realm of underwater exploration and operations, soft robots exhibit considerable application potential due to their capacity for agile and complex deformations as well as their inherent compliance. These characteristics grant them excellent environmental adaptability and reduce damage to delicate samples and organisms. Nonetheless, existing underwater soft robots are primarily designed to mimic the movements of marine organisms or for specific functions, and little attention is paid to the camouflage ability. To address these challenges, in this study, a reconfigurable transparent soft robot with variable stiffness for underwater operations is presented. The design and fabrication methodology of the robot module is presented, followed by the kinematic analysis and stiffness characterization. Leveraging the proposed robot module, a soft manipulator and a soft gripper are designed for underwater operations. The soft manipulator excels in underwater pipeline detection and obstacle avoidance, while the soft gripper showcases considerable load‐bearing capacity (about 71 times its weight), making it suitable for tasks such as retrieving aquatic biological samples or garbage fishing. The proposed reconfigurable soft robot demonstrates robust camouflage capabilities, high environmental adaptability, and notable versatility, suggesting potential solutions to existing challenges in the field of underwater exploration. [ABSTRACT FROM AUTHOR]

Soft robotics, an emerging field that focuses on the development of robots utilizing soft, flexible, and deformable materials, is revolutionizing traditional robotics (reliant on rigid materials and motors) and broadening its range of applications and potential uses. In addition, by emulating the structure, function, and characteristics of biological systems, bioinspired materials are facilitating significant progress in a diverse array of soft robotic applications. This review offers an overview of bioinspired materials employed in soft robotics, exploring their potential applications, challenges, and future research directions. For an intuitive understanding, soft robots based on the primary abilities required and the habitats (terrestrial, aquatic, aerial) of the animals and plants they mimic are categorized. Furthermore, real‐world applications of developed soft robots in everyday human life are presented. The novel category classification and comprehensive analysis presented in this review provide insights into the development of soft robotic systems with the potential to transform various industries and enhance quality of life. [ABSTRACT FROM AUTHOR]

Inflatable multistable materials have significantly advanced the design of shape‐preserving soft robotic arms, offering substantial benefits in terms of shape adaptability, energy efficiency, and safety, ensuring operational reliability even in the event of sudden power loss. However, existing strategies for realizing multistable arms often limit themselves to a single mode of multistability, commonly with rotationally symmetric designs favoring extension stability and asymmetric designs inducing bending stability. To address the limitation, this study introduces a pioneering platform termed multimodal multistability that utilizes geometrical frustration. A single cylindrical symmetric cell, designed for extension bistability, could achieve frustrated multistable states in bending by controlling the cell with multiple degrees of freedom incorporated pneumatic actuator. This platform extends the spectrum of attainable stable trajectories while preserving essential attributes of arms, such as load‐bearability, programmability, and reversibility of shape changes. Leveraging a pneumatic system with four degrees of freedom for pressure control, not only enables capturing previously unexplored stable configurations in mechanical metastructures but also allows for the control of their deformation modes. With applications spanning space exploration, medical instruments, and rescue missions, the multimodal multistability promises unparalleled flexibility and efficiency in the design and operation of soft robots. [ABSTRACT FROM AUTHOR]

Soft and tensegrity structures are two configurations that have appeared as robots continue to draw inspiration from nature and diversify beyond rigid machines toward compliant systems. One artificial manifestation of a biological attribute that is an active research topic is the body's capacity to calibrate its stiffness for adapting its behavior to a given task. This study brings together these designs spaces and presents a soft tensile element named FlexiStiff for tensegrity structures to enable transitioning between flexible and stiff states for variable load‐bearing capability and compliance. The device's tensile stiffness constant can be increased by 4400% with a change in pressure. It can provide a high blocking force of 535.5 N and can endure elongation up to 184%. It is assembled using four commercially available materials and a two‐step fabrication method consisting of 3D printing and elastomer curing. As opposed to classical tensegrities for which shape change is inexpensive in terms of energy, this work betokens a new stage in their design wherein the arrangement can radically alter the magnitude of its demand for external energy for shape morphing, a crucial characteristic for operation in partially mapped environments that present diverse terrains and disturbances of varying intensities prompting adaptability. [ABSTRACT FROM AUTHOR]

