Complexity from simplicity: Confinement directs morphogenesis and motility in nematic polymers

Clement, Arul; Babaei, Mahnoush; Phadikar, Jayanta; Lee, Da Wei; Skandani, A. Alipour; Shankar, M. Ravi

doi:10.1016/j.eml.2021.101362

Cited by 3 publications

(16 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[ 31,32 ] Light or heat‐induced snapping is reported in various LCPs‐based bistable soft active structures such as doubly clamped buckled strips, [ 6,33–35 ] cylindrical shells, [ 36 ] twisted ribbons, [ 22 ] and circular bilayered rings. [ 37 ] However, snapping in most studies (not limited to LCPs) is not self‐sustained without either manually changing the mechanical or stimuli‐responsive actuation inputs [ 6,16–21,33 ] or imposing external physical constraints. [ 22,34,35 ] This largely hinders their potential applications for untethered and autonomous motion in soft robots.…”

Section: Introductionmentioning

confidence: 99%

Self‐Sustained Snapping Drives Autonomous Dancing and Motion in Free‐Standing Wavy Rings

Zhao

Hong

et al. 2022

Advanced Materials

View full text Add to dashboard Cite

Snapping has enabled diverse unique functionalities, including amplified force and fast response, [15] high-speed motion (crawling, [16] swimming, [16,17] and jumping [18][19][20][21] ), physical intelligence, [22] and mechanical memory operation. [23] Among different soft active materials, anisotropic smart materials such as liquidcrystal polymers (LCPs) [24][25][26] have recently attracted growing interest in untethered actuation and motion [27][28][29][30] due to their two-way shape memory effects. LCPs can reversibly shrink or elongate by shifting between the nematic and the isotropic states in response to thermal, photo-, or chemical stimulations. [31,32] Light or heatinduced snapping is reported in various LCPs-based bistable soft active structures such as doubly clamped buckled strips, [6,[33][34][35] cylindrical shells, [36] twisted ribbons, [22] and circular bilayered rings. [37] However, snapping in most studies (not limited to LCPs) is not self-sustained without either manually changing the mechanical or stimuliresponsive actuation inputs [6,[16][17][18][19][20][21]33] or imposing external physical constraints. [22,34,35] This largely hinders their potential applications for untethered and autonomous motion in soft robots. Achieving self-sustained snapping under constant external stimuli remains challenging and yet largely unexplored, because it needs to repeatedly store and release the strain energy for autonomous reversible switch between two stable states in response to constant external stimuli.Here, we report leveraging wavy ring geometry for achieving self-sustained snapping and autonomous motion in a library of freestanding liquid-crystal elastomers (LCEs) rings in response to constant heat or light. In contrast to doubly clamped buckled strips, [6,[33][34][35] a circular elastic ring can undergo snapping instabilities under simple mechanical forces such as bending or twisting without the need of external physical constraints, [38,39] since the closed-loop ring shape imposes an intrinsic geometric constraint. We show that the snapping behavior and snapping-induced motion can be programmed by the geometric asymmetries during fabrication for autonomous periodic dancing or crawling motions on a hot surface or under infrared light. The highly symmetric LCE wavy ring can achieve steady-state, periodic dancinglike motions via snapping-induced non-stopping flipping. To achieve directional motion, we explore the strategy of introducing geometric asymmetries to break the symmetric shape Harnessing snapping, an instability phenomenon observed in nature (e.g., Venus flytraps), for autonomy has attracted growing interest in autonomous soft robots. However, achieving self-sustained snapping and snappingdriven autonomous motions in soft robots remains largely unexplored. Here, harnessing bistable, ribbon ring-like structures for realizing self-sustained snapping in a library of soft liquid-crystal elastomer wavy rings under constant thermal and photothermal actuation are reported. The self-sustained snapping ...

show abstract

Section: Introductionmentioning

confidence: 99%

Self‐Sustained Snapping Drives Autonomous Dancing and Motion in Free‐Standing Wavy Rings

Zhao

Hong

et al. 2022

Advanced Materials

View full text Add to dashboard Cite

show abstract

“…In the process of annealing, the strips also develop small, but critical, transverse curvature; this is achieved by adhering the strip lengthwise to a thin cylinder during annealing. 13 Given this process of annealing, we assume in this work that the annealed configuration with transverse curvature is stress-free, i.e. , the natural state.…”

Section: Three-dimensional Formulation Nematic Patterning and Constit...mentioning

confidence: 99%

“…, ref. 13 and 14). However, this highly programmable nature of LCEs necessitates the use of modeling to explore the vast space of design parameters.…”

Section: Introductionmentioning

confidence: 99%

“…In particular, it accounts for the transverse curvature that provides a rich space of configurations. 13…”

Section: Introductionmentioning

confidence: 99%

“…The observations of interest from ref. 13 require thin strips with a hierarchy of dimensions, i.e. , the thickness is much smaller than the width, which is in turn much smaller than the length.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A dimensionally-reduced nonlinear elasticity model for liquid crystal elastomer strips with transverse curvature

LoGrande,

Shankar,

Dayal

2023

Soft Matter

Self Cite

View full text Add to dashboard Cite

show abstract

Defected twisted ring topology for autonomous periodic flip–spin–orbit soft robot

Qi,

Li,

Hong

et al. 2024

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Periodic spin–orbit motion is ubiquitous in nature, observed from electrons orbiting nuclei to spinning planets orbiting the Sun. Achieving autonomous periodic orbiting motions, along circular and noncircular paths, in soft mobile robotics is crucial for adaptive and intelligent exploration of unknown environments—a grand challenge yet to be accomplished. Here, we report leveraging a closed-loop twisted ring topology with a defect for an autonomous soft robot capable of achieving periodic spin-orbiting motions with programmed circular and re-programmed irregular-shaped trajectories. Constructed by bonding a twisted liquid crystal elastomer ribbon into a closed-loop ring topology, the robot exhibits three coupled periodic self-motions in response to constant temperature or constant light sources: inside-out flipping, self-spinning around the ring center, and self-orbiting around a point outside the ring. The coupled spinning and orbiting motions share the same direction and period. The spinning or orbiting direction depends on the twisting chirality, while the orbital radius and period are determined by the twisted ring geometry and thermal actuation. The flip–spin and orbiting motions arise from the twisted ring topology and a bonding site defect that breaks the force symmetry, respectively. By utilizing the twisting-encoded autonomous flip–spin–orbit motions, we showcase the robot’s potential for intelligently mapping the geometric boundaries of unknown confined spaces, including convex shapes like circles, squares, triangles, and pentagons and concaves shapes with multi-robots, as well as health monitoring of unknown confined spaces with boundary damages.

show abstract

Complexity from simplicity: Confinement directs morphogenesis and motility in nematic polymers

Cited by 3 publications

References 42 publications

Self‐Sustained Snapping Drives Autonomous Dancing and Motion in Free‐Standing Wavy Rings

Self‐Sustained Snapping Drives Autonomous Dancing and Motion in Free‐Standing Wavy Rings

A dimensionally-reduced nonlinear elasticity model for liquid crystal elastomer strips with transverse curvature

Defected twisted ring topology for autonomous periodic flip–spin–orbit soft robot

Contact Info

Product

Resources

About