Alginate Sphere-Based Soft Actuators
Abstract
1. Introduction
2. Fabrication Strategies for Alginate Spheres
3. Functionalisation Approaches
4. Actuation Mechanisms and Performance
System/Material | Stimulus | Max Actuation Strain (%) | Blocking Force (N) | Response Time | Actuation Mode | Application Domain | Reversibility/Cyclic Use | Reference |
---|---|---|---|---|---|---|---|---|
Alginate-g-P(NIPAm-co-NDEAm)/SC | Temperature, pH, light | ~50% | Not reported | 1–3 min | Volumetric swelling/deswelling | Controlled agrochemical release | High, multi-cycle-tested | [56] |
Magnetic alginate beads | Magnetic field | ~10% | Not reported | Instantaneous | Magnetic rotation/translation | Targeted drug delivery | High, magnetic field-controlled | [57,107,108] |
Braided hydrogel muscle | Temperature (cooling from 60 °C) | 7–8% | 5–6 N | Slow (minutes) | Contraction due to swelling | Artificial muscles/soft robotics | Moderate (fatigue observed) | [50] |
Electroactive alginate–polycarbazole | Electric field (low voltage) | 1–2% | Low (µN-mN) | Seconds | Voltage-induced deformation | Electroactive sensing or actuation | Limited (electrochemical fatigue) | [55] |
Photothermal GO–alginate bilayers | NIR light | 15–20% | Not reported | Fast (~seconds) | Bending/folding due to heating | Microrobotics, biomedical folding | Good, NIR-cycled | [94] |
Magnetic alginate micromotors | Magnetic field | ~12% | Not reported | Sub-second rotation | Magnetic propulsion | Remote-controlled microswimmers | Yes, in fluid environment | [103,109] |
pH-responsive Ca–alginate beads | pH variation (acidic) | 5–10% | Not applicable | 2–5 min | Swelling and gel softening | Environmental remediation | Yes, but pH-limited | [110,111] |
Triboluminescent EuD4TEA–alginate beads | Mechanical impact | Swelling-dependent | Not applicable | Instantaneous flash | Optical emission due to deformation | Mechanical sensing and diagnostics | No, single flash | [96] |
Piezoelectric alginate microspheres | Electric field (piezoelectric) | 0.5–1% | Very low | Milliseconds | Electric field-induced deformation | Biosignal-responsive systems | Yes, piezoelectric loop | [112] |
5. Design Logic and Actuation Modelling
5.1. Integration into Functional Architectures
5.2. Fundamental Actuation Models
5.3. Stimuli-Induced Actuation Models
6. Application Demonstrations and Potential
6.1. Microrobotic Locomotion and Artificial Muscles
6.2. Shape Morphing and Biomimetic Resilience
6.3. Biomedical Delivery and Regenerative Applications
6.4. Sustainable Actuator Solutions
7. Outlook
- ▪ Integrate actuation, sensing and mechanical logic into unified composite hydrogels with reconfigurable and adaptive functionality.
- ▪ Develop real-time, multiphysics modelling platforms that incorporate environmental coupling and deformation-based feedback mechanisms.
- ▪ Scale high-resolution fabrication strategies capable of encoding spatial heterogeneity and internal actuation logic across large bead or scaffold arrays.
- ▪ Incorporate adaptive features such as mechanical memory, self-healing or chemo-mechanical conditioning to improve devices’ resilience and operational lifespan.
- ▪ Transition to using recyclable, biodegradable and bio-derived alginate composites to align with sustainability and circular economy frameworks.
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
References
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Khanam, U.S.; Jeong, H.T.; Mutlu, R.; Aziz, S. Alginate Sphere-Based Soft Actuators. Gels 2025, 11, 432. https://doi.org/10.3390/gels11060432
Khanam US, Jeong HT, Mutlu R, Aziz S. Alginate Sphere-Based Soft Actuators. Gels. 2025; 11(6):432. https://doi.org/10.3390/gels11060432
Chicago/Turabian StyleKhanam, Umme Salma, Hyeon Teak Jeong, Rahim Mutlu, and Shazed Aziz. 2025. "Alginate Sphere-Based Soft Actuators" Gels 11, no. 6: 432. https://doi.org/10.3390/gels11060432
APA StyleKhanam, U. S., Jeong, H. T., Mutlu, R., & Aziz, S. (2025). Alginate Sphere-Based Soft Actuators. Gels, 11(6), 432. https://doi.org/10.3390/gels11060432