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

Abstract

Many creatures have the ability to traverse challenging environments by using their active muscles with anisotropic structures as the motors in a highly coordinated fashion. However, most artificial robots require multiple independently activated actuators to achieve similar purposes. Here we report a hydrogel-based, biomimetic soft robot capable of multimodal locomotion fueled and steered by light irradiation. A muscle-like poly(N-isopropylacrylamide) nanocomposite hydrogel is prepared by electrical orientation of nanosheets and subsequent gelation. Patterned anisotropic hydrogels are fabricated by multi-step electrical orientation and photolithographic polymerization, affording programmed deformations. Under light irradiation, the gold-nanoparticle-incorporated hydrogels undergo concurrent fast isochoric deformation and rapid increase in friction against a hydrophobic substrate. Versatile motion gaits including crawling, walking, and turning with controllable directions are realized in the soft robots by dynamic synergy of localized shape-changing and friction manipulation under spatiotemporal light stimuli. The principle and strategy should merit designing of continuum soft robots with biomimetic mechanisms.

Engineering Tough Metallosupramolecular Hydrogel Films with Kirigami Structures for Compliant Soft Electronics

“…attract extensive interests because of their promising applications in molecular separation, [4] medical dressings, [5] soft actuators, [6,7] flexible electronics, [8,9] etc. For example, using soft and stretchable materials as the substrate of flexible electronics requires the hydrogels to have robust mechanical performances, suitable thickness, and good compliance to wrap on target objects/organs with complex geometries.…”

Plasmonic Nanostructures for Photothermal Conversion

“…Photons emitted by a light source and absorbed by a photoactive agent may produce mechanical motions by 1) photothermal expansion; [ 78,79 ] 2) conformational change; [ 80,81 ] or 3) phase transition (e.g., glass transition of shape‐memory materials, [ 82,83 ] nematic‐isotropic transition of liquid crystals, [ 84,85 ] and hydrophilic–hydrophobic transition of hydrogels. [ 86,87 ] )…”

Recent progress in the shape deformation of polymeric hydrogels from memory to actuation

“…In addition, the anisotropic structure of actuating hydrogels can also be endowed with and coded by electrostatic repulsion during the fabrication process. 21,51,52,70,71 For example, Aida and coworkers developed an innovative actuating hydrogel with oriented electrolyte nanosheets. 51 The actuating hydrogel was polymerized from a NIPAm hydrogel precursor and contained titanate(IV) nanosheets (TiNSs).…”

“…Compared with other shape deformation materials such as shape memory alloys 16 and liquid crystalline actuators, 17 shape transformation hydrogels can provide larger-scale deformation due to their so and wet properties. 18,19 Therefore, shape deformation hydrogels have attracted tremendous attention and shown potential applications in so robots, 20,21 biomimetic devices 22,23 and intelligent valves. 24,25 Shape deformation hydrogels can be divided into two types based on the shape deformation direction.…”