Electrohydrodynamic (EHD) pumps generate fluid flow without mechanical moving parts, offering silent operation and scalability; they represent promising power sources for fluid‐driven robotic systems. Fiber pumps, a recently developed class of EHD pumps, employ double‐helix electrodes embedded along the inner wall of a tube. However, in conventional fiber pumps, only a portion of the electrode surface is exposed to the working fluid, which limits their output performance. This article proposes an EHD fiber pump with dual‐flow channels that enable fluid flow both inside and outside the electrodes, fully exposing the electrode surface. Pumps with the proposed design are fabricated and characterized. The proposed pump achieves a flow rate of 1327.1 mL/min and a pressure of 3.6 kPa at 10 kV, exhibiting improvements of up to 2.8‐fold in specific flow rate, 1.9‐fold in specific pressure, 5.7‐fold in power density, and 6.3‐fold in efficiency compared with a reference design inspired by traditional fiber pumps. To demonstrate the applicability of the proposed design to fluid‐driven systems, the pump is integrated into a soft robotic fish, which achieves swimming at 25.2 mm/s. These results highlight the effectiveness of the dual‐channel configuration and underscore the potential for enhancing the performance of EHD fiber pumps.

This study presents a biomimetic underwater robot driven by a quasi-direct-drive (QDD) actuation system designed to overcome the continuous torque limitations of conventional direct drive (DD) configurations. The QDD system integrates a brushless DC motor with a low-ratio $4: 1$ planetary gearbox, enabling efficient torque amplification while maintaining high responsiveness and mechanical simplicity. A robotic fish prototype was developed and experimentally characterized in terms of thrust force, tail beat amplitude, and swimming speed. Results demonstrated that the QDD configuration produced a peak thrust of approximately 52 N at 10 Hz, which was 2.7 times greater than that of the DD design. The QDD robot also maintained a tail beat amplitude of about 200 mm at 7 Hz and achieved a maximum swimming speed of $175 \mathrm{~mm} / \mathrm{s}$ at 5 Hz, representing a 16% improvement over the DD robot. These findings verify that the QDD actuation effectively enhances propulsion performance by sustaining large tail kinematics at high frequencies. The proposed QDD approach combines the structural simplicity and robustness of DD systems with improved torque capacity, offering a promising framework for high-performance and agile biomimetic underwater robots.

The use of mechanical metamaterials, which achieve unique structural properties through geometric patterns, could serve as an approach to designing the static shape and active deformations of dielectric elastomer actuators (DEAs). We present results from a preliminary investigation on the integration of mechanical metamaterials with DEAs. In our approach, thin, rigid plates are attached to a pre-stretched DEA as metamaterial elements, forming a three-dimensional shape and enabling out-of-plane actuation. We characterized the actuation performance of the metamaterial-reinforced DEAs, which exhibited active deformations as a function of the applied voltage, thereby illustrating the feasibility of the concept.

Tensegrity robots offer significant potential for disaster rescue and environmental monitoring. Traditional designs, however, rely on non-consumable electromechanical bodies that impose passive weight, reduce payload efficiency, and inevitably result in persistent electronic waste upon mission completion. To resolve this challenge, we propose a fully edible, power-autonomous, membrane-driven tensegrity robot that achieves a paradigm shift from a robot carrying food to a robot that is self-sustenance. The robot employs a stiff-compliant coupled architecture, utilizing food-grade cookies as compressive members and gelatin-based membranes as tensile elements. To enable electronics-free terrestrial locomotion, we integrated a fully edible pneumatic energy system that exploits the neutralization reaction between citric acid and sodium bicarbonate to generate carbon dioxide gas. This gas is modulated into pulsatile signals by a monostable fluidic logic valve, triggering out-of-plane expansion of the membrane surfaces. This expansion shifts the robot’s center of mass to induce a controllable rolling gait. Furthermore, the robot offers high metabolizable energy owing to its carbohydrate-rich composition (54.1 percent). To ensure biological safety, we conducted comprehensive evaluations ranging from in vitro simulated digestion to in vivo trials with live mice, confirming the system’s biocompatibility and metabolic integration. The proposed method provides a sustainable, zero-waste solution for wildlife vaccination, covert ecological monitoring, and autonomous emergency sustenance, effectively eliminating the ecological footprint of robotic deployment in sensitive environments. One-Sentence Summary A power-autonomous, fully edible tensegrity robot that shifts the paradigm from carrying food to being sustenance.

