Undergraduate Student Georgia Institute of Technology, Auburn Univerwsity, Medizinische Hochschule Hannover Kennesaw, Georgia, United States
Introduction: For several decades, the field of robotics has aided in the development of innovative medical devices, including surgical robots, robotic prosthetics, and assistive implantable devices. Soft robotics are particularly suitable for medical applications due to their flexibility and biocompatibility (Cianchetti, Laschi, Menciassi & Dario, 2018). Typically, soft robotics for medical applications are modeled after humans or animals. However, recent research has been inspired by the structure-determined movements of plants, leading to the exploration of plant-inspired soft robotics (Xu, Zhou, Zhang, Zhang, Wang, & Wang, 2021).
Human and animal-inspired soft robotics often feature joints, which can induce stress in specific areas, resulting in faster wear and tear. In contrast, plant-inspired robotics move as a whole structure without joints, thereby reducing wear over time and increasing longevity. The most notable plant for its movement is the Venus flytrap, a carnivorous plant known for its rapid response to mechanical stimuli. Unlike most plants that bend slowly due to osmosis, the Venus flytrap exhibits a rapid closing of its lobes when trigger hairs are stimulated.
Although the motion principle of the Venus flytrap is explained by snapping, it is still unknown how the plant utilizes cellular topology to achieve tissular motion. Therefore, it is crucial to uncover the plant's structural and cellular morphology. Additionally, understanding which cellular areas of the Venus flytrap contribute most significantly to shape deformation is essential for comprehending its snapping mechanism. The primary cellular structures of the Venus flytrap are the lobes, midrib, and epidermis, as illustrated in Figure 1.
Materials and
Methods: To understand the structural morphology of the Venus flytrap, a 3D scanner is used to model the plant's growth across six stages. To further investigate the rapid snapping phenomenon, it is imperative to understand the cellular morphology. Initially, samples are collected from each of the six stages, consisting of days 2, 11, 15, 18, 22, and 30. The main portion of the trap is separated from the stem and embedded in agarose. Subsequently, the agarose-embedded Venus flytrap is sectioned using a Vibratome to obtain thin tissue slices. Three samples for each stage are used, and we collect about eight tissue sections from each sample.
Once the thin tissue slices are collected, a confocal microscope is utilized to record the size and shape of the cells. To analyze the cellular regions (lobes, midrib, epidermis), the confocal images are used to create a segmentation image, from which a representative number of cells for each cellular region are randomly selected. The changes in cellular areas and length-width ratios are then compared across the six stages to understand the development and mechanics of the Venus flytrap's snapping mechanism.
Results, Conclusions, and Discussions: Understanding the multiscale morphology of the Venus flytrap brings us closer to deciphering the structural mechanisms underlying its rapid shape deformation. According to the 3D morphology data shown in Figure 2, the plant primarily expands in the lobe regions. The cellular confocal images in Figure 3 further demonstrate continuous growth in the lobe regions, driven predominantly by an increase in cell number and size. However, additional research is required to determine whether the lobe region is the primary contributor to the snapping motion.
As illustrated in Figure 4, the epidermis and midrib cells became slightly more circular, while the cells in the lobe elongated initially and then expanded. This morphological insight allows us to consider factors such as density and porosity in structural designs when developing Venus flytrap-inspired soft robotics for medical applications.
The potential applications of this research are very useful. Venus flytrap-inspired soft robotics can function as pneumatic actuators capable of performing gripping motions with high mechanical strength for purposes such as assisting in small movements for medical procedures or handling fragile objects. Additionally, hydrogel-based actuators inspired by the Venus flytrap can be used in tissue repair when combined with cells or serve as switches due to osmosis, as depicted in Figure 5. Furthermore, ongoing research explores plant-inspired implantable assistive devices designed to provide opening and closing movements for valve repair and replacement.
Acknowledgements (Optional): I would like to thank the Georgia Institute of Technology and the Nakatani Program for supporting and funding this Research. I am very grateful for all that I learned and achieved through this program.
