Reversible kink instability drives ultrafast jumping in nematodes and soft robots.

Entomopathogenic nematodes (EPNs) exhibit a bending-elastic instability, or kink, before becoming airborne, a feature hypothesized but not proven to enhance jumping performance. Here, we provide the evidence that this kink is crucial for improving launch performance. We demonstrate that EPNs actively modulate their aspect ratio, forming a liquid-latched closed loop over a slow timescale O (1 s), then rapidly open it O (10 µs), achieving heights of 20 body lengths (BL) and generating ∼ 10 4 W/Kg of power. Using jumping nematodes, a bio-inspired Soft Jumping Model (SoftJM), and computational simulations, we explore the mechanisms and implications of this kink. EPNs control their takeoff direction by adjusting their head position and center of mass, a mechanism verified through phase maps of jump directions in simulations and SoftJM experiments. Our findings reveal that the reversible kink instability at the point of highest curvature on the ventral side enhances energy storage using the nematode's limited muscular force. We investigated the impact of aspect ratio on kink instability and jumping performance using SoftJM, and quantified EPN cuticle stiffness with AFM, comparing it with C. elegans . This led to a stiffness-modified SoftJM design with a carbon fiber backbone, achieving jumps of ∼25 BL. Our study reveals how harnessing kink instabilities, a typical failure mode, enables bidirectional jumps in soft robots on complex substrates like sand, offering a novel approach for designing limbless robots for controlled jumping, locomotion, and even planetary exploration.

Soft robots equipped with multifunctionalities have been increasingly needed for secure, adaptive, and autonomous functioning in unknown and unpredictable environments. Robotic stacking is a promising solution to increase the functional diversity of soft robots, which are required for safe human-machine interactions and adapting in unstructured environments. However, most existing multifunctional soft robots have a limited number of functions or have not fully shown the superiority of the robotic stacking method. In this study, we present a novel robotic stacking strategy, Netting-Rolling-Splicing (NRS) stacking, based on a dimensional raising method via 2D-to-3D rolling-and-splicing of netted stackable pneumatic artificial muscles to quickly and efficiently fabricate multifunctional soft robots based on the same, simple, and cost-effective elements. To demonstrate it, we developed a TriUnit robot that can crawl 0.46 ± 0.022 body length per second (BL/s) and climb 0.11 BL/s, and can carry a 3 kg payload while climbing. Also, the TriUnit can be used to achieve novel omnidirectional pipe climbing including rotating climbing, and conduct bionic swallowing-and-regurgitating, multi-degree-of-freedom manipulation based on their multimodal combinations. Apart from these, steady rolling, with a speed of 0.19 BL/s, can be achieved by using a pentagon unit. Furthermore, we applied the TriUnit pipe climbing robot in panoramic shooting and cargo transferring to demonstrate the robot's adaptability for different tasks. The NRS stacking-driven soft robot here has demonstrated the best overall performance among existing stackable soft robots, representing a new and effective way for building multifunctional and multimodal soft robots in a cost-effective and efficient way.

Soft robotics has emerged as a promising technology that holds great potential for various application areas. This is due to soft materials unique properties, including flexibility, safety, and shock absorption, among others. Despite many advancement in the field, the development of effective design methodologies and production techniques for soft robots remains a challenge. Although numerous robot prototypes have been proposed in recent years, their designs are often complex and difficult to produce. As such, there is a need for more efficient and unified design approaches that can facilitate the production of soft robots with desirable properties. In this paper, we propose a method for designing soft robots using elastic beams and spatial compliant mechanisms. The method is based on an evolutionary approach that enables the creation of designs with both high motion and force transmission ratios. Specifically, we focus on the development of locomotion mechanisms using a central linear actuator. Our approach involves the use of commonly available plastic materials and a 3D printer to manufacture the designs. We demonstrate the feasibility of our approach by presenting experimental results that show successful production and realworld operation. Overall, our findings suggest that the use of elastic beams and an evolutionary approach can facilitate the creation of soft robots with desirable locomotion properties, including fast locomotion up to 3.7 body lengths per second, locomotion with a payload, and underwater locomotion. This method has the potential to enable the development of more efficient and practical soft robots for various applications.