Magnetic liquid metal (MLM) is a mixture of magnetic particles with gallium‐based liquid metals which utilizes an unconventional combination of fluidity, high thermal/electrical conductivity, biocompatibility, and magnetism. Recently, from materials to applications, studies on MLMs have drastically increased. Single or multiple MLMs can be precisely positioned or can act as a carrier for handling other objects. MLMs are also used in biomedical applications such as cancer treatment by hyperthermia and precision delivery of cancer drugs on tumors, or antibacterial coating which kills bacteria. In electronics applications, MLMs are used for magnetic field‐driven patterning of metallic lines, reconfigurable interconnects, electronic tattoos, and reconfigurable electromagnetic wave shielding. Phase change (solid/liquid) of MLMs adds another unique capability, morphing. A combination of innovations in the micro/nano robots and MLMs has huge potential to bring an unprecedented disruptive technology for a wide variety of applications including self‐morphing shape‐recovery robots, highly localized cancer treatment, and reconfigurable stealth/camouflage, among others. This article comprehensively reviews recent developments in MLMs from the materials to methods of preparation, locomotion of MLMs, their applications, and future outlooks. [ABSTRACT FROM AUTHOR]

Soft pneumatic joint actuators show great potential in applications such as medical machinery, wearable devices, and soft grippers due to their inherent compliance. However, due to the internal friction and periodic relaxation of the elastic materials, the output force of soft pneumatic joint actuators has complex hysteresis characteristics, which seriously affects their control accuracy. To address the asymmetry hysteresis of actuator output force, a neural network model combining a bidirectional long-short-term memory network (BiLSTM) and a multilayer perceptron (MLP) is proposed. The MLP serves as the output layer of the BiLSTM, which is utilized to capture the time dependency of the actuator output force. By applying further nonlinear transformations, the feature representation of the BiLSTM output is retrieved and merged, improving the prediction and generalization capabilities of the model. The experimental results show that the BiLSTM-MLP model has a maximum output force error of only 0.306 N, an average error of less than 0.08 N, and a goodness of fit more than 0.999. Compared with the MLP, LSTM, BiLSTM, and improved PI models, the BiLSTM-MLP model can have higher prediction accuracy, better characterize the hysteresis properties of soft joint actuators, and provides a promising approach for hysteresis modeling of various elastomer actuators. [ABSTRACT FROM AUTHOR]

Soft robots have been advancing rapidly, but their control is still limited by rigid control elements. Soft valves offer a solution to this problem by enabling soft robots to no longer rely on rigid control elements. They have become an emerging research topic in soft robotics. However, with a large number of publications on soft valves, it may be challenging for researchers to quickly grasp the advanced technology related to soft valves. To address this issue, this article summarizes the current state of development in soft valves. The design principles and applications of soft valves in terms of structures and materials are discussed, along with the modeling ideas for soft valves. Finally, the current challenges faced by soft valves are outlined, and potential solutions to these problems are proposed. [ABSTRACT FROM AUTHOR]

Soft robots can adaptively interact with unstructured environments. However, nonlinear soft material properties challenge modeling and control. Learning‐based controllers that leverage efficient mechanical models are promising for solving complex interaction tasks. This article develops a closed‐loop pose/force controller for a dexterous soft manipulator enabling dynamic pushing tasks using deep reinforcement learning. Force tests investigate the mechanical properties of a soft robot module, resulting in orthogonal forces of 9−13$9 - 13$ N. Then, the policy is trained in simulation leveraging a dynamic Cosserat rod model of the soft robot. Domain randomization mitigate the sim‐to‐real gap while careful reward engineering induced pose and force control even without explicit force inputs. Despite the approximate simulation, the sim‐to‐real transfer achieved an average reaching distance of 34±14$34 \pm 14$ mm (8.1%L±3.4%L$ L \pm L$), an average orientation error of 0.40±0.29$0.40 \pm 0.29$ rad (23°±17°$\left(23\right)^{\circ} \pm \left(17\right)^{\circ}$) and applied pushing forces up to 3$3$ N. Such performance is reasonable for the intended assistive tasks of the manipulator. The experiments uncovered that the soft robot interacting with the environment exhibited torsional and counter‐balancing movements. Although not explicitly enforced, they emerged from the mechanical intelligence of the manipulator. The results demonstrate the potential of soft robotic manipulation via reinforcement learning. [ABSTRACT FROM AUTHOR]

Herein, the design, modeling, and validation of high‐flow, fluid‐driven, membrane valves tailored specifically for applications in soft robotic systems are described. Targeting the piping problem in hyper‐actuated soft robots, two fluid‐driven membrane valve designs that can admit flows of up to 871 mg s−1$871 \textrm{ } \textrm{ } \text{mg} \textrm{ } \left(\text{s}\right)^{- 1}$ while weighing less than 20 g$false$ are introduced. A mathematical model to predict fluid flow by representing the displacement of the membrane as a scalar quantity influenced by the balance of pressures applied across the valve's ports is established. The model incorporates six parameters with direct physical relevance, enhancing its usefulness in valve design and system integration. In an experimental validation, flow rates with deviations within 4% are predicted and the onset of flow is correctly identified with an error rate of less than 1%. In addition, applications of these valves for flow amplification and for the creation of a fluid‐driven oscillator are experimentally demonstrated. This research contributes to the advancement of soft robotics by providing a tool for designing, optimizing, and controlling fluid‐driven systems and it lays the groundwork for the future development of embedded, fluid‐controlled valve networks that can be used to realize hyper‐actuated soft robotic systems. [ABSTRACT FROM AUTHOR]

