Actuation systems in plants as prototypes for bioinspired devices

Burgert, Ingo; Fratzl, Peter

doi:10.1098/rsta.2009.0003

Cited by 310 publications

(287 citation statements)

References 81 publications

Supporting

Mentioning

278

Contrasting

Order By: Relevance

“…Shape-changing materials are not very prevalent in synthetic systems but are widespread in nature, particularly in plants [9][10][11][12][13][14][15][16][17][18] . Because of the limited chemical resources and processing conditions, plants have evolved mechanisms that rely on their internal heterogeneous architecture to achieve shape change upon external stimulus [9][10][11][12] .…”

mentioning

confidence: 99%

“…Because of the limited chemical resources and processing conditions, plants have evolved mechanisms that rely on their internal heterogeneous architecture to achieve shape change upon external stimulus [9][10][11][12] . Hydration-triggered shape change in natural systems offers a passive, yet dramatic, response with only changes in surrounding humidity levels and is exhibited in diverse seed dispersal units, such as pinecones, wheat awn structures and orchid tree seedpods (Supplementary Movie 1).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Self-shaping composites with programmable bioinspired microstructures

et al. 2013

View full text Add to dashboard Cite

Shape change is a prevalent function apparent in a diverse set of natural structures, including seed dispersal units, climbing plants and carnivorous plants. Many of these natural materials change shape by using cellulose microfibrils at specific orientations to anisotropically restrict the swelling/shrinkage of their organic matrices upon external stimuli. This is in contrast to the material-specific mechanisms found in synthetic shape-memory systems. Here we propose a robust and universal method to replicate this unusual shape-changing mechanism of natural systems in artificial bioinspired composites. The technique is based upon the remote control of the orientation of reinforcing inorganic particles within the composite using a weak external magnetic field. Combining this reinforcement orientational control with swellable/ shrinkable polymer matrices enables the creation of composites whose shape change can be programmed into the material's microstructure rather than externally imposed. Such bioinspired approach can generate composites with unusual reversibility, twisting effects and site-specific programmable shape changes.

show abstract

mentioning

confidence: 99%

mentioning

confidence: 99%

Self-shaping composites with programmable bioinspired microstructures

et al. 2013

View full text Add to dashboard Cite

show abstract

“…The shape transformations of biological organisms [1][2][3][4][5][6] have been the inspiration for many products in the field of artificial muscles, 7-13 soft robotics, 14-19 sensors 20 and complex shape engineering. 21,22 For example, the leaves of the Venus flytrap snap together to capture insects by virtue of the synergy between the hydroelastic instability and asymmetric expansion of the inner and outer surfaces at the cellular level.…”

Section: Introductionmentioning

confidence: 99%

A monolithic hydro/organo macro copolymer actuator synthesized via interfacial copolymerization

et al. 2017

View full text Add to dashboard Cite

Synthetic polymer actuators have attracted increasing attention for their potential applications in artificial muscles, soft robotics and sensors. The majority of previous efforts have focused on smart hydrogels with bilayer structures that can change their shape in response to environmental stimuli, such as temperature, light and certain chemicals. However, the practical application of hydrogels is limited because of their low modulus and weak mechanical strength. Here we synthesized a robust monolithic actuator of a macro-scale hydro/organo binary cooperative Janus copolymer film. The process involves direct, one-step interfacial polymerization of immiscible hydrophilic and hydrophobic vinyl monomer solutions, and the resultant product exhibited binary cooperative shape transformation to multiple external stimuli. The Janus copolymer film can work in both aqueous solutions and organic solvents, with bidirectional and site-specific bending arising from cooperative asymmetric swelling/shrinking of the hydrogel and organogel networks. In addition, the as-prepared Janus copolymer film can act as a sensor element for solvent leakage detection. This binary cooperative strategy is applicable to most immiscible monomer systems and provides a general approach to developing novel functional copolymer materials. NPG Asia Materials (2017) 9, e380; doi:10.1038/am.2017.61; published online 19 May 2017 INTRODUCTIONThe shape transformations of biological organisms [1][2][3][4][5][6] have been the inspiration for many products in the field of artificial muscles, 7-13 soft robotics, 14-19 sensors 20 and complex shape engineering. 21,22 For example, the leaves of the Venus flytrap snap together to capture insects by virtue of the synergy between the hydroelastic instability and asymmetric expansion of the inner and outer surfaces at the cellular level. 2 The layered anisotropic orientated cellulose fibrils induce hygroscopic movements of pine cones, 1 wheat awns, 3 orchid tree seedpods 6 and other plants. By mimicking the sophisticated hierarchical structures present in nature, the motion of polymer films has been successfully demonstrated in several cases. [23][24][25][26][27][28][29][30] For example, hydrogel bilayers embedded with intersecting inorganic platelets or cellulose fibrils have exhibited pine-cone-like bending and pod-like twisting motions. 24,31 However, the practical applications of these actuators were limited because of the low modulus and weak mechanical strength of the hydrogels. 32 Elastomer single layer films, such as azobenzene polymer films synthesized using an elaborate molecular design, 13,27 can achieve smart responsive curving. However, these films require a unidirectional stimulus to generate anisotropic contraction/expansion of their two sides; this factor limits the film thickness to the micrometer or sub-millimeter level. 27,[33][34][35] Therefore,

show abstract

“…displacement or force) as a response to a change in humidity occurring for example between day and night [1,2]. They are interesting examples for bioinspired materials design, as they typically operate without metabolic energy meaning that actuation is achieved through the arrangement or architecture of the underlying constituent materials (cellulose fibrils, hemicellulose, lignin, etc.)…”

Section: Introductionmentioning

confidence: 99%

Pressurized honeycombs as soft-actuators: a theoretical study

Guiducci

Fratzl

Bréchet

et al. 2014

J. R. Soc. Interface.

Self Cite

View full text Add to dashboard Cite

The seed capsule of Delosperma nakurense is a remarkable example of a natural hygromorph, which unfolds its protecting valves upon wetting to expose its seeds. The beautiful mechanism responsible for this motion is generated by a specialized organ based on an anisotropic cellular tissue filled with a highly swelling material. Inspired by this system, we study the mechanics of a diamond honeycomb internally pressurized by a fluid phase. Numerical homogenization by means of iterative finite-element (FE) simulations is adapted to the case of cellular materials filled with a variable pressure fluid phase. Like its biological counterpart, it is shown that the material architecture controls and guides the otherwise unspecific isotropic expansion of the fluid. Deformations up to twice the original dimensions can be achieved by simply setting the value of input pressure. In turn, these deformations cause a marked change of the honeycomb geometry and hence promote a stiffening of the material along the weak direction. To understand the mechanism further, we also developed a micromechanical model based on the Born model for crystal elasticity to find an explicit relation between honeycomb geometry, swelling eigenstrains and elastic properties. The micromechanical model is in good qualitative agreement with the FE simulations. Moreover, we also provide the force-stroke characteristics of a soft actuator based on the pressurized anisotropic honeycomb and show how the internal pressure has a nonlinear effect which can result in negative values of the in-plane Poisson's ratio. As nature shows in the case of the D. nakurense seed capsule, cellular materials can be used not only as low-weight structural materials, but also as simple but convenient actuating materials.

show abstract

Actuation systems in plants as prototypes for bioinspired devices

Cited by 310 publications

References 81 publications

Self-shaping composites with programmable bioinspired microstructures

Self-shaping composites with programmable bioinspired microstructures

A monolithic hydro/organo macro copolymer actuator synthesized via interfacial copolymerization

Pressurized honeycombs as soft-actuators: a theoretical study

Contact Info

Product

Resources

About