In this contribution, we introduce a biomimetic underwater robot integrated with quasi-direct-drive (QDD) actuation as a method to improve the swimming performance. For this purpose, a planetary gearbox is combined with a high-power brushless motor to ensure mechanical simplicity and high torque output. This QDD system is further integrated with a head and flexible body, forming a fish-type underwater robot working under a tethered condition. Experimental results show that both thrust force and tail amplitude are significantly enhanced compared to a robot without QDD, highlighting the strong potential of the proposed approach.

ABSTRACT Acrylic pressure‐sensitive adhesives (PSAs) and silicone elastomers are widely used in soft robotics; however, robust bonding between these dissimilar soft materials remains challenging without primers or stiff intermediate layers that compromise compliance. Because these materials provide complementary mechanical and functional properties, reliable integration is essential for expanding soft robot design freedom. Herein, a simple bonding method is presented that eliminates primers and stiff intermediate layers by combining oxygen‐plasma activation of the PSA with surfactant‐assisted interfacial activation of uncured silicone during curing. This approach enables strong bonding while preserving material compliance. The resulting interface achieves an adhesion strength of 0.4 N/mm, approximately fivefold higher than that of the control, while optimization of the surfactant concentration and plasma conditions increases it to 0.5 N/mm. Further optimization of curing conditions increases the adhesion strength to 1.61 N/mm, corresponding to an approximately twentyfold improvement over the control. The bonded interface retains over 90% of its adhesion strength after 72 h under both ambient storage and water immersion. Mechanical characterization confirms that the intrinsic compliance of the PSA and silicone elastomer is largely preserved. The applicability of the method is demonstrated using an electrically driven jellyfish robot that achieves underwater swimming at 2.5 mm/s.

Integrating silicone with non-extensible materials is a common strategy used in the fabrication of fluidically-driven soft actuators, yet conventional approaches often rely on irreversible adhesives or embedding processes that are labor-intensive and difficult to modify. This work presents silicone-glossy paper bonding (SGB), a rapid, adhesive-free, and solvent-reversible bonding approach that forms robust silicone-paper interfaces simply through contact. The SGB interface withstands high mechanical loads (shear strength > 61 kPa) and can be fully detached and reassembled via ethanol immersion without loss of performance, enabling component reuse and rapid redesign. Characterization studies indicate that surface functional groups primarily govern adhesion on the glossy paper and the modulus of the silicone, while durability and environmental response clarify the conditions for reversible debonding. The results further suggest a synergistic interaction of hydrogen bonding and oligomer diffusion, yielding strong yet reconfigurable adhesion. Soft actuators fabricated using SGB design exhibit equal or greater performance compared to conventional embedded-layer design and enable programmable actuation modes, including contraction, bending, and twisting. By simplifying fabrication while supporting reuse and rapid iteration, SGB offers a scalable and sustainable platform for rapid prototyping in soft robotics.

Soft robots are promising platforms for underwater exploration and biological sampling because of their compliance and adaptability. Dielectric elastomer actuators (DEAs), particularly bending DEAs, are appealing for underwater soft robots because they enable diverse robotic architectures. However, previously reported underwater bending DEAs still present opportunities for improvement in deformation capability, particularly in terms of deformation magnitude and actuation speed. Therefore, this paper presents an underwater DEA consisting of a layered elastomeric structure with an encapsulated water electrode and inextensible materials, which together generate unidirectional bending deformation when a high voltage is applied between the internal water electrode and the surrounding water. Consequently, the actuator achieves a maximum bending angle of 308.5° (corresponding to a curvature of 0.09/mm), which agrees well with predictions from an analytical model. Additionally, it attains an average actuation speed magnitude of 172.2°/s and a blocked force of 57.2 mN while maintaining stable actuation over 1000 cycles. The actuator was further demonstrated as an electrically driven biohybrid luminescent device incorporating Pyrocystis lunula and as a soft gripper capable of manipulating a live jellyfish. These results highlight the potential of the proposed DEA for advancing underwater soft robotic systems.

