A Fast Bipedal Biohybrid Crawler Driven by Single Muscle Swinging.

A systematic trend analysis of 3D printing techniques used in specific soft robotic elements

Distinguished from traditional robots made of rigid materials, soft robots have great potential in fields such as human–robot interaction and biomedical applications due to their mechanical pliability. Soft actuators are one of the most important components in soft robotics systems and can be activated by external stimuli such as heat, light, humidity, electric fields, or magnetic fields. Among them, magnetically responsive soft actuators composed of strong magnetic composite can achieve multi‐degree‐of‐freedom wireless remote control and reversible driving action, which have considerable application potential. In this perspective, we first discuss the properties and actuation mechanisms of the strong‐magnetic flexible composites. Then, the preparation method of magnetic actuators by strong‐magnetic flexible composites are briefly introduced. Next, various applications of magnetically responsive soft actuators, such as grasping, walking, swimming, and sensing control, are highlighted. Finally, current opportunities and challenges for stimulus‐responsive soft robots are discussed. This review provides scientists with the latest technological advances and information needed to design and develop the next generation of soft bionic robotic systems, and further demonstrates the future applications of these robots are vast and promising.

Conventional robots are constructed with rigid parts and materials, restricting their ability to deform freely and adapt to the external environment. Performing tasks such as handling delicate materials and navigating narrow pathways is challenging for these typical robots made of stiff materials. However, there is a growing demand for such functions in various industries. Recent advances in soft robotics have garnered considerable attention as solutions to these challenges. Soft robotic systems in various forms present a systematic solution for performing unique tasks. The goal of soft robotics research is to develop advanced technologies, incorporating innovative robotic mechanisms based on soft materials and structures to enhance adaptability. Soft robots find broad applications in diverse fields, including industry, healthcare, and field exploration. Soft component technology plays a crucial role in configuring soft robots. Soft actuators introduce new types of motion and operation mechanisms, while soft sensors measure the deformation of the actuators with a tiny stiffness change. These advancements in soft actuators and sensors encourage researchers to explore new robotic designs and applications. Additionally, the component technology enables the integration of soft and typical robots into hybrid B Youngsu Cha

Robots are traditionally confined to controlled environments such as factories, where human interactions are limited. However, the demand for robots that are capable of collaborating with humans is increasing. To achieve symbiosis, integrating the physical flexibility and environmental adaptability of living organisms into robotic systems is crucial. An example of such a robot is a biohybrid robot driven by three-dimensional (3D) cultured skeletal muscle cells. These muscle cells, which are composed of myoblasts and an extracellular matrix (ECM), contract and generate force in response to external stimuli. The standardization of such 3D-cultured skeletal muscle cells is essential for practical applications. However, their complete standardization has not yet been achieved. The contractile force of 3D-cultured skeletal muscle cells produced via 3D printing is still insufficient for practical applications as actuators in biohybrid robots. In a previous study, we developed a simple fabrication method for 3D-cultured skeletal muscle cells. These bio-cultured artificial muscle (BiCAM) cells can control the shape and cell alignment of tissues. Differences in the composition of an ECM have been suggested to affect the contractile force of 3D skeletal muscle tissues; however, their impact on the response characteristics remains poorly understood. In this study, we investigated how the ECM composition influences the contractile force of 3D skeletal muscle cells in biohybrid robots as a step toward their eventual standardization. Compared with tissues cultured under MF conditions, in which electrically induced contraction was previously confirmed, tissues cultured under CM conditions exhibited an approximately two-fold greater contractile force at voltage amplitudes of 10 and 30 V. Furthermore, the fabrication success rate was 100 under CM conditions but only 62.5-70 under other ECM conditions. In contrast, although CM tissues generated larger forces, tissues cultured under MgF and CMg conditions exhibited higher-frequency response. These findings demonstrated that the BiCAM is a viable actuator and offers new possibilities for the design of biohybrid robots.