In this paper we present the design of a fin-like dielectric elastomer actuator (DEA) that drives a miniature autonomous underwater vehicle (AUV). The fin-like actuator is modular and independent of the body of the AUV. All electronics required to run the actuator are inside the 100 mm long 3D-printed body, allowing for autonomous mobility of the AUV. The DEA is easy to manufacture, requires no pre-stretch of the elastomers, and is completely sealed for underwater operation. The output thrust force can be tuned by stacking multiple actuation layers and modifying the Young's modulus of the elastomers. The AUV is reconfigurable by a shift of its center of mass, such that both planar and vertical swimming can be demonstrated on a single vehicle. For the DEA we measured thrust force and swimming speed for various actuator designs ran at frequencies from 1 Hz to 5 Hz. For the AUV we demonstrated autonomous planar swimming and closed-loop vertical diving. The actuators capable of outputting the highest thrust forces can power the AUV to swim at speeds of up to 0.55 body lengths per second. The speed falls in the upper range of untethered swimming robots powered by soft actuators. Our tunable DEAs also demonstrate the potential to mimic the undulatory motions of fish fins.

Cheetahs achieve high-speed movement and unique athletic gaits through the contraction and expansion of their limbs during the gallop. However, few soft robots can mimic their gaits and achieve the same speed of movement. Inspired by the motion gait of cheetahs, here the resonance of double spiral structure for amplified motion performance and environmental adaptability in a soft-bodied hopping micro-robot is exploited. The 0.058g, 10mm long tethered soft robot is capable of achieving a maximum motion speed of 42.8 body lengths per second (BL/s) and a maximum average turning speed of 482° s-1 . In addition, this robot can maintain high speed movement even after flipping. The soft robot's ability to move over complex terrain, climb hills, and carry heavy loads as well as temperature sensors is demonstrated. This research opens a new structural design for soft robots: a double spiral configuration that efficiently translates the deformation of soft actuators into swift motion of the robot with high environmental adaptability.

Soft robots show excellent body compliance, adaptability, and mobility when coping with unstructured environments and human-robot interactions. However, the moving speed for soft locomotion robots is far from that of their rigid partners. Rolling locomotion can provide a promising solution for developing high-speed robots. Based on different rolling mechanisms, three rolling soft robot (RSR) prototypes with advantages of simplicity, lightweight, fast rolling speed, good compliance, and shock resistance are fabricated by using dielectric elastomer actuators. The experimental results demonstrate that the impulse-based and gravity-based RSRs can move both stably and continuously on the ground with a maximum speed higher than 1 blps (body length per second). The ballistic RSR exhibits a high rolling speed of ∼4.59 blps. And during its accelerating rolling process, the instantaneous rolling speed of the robot prototype reaches about 0.65 m/s (13.21 blps), which is much faster than most of the previously reported locomotion robots driven by soft responsive materials. The structure design and implementation methods based on different rolling mechanisms presented can provide guidance and inspiration for creating new, fast-moving, and hybrid mobility soft robots.

Light is increasingly being used to drive soft robots and soft actuators. In this paper, a light-driven soft robot with compound motion patterns based on gas-liquid phase transition chamber is proposed, which inspired by the frog and the larvae of gall midges. When a light source with a power density of about 1.25 W/cm2 is illuminated on the upper surface of the auxiliary pneumatic chamber, the previously non-existent main pneumatic chamber can be expanded quickly within less than 3 s, and generate enormous thrust. This allows the soft robot (length: 3 cm; width: 0.7 cm; weight: 0.36 g) to quickly release from the magnet attractive field and perform a jump with a height of 50.8 cm in less than 1 s, approximately 16 times the body length of the entire soft robot. The proposed soft robot can also be combined with a photothermal bending film to achieve directional crawling. At the same time, by fixing the foot of the soft robot on the base and using light irradiate it, an object weighing about 5 times the overall weight can be ejected to a horizontal distance of 16.9 cm. This untethered pneumatic soft robot has broad prospects in soft jumping robots and wireless actuators, and the proposed pneumatic triggered chamber can also be further applied to other application fields.

Jumping is an important locomotion function to extend navigation range, overcome obstacles, and adapt to unstructured environments. In that sense, continuous jumping and direction adjustability can be essential properties for terrestrial robots with multimodal locomotion. However, only few soft jumping robots can achieve rapid continuous jumping and controlled turning locomotion for obstacle crossing. Here, we present an electrohydrostatically driven tethered legless soft jumping robot capable of rapid, continuous, and steered jumping based on a soft electrohydrostatic bending actuator. This 1.1 g and 6.5 cm tethered soft jumping robot is able to achieve a jumping height of 7.68 body heights and a continuous forward jumping speed of 6.01 body lengths per second. Combining two actuator units, it can achieve rapid turning with a speed of 138.4° per second. The robots are also demonstrated to be capable of skipping across a multitude of obstacles. This work provides a foundation for the application of electrohydrostatic actuation in soft robots for agile and fast multimodal locomotion.