Soft robotics, a research field wherein robots are fabricated from compliant materials, has sparked widespread research interest because of its potential applications in a variety of scenarios. In soft robots, luminescence is an important functionality for communication and information transmission, and it is typically achieved through electroluminescence, which relies on synthetic substances activated by external electric sources, such as batteries. This paper focuses on the use of luciferase, a biologically derived luminescent enzyme, as a luminescent material. Bioluminescence, which is triggered by the luciferin-luciferase reaction, is highly energy-efficient, nontoxic, and eco-friendly. In this regard, a mammalian cell-derived secreted luciferase bioluminescent liquid was developed. This bioluminescent liquid is strongly bright, stable, freezable, and scalable for use as a soft robotic material. To investigate the applicability of this bioluminescent liquid to soft robotics, it was incorporated as an electrode in electrically driven soft actuators, sensors, and robots. Specifically, dielectric elastomer sensors (DESs) and dielectric elastomer actuators (DEAs) were fabricated and characterized using established fabrication processes. The resistivity of the bioluminescent liquid was found to be 448.1 Omegacm. When the DES was subjected to uniaxial strain, it exhibited a linear response and large deformation of up to 200% strain, with a simultaneous luminance change of 27%. The DEA displayed an areal strain of 46.0% and a luminance change of 31% at an applied voltage of 3.4 kV. The waterproof bending DEA generated a tip angle of 21.8 degrees at 10 kV and was applied to a jellyfish robot that could swim in water at a speed of 2.1 mm/s. The experimental results demonstrated the successful operation of these devices, validating the concept of energy-efficient, safe, and environmentally friendly bioluminescent soft robots.

Robots play an ever-expanding role in society by performing a broad range of tasks. However, there are growing concerns about their environmental sustainability, as many conventional robotic systems rely on materials that are neither renewable nor degradable. Consequently, significant efforts are being made to develop eco-friendly robots built from sustainable and biodegradable materials. In this context, plants represent a promising direction, as the biomaterials composing plants are biodegradable, and their inherent multifunctionality as living organisms, including sensing, actuation, energy harvesting, and self-healing, makes them strong candidates for realizing biodegradable robotic systems. Moreover, they are abundant and renewable resources. Recent studies have demonstrated plant-based robotic systems that harness some of these features, helping to establish plant robotics as an emerging research field. Among the many functions plants offer, actuation is pivotal, as it enables physical robotic motion, such as locomotion and grasping, which substantially broadens the potential applications of plant robots. Focusing on plant movement, this article reviews key plant species and their behaviors through the perspective of actuation characteristics. It also examines the current landscape of plant-based robotic systems and outlines future research directions in this rapidly growing field.

Edible robotics offers novel applications in which actuators play a key role. However, most existing edible actuators rely on 3D structures that require complex and laborious fabrication processes, hindering rapid prototyping and deployment. To address this issue, this study explores the use of planar configurations, specifically pouch motors, for edible actuators. These actuators are lightweight and can be fabricated quickly via heat sealing. Two types of edible pouch motors are developed using an agar‐based film: linear and angular actuators, and their actuation performances are characterized. The linear pouch motor (1.16 g) exhibits a strain of 30.6% and a force of 13.6 N at an input pressure of 5 kPa, demonstrating performance comparable to nonedible counterparts and durability up to 1000 actuation cycles. The angular pouch motor (0.42 g) achieves a rotation angle of 121.3° at 10 kPa and a torque of 0.11 N m at 16 kPa. Experimental results closely align with theoretical predictions. Furthermore, an edible pouch gripper (2.6 g) successfully performs a pick‐and‐place operation with a 97.0 g potato and fully dissolves in hot water while maintaining its grip. These findings validate the feasibility of planar edible actuators and highlight their potential for advancing future edible robotics.

Plants respond physically to external stimuli (such as light and electricity), and these stimuli-responsive physical behaviors facilitate plants being used as actuators for robotic systems. However, achieving robot mobility through plants remains challenging. Moreover, there is a lack of quantitative knowledge of the actuation characteristics of plants. In this study, to achieve the mobility of robots by plants, we employed Mimosa pudica as the target plant and investigated its actuation characteristics. Specifically, we focused on a specific part of the plant called the pinnule, which is a small leaf that exhibits the motions of closing and opening. The experimental results revealed that the average closing and opening times over the tested voltage were 4.5 s and 798 s, respectively. The measured force of the pinnule was up to 0.19 mN, which corresponded to a power density of 0.16 x 10(-3) W/kg. We then designed and fabricated a mobile robot that could locomote on the water surface by exploiting the rowing movement of the pinnules. The experimental results indicated that the robot (mass 0.5 g) was able to move on the water surface in response to the voltage input, exhibiting speeds of up to 3.3 x 10(2) mu m/s and a thrust force of up to 52.3 mu N. These values were in good agreement with the model predictions. The results of this study further promote the integration of plants into robots, advancing the development of sustainable, environmentally friendly robotics.