Millions of years’ evolution has imparted life on earth with excellent environment adaptability. Of particular interest to scientists are some plants capable of macroscopically and reversibly altering their morphological and mechanical properties in response to external stimuli from the surrounding environment. These intriguing natural phenomena and underlying actuation mechanisms have provided important design guidance and principles for man-made soft robotic systems. Constructing bio-inspired soft robotic systems with effective actuation requires the efficient supply of mechanical energy generated from external inputs, such as temperature, light, and electricity. By combining bio-inspired designs with stimuli-responsive materials, various intelligent soft robotic systems that demonstrate promising and exciting results have been developed. As one of the building materials for soft robotics, hydrogels are gaining increasing attention owing to their advantageous properties, such as ultra-tunable modulus, high compliance, varying stimuli-responsiveness, good biocompatibility, and high transparency. In this review article, we summarize the recent progress on plant-inspired soft robotics assembled by stimuli-responsive hydrogels with a particular focus on their actuation mechanisms, fabrication, and application. Meanwhile, some critical challenges and problems associated with current hydrogel-based soft robotics are briefly introduced, and possible solutions are proposed. We expect that this review would provide elementary tutorial guidelines to audiences who are interested in the study on nature-inspired soft robotics, especially hydrogel-based intelligent soft robotic systems.

More than 130,000 people have strokes each year in the United States [1]. Of these victims, 76% are left with disabilities that cost the nation over $54 billion in lost work and medical fees. One prominent disability is upper extremity hemiplegia, which occurs among approximately 50% of stroke sufferers [2]. Robotic technology has the potential to provide an automated platform for controlled rehabilitation and assisted, task-oriented therapy. Several systems have been designed to assist in patient articulation of an impaired hand using rigid robotic components. While these products have been successful in articulating the pure bending motions of the four fingers, the limited capabilities of rigid technologies fail to reproduce the complicated motion path [5] of the thumb during opposition grasp (see Figure 1). This is the most important articulation for normal hand function and specifically for picking up everyday objects. To date, robotic systems for thumb rehabilitation have not been widely investigated [3] apart from some recent work [4] that used a multi-joint rigid robot.

Ultrasound imaging procedures are deemed as one of the most convenient and least invasive medical diagnostic imaging modalities and have been widely utilized in health care providers, which are expecting semiautomatic or fully-automatic imaging systems to reduce the current clinical workloads. This paper presents a portable and wearable soft robotic system which has been designed with the purpose of replacing the manual operation to cooperatively steer the ultrasound probe. This human-compliant soft robotic system, which is equipped with four separated parallel soft pneumatic actuators and is able to achieve movements in three directions. Vacuum suction force is introduced to attach the robot onto the intended body location. The design and fabrication of this soft robotic system are illustrated. To our knowledge, this is the first body-attached soft robot for compliant ultrasound imaging. The feasibility of the system is demonstrated through proof-of-concept experiments.

Asymmetric bending enables rapid and efficient crawling motions in a soft robotic system. However, achieving asymmetric motion in soft robots with temperature‐responsive liquid crystal elastomers (LCEs) necessitates complex Joule heating configurations or precise temperature regulation. Herein, a simple electroless plating method is presented for patterning asymmetric temperature gradients on paper substrates, thereby facilitating the development of Joule heating, caterpillar‐inspired soft robots. Cellulose‐based paper substrates provide distinct advantages due to their porous structure, which enables facile electrode deposition via solution‐based processes and offers high mechanical deformability. Leveraging these material properties, Cu electrodes are asymmetrically deposited onto paper substrates by varying electrode widths. This variation induces differences in electrical resistance, generating significant temperature gradients across the substrate. Furthermore, it is demonstrated that temperature gradients could be modulated by adjusting the extent of Cu enhancement in the electrode patterns. it is fabricated energy‐efficient soft robots capable of directional crawling at a low actuation voltage of 0.5 V by integrating the paper substrate with LCEs in a bilayer architecture. The simplicity of the electrode patterning process, combined with the eco‐friendly nature of paper‐based actuators, presents a promising approach for the scalable and sustainable fabrication of soft robots with complex locomotion capabilities.

