Khanam Umme Salma, Jeong Hyeon Teak, Mutlu Rahim, Aziz Shazed
School of Life and Medical Sciences, University of Hertfordshire, Hatfield AL10 9AB, UK.
Division of Energy Engineering, Daejin University, Pocheon 11159, Republic of Korea.
Gels. 2025 Jun 5;11(6):432. doi: 10.3390/gels11060432.
Alginate hydrogels offer distinct advantages as ionically crosslinked, biocompatible networks that can be shaped into spherical beads with high compositional flexibility. These spherical architectures provide isotropic geometry, modularity and the capacity for encapsulation, making them ideal platforms for scalable, stimuli-responsive actuation. Their ability to respond to thermal, magnetic, electrical, optical and chemical stimuli has enabled applications in targeted delivery, artificial muscles, microrobotics and environmental interfaces. This review examines recent advances in alginate sphere-based actuators, focusing on fabrication methods such as droplet microfluidics, coaxial flow and functional surface patterning, and strategies for introducing multi-stimuli responsiveness using smart polymers, nanoparticles and biologically active components. Actuation behaviours are understood and correlated with physical mechanisms including swelling kinetics, photothermal effects and the field-induced torque, supported by analytical and multiphysics models. Their demonstrated functionalities include shape transformation, locomotion and mechano-optical feedback. The review concludes with an outlook on the existing limitations, such as the material stability, cyclic durability and integration complexity, and proposes future directions toward the development of autonomous, multifunctional soft systems.
藻酸盐水凝胶作为离子交联的生物相容性网络具有显著优势，能够被加工成具有高度成分灵活性的球形微珠。这些球形结构提供了各向同性的几何形状、模块化和封装能力，使其成为可扩展的、刺激响应驱动的理想平台。它们对热、磁、电、光和化学刺激的响应能力已在靶向递送、人造肌肉、微型机器人和环境界面等领域得到应用。本综述探讨了基于藻酸盐微球的致动器的最新进展，重点关注诸如液滴微流控、同轴流和功能表面图案化等制造方法，以及使用智能聚合物、纳米颗粒和生物活性成分引入多刺激响应性的策略。通过分析模型和多物理场模型，理解了致动行为并将其与包括溶胀动力学、光热效应和场致转矩在内的物理机制相关联。它们已展示的功能包括形状转变、运动和机械光反馈。综述最后展望了现有局限性，如材料稳定性、循环耐久性和集成复杂性，并提出了未来朝着自主、多功能软系统发展的方向。
