4D printing technology represents a new generation of additive manufacturing methods that enable three-dimensional(3D)printed structures to change their shapes or properties over time(the fourth dimension)in response ...4D printing technology represents a new generation of additive manufacturing methods that enable three-dimensional(3D)printed structures to change their shapes or properties over time(the fourth dimension)in response to external stimuli such as temperature,magnetic fields,and light.Among the most popular types of 4D-printed structures are thermally responsive bilayer actuators using shape memory polymers,valued for their programmability and convenience.However,achieving precise deformations without collisions is hindered by the nonlinear and time-varying morphing process of these bilayer actuators,which is crucial for creating dynamically controllable shapes on demand in 4D printing.This study presents a rapid and effective design and optimization strategy for 4D printed self-folding structures that can be sequentially and accurately folded.Theoretical analyses were conducted to guide the design of the folding processes.The response surface method(RSM)was used to investigate key parameters affecting the design of 4D-printed bilayer actuators.The results indicate that increasing printing speed enhances internal strain,whereas higher printing temperatures,layer heights,or actuator heights have the opposite effect.The RSM model achieved an R-squared value of 0.983,accurately capturing the coupling effects of these variables on the output responses,thereby enabling controlled timescales for bending motion and sequential folding without collisions.These findings can be applied to enhance the design and acceleration of 4D-printed self-folding structures,ensuring controlled speed of shape transformation.To validate this concept,a self-folding hand-shaped structure with five fingers was designed and fabricated,demonstrating how design and printing parameters can precisely control the timescale of shape changes for each finger based on the design specifications.展开更多
Programmable/reprogrammable magneto-responsive composites(MRCs)are highly desirable for applications in soft robotics,morphable actuators,and biomedical devices due to their capabilities of undergoing reversible,compl...Programmable/reprogrammable magneto-responsive composites(MRCs)are highly desirable for applications in soft robotics,morphable actuators,and biomedical devices due to their capabilities of undergoing reversible,complex,untethered,and rapid deformations.However,current MRC-based devices primarily rely on soft matrices,which revert to their original shapes and cease functioning when external magnetic fields are removed.Moreover,their magnetization programming,deformations,and functioning need to alternate between encoding and actuation platforms,limiting the adaptability and efficiency.Here,we present a reprogrammable magnetic shape-memory composite(RM-SMC)integrating a shape-memory polymer(SMP)skeleton with phase-transition magnetic microcapsules.High-intensity laser melts microcapsules for magnetic realignment under programmed fields,while low-intensity laser softens SMP for structural reconfiguration without compromising integrity.This dual-laser strategy facilitates in situ magnetization programming,shape morphing,and function execution within a single material system.Our innovative approach enables unique applications,including omnidirectional multi-degree-of-freedom actuators that can activate light switches,solar trackers that optimize energy capture,and adaptive impellers that modulate fluid pumping.By eliminating platform alternation and enabling shape/function retention post-actuation,the RM-SMC platform overcomes critical limitations in conventional MRCs,establishing a paradigm for multifunctional devices requiring persistent configuration control and field-independent operation.展开更多
基金supported by National Natural Science Foundation of China(Grant No.52375272)Zhejiang Provincial Natural Science Foundation of China(Grant No.LR22E050006)China Postdoctoral Science Foundation(Grant Nos.2024M751644,2024M754069).
文摘4D printing technology represents a new generation of additive manufacturing methods that enable three-dimensional(3D)printed structures to change their shapes or properties over time(the fourth dimension)in response to external stimuli such as temperature,magnetic fields,and light.Among the most popular types of 4D-printed structures are thermally responsive bilayer actuators using shape memory polymers,valued for their programmability and convenience.However,achieving precise deformations without collisions is hindered by the nonlinear and time-varying morphing process of these bilayer actuators,which is crucial for creating dynamically controllable shapes on demand in 4D printing.This study presents a rapid and effective design and optimization strategy for 4D printed self-folding structures that can be sequentially and accurately folded.Theoretical analyses were conducted to guide the design of the folding processes.The response surface method(RSM)was used to investigate key parameters affecting the design of 4D-printed bilayer actuators.The results indicate that increasing printing speed enhances internal strain,whereas higher printing temperatures,layer heights,or actuator heights have the opposite effect.The RSM model achieved an R-squared value of 0.983,accurately capturing the coupling effects of these variables on the output responses,thereby enabling controlled timescales for bending motion and sequential folding without collisions.These findings can be applied to enhance the design and acceleration of 4D-printed self-folding structures,ensuring controlled speed of shape transformation.To validate this concept,a self-folding hand-shaped structure with five fingers was designed and fabricated,demonstrating how design and printing parameters can precisely control the timescale of shape changes for each finger based on the design specifications.
基金supported by the National Natural Science Foundation of China(Nos.52075516,61927814,62325507,and 52122511)the National Key Research and Development Program of China(No.2021YFF0502700)+2 种基金the Major Scientific and Technological Projects in Anhui Province(202103a05020005,202203a05020014)the Students’Innovation and Entrepreneurship Foundation of USTC(CY2022G09)the Hefei Municipal Natural Science Foundation(No.HZR2450)。
文摘Programmable/reprogrammable magneto-responsive composites(MRCs)are highly desirable for applications in soft robotics,morphable actuators,and biomedical devices due to their capabilities of undergoing reversible,complex,untethered,and rapid deformations.However,current MRC-based devices primarily rely on soft matrices,which revert to their original shapes and cease functioning when external magnetic fields are removed.Moreover,their magnetization programming,deformations,and functioning need to alternate between encoding and actuation platforms,limiting the adaptability and efficiency.Here,we present a reprogrammable magnetic shape-memory composite(RM-SMC)integrating a shape-memory polymer(SMP)skeleton with phase-transition magnetic microcapsules.High-intensity laser melts microcapsules for magnetic realignment under programmed fields,while low-intensity laser softens SMP for structural reconfiguration without compromising integrity.This dual-laser strategy facilitates in situ magnetization programming,shape morphing,and function execution within a single material system.Our innovative approach enables unique applications,including omnidirectional multi-degree-of-freedom actuators that can activate light switches,solar trackers that optimize energy capture,and adaptive impellers that modulate fluid pumping.By eliminating platform alternation and enabling shape/function retention post-actuation,the RM-SMC platform overcomes critical limitations in conventional MRCs,establishing a paradigm for multifunctional devices requiring persistent configuration control and field-independent operation.
