Lidong Zhang

Programmable soft actuators require independent control over both deformation pathways and driving‐force output, yet conventional shape‐memory systems generally encode these functions within a fixed network and therefore exhibit predetermined recovery behavior. Herein, we report a porous shape‐memory polymer/hydrogel actuator (SMP‐Net gel) that transforms fixed‐force shape recovery into ion‐programmable actuation. The actuator integrates a thermally programmable glycerol‐polycaprolactone methacrylic anhydride (GPCL‐MA) scaffold with an interpenetrating PAM/PVA hydrogel network. The porous scaffold determines the macroscopic shape‐memory trajectory, whereas the confined hydrogel functions as a Hofmeister‐responsive internal force reservoir. Ion‐specific regulation of chain aggregation and hydrogen bonding enables broad adjustment of the mechanical state, with strain and stress tunable over 43%–140% and 0.83–1.80 MPa, respectively, while simultaneously accelerating or retarding NIR‐triggered shape recovery. This dual‐driving architecture further supports reversible shape programming, controllable bending amplitude, recovery‐time regulation, and spatially selective deformation under localized NIR irradiation. Remote gripping, release, and multistep motion demonstrate the capability of the SMP‐Net gel for complex actuation tasks. This work establishes a general strategy for integrating shape‐memory scaffolds with ion‐regulated soft networks, opening a new route toward adaptive actuators, biomimetic machines, and intelligent soft robotic systems.

Programmable soft actuators require independent control over both deformation pathways and driving‐force output, yet conventional shape‐memory systems generally encode these functions within a fixed network and therefore exhibit predetermined recovery behavior. Herein, we report a porous shape‐memory polymer/hydrogel actuator (SMP‐Net gel) that transforms fixed‐force shape recovery into ion‐programmable actuation. The actuator integrates a thermally programmable glycerol‐polycaprolactone methacrylic anhydride (GPCL‐MA) scaffold with an interpenetrating PAM/PVA hydrogel network. The porous scaffold determines the macroscopic shape‐memory trajectory, whereas the confined hydrogel functions as a Hofmeister‐responsive internal force reservoir. Ion‐specific regulation of chain aggregation and hydrogen bonding enables broad adjustment of the mechanical state, with strain and stress tunable over 43%–140% and 0.83–1.80 MPa, respectively, while simultaneously accelerating or retarding NIR‐triggered shape recovery. This dual‐driving architecture further supports reversible shape programming, controllable bending amplitude, recovery‐time regulation, and spatially selective deformation under localized NIR irradiation. Remote gripping, release, and multistep motion demonstrate the capability of the SMP‐Net gel for complex actuation tasks. This work establishes a general strategy for integrating shape‐memory scaffolds with ion‐regulated soft networks, opening a new route toward adaptive actuators, biomimetic machines, and intelligent soft robotic systems.

Hydrogels have emerged as promising candidates for next‐generation implantable biomedical stents. However, the scalable fabrication of hydrogel three‐dimensional (3D) stents with sufficient mechanical support remains a major challenge, owing to the intrinsic flexibility of hydrogel materials. Here, inspired by the water‐welding mechanism of the butterfly proboscis, we report a facile water‐mediated welding strategy for sodium alginate (SA) films, which enables the assembly of fully integrated 3D stents using only water as the processing medium. The as‐prepared solid‐walled 3D stents can be seamlessly converted into hollow‐walled architectures via a metal ion‐induced asymmetric crosslinking followed by solvent exchange. Notably, the hollow‐walled structure enables the mechanical support force five times that of solid‐walled ones, rendering these hydrogel 3D stents highly attractive for biodegradable medical stents. This work provides a versatile and environmentally benign route to engineer 3D hydrogel stents, thereby advancing the development of advanced implantable biomedical devices.

The selective breakdown of ionic coordination bonds allows the sodium alginate hydrogel electrodes to quickly turn from stiff to soft in 7 seconds, making them suitable for minimally invasive brain–computer interfaces.

While three ‐ dimensional (3D) printing enables fabrication of hollow geometries through precise ink deposition, its reliance on photo‐ or thermal‐curing often compromises resolution and biocompatibility. Alternatively, aqueous‐phase chemical reactions offer a novel pathway for direct conversion of polymer films into high‐resolution hollow structures without requiring external energy inputs or templates, yielding superior mechanical integrity. Despite these advances, the incorporation of living cells during hollow hydrogel formation remains a critical challenge. This review provides a comprehensive analysis of two key fabrication strategies: 1) chemical reaction‐driven assembly in aqueous media and 2) 3D printing technologies. The respective design principles are critically evaluated. A systematic comparison reveals distinct advantages—aqueous‐phase chemical methods offer enhanced resolution and mechanical strength, whereas 3D printing enables the control of customized geometries. Beyond fabrication, how these hollow hydrogel architectures exhibit transformative applications in drug delivery, tissue engineering, and biosensing are explored. By identifying current limitations and future opportunities, this review outlines a roadmap for the rational design of hollow hydrogels that can bridge the gap between structural engineering and clinical translation.

Interventional catheter, a medical device characterized by a gradient hardness from one end to the other, exhibits enhanced flexibility upon insertion into the human body. This unique configuration accommodates various anatomical structures and surgical requirements. This study reports, for the first time, a degradable hydrogel interventional catheter with gradient hardness. A novel aqueous reaction methodology is developed, enabling the direct transformation of a solid sodium alginate (SA) film strip into a hollow hydrogel interventional catheter. This process involves copper ions‐induced asymmetry crosslinking in an aqueous solution, solvent exchange in ethanol, removal of copper ions by ethylenediaminetetraacetic acid, and subsequent bimetallic crosslinking in CaCl₂ and FeCl₃ aqueous solutions. This method results in gradient‐hardness hydrogel interventional catheters without surface defects such as protrusions and pits. The hydrogel interventional catheter demonstrates gradient robustness with mechanical strength reaching 5.5 MPa for the soft head and 28 MPa for the hard tail. By incorporating a gradual stiffness variation, the hydrogel catheter with superior lubricity and flexibility more effectively adapts to the anatomical structures of the human body, potentially minimizing tissue damage and expediting surgical procedures. Consequently, it shows significant potential as a medical interventional catheter.