Driving cycle construction has become more popular around the world to estimate pollution emission and traffic analysis. This paper presents the traffic based analysis related to performance of B128 and B130 route in Galle, Sri Lanka using basic traffic engineering parameters such as travel time, average and maximum speed, average acceleration and deceleration. So the main objective of this paper is to identify traffic related parameters of above routes at Galle. The driving data was collected using on board measurement method by installing a prototype GPS tracking device in light-duty cars (AXIO, AQUA, FIT, Vitz). The cycle construction was done according to the segment based cycle construction method and roads were segmented considering the major intersections. Driving cycles were constructed for morning peak, noon peak, evening peak and off peak hours in B130 route and off peak hours in B128 route and the travel time, average speed, maximum speed, average acceleration and average deceleration were obtained. According to results, the maximum average speed of 27.53 km/h was obtained at off peak hours and travel time of 892s is taken to travel from Hapugala junction to Galle in noon peak hours. However the maximum speed was obtained at noon peak hours.

Soft robots are capable of mimicking the complex motion of animals. Soft robotic systems are defined by their compliance, which allows for continuous and often responsive localized deformation. These features make soft robots especially interesting for integration with human tissues, for example, the implementation of biomedical devices, and for robotic performance in harsh or uncertain environments, for example, exploration in confined spaces or locomotion on uneven terrain. Advances in soft materials and additive manufacturing technologies have enabled the design of soft robots with sophisticated capabilities, such as jumping, complex 3D movements, gripping and releasing. In this Review, we examine the essential soft material properties for different elements of soft robots, highlighting the most relevant polymer systems. Advantages and limitations of different additive manufacturing processes, including 3D printing, fused deposition modelling, direct ink writing, selective laser sintering, inkjet printing and stereolithography, are discussed, and the different techniques are investigated for their application in soft robotic fabrication. Finally, we explore integrated robotic systems and give an outlook for the future of the field and remaining challenges.

The use of soft robots to interact with soft, fragile, and even living things has spurred interest in the development of soft robotic systems that can deform and adapt themselves to their environment through their inherent compliance. Current soft pneumatic actuator concepts require significant redesign to be repurposed from one function to another, and a complete soft robotic system may be composed of multiple types of actuators with varying materials, designs, and manufacturing methods. This complicates the process of designing and manufacturing soft robots that can tackle new tasks and environments. This work introduces a repeatable pattern of pouch motors with geometric constraints allowing the actuator to produce a programmable bending deformation. By varying the dimensions of the pattern, it is possible to produce different motions that can be used to build diverse robotic components, such as a soft robotic arm or a large soft robotic gripper.

Hamstring muscle strains are one of the most frequent injuries in sports. They are thought to occur during the late swing phase of gait when the hamstring is lengthening and eccentrically contracting. PURPOSE: The purpose of this study was to assess the difference in injury risks during testing at maximum and sub-maximum speeds by identifying kinematic differences at the hip and knee during the late swing phase of both speeds. METHODS: Ten athletes (21.8 ±3.5 years, 1.78 ± 0.07m, 78.11 ± 13.90kg) with no history of lower extremity injuries in the past 6 months, who could run faster than 6.83m/s were tested. Informed consent was obtained prior to testing. Kinematic data was collected using an 8 camera motion capture system sampling at 240Hz. Five maximum speed trials were conducted, after which an average speed was calculated and 90% of this speed was used for the 5 sub-maximal speed trials. Sprinting speed was monitored using two sets of infrared photocells. Subjects ran within ±5% of the indicated speed for all trials. Analysis was performed on one gait cycle for each subject's dominant limb. A series of paired t-test were used to test for significant differences between the two test speeds (α=0.05). RESULTS: Significant differences existed between maximum and sub-maximum running speeds (p<0.01). The average stance phase as a percentage of the gait cycle was 16.96% and 18.17% for maximum and sub-maximum speeds, respectively (p=0.004). The maximum hip flexion angle was significantly larger for the maximum speed (76.97o) when compared to the sub-maximum (74.25o) speed (p=0.01). The knee flexion angle at the point of maximum hip flexion were 78.98° and 75.98° for the maximum and sub-maximum sprinting speeds, respectively (p=0.02). Therefore, the knee was more extended during the sub-maximum sprinting speed. The average stride length during sub-maximum sprinting was significantly longer than the stride length during the maximum sprinting speed (p=0.008). CONCLUSIONS: Based on the results of this study, joint kinematics are different between the maximum and sub-maximum speeds indicating the importance of completing biomechanical testing at a maximum speed when assessing the potential for hamstring injuries.

