Programming Shape-Morphing Behavior of Zwitterionic Polymer/Liquid Crystal Composite with Humidity-responsive Self-healing Performance

In this study,a zwitterionic polymer/liquid crystals composite film with programming shape-morphing behavior and humidityresponsive self-healing performance was prepared by blending a zwitterionic polymer and liquid crystalline azobenzene compound in solution,followed by film-forming in a mold without tedious or multistep synthetic route.The as-obtained zwitterionic polymer/liquid crystal composite film exhibited programming shape-morphing behavior under different stimuli.In this process,the temporary shape of the composite film was memorized after the removal of the stimuli.Such characteristics would fit the requirements of intelligence and energy-saving for stimuliresponsive shape-changing materials.Moreover,the composite film showed humidity-responsive self-healing performances under wet conditions at room temperature.In summary,the simple design and preparation route of the zwitterionic polymer/liquid crystal composite film with programming shape-morphing behavior and mild condition-responsive self-healing performance look promising for the fabrication and practical application of novel photo-driven devices and soft robotics.

Light-based 3D printing of stimulus-responsive hydrogels forminiature devices:recent progress and perspective

Miniature devices comprising stimulus-responsive hydrogels with high environmental adaptability are now considered competitive candidates in the fields of biomedicine,precise sensors,and tunable optics.Reliable and advanced fabricationmethods are critical formaximizing the application capabilities ofminiature devices.Light-based three-dimensional(3D)printing technology offers the advantages of a wide range of applicable materials,high processing accuracy,and strong 3D fabrication capability,which is suitable for the development of miniature devices with various functions.This paper summarizes and highlights the recent advances in light-based 3D-printed miniaturized devices,with a focus on the latest breakthroughs in lightbased fabrication technologies,smart stimulus-responsive hydrogels,and tunable miniature devices for the fields of miniature cargo manipulation,targeted drug and cell delivery,active scaffolds,environmental sensing,and optical imaging.Finally,the challenges in the transition of tunable miniaturized devices from the laboratory to practical engineering applications are presented.Future opportunities that will promote the development of tunable microdevices are elaborated,contributing to their improved understanding of these miniature devices and further realizing their practical applications in various fields.

4D biofabrication via instantly generated graded hydrogel scaffolds

Formation of graded biomaterials to render shape-morphing scaffolds for 4D biofabrication holds great promise in fabrication of complex structures and the recapitulation of critical dynamics for tissue/organ regeneration.Here we describe a facile generation of an adjustable and robust gradient using a single-or multi-material one-step fabrication strategy for 4D biofabrication.By simply photocrosslinking a mixed solution of a photocrosslinkable polymer macromer,photoinitiator(PI),UV absorber and live cells,a cell-laden gradient hydrogel with pre-programmable deformation can be generated.Gradient formation was demonstrated in various polymers including poly(ethylene glycol)(PEG),alginate,and gelatin derivatives using various UV absorbers that present overlap in UV spectrum with that of the PI UV absorbance spectrum.Moreover,this simple and effective method was used as a universal platform to integrate with other hydrogel-engineering techniques such as photomask-aided microfabrication,photo-patterning,ion-transfer printing,and 3D bioprinting to fabricate more advanced cell-laden scaffold structures.Lastly,proof-of-concept 4D tissue engineering was demonstrated in a study of 4D bone-like tissue formation.The strategy’s simplicity along with its versatility paves a new way in solving the hurdle of achieving temporal shape changes in cell-laden single-component hydrogel scaffolds and may expedite the development of 4D biofabricated constructs for biological applications.

Wireless Autonomous Soft Crawlers for Adjustable Climbing Actuation

Artificial soft actuators,featured with non-equilibrium internal circumstance and fast,programmable shape transformations,have attracted strong research interest recently due to their flexibility,highly controllable,and designability.However,wireless soft actuators,achieving the locomotion on different large slopes with multiple energy conversion,have been rarely reported.Herein,we create a asymmetric bilayer strategy to construct autonomous soft crawler via“breathing”moisture to motivate the mechanical deformation.The soft crawlers present conspicuous performances including periodic tumbler locomotion predicted via improved Timoshenko’s equation,multiple reversible shape-morphing(circle,helix,despiralization,etc.)determined by their fiber orientation,controlled drive mode(front drive and rear drive)and rapid climb speed(4.76 cm/min)at wide slope angles.Through architecture design,they can be series-wound or shunt-wound to construct multijoint complex actuators.Besides climbing,a intelligent soft ring-pull with admirable cycle performance for preventing overheating or something untouchable,has been proposed.The soft crawlers also realize multiple energy conversion to be actuated by light irradiation.We envision that this soft crawler system has an enormous potential in intelligent machine,microscopic diagnosis and treatment,biosensing,energy harvesting and conversion.