Ionic electrochemical actuators, which convert electrical energy into mechanical energy through electrochemical‐induced ion migration, show great potential in biomimetic soft robots. However, their applications are still limited due to the influence of the electrode materials and actuator performance. Here, an MXene/carbon nanotube (CNT) heterostructural electrode‐based ionic actuator is developed and realizes dexterous touch manipulation mimicking humans. In this MXene/CNT heterostructure, one‐dimensional CNTs are chemically interconnected into layered two‐dimensional MXene nanosheets, increasing their interlayer spacing, promoting mechanical stability, and enhancing specific surface area, which facilitates the ion migration and storage as well as electrochemical actuation. Accordingly, the MXene/CNT actuator can output excellent mechanical deformation under 2.5 V voltage, including large peak‐to‐peak deformation (displacement 24 mm, strain 1.54%), wide frequency response (0.1–15 Hz), large force (5 mN) and good cycling stability. The actuators can be used to construct artificial fingers to achieve gentle, multi‐point, variable frequency, and synergistic touching on fragile smartphone screens, including pressing a phone number to make a call and tapping an electronic drum. Especially, this finger can tap the drum at a high frequency (13 Hz), exceeding the tapping frequency that real human fingers can reach, which demonstrates its prospect in human‐computer interaction. [ABSTRACT FROM AUTHOR]

Engineering systems that leverage the flexibility and softness of soft materials have been fostering revolutionary progress and broad interest across various applications. The inherently flexible mechanical properties of these materials lay the groundwork for engineering systems that can adapt comparably to biological organisms, enabling them to adjust to unpredictable environments effectively. However, alongside the positive benefits of softness, these systems face challenges such as low durability, continuous energy demands, and compromised task performance due to the inherently low stiffness of soft materials. These limitations pose significant obstacles to the practical impact of soft engineering systems in the real world beyond innovative concepts. This review presents a strategy that employs materials with variable stiffness to balance adaptability advantages with the challenge of low rigidity. The developments are summarized in materials capable of stiffness modulation alongside their applications in electronics, robotics, and biomedical fields. This focus on stiffness modulation at the material unit level is a critical step toward enabling the practical application of soft engineering systems in real‐world scenarios. [ABSTRACT FROM AUTHOR]

Accurately controlling the dynamic response and suppression of undesirable dynamics such as overshoots and vibrations is a vital requirement for soft robots operating in industrial environments. Pneumatically actuated soft robots usually undergo large overshoots and significant vibrations when deactuated because of their highly flexible bodies. These large vibrations not only decrease the reliability and accuracy of the soft robot but also introduce undesirable characteristics in the system. For example, it increases the settling time and damages the body of the soft robot, compromising its structural integrity. The dynamic behavior of the soft robots on deactuation needs to be accurately controlled to increase their utility in real-world applications. The literature on pneumatic soft robots still does not sufficiently address the issue of suppressing undesirable vibrations. To address this issue, we propose the use of impedance control to regulate the dynamic response of pneumatic soft robots since the superiority of impedance control is already established for rigid robots. The soft robots are highly nonlinear systems; therefore, we formulated a nonlinear discrete sliding mode impedance controller to control the pneumatic soft robots. The formulation of the controller in discrete-time allows efficient implementation for a high-order system model without the need for state-observers. The simplification and efficiency of the proposed controller enable fast implementation of an embedded system. Unlike other works on pneumatic soft robots, the proposed controller does not require manual tuning of the controller parameters and automatically calculates the parameters based on the impedance value. To demonstrate the efficacy of the proposed controller, we used a 6-chambered parallel soft robot as an experimental platform. We presented the comparative results with an existing state-of-the-art controller in SMC control of pneumatic soft robots. The experiment results indicate that the proposed controller can effectively limit the amplitude of the undesirable vibrations. [ABSTRACT FROM AUTHOR]

