Resolving Form–Structure–Function Relationships in Plants with MRI for Biomimetic Transfer

Abstract

In many biomimetic approaches, a deep understanding of the form–structure–function relationships in living and functionally intact organisms, which act as biological role models, is essential. This knowledge is a prerequisite for the identification of parameters that are relevant for the desired technical transfer of working principles. Hence, non-invasive and non-destructive techniques for static (3D) and dynamic (4D) high-resolution plant imaging and analysis on multiple hierarchical levels become increasingly important. In this study we demonstrate that magnetic resonance imaging (MRI) can be used to resolve the plants inner tissue structuring and functioning on the example of four plant concept generators with sizes larger than 5 mm used in current biomimetic research projects: Dragon tree (Dracaena reflexa var. angustifolia), Venus flytrap (Dionaea muscipula), Sugar pine (Pinus lambertiana) and Chinese witch hazel (Hamamelis mollis). Two different MRI sequences were applied for high-resolution 3D imaging of the differing material composition (amount, distribution, and density of various tissues) and condition (hydrated, desiccated, and mechanically stressed) of the four model organisms. Main aim is to better understand their biomechanics, development, and kinematics. The results are used as inspiration for developing novel design and fabrication concepts for bio-inspired technical fiber-reinforced branchings and smart biomimetic actuators.

4D pine scale: biomimetic 4D printed autonomous scale and flap structures capable of multi-phase movement

“…It is a very promising prospect for future biological studies to investigate the interrelation of scale architecture (cellular characteristics at different regions) in combination with the scale biomechanics (e.g. by AFM measurements) and the locally successive evaporation of water (probably via MRI) [48,49], altogether leading to the observed multi-phase motion. Our analyses show the potential of full-field 3D displacement and deformation analyses for evaluation and validation of movement principles in plants and technical structures.…”

A seed flying like a bullet: ballistic seed dispersal in Chinese witch-hazel (Hamamelis mollisOLIV., Hamamelidaceae)

“…We additionally dried one complete, closed fruit at room temperature until the fruit with the respective endocarps were split open, but the seeds not yet released. In this state, the fruit was imaged using magnetic resonance imaging (MRI), which was performed on a 7 T Bruker Biospec 70/20 small animal scanner using a surface 2 cm cryo-coil (both from Bruker Biospin, Ettlingen, Germany) (see also [18,19]). A three-dimensional (3D) UTE (ultra-short echotime) sequence was chosen for highresolution 3D imaging as it provides a suitable signal-to-noise ratio for specimen with short T2* relaxation time.…”

Active Materials

“…TS: I have to say that the last 20 years have been perfect for doing biomimetics, since many of the testing devices were developed and made accessible at a reasonable price to university institutes. At the moment we use various instruments from electron microscopy such as SEM, TEM, FIB TEM, and FIB SEMs, 1 but we also use microcomputed tomography (µCT) and magnetic resonance imaging (MRI) [Hesse et al 2019a[Hesse et al , 2019b. The latter becomes important for us because we can test living plants: one can load and unload them, take them outside and let them grow under a specific load regime, and see how they react structurally to this regime.…”

“…From the point of view of technical applications, these numerical models are the language to speak with engineers and materials scientists, because it is the language they are used to. As to various types of visualization, we use all necessary and available approaches, from light microscopy through SEM and TEM to confocal laser microscopy, µCT, and MRI, and combine these studies with (micro)mechanical tests to analyze quantitatively the form-structure-function relationship on all hierarchical levels necessary [Hesse et al 2019a[Hesse et al , 2019b. KK: The last question is a more general one.…”