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Navigating and exploring the surfaces of bodies of water allow swimming robots to perform a range of measurements while efficiently communicating and harvesting energy from the Sun. Such environments are often highly unstructured and cluttered with plant matter, animals, and debris, which require robots to move swiftly. We report a fast (5.1 centimeters per second translation and 195 degrees per second rotation), centimeter-scale swimming robot with high maneuverability and autonomous untethered operation. Locomotion is enabled by a pair of soft, millimeter-thin, undulating pectoral fins, in which traveling waves are electrically excited to generate propulsion. The actuators, robot design, and power supply are codesigned to enable high-performance locomotion in a scaled-down system. A single soft electrohydraulic actuator per side generates the traveling wave. A compact and lightweight power supply enables untethered operation, made possible by decreasing the operating voltage of the electrohydraulic actuators to below 500 volts and their power consumption to 35 milliwatts. By an experimental study and by modeling, we determined optimum dimensions and operating conditions across designs and size scales. The robots navigate through narrow spaces and through grassy plants and push objects weighing more than 16 times their body weight. Such robots can allow exploration of complex environments as well as continuous measurement of plant and water parameters for aquafarming.
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http://dx.doi.org/10.1126/scirobotics.adr0721 | DOI Listing |
Trends Biotechnol
September 2025
Czech Advanced Technology and Research Institute (CATRIN), Palacký University Olomouc, Šlechtitelů 27, 77900, Olomouc, Czech Republic; Nanotechnology Centre, Centre for Energy and Environmental Technologies, Technical University of Ostrava (VSB), 17 Listopadu 2172/15, 70800 Ostrava, Poruba, Czech
Exploring mobility beyond traditional robotic systems such as walking, swimming, and jumping, flight through dispersal, gliding, or hovering remains an untapped frontier for advanced stimulus-responsive and -sensing materials. Nature-inspired engineering has been a foundational aspect of robotic innovations, and biohybrid and biomimetic flying seeds are now becoming a significant example of this concept. By mimicking the aerodynamic properties and dispersal mechanisms of natural seeds, semi- and fully artificial systems are being designed for environmental monitoring, precision agriculture, and disease management applications that require wide-area coverage.
View Article and Find Full Text PDFAcc Mater Res
August 2025
Department of Mechanical Engineering, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213, United States.
The concept of micrometer-scale swimming robots, also known as microswimmers, navigating the human body to perform robotic tasks has captured the public imagination and inspired researchers through its numerous representations in popular media. This attention highlights the enormous interest in and potential of this technology for biomedical applications, such as cargo delivery, diagnostics, and minimally invasive surgery, as well as for applications in microfluidics and manufacturing. To achieve the collective behavior and control required for microswimmers to effectively perform such actions within complex, in vivo and microfluidic environments, they must meet a strict set of engineering criteria.
View Article and Find Full Text PDFBiomimetics (Basel)
July 2025
School of Information and Communication Engineering, Hainan University, Haikou 570228, China.
This paper presents a bionic dual-fin underwater robot, inspired by the ocean sunfish, that achieves multiple swimming motions using only two vertically arranged fins. This work demonstrates that a mechanically simple platform can execute complex 2-D and 3-D motions through advanced control strategies, eliminating the need for auxiliary actuators. We control the two fins independently so that they can perform cooperative actions in the water, enabling the robot to perform various motions, including high-speed cruising, agile turning, controlled descents, proactive ascents, and continuous spiraling.
View Article and Find Full Text PDFBiomimetics (Basel)
July 2025
CAS Key Laboratory of Bio-Inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
Shark skin exhibits a well-defined multilayered architecture, consisting of three-dimensional denticles and an underlying dermal layer, which contributes to its passive drag reduction. However, the active drag reduction mechanisms of this interface remain largely unexplored. In this study, the Marangoni effect potentially arising from the active secretion of mucus on shark skin is investigated.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
August 2025
Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan.
Vertebrate locomotion is due to the interplay of neural oscillators and sensory feedback loops in the spinal cord that interact with the body and the environment. Here, we study these circuits with a focus on undulatory locomotion as produced by elongated fish such as eels and lampreys. We address three questions: i) How do proprioception (stretch feedback) and exteroception (pressure on skin) interact with local oscillators to generate stable swimming patterns? ii) Can these feedback loops also contribute to dry ground locomotion? iii) Can they explain the remarkable robustness of eels against spinal cord transections? To address these questions, we developed abstract models of the locomotion circuits based on coupled phase oscillators, local stretch and pressure feedback loops, and simulated muscle models that were tested both in simulation and with a real undulatory robot.
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