The development of accurate sensing strategies for soft robotic systems represents an ongoing challenge. In general, it is difficult to integrate a sensory system that preserves the robot's compliance while simultaneously providing accurate measurements. Dielectric elastomer (DE) transducers offer a potential solution to this problem owing to their ability to function as soft actuators and sensors at the same time, thus enabling the realization of self-sensing soft robotic systems. In this work, we propose a bi-modal sensory scheme for a DE-based soft robot, which allows simultaneous estimation of the robot's own configuration and detection of external contacts without relying on any external sensors. Self-sensing proprioception and contact detection are performed at the same time while actuating the robot, based on online processing of electrical signals measured directly at the actuators' level, i.e., DEs' voltage and current. Both estimation tasks are achieved in real time by means of artificial neural networks. After describing the system and the bi-modal self-sensing architecture, the approach is validated experimentally on a DE soft robot.

Soft robots powered by sustainable energy abundantlyavailableon Earth, such as heat, humidity, sunlight, osmotic potential, pHvariation, triboelectricity, and wind, represent a promising shifttoward eco-friendly and autonomous robotic systems. Efficiency dependson selecting and engineering responsive materials that directly transformenvironmental stimuli into mechanical actuation and motion, or harvestand store environmental energy to power actuators. Thermo-responsivematerials undergo shape changes with temperature variations, whilehygroscopic materials leverage moisture adsorption to induce actuation.Photothermal materials convert sunlight into heat and can combinethermal or hygroscopic actuators for controlled deformation. Osmoticprocesses drive movement through fluidic interactions, whereas pH-sensitivehydrogels respond to chemical gradients, facilitating controlled motion.Triboelectric materials generate electricity via contact-induced chargetransfer, enabling self-powered sensing and actuation, while wind-dispersedstructures exploit aerodynamic forces for unique movements. This reviewexplores the critical roles of chemical, physical, mechanical, andenvironmental properties of materials in designing soft robots forsustainable and autonomous operation. Importantly, the review distinguishesbetween the broad concept of environmental energy and operation thatis energetically sustainable. It systematically evaluates reportedactuators and soft robotic systems based on whether their requiredenergy sources and operating conditions are naturally occurring andregenerable, or instead depend on restricted environmental ranges,auxiliary inputs, or laboratory-controlled conditions. By examiningmaterial behavior, integration into multifunctional composites, andmechanism design for exploiting sustainable energy, this review identifiesboth established and emerging pathways toward environmentally realistic,autonomous, and long-lived soft robotic systems, with potential applicationsin environmental monitoring, reforestation, and other robotic domains.

This paper presents a novel piezoelectric‐driven and sensing soft robot designed to address the lack of intrinsic sensing capabilities in soft robotic systems. While significant progress is made in soft robot locomotion, most designs still rely on external sensors or complex embedded systems for environmental perception, increasing system complexity, weight, and energy consumption. Developing soft robots with integrated sensing functionalities is crucial for enhancing autonomous interaction and detection, particularly in unstructured environments. The proposed robot features a PVDF/Cu‐based piezoelectric flexible actuator and two asymmetrical arc‐shaped legs, fabricated using a simple and cost‐effective process. Finite element simulations and experiments reveal that its motion is influenced by structural dimensions, voltage amplitude, frequency, and waveform. The optimal configuration—11 mm body length, 6 mm rear leg, 4 mm front leg, 200 Vpp, and ≈100.56 Hz resonance frequency—enables slope climbing, obstacle traversal, and load carrying. Beyond locomotion, the robot leverages the inverse piezoelectric effect to sense mechanical wave signals, similar to how spiders detect web vibrations. By analyzing wave amplitudes, it identifies excitation sources, demonstrating potential for structural health monitoring, environmental sensing, and intelligent micro‐robotics.