Soft robotic bodies are susceptible to mechanical fatigue, punctures, electrical breakdown, and aging, which can result in the degradation of performance or unexpected failure. To overcome these challenges, a soft self-healing robot is created using a thermoplastic methyl thioglycolate-modified styrene-butadiene-styrene (MG-SBS) elastomer tube fabricated by melt-extrusion, to allow the robot to self-heal autonomously at room temperature. After repeated damage and being separated into several parts, the robot is able to heal its stiffness and elongation to break to enable almost complete recovery of robot performance after being allowed to heal at room temperature for 24 h. The self-healing capability of the robot is examinedacross the material scale to robot scale by detailed investigations of the healing process, healing efficiency, mechanical characterization of the robot, and assessment of dynamic performance before and after healing. The self-healing robot is driven by a new micro two-way shape-memory alloy (TWSMA) spring actuator which achieved a crawling speed of 21.6cm/min, equivalent to 1.57 body length per minute. An analytical model of the robot is created to understand the robot dynamics and to act as an efficient tool for self-healing robot design and optimization. This work therefore provides a new methodology to create efficient, robust, and damage-tolerant soft robots.

Natural animals always provide inspirations for soft robot designs, and the evolved locomotion mechanisms perfectly adapted to specific environments motivate a lot of robots to pursue superior mobility. The small stomatopod named Nannosquilla decemspinosa possesses a unique form of locomotion—backward somersaulting which allows the animal to move flexibly and rapidly on soft and moist sand. In this letter, we present a bio-inspired dynamic somersaulting soft robot (SomBot) with ultra-fast moving speed (maximum speed is over 0.94 m/s). To mimic the unique somersaulting of the stomatopod, a simple prototype containing a pneu-net actuator body and a suction is developed. With the help of the controllable anchoring exerted by the suction, the curling deformation of the body actuator can be converted into the fast somersaulting movements. The dynamic somersaulting mechanism is modelled and analyzed. Deformation tests are conducted for the body actuator to provide guidance for the somersaulting control. The fully soft SomBot prototype exhibits a much faster speed (9.2 body lengths per second) than the reported fast-moving soft robots, which demonstrates the dynamic somersaulting mechanism has great potential for designing soft locomotion robots with superior mobility.

Conventional catheter- or probe-based in vivo biomedical sensing is uncomfortable, inconvenient, and sometimes infeasible for long-term monitoring. Existing implantable sensors often require an invasive procedure for sensor placement. Untethered soft robots with the capability to deliver the sensor to the desired monitoring point hold great promise for minimally invasive biomedical sensing. Inspired by the locomotion modes of snakes, we present here a soft kirigami robot for sensor deployment and real-time wireless sensing. The locomotion mechanism of the soft robot is achieved by kirigami patterns that offer asymmetric tribological properties that mimic the skin of the snake. The robot exhibits good deployability, excellent load capacity (up to 150 times its own weight), high-speed locomotion (0.25 body length per step), and wide environmental adaptability with multimodal movements (obstacle crossing, locomotion in wet and dry conditions, climbing, and inverted crawling). When integrated with passive sensors, the versatile soft robot can locomote inside the human body, deliver the passive sensor to the desired location, and hold the sensor in place for real-time monitoring in a minimally invasive manner. The proof-of-concept prototype demonstrates that the platform can perform real-time impedance monitoring for the diagnosis of gastroesophageal reflux disease.

