A group of scientists from the Chinese Academy of Sciences has set their sights on plant tissues that exhibit motion as a source of inspiration for the development of artificial actuators. These bioinspired actuators have the potential for a wide range of applications, including soft robotics, prosthetics, and smart biomedical devices.
In a perspective paper published in the journal Nano Research, the research team delves into the mechanisms underlying plant motion speed regulation and how this knowledge can be translated into the creation of artificial actuators. These specially designed actuators can respond to environmental stimuli like humidity, solvents, heat, light, and electricity, converting these energy sources into shape transformations.
Plants, through billions of years of evolution, have evolved various strategies to alter their shapes, allowing them to obtain nutrients, disperse seeds, adapt to environmental conditions, and alleviate stress. Feilong Zhang, a researcher at the Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, emphasizes that drawing inspiration from nature can lead to the development of artificial actuators with a broad spectrum of motion speeds, ranging from ultrafast to ultraslow. This breakthrough opens up new possibilities in the field of advanced robotics and device development.
Numerous plant species exhibit remarkable motion abilities. For instance, Venus flytraps capture insects by closing their lobes when triggered, while sundew plants curl their leaves around prey. The Mimosa pudica plant responds to rainy days by closing its leaves to avoid water droplets, and even some dead plant tissues can change shape, such as pine cone scales, wheat awns, seed pods, ice plant seed capsules, and dandelion seed bristles.
The living plants’ motion and shape changes are governed by ion channels, while dead plant tissues demonstrate hygroscopic motions, which are tied to moisture fluctuations. The unique structures and compositions of these dead plant tissues serve as natural models for artificial actuators.
Precise control over movement is a hallmark of these plants. For instance, pine cones change shape slowly to ensure they open only in extended dry conditions, facilitating seed dispersion by wind and animals.
Traditionally, research has concentrated on understanding how plant tissues move, with less attention given to the regulation of motion speed. In their perspective paper, the research team focuses on unraveling the speed regulation strategies employed by plant tissues and proposing potential approaches for controlling the speed of biomimetic actuators.
The team examines the mechanisms responsible for shape changes, offering insights into strategies for managing motion speed. They also explore various models inspired by plants to create bioinspired artificial actuators that cater to different speed requirements in various scenarios. Challenges and opportunities in the development of artificial actuators are also discussed, along with potential strategies for speed regulation.
While current bioinspired artificial actuators have made significant strides, they still fall short of replicating the extreme speeds observed in nature. Thus, the team acknowledges the existence of challenges and opportunities in exploring the mechanisms of natural plant tissues with extreme speeds and in developing biomimetic artificial actuators for diverse applications.
The scientists envision future research combining genetics and biomechanics, enabled by biotechnological tools like CRISPR-Cas9, to study plant motion mechanisms at various scales. They also anticipate that advancements in responsive materials and manufacturing technologies, such as multi-component 3D printing, will lead to the creation of more complex and functional actuators for specific practical applications, inspired by plant species.
In their ongoing work, the team aims to further refine the design principles of biomimetic actuators to replicate the complexity and efficiency of biological systems. Their ultimate goal is to develop actuators that can mirror the intricate motions found in nature.