Revolutionary Light-Driven Artificial Muscles Enable High-Stroke Actuation in Underwater Robots

In a groundbreaking development that promises to revolutionize the undercurrents of soft robotics, a Korean research team has engineered a remarkable light-powered artificial muscle that operates seamlessly in underwater environments. This innovation, spearheaded by Dr. Hyun Kim of the Korea Research Institute of Chemical Technology (KRICT), alongside collaborators Prof. Habeom Lee from Pusan National University and Prof. Taylor H. Ware from Texas A&M University, marks a significant advance in the field of soft robotics, aimed at creating versatile, untethered robotic systems.

Traditionally, soft robotic actuators have relied primarily on various forms of energy such as electrical power, thermal energy, or pneumatic pressure to facilitate movement. However, these systems often face significant challenges when deployed in aquatic environments, where intricate components like wires, batteries, and motors are vulnerable to water exposure. Such exposure introduces a host of complications that can hinder the effective operation of these robotic systems, making them less reliable and limiting their potential applications in real-world underwater scenarios.

In response to these limitations, the research team has developed artificial muscles utilizing azobenzene-functionalized semicrystalline liquid crystal elastomers (AC-LCEs). The unique properties of these elastomers allow them to actuate in response to light, offering a promising alternative to conventional materials and methods. However, achieving successful actuation underwater has proven to be a complex task, largely due to the cooling effects associated with water, which can severely impede the responsiveness of traditional photothermal materials.

Photochemical actuators have previously been restricted to simple bending motions due to their reliance on molecular-level adjustments that primarily occur at or near the material’s surface. Recognizing this constraint, the research team meticulously engineered the AC-LCEs to enhance stiffness and control over their structural properties. By embedding azobenzene molecules into a specifically designed liquid crystal elastomer, they achieved materials capable of contracting when exposed to ultraviolet light and expanding in response to visible light, creating a dynamic interplay of movement and response.

One of the most innovative aspects of these AC-LCEs is their ability to maintain a temporarily deformed state even once the light source is removed, which allows for the introduction of a “latch-like” locking mechanism. This unique feature enables more sophisticated control of robotic motion, offering the potential for both sequential and spatial manipulation. Such advancements provide exciting opportunities for underwater applications, where dexterous and multi-functional movement is essential.

The experiments conducted by the research group led to the fabrication of both linear and ring-shaped spring structures, which were then integrated into prototypes of underwater robots. The actuators developed demonstrated strikingly high actuation strains—more than triple those observed in previous azobenzene-based actuators. Additionally, the work capacity generated by these artificial muscles outweighs that of mammalian muscle tissue by a factor of two, highlighting their immense potential for high-performance underwater applications.

Moreover, the researchers’ innovative approach to controlling the chirality of the coiled spring structures allowed them to design the direction of actuation reversibly. This level of control offers remarkable versatility in robotic applications, enabling the development of underwater robots that can not only grip and release objects but also navigate complex environments, such as moving through narrow pipes. Crucially, these robotic systems achieve this without the need for batteries, wires, or pumps, representing a significant leap forward in the capabilities of untethered robotic technologies.

The underwater robots showcased by the team performed reliably over 100 continuous light cycles, demonstrating the robustness and efficiency of the artificial muscle actuation system. The implications of this research are profound, indicating not only a potential application in soft robotics but also paving the way for future deployments in dynamic underwater environments where adaptability and agility are paramount.

KRICT, the institute behind this groundbreaking work, has been dedicated to advancing chemical technologies since its establishment in 1976. It serves as a critical player in fostering innovations across various fields, including chemistry, material science, and environmental engineering. As the research team looks towards commercializing this technology by 2030, they are focused on exploring material scalability and integration into viable systems for practical applications.

Through continued research and development, the team is optimistic that these innovations will transform underwater robotics and expand possibilities for soft robotic applications in diverse and challenging environments. It is an exciting time for technology and robotics, with this research representing a meaningful step forward in the field.

The findings from this extensive study have been acknowledged in the scientific community and are set to be published as a back cover article in the February 2025 issue of the esteemed journal Small. The article and ensuing discourse will further stimulate interest in light-powered soft robotics and biocompatible actuators, creating a cascade of new opportunities and inquiries within the realm of material science and robotic engineering.

As the landscape of robotics evolves, this research signifies a pivotal moment, encapsulating the potential for innovative engineering to address complex problems posed by underwater exploration and manipulation. The successful deployment of light-powered actuators in softer, more adaptable robotic systems is likely to inspire further breakthroughs that can affect various sectors, including environmental conservation, underwater exploration, and even aquatic agriculture.

The journey from concept to realization has been painstaking, showcasing the determination of the research team to push the boundaries of what is possible within the realm of soft robotics. Their dedication embodies the spirit of scientific inquiry and innovation that the modern era demands, representing a forward-thinking approach to creating solutions that harmonize with existing ecosystems while maximizing efficiency and performance.

As they prepare for the next stages of development, including scalability and further integrations, this research team sets the stage for new trajectories in soft robotic applications, capturing the imagination of engineers and scientists alike who envision a future where robots operate in harmony with the natural world.

The ripple effects of their work will undoubtedly extend far beyond the immediate field of soft robotics, inspiring interdisciplinary collaborations and igniting interest across various sectors of research and application within technology, biology, and environmental sciences.

Subject of Research: Light-Powered Artificial Muscles in Underwater Soft Robotics
Article Title: Azobenzene-Functionalized Semicrystalline Liquid Crystal Elastomer Springs for Underwater Soft Robotic Actuators
News Publication Date: February 25, 2025
Web References: KRICT
References: DOI
Image Credits: Korea Research Institute of Chemical Technology (KRICT)

Keywords

Light-powered actuators, soft robotics, underwater robotics, azobenzene, liquid crystal elastomers, smart materials, bioinspired engineering, actuation systems, robotics innovation, environmental engineering, material science.

Tags: azobenzene-functionalized materialschallenges in aquatic roboticsDr. Hyun Kim research teamenergy efficiency in soft actuatorshigh-stroke actuation technologyKorean research in roboticslight-driven artificial musclesliquid crystal elastomers in roboticssoft robotics advancementsunderwater robotics innovationuntethered robotic systemsversatile underwater robotic applications