Theoretical and empirical work indicates that the central nervous system is able to stabilize motor performance by selectively suppressing task-relevant variability (TRV), while allowing task-equivalent variability (TEV) to occur. During unperturbed bipedal standing, it has previously been observed that, for task variables such as the whole-body center of mass (CoM), TEV exceeds TRV in amplitude. However, selective control (and correction) of TRV should also lead to different temporal characteristics, with TEV exhibiting higher temporal persistence compared to TRV. The present study was specifically designed to test this prediction. Kinematics of prolonged quiet standing (5 minutes) was measured in fourteen healthy young participants, with eyes closed. Using the uncontrolled manifold analysis, postural variability in six sagittal joint angles was decomposed into TEV and TRV with respect to four task variables: (1) center of mass (CoM) position, (2) head position, (3) trunk orientation and (4) head orientation. Persistence of fluctuations within the two variability components was quantified by the time-lagged auto-correlation, with eight time lags between 1 and 128 seconds. The pattern of results differed between task variables. For three of the four task variables (CoM position, head position, trunk orientation), TEV significantly exceeded TRV over the entire 300 s-period.The autocorrelation analysis confirmed our main hypothesis for CoM position and head position: at intermediate and longer time delays, TEV exhibited higher persistence than TRV. Trunk orientation showed a similar trend, while head orientation did not show a systematic difference between TEV and TRV persistence. The combination of temporal and task-equivalent analyses in the present study allow a refined characterization of the dynamic control processes underlying the stabilization of upright standing. The results confirm the prediction, derived from computational motor control, that task-equivalent fluctuations for specific task variables show higher temporal persistence compared to task-relevant fluctuations.

We present the first report of Heterorhabditis bacteriophora entomopathogenic nematodes isolated from sandy loam soil obtained from Walkerville, South of Johannesburg, Gauteng province, South Africa. A survey was conducted to collect soil samples and isolate entomopathogenic nematodes between 2012 and 2016. Entomopathogenic nematodes are insect-killing microscopic worms found in soil and have a symbiotic relationship with insect pathogenic bacteria. Molecular and morphological techniques including genomic DNA extractions, polymerase chain reaction and sequencing of the 18S rDNA, phylogenetic analysis, light microscopy and scanning electron microscopy were used to identify entomopathogenic nematodes from the collected soil samples. H. bacteriophora was recovered in one out of 80 soil samples from an uncultivated grassland and the frequency of its isolation from soil samples in our study was 2%. Phylogenetic tree analysis revealed that the South African isolate was grouped with the strain H. bacteriophora strain 56-C. H. bacteriophora. The body length, body width and tail of the isolate are slightly shorter than the previously described H. bacteriophora. This is the first H. bacteriophora species to be isolated and reported from South African soil and future studies will explore its potential as a biological control agent of problematic insect pests in agricultural industries.

Entomopathogenic nematodes (EPNs) are microscopic roundworms used in biocontrol. EPNs are obligate insect parasites, they live in soil, and they are especially effective against soilborne insects. They are a good alternative to chemical pesticides thanks to their advantages, such as prolonged longevity, broad host range and mass production suitability. However, EPNs cannot compete with chemical pesticides due to high production costs and short shelf life. The aim of this study was to determine the reproduction capacity of the Turkish hybrid Heterorhabditis bacteriophora Poinar, 1976 (Rhabditida: Heterorhabditidae) HBH strain and then compare it with its parents to improve its liquid culture yield. In this way, it is aimed to reveal the effects behind the high reproduction potential of the hybrid HBH strain. All experiments were performed at Bursa Uludağ University, Faculty of Agriculture, Department of Plant Protection, in 2020. All cadavers were periodically dissected, hermaphrodites were counted and their body lengths were measured. Compared to its parents, the hybrid HBH strain had greater hermaphrodite counts, with mean 66 individuals within 12 days, and hermaphrodite body length, with mean 3.88 mm. The results obtained from this study should provide information for commercial EPN production development.

Soft robots typically exhibit limited agility due to inherent properties of soft materials. The structural design of soft robots is one of the key elements to improve their mobility. Inspired by the Archimedean spiral geometry in nature, here, a fast‐moving spiral‐shaped soft robot made of a piezoelectric composite with an amorphous piezoelectric vinylidene fluoride film and a layer of copper tape is presented. The soft robot demonstrates a forward locomotion speed of 76 body length per second under the first‐order resonance frequency and a backward locomotion speed of 11.26 body length per second at the third‐order resonance frequency. Moreover, the multitasking capabilities of the soft robot in slope climbing, step jumping, load carrying, and steering are demonstrated. The soft robot can escape from a relatively confined space without external control and human intervention. An untethered robot with a battery and a flexible circuit (a payload of 1.665 g and a total weight of 1.815 g) can move at an absolute speed of 20 mm s−1 (1 body length per second). This study opens a new generic design paradigm for next‐generation fast‐moving soft robots that are applicable for multifunctionality at small scales.