Flexible grippers require appropriate stiffness to ensure stability and efficiency in unpredictable environments. While combining materials with variable stiffness and elastomers holds significant promise in this regard, concurrently achieving actuation and stiffness modulation typically results in heightened structural complexity and responsiveness issues. In this study, a giant electrorheological dielectric elastomer (GERDE) with high dielectric and high electrorheological (ER) properties is obtained by introducing giant electrorheological particles into silicone elastomers, further substantiating the ability to functionally couple actuation and stiffness‐tuning, as well as application of a flexible gripper in mimicking emotive calligraphy. Specifically, GERDE exhibits better actuating (area strain rate of 33%) and ER performance (storage modulus increment of 1.5 MP) than existing conventional dielectric elastomer (DE) actuators (such as PDMS and VHB4910) under a low electric field. Compared to reported flexible grippers, bionic flexible grippers based on GERDE actuator have enhanced actuation, stiffness adjustment capability (i.e., stiffness is increased by 2.4 times), fast response (≈180 ms), and coupling effect, and can write Chinese calligraphy of different emotions by the same trajectory. This work provides ideas and methods for achieving the integration of actuator‐variable stiffness and emotional transmission in robots. [ABSTRACT FROM AUTHOR]

Cables are critical in engineering structures for load‐bearing, electronic connection, and mechanical transmission. Various cable‐crawling robots (CCRs) have been developed to perform scheduled inspection or convey supplies. Most existing CCRs are often actuated by motors and used in large‐scaled engineering structures. The heavy bodies of these CCRs can cause damage or even casualties once slippage or drop occurs. A small and lightweight CCR that can crawl on thin cables is highly demanded for safety inspection in narrow and confined inner spaces of engineering structures. Herein, a soft CCR (weight, 2.1 g; length, 43 mm) is developed by utilizing multilayered dielectric elastomer actuators. Compared with existing solutions, this CCR achieves crawling on thin cables (diameter: <1 mm) while crawling fastest (horizontal: 0.72 body length per second). The CCR is also capable of transporting objects (horizontal: 3.69 times its own weight; vertical: 0.76 times its own weight), climbing upward on a vertical cable, and locomoting across the water–air interface. The CCR is also demonstrated to crawl on a slack cable and circular/spiral cables. Finally, the soft robot, equipped with an endoscope, demonstrates inspections on a tensegrity structure as well as in an airplane wing model with a preplaced cable. [ABSTRACT FROM AUTHOR]

The fluid‐transportation functions based on the volume‐regulating behavior of the chamber‐like organs inspire the development of artificial organs. Due to the intrinsic compliance of soft robotics for biomimicking purposes and the volume‐regulation capability of the 3D origami patterns, the soft robots with origami patterns show promising potential in such research. However, the folding deformation of the origami facets cannot be straightforwardly implemented as the actuation or the body movement, and the predetermined movements of the pattern limit the appropriate functions for specific applications. In this work, an origami‐patterned rigidification (OPR) method is proposed for applying rigid origami mechanisms (herein, the cuboctahedron origami ball) to the chamber‐like structure of soft robots. The motion of the soft robot is programmed by purposefully rigidified the soft chamber following the pattern. The resultant OPR structures are granted with functions corresponding to the predetermined motion of the pattern, and the expanded movements through the bifurcation brought by the soft–rigid characteristics. The concept, design, and fabrication of the OPR robot are presented. By analyzing the deformation of the soft creases, the kinematic models of the predetermined and expanded degrees of freedom are presented and verified by experiments. The extended functions of two OPR robots are demonstrated. [ABSTRACT FROM AUTHOR]

Soft pneumatic actuators (SPAs) have applications in various domains due to their compliance, low cost, and lightweight characteristics. Herein, a geometric origami design for 3‐degree of freedom (DoF) SPAs is presented, which enables manufacturing using 3D printing at one go without any support structure. The proposed method uses a general design parameterization that works for multiple types of cylindrical origami patterns (Kresling, cylindrical Miura, Yoshimura, and Accordion). It is shown that a 3‐DoF pneumatic actuator capable of bending and extension can be constructed by superimposing two cylindrical origami patterns to create a separation of chambers inside of the module. In addition, the design parameters are chosen to reduce the strain during deformation and maximize the output forces of the origami actuator. The actuator is manufactured, and its motion and force profiles are experimentally characterized. The designed origami actuator can bend from −12.2°±0.2°$- 12.2 \circ \pm 0.2 \circ$ to 94.7°±0.9°$94.7 \circ \pm 0.9 \circ$ and the length during operation can vary between 50%$50 \%$ and 126%$126 \%$ of the initial length. [ABSTRACT FROM AUTHOR]

This paper details the design and preliminary demonstrations for a compact climbing robot named EEWOC (Extended-reach Enhanced Wheeled Orb for Climbing). This novel platform utilizes the EEMMMa limb (Elastic Extending Mechanism for Mobility and Manipulation), detailed in previous work. This highly extendable and bendable robotic limb utilizes a unique tape spring structure for long reach in a small, lightweight package. EEWOC combines this limb with additional degrees of freedom and two magnetic grippers to allow it to ascend vertical metal surfaces by consecutively extending and gripping. It is also equipped with wheels for horizontal mobility. A key advantage of this system is EEWOC's ability to bend to place its grippers around obstacles or corners and above ledges. The prototype is small and lightweight, with a profile of 25x30x30 cm and weight of 1.8 kg, while able to extend its limb up to 1.2 m away. With versatile movement options, EEWOC has the potential to fully traverse large metal structures such as ships or buildings for use in inspection tasks. This paper presents a detailed view of the overall system and mechanism design, and successful climbing demonstrations are shown on steel structures. The paper concludes by detailing EEWOC's future capabilities and additional tests and theories needed to refine its maneuvers and control.