Electrohydrodynamic (EHD) pumps made from flexible or stretchable materials are a promising pumping element for fluidically driven soft robots. In most soft robotic systems, EHD pumps are used separately or connected in series with their target components, such as actuators, which can limit design flexibility and complicate implementation. To address this issue, this paper presents an EHD soft actuator that integrates a pump, actuator, and reservoir into a single device. In this design, the EHD pump is implemented as a flexible PCB, which also serves as a strain-limiting layer, enhancing bending actuation. Additionally, the interdigitated electrodes on the flexible PCB generate fringe electric fields, introducing electroadhesion as an unprecedented functionality for EHD-driven soft actuators. Experimental results from the fabricated actuators demonstrate voltage-controllable actuation, achieving a maximum bending angle of 56.0 degrees and a force of 31.0 mN. The actuators are then incorporated into a soft gripper, where electroadhesion enhances the holding force, with a 1.3x increase for a dielectric object and a 2.9x increase for a conductive object. These enhancements are observed in comparison to a control experiment in which gripping is performed using non-electric, fluidic actuation alone. The results validate the successful implementation of the highly integrated, multifunctional EHD soft actuator, highlighting its potential for soft robotic applications.

Electrohydraulic soft actuators exhibit large deformations and can operate with high speed and efficiency. In this study, we present a preliminary investigation of a multifunctional electrohydraulic soft actuator designed to enhance performance. By incorporating an interdigitated electrode design, the actuator enables both actuation and electroadhesion. Electroadhesion increases the frictional interaction between the device and contacted objects, making it particularly suitable for soft grippers, where adhesion forces improve the holding force. Experimental results demonstrate that the integrated actuator exhibits voltage-controllable actuation similar to traditional devices while also enabling electroadhesion, allowing it to hold an object even with a single actuator. These findings confirm the feasibility of the proposed actuator concept.

This paper presents a soft electrohydraulic actuator integrated with electrically controlled adhesion. Soft electrohydraulic actuators are a type of soft actuation technology known for their versatility and promising features, enabling the creation of diverse soft robotic systems. Integrating electroadhesion functionality into this actuation technology is expected to further enhance its versatility by making it multifunctional. In the actuator proposed in this study, electroadhesion is incorporated by modifying a partial domain of the electrode to have an interdigitated shape, which generates not only actuation but also electrostatic attractive forces to nearby objects simultaneously. Additionally, the geometry of the pouch is modified from a rectangular to a non-rectangular shape to stabilize actuated deformation. The experimental results clarified the actuation performance and electroadhesion forces of the proposed actuator, while a 23% improvement in holding force was observed in the form of a gripper, demonstrating the effectiveness of the actuator with intrinsic electroadhesion.

Electrohydraulic soft actuators are a promising soft actuation technology for constructing bio-inspired underwater robots owing to the features of this technology such as large deformations and forces, fast responses, and high electromechanical efficiencies. However, this actuation technology requires high voltages, thereby limiting the use of these actuators in water and hindering the development of underwater robots. This paper describes a method for creating bio-inspired underwater robots using silicone-layered electrohydraulic soft actuators. The silicone layer functions as an insulator, enabling the application of high voltages underwater. Moreover, bending and linear actuation can be achieved by applying the silicone layers on one or both sides of the actuator. As a proof of concept, bending and linear actuators with planar dimensions of 20 mm × 40 mm (length × width) are fabricated and characterized. Underwater actuation is observed in both types of actuators. The bending actuators exhibit a bending angle and blocked force of 39.0° and 9.6 mN, respectively, at an applied voltage of 10 kV. Further, the linear actuators show a contraction strain and blocked force of 6.6% and 956.1 mN, respectively, at an applied voltage of 10 kV. These actuators are tested at a depth near the surface of water. This ensured that they can operate at least at that depth. The actuators are subsequently used to implement various soft robotic devices such as a ray robot, a fish robot, a water-surface sliding robot, and a gripper. All of the robots exhibit movements as expected; up to 31.2 mm/s (0.91 body length/s) of locomotion speed is achieved by the swimming robots and a retrieve and place task is performed by the gripper. The results obtained in this study indicate the successful implementation of the actuator concept and its high potential for constructing bio-inspired underwater robots and soft robotics applications.