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1. Soft Robotic Snake Locomotion on Curved Surfaces

   https://doi.org/10.1177/21695172251395478  

   Arachchige, Dimuthu_D K; Perera, Dulanjana M; Huzaifa, Umer; Kanj, Iyad; Godage, Isuru S (December 2025, Soft Robotics)

   Snakes possess an extraordinary ability to traverse diverse terrains, thanks to their continuous bending and distributed surface contacts. While robotic snakes have replicated some of these locomotion capabilities, most existing designs rely on a rigid, articulated approach. However, the discrete nature of rigid-bodied construction poses challenges in maintaining a uniform distributed force, particularly when traversing curved surfaces. This article explores the locomotion potential of soft robotic snakes (SRSs) made primarily from soft, elastic materials, focusing on their ability to navigate curved surfaces. We introduce a novel locomotion gait specifically tailored for curved terrain, with parameterized movements to accommodate varying degrees of steepness. Recognizing the critical role of surface grip in locomotion on curved surfaces, we also present a mathematical model to adjust the gripping force exerted by distributed contacts, enhancing stability. Extensive experiments with our SRS prototype validate the effectiveness, viability, and robustness of the proposed locomotion strategies. Our findings pave the way for SRS applications in challenging environments such as cylindrical ducts, pipelines, and confined spaces, where traditional robotic systems may face limitations. 

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2. Magttice: a lattice model for hard-magnetic soft materials

   https://doi.org/10.1039/D0SM01662D  

   Ye, Huilin; Li, Ying; Zhang, Teng (January 2021, Soft Matter)

   null (Ed.)

   Magnetic actuation has emerged as a powerful and versatile mechanism for diverse applications, ranging from soft robotics, biomedical devices to functional metamaterials. This highly interdisciplinary research calls for an easy to use and efficient modeling/simulation platform that can be leveraged by researchers with different backgrounds. Here we present a lattice model for hard-magnetic soft materials by partitioning the elastic deformation energy into lattice stretching and volumetric change, so-called ‘magttice’. Magnetic actuation is realized through prescribed nodal forces in magttice. We further implement the model into the framework of a large-scale atomic/molecular massively parallel simulator (LAMMPS) for highly efficient parallel simulations. The magttice is first validated by examining the deformation of ferromagnetic beam structures, and then applied to various smart structures, such as origami plates and magnetic robots. After investigating the static deformation and dynamic motion of a soft robot, the swimming of the magnetic robot in water, like jellyfish's locomotion, is further studied by coupling the magttice and lattice Boltzmann method (LBM). These examples indicate that the proposed magttice model can enable more efficient mechanical modeling and simulation for the rational design of magnetically driven smart structures. 

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3. Multimodal Soft Robotic Actuation and Locomotion

   https://doi.org/10.1002/adma.202308829  

   Yao, Dickson R; Kim, Inho; Yin, Shukun; Gao, Wei (May 2024, Advanced Materials)

   Diverse and adaptable modes of complex motion observed at different scales in living creatures are challenging to reproduce in robotic systems. Achieving dexterous movement in conventional robots can be difficult due to the many limitations of applying rigid materials. Robots based on soft materials are inherently deformable, compliant, adaptable, and adjustable, making soft robotics conducive to creating machines with complicated actuation and motion gaits. This review examines the mechanisms and modalities of actuation deformation in materials that respond to various stimuli. Then, strategies based on composite materials are considered to build toward actuators that combine multiple actuation modes for sophisticated movements. Examples across literature illustrate the development of soft actuators as free‐moving, entirely soft‐bodied robots with multiple locomotion gaits via careful manipulation of external stimuli. The review further highlights how the application of soft functional materials into robots with rigid components further enhances their locomotive abilities. Finally, taking advantage of the shape‐morphing properties of soft materials, reconfigurable soft robots have shown the capacity for adaptive gaits that enable transition across environments with different locomotive modes for optimal efficiency. Overall, soft materials enable varied multimodal motion in actuators and robots, positioning soft robotics to make real‐world applications for intricate and challenging tasks. 

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4. Soft Tubular Strain Sensors for Contact Detection

   https://doi.org/10.1007/978-3-031-38857-6_16  

   Dai, Kevin; Elangovan, Abirami; Whirley, Karen; Webster-Wood, Victoria A (August 2023, Springer, Cham.)

   Sensing and actuation are intricately connected in soft robotics, where contact may change actuator mechanics and robot behavior. To improve soft robotic control and performance, proprioception and contact sensors are needed to report robot state without altering actuation mechanics or introducing bulky, rigid components. For bioinspired McKibben-style fluidic actuators, prior work in sensing has focused on sensing the strain of the actuator by embedding sensors in the actuator bladder during fabrication, or by adhering sensors to the actuator surface after fabrication. However, material property mismatches between sensors and actuators can impede actuator performance, and many soft sensors available for use with fluidic actuators rely on costly or labor-intensive fabrication methods. Here, we demonstrate a low-cost and easy-to manufacture-tubular liquid metal strain sensor for use with soft actuators that can be used to detect actuator strain and contact between the actuator and external objects. The sensor is flexible, can be fabricated with commercial-off-the-shelf components, and can be easily integrated with existing soft actuators to supplement sensing, regardless of actuator shape or size. Furthermore, the soft tubular strain sensor exhibits low hysteresis and high sensitivity. The approach presented in this work provides a low-cost, soft sensing solution for broad application in soft robotics. 

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5. FRESH-Printing of a Multi-actuator Biodegradable Robot Arm for Articulation and Grasping

   https://doi.org/10.1007/978-3-031-38857-6_10  

   Williamson, Avery S; Sun, Wenhuan; Sukhnandan, Ravesh; Coffin, Brian; Majidi, Carmel; Feinberg, Adam; Yao, Lining; Webster-Wood, Victoria A (August 2023, Springer, Cham.)

   The recent popularity of soft robots for marine applications has established a need for the reliable fabrication of actuators that enable locomotion, articulation, and grasping in aquatic environments. These actuators should also reduce the negative impact on sensitive ecosystems by using biodegradable materials such as organic hydrogels. Freeform Reversible Embedding of Suspended Hydrogels (FRESH) printing can be used for additive manufacturing of small-scale biologically derived, marine-sourced hydraulic actuators by printing thin-wall structures out of sustainably sourced calcium-alginate hydrogels. However, controlling larger alginate robots with complex geometries and multiple actuation mechanisms remains challenging due to the reduced strength of such soft structures. For tethered hydrogel hydraulic robots, a direct interface with fluid lines is necessary for actuation, but the drag forces associated with tethered lines can quickly overcome the actuation force of distal and extremity structures. To overcome this challenge, in this study, we identify printing parameters and interface geometries to allow the working fluid to be channeled to distal components of FRESH-printed alginate robots and demonstrate a proof-of-concept biodegradable robotic arm for small object manipulation and grasping in marine environments. 

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