Abstract: Conventional mobile robots have difficulty navigating highly unstructured spaces such as caves and forests. In these environments, a highly extendable limb could be useful for deploying hooks to climb over terrain, or for reaching hard-to-access sites for sample collection. This article details a new form of a multimodal mobile robot that utilizes a novel tape spring limb named EEMMMa (elastic extending mechanism for mobility and manipulation). Its innovative U-shaped tape structure allows it to handle loads in tension as well as compression. It can also bend using mechanical multiplexing for a lightweight and compact design that is well suited for mobile robots. For mobility, the limb can extend prismatically to deploy grappling hook anchors to suspend and transport the main body, or even serve as legs. For manipulation, the limb can morph its shape to bend around or over obstacles, allowing it to retrieve distant objects or position cameras around corners. The EEMMMa-1 prototype detailed in this article successfully demonstrates climbing ladders and shelves in 1.5 body lengths per second, and can bend up to 100 deg. A simplified model of the bending kinematics is developed and analyzed. This article concludes by detailing future EEMMMa applications and theories to strengthen the model in future studies.

As a new class of robots, soft continuum manipulators have attracted attention due to their flexibility and compliance. However, these characteristics create challenges for precise modeling and control. This study proposes a hybrid offline and online data‐driven scheme to achieve high‐precision tracking control of a soft continuum manipulator. First, a novel multiscale deep neural network learns the manipulator model offline. Specifically, the feature fusion module extracts highly discriminative features and captures long‐term dependencies from the temporal trajectory data. The self‐attention module strengthens the ability to represent fusion features and enhances the model prediction accuracy. Then, the learnt model is updated using multisensor data online, and the proposed controller further compensates for the updated model and enhances the tracking accuracy in the movement stage. Finally, the experimental results demonstrate a significant improvement in motion accuracy under different trajectory‐tracking scenarios (i.e., deviations of

The precise control of soft and continuum robots requires knowledge of their shape, which has, in contrast to classical rigid robots, infinite degrees of freedom. To partially reconstruct the shape, proprioceptive techniques use built‐in sensors, resulting in inaccurate results and increased fabrication complexity. Exteroceptive methods so far rely on expensive tracking systems with reflective markers placed on all components, which are infeasible for deformable robots interacting with the environment due to marker occlusion and damage. Here, a regression approach is presented for three‐dimensional key point estimation using a convolutional neural network. The proposed approach uses data‐driven supervised learning and is capable of online markerless estimation during inference. Two images of a robotic system are captured simultaneously at 25 Hz from different perspectives and fed to the network, which returns for each pair the parameterized key point or piecewise constant curvature shape representations. The proposed approach outperforms markerless state‐of‐the‐art methods by a maximum of 4.5% in estimation accuracy while being more robust and requiring no prior knowledge of the shape. Online evaluations on two types of soft robotic arms and a soft robotic fish demonstrate the method's accuracy and versatility on highly deformable systems.

Origami, the art of paper folding, has emerged as a versatile technique for crafting intricate 3D structures from 2D sheets. Combined with the magnetic actuation, origami paper becomes the building blocks for cost‐effective, wirelessly controllable magnetic robots. Herein, a biodegradable magnetic paper with excellent formability and recyclability is developed, facilitating its convenient utilization and disposal. The programable magnetic paper, fabricated with specific magnetization and crease patterns, enables the transformation of 2D sheets into predetermined 3D structures. Leveraging the lightweight and pliable nature of paper‐based materials, exceptional control of origami robots with fast response is demonstrated, enabling a wide range of locomotion. Furthermore, the paper‐based approach enables the incorporation of electronic functionality into magnetic actuators. By introducing conductive nanoparticles into magnetic paper, an electrically conductive substance is created. Constructing electronic circuits and integrating electronic components onto the paper‐based printed circuit board platform enables the repairing of broken circuits inside complicated equipment and optical sensing of surrounding environments in conjunction with locomotive robots. The origami robots have a huge potential to be facilitated in diverse fields with various functions, demonstrating complex locomotion, and integrating chemical, optical, thermal, and mechanical sensors for monitoring environmental conditions in hard‐to‐reach locations. The array of possibilities holds significant promise for the widespread application of these origami magnetic robots across a diverse spectrum of research fields in soft robotics.

