Bioinspired underwater locomotion of light-driven liquid crystal gels

Abstract

Soft-bodied aquatic invertebrates, such as sea slugs and snails, are capable of diverse locomotion modes under water. Recapitulation of such multimodal aquatic locomotion in small-scale soft robots is challenging, due to difficulties in precise spatiotemporal control of deformations and inefficient underwater actuation of existing stimuli-responsive materials. Solving this challenge and devising efficient untethered manipulation of soft stimuli-responsive materials in the aquatic environment would significantly broaden their application potential in biomedical devices. We mimic locomotion modes common to sea invertebrates using monolithic liquid crystal gels (LCGs) with inherent light responsiveness and molecular anisotropy. We elicit diverse underwater locomotion modes, such as crawling, walking, jumping, and swimming, by local deformations induced by selective spatiotemporal light illumination. Our results underpin the pivotal role of the physicomechanical properties of LCGs in the realization of diverse modes of light-driven robotic underwater locomotion. We envisage that our results will introduce a toolbox for designing efficient untethered soft robots for fluidic environments.

3D Microstructures of Liquid Crystal Networks with Programmed Voxelated Director Fields

“…Shape programmability of both LCEs and LCNs has gained much attention in the burgeoning fields of soft robotics and stimuli‐responsive structures and devices, [ 23–37 ] albeit relying on simple 2D initial geometries, such as thin films, has hampered their extensive applications. In recent years, the development of new chemical formulations, like thiol–acrylate click chemistry, and novel fabrication techniques, like 3D printing, have introduced new opportunities in the shape‐change programmability of LCEs and LCNs through the manipulation of their initial geometry to 3D shapes.…”

“…Microscale 3D LCE and LCN structures with programmable director fields are in high demand for their potential use in the development of soft microrobots and devices. [ 24,55–60 ] We expect that our strategy will enable such advanced small‐scale constructs with predetermined shape transformations necessary for their locomotion and functions.…”

Desynchronized Liquid Crystalline Network Actuators with Deformation Reversal Capability

“…By adjusting the alignment of mesogens and/or the distribution of crosslinking domains, monolithic LCNs can display a wide range of predesignated deformations, including those based on contraction/extension, bending, twisting and their various possible combinations [11][12][13][14][15][16][17][18][19] . Accordingly, a myriad of complex shapes (e.g., wave, accordion, helix, saddle shapes, periodical patterns and 3D pro les of Gaussian curvatures) [20][21][22][23][24][25][26][27][28][29] as well as robotic and bionic motions (e.g., gripping, rolling, walking, swimming and oscillating) [30][31][32][33][34][35][36][37][38][39][40] have been achieved, making the eld ourish. Up to date, the reversible shape change of LCNs only involves two shapes corresponding to the isotropic state (disordered state) and the LC phase (ordered state), respectively.…”

Light-steered locomotion of muscle-like hydrogel by self-coordinated shape change and friction modulation

“…Among all methods of locomotion for soft robots, light actuation is particularly attractive, because the non-contact means of manipulation with high spatiotemporal resolution affords flexibility in motile direction and mode 20,[23][24][25][26][27][28] . In addition, muscle-like hydrogels with anisotropic structure and fast response should favor the programmed deformation/locomotion of the soft robots, although the material design has been a longstanding challenge.…”