Endowing tactile feedback for prosthetic hands is profound for upper‐limb amputees. However, existing prosthetic hands are generally not in possession of the embedded sensory feedback. Herein, a flexible tactile sensor array which can be integrated into an untethered soft prosthetic hand to achieve static and dynamic discrimination tasks is presented. The flexible piezoresistive sensory arrays with 25 sensor units which can be arranged on five fingers of the soft prosthetic hand are fabricated. According to the collected large‐scale tactile dataset (including pressure distribution and pressure magnitude) during different grasping tasks, a learning‐based classification model that can reveal the correspondences between tactile information and object attributes while interacting with touched objects is developed. To transfer tactile information extracted from tactile sensor arrays, a wearable vibrotactile feedback band with a spatial coding feedback strategy is implemented by selectively activating vibrotactile motors located on the skin of the upper arm. In a set of tests performed by an individual with transradial amputation and eight able‐bodied subjects, the soft prosthetic hand integrated with tactile sensor arrays can help the users regain finger tactile sensation, discriminate grasped objects, and achieve real‐time dynamic rolling detection.

In the realm of underwater exploration and operations, soft robots exhibit considerable application potential due to their capacity for agile and complex deformations as well as their inherent compliance. These characteristics grant them excellent environmental adaptability and reduce damage to delicate samples and organisms. Nonetheless, existing underwater soft robots are primarily designed to mimic the movements of marine organisms or for specific functions, and little attention is paid to the camouflage ability. To address these challenges, in this study, a reconfigurable transparent soft robot with variable stiffness for underwater operations is presented. The design and fabrication methodology of the robot module is presented, followed by the kinematic analysis and stiffness characterization. Leveraging the proposed robot module, a soft manipulator and a soft gripper are designed for underwater operations. The soft manipulator excels in underwater pipeline detection and obstacle avoidance, while the soft gripper showcases considerable load‐bearing capacity (about 71 times its weight), making it suitable for tasks such as retrieving aquatic biological samples or garbage fishing. The proposed reconfigurable soft robot demonstrates robust camouflage capabilities, high environmental adaptability, and notable versatility, suggesting potential solutions to existing challenges in the field of underwater exploration.

Bacterial cellulose (BC) produced by acetic acid bacteria is a promising biomaterial that exhibits exceptional mechanical strength, biocompatibility, and biodegradability. In this study, we have successfully fabricated BC composites with various materials such as alumina fibers, zirconia particles, carbon nanotubes, and magnetic particles by adding each material to the culture medium. We also demonstrate the actuation of BC‐magnetic particle composites by a magnetic field. Furthermore, we have achieved the patterning of arbitrarily shaped patterns onto BC pellicles by placing templates in the culture medium. These findings suggest that BC composites have the potential to be applied in various fields such as tissue engineering and drug delivery. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Soft pneumatic actuators (SPAs) hold great promise for simple and effective actuation of soft robots. Multi‐degree‐of‐freedom SPAs are highly desired as they enable diverse motion forms and improve possibility for soft robots to navigate challenging environments and perform complex tasks. Herein, this study proposes two novel origami‐based SPAs (O‐SPAs), namely the Flasher origami‐inspired SPA (FO‐SPA) and the Kresling origami‐inspired SPA (KO‐SPA), which are fabricated entirely from soft silicone without any rigid supports. A finite element model is developed to predict the deformation behavior of O‐SPAs and the deformability and dynamic response of O‐SPAs are characterized through performance tests. Simulation experiments are carried out to investigate the impact of different structural parameters on their performance. These O‐SPAs are highly sensitive to low negative pressure, exhibiting 80% of maximum deformation at −4 kPa. Based on the Flasher and Kresling origami pattern, the actuators are capable of generating compound motions including contraction, twisting, and radial motions. These motions can be used as "building blocks" for the rapid reconfiguration of various soft robots. The study has successfully enriched the types of existing SPAs by providing important multiple motions through origami, with great potential to facilitate the rapid and low‐cost design of soft robots. [ABSTRACT FROM AUTHOR]

Small robots for drug transportation, environmental detection and military reconnaissance have been a popular research topic in the field of robotics. Recently, people have proposed using light-driven actuators to make flexible and remote-controllable small robots. Herein, we reviewed the research on light-driven soft robots in recent years. First, we summarized and compared the performance and fabrication method of light-driven actuators. Then, we classified and summarized the structures of robots according to their move mode. After that, we described how to control the robot. Finally, the challenges of light-driven robots are discussed. [ABSTRACT FROM AUTHOR]

Natural organisms offer a rich source for the construction of soft robots exhibiting autonomous and intelligent behaviors, encompassing attributes like motion, perception, and adaptability to environmental shifts. Drawing inspiration from these biological models, a multitude of soft robots have emerged, each distinguished by unique structures and functionalities enabling diverse actions, including swimming, crawling, swinging, walking, and tumbling. In this review, several soft robots and their motion modes from the perspective of specific native species are addressed. The actuation methods of soft robots are discussed, encompassing chemical, electrical, ultrasonic, optical, and magnetic actuation mechanisms. Furthermore, the application domains of soft robots, encompassing areas such as vessel recanalization, targeted drug delivery, cargo manipulation, and sensing are explored, providing a concise summary of their roles and potentials. The current challenges encountered in this research field are highlighted, and promising directions pertaining to soft robots are emphasized. [ABSTRACT FROM AUTHOR]

Soft fiber-reinforced actuators have demonstrated significant potential across various robotics applications. However, the actuation motion in these actuators is typically limited to a single type of motion behavior, such as bending, extending, and twisting. Additionally, a combination of bending with twisting and extending with twisting can occur in fiber-reinforced actuators. This paper presents two novel hybrid actuators in which shape memory alloy (SMA) wires are used as reinforcement for pneumatic actuation, and upon electrical activation, they create a twisting motion. As a result, the hybrid soft SMA-reinforced actuators can select between twisting and bending, as well as twisting and extending. In pneumatic mode, a bending angle of 40° and a longitudinal strain of 20% were achieved for the bending/twisting and extending/twisting actuators, respectively. When the SMA wires are electrically activated by the Joule effect, the actuators achieved more than 90% of the maximum twisting angle (24°) in almost 2 s. Passive recovery, facilitated by the elastic response of the soft chamber, took approximately 10 s. The double-helical reinforcement by SMA wires not only enables twisting in both directions but also serves as an active recovery mechanism to more rapidly return the finger to the initial position (within 2 s). The resulting pneumatic–electric-driven soft actuators enhance dexterity and versatility, making them suitable for applications in walking robots, in-pipe crawling robots, and in-hand manipulation. [ABSTRACT FROM AUTHOR]

Herein, this study contributes significantly to the advancement of continuum manipulators in two main aspects. First, a modularization concept and a hybrid actuation scheme to create a novel origami continuum manipulator with exceptional deformability are introduced. Second, an accurate model and framework for the forward and inverse kinematic analysis of origami manipulators are proposed. Specifically, each origami manipulator module can achieve axial extension and bending deformation by coordinated actuation of shape memory alloy (SMA) and pneumatic muscles, and the manipulator's end is equipped with a deformable gripper based on waterbomb origami and actuated by SMA. Through careful consideration of the self‐weight and torque balance, an accurate kinematic model based on the Denavit–Hartenberg method is established, which enables one to effectively predict the reachable extreme positions and spatial poses of the manipulator and solve the inverse kinematics using a genetic algorithm. Comprehensive experiments are conducted to validate the design's rationality and model's accuracy. In these tests, the rich spatial configurations are not only demonstrated that can be achieved by integrating hybrid actuators with origami modules but also the accuracy and reliability of the kinematic model are confirmed, opening up possibilities for the advancement and application of origami‐inspired robotics in various fields. [ABSTRACT FROM AUTHOR]

Soft metamaterials have attracted extensive attention due to their remarkable properties. These materials hold the potential to program and control the morphing behavior of soft machines, however, their combination is limited by the poor reprogrammability of metamaterials and incompatible communication between them. Here, printable and recyclable soft metamaterials possessing reprogrammable embedded intelligence to regulate the morphing of soft machines are introduced. These metamaterials are constructed from interconnected and periodically arranged logic unit cells that are able to perform compound logic operations coupling multiplication and negation. The scalable computation capacity of the unit cell empowers it to simultaneously process multiple fluidic signals with different types and magnitudes, thereby allowing the execution of sophisticated and high‐level control operations. By establishing the laws of physical Boolean algebra and formulating a universal design route, soft metamaterials capable of diverse logic operations can be readily created and reprogrammed. Besides, the metamaterials' potential of directly serving as fluidic processors for soft machines is validated by constructing a soft latched demultiplexer, soft controllers capable of universal and customizable morphing programming, and a reprogrammable processor without reconnection. This work provides a facile way to create reprogrammable soft fluidic control systems to meet on‐demand requirements in dynamic situations. [ABSTRACT FROM AUTHOR]

Origami is a rich source of inspiration for creating soft actuators with complex deformations. However, implementing the re‐foldability of origami on soft actuators remains a significant challenge. Herein, a universal and programmable re‐foldability strategy is reported to integrate multiple origami patterns into a single soft origami actuator, thereby enabling multimode morphing capability. This strategy can selectively activate and deactivate origami creases through variable stiffness fibers. The utilization of these fibers enables the programmability of crease pattern quantity and types within a single actuator, which expands the morphing modes and deformation ranges without increasing their physical size and chamber number. The universality of this approach is demonstrated by developing a series of re‐foldable soft origami actuators. Moreover, these soft origami actuators are utilized to construct a bidirectional crawling robot and a multimode soft gripper capable of adapting to object size, grasping orientation, and placing orientation. This work represents a significant step forward in the design of multifunctional soft actuators and holds great potential for the advancement of agile and versatile soft robots. [ABSTRACT FROM AUTHOR]

Soft robots that incorporate elastomeric matrices and flexible materials have gained attention for their unique capabilities, surpassing those of rigid robots, with increased degrees of freedom and movement. Research has highlighted the adaptability, agility, and sensitivity of soft robotic actuators in various applications, including industrial grippers, locomotive robots, wearable assistive devices, and more. It has been demonstrated that bellow-shaped actuators exhibit greater efficiency compared to uniformly shaped fiber-reinforced actuators as they require less input pressure to achieve a comparable range of motion (ROM). Nevertheless, the mathematical quantification of the performance of bellow-based soft fluidic actuators is not well established due to their inherent non-uniform and complex structure, particularly when compared to fiber-reinforced actuators. Furthermore, the design of bellow dimensions is mostly based on intuition without standardized guidance and criteria. This article presents a comprehensive description of the quasi-static analytical modeling process used to analyze bellow-based soft actuators with linear extension. The results of the models are validated through finite element method (FEM) simulations and experimental testing, considering elongation in free space under fluidic pressurization. This study facilitates the determination of optimal geometrical parameters for bellow-based actuators, allowing for effective biomimetic robot design optimization and performance prediction. [ABSTRACT FROM AUTHOR]

Soft robotics faces challenges in attaining control methods that ensure precision from hard-to-model actuators and sensors. This study focuses on closed-chain control of a segment of PAUL, a modular pneumatic soft arm, using elastomeric-based resistive sensors with negative piezoresistive behaviour irrespective of ambient temperature. PAUL's performance relies on bladder inflation and deflation times. The control approach employs two neural networks: the first translates position references into valve inflation times, and the second acts as a state observer to estimate bladder inflation times using sensor data. Following training, the system achieves position errors of 4.59 mm, surpassing the results of other soft robots presented in the literature. The study also explores system modularity by assessing performance under external loads from non-actuated segments. [ABSTRACT FROM AUTHOR]

Biological species can walk, swim, fly, jump, and climb with fast response speeds and motion complexity. These remarkable functions are accomplished by means of soft actuation organisms, which are commonly composed of muscle tissue systems. To achieve the creation of their biomimetic artificial counterparts, various biomimetic stimuli-responsive materials have been synthesized and developed in recent decades. They can respond to various external stimuli in the form of structural or morphological transformations by actively or passively converting input energy into mechanical energy. They are the core element of soft actuators for typical smart devices like soft robots, artificial muscles, intelligent sensors and nanogenerators. Significant progress has been made in the development of bioinspired stimuli-responsive materials. However, these materials have not been comprehensively summarized with specific actuation mechanisms in the literature. In this review, we will discuss recent advances in biomimetic stimuli-responsive materials that are instrumental for soft actuators. Firstly, different stimuli-responsive principles for soft actuators are discussed, including fluidic, electrical, thermal, magnetic, light, and chemical stimuli. We further summarize the state-of-the-art stimuli-responsive materials for soft actuators and explore the advantages and disadvantages of using electroactive polymers, magnetic soft composites, photo-thermal responsive polymers, shape memory alloys and other responsive soft materials. Finally, we provide a critical outlook on the field of stimuli-responsive soft actuators and emphasize the challenges in the process of their implementation to various industries. [ABSTRACT FROM AUTHOR]

Soft robots have significant advantages in flexibility and adaptability and have potential applications in the field of engineering. Unlike traditional manufacturing methods, three-dimensional (3D) printing provides a fast way to fabricate customized and multi-functional robots. However, the fabrication of soft robots requires multimaterial printers and the high-accuracy multi-step assembly process. Among them, fused deposition modeling (FDM) technology has taken the lead compared to other 3D printing methods due to its ease of use, accuracy, and repeatability. However, the FDM multimaterial printing has not been thoroughly explored. Here, we proposed a rigid and flexible material integrated printing approach based on FDM 3D printing technology and reported a cable-driven flexible pipe robot based on Yoshimura origami crease patterns. The implementations show that the robot can realize four-direction bending effectively by the corresponding drive control, which indicates the feasibility of our design and manufacturing method. The proposed approach paves an effective way to design and fabricate the rigid-flexible robot and other devices in the future. [ABSTRACT FROM AUTHOR]