Compliance for Resistance: The Intrinsic Extraordinary Isotropic Anti-Fatigue Performance of Fish Bladder

Area of Science:

• Materials Science
• Biomaterials Engineering
• Soft Robotics

Background:

• Fatigue failure is a major limitation for soft materials in biomedical implants and soft robotics.
• Current strategies like stiffening or alignment often lead to anisotropy and poor multidirectional loading resistance.
• A significant gap exists between the fracture toughness and fatigue threshold of synthetic soft materials.

Purpose of the Study:

• To investigate the fatigue resistance mechanisms of biological soft tissues.
• To develop a biohybrid hydrogel mimicking these mechanisms for enhanced durability.
• To address the limitations of synthetic soft materials in fatigue-prone applications.

Main Methods:

• Analysis of the multilayered, hierarchical fibrous architecture of silver carp fish bladders.
• Investigating the "compliance for resistance" mechanism involving fiber dynamics, sacrificial bonds, and interfacial sliding.
• Designing and fabricating a biohybrid hydrogel to replicate the observed anti-fatigue strategies.

Main Results:

• Silver carp fish bladders exhibit exceptional isotropic fatigue resistance (∼6000 J·m^{- 2}), approaching their fracture toughness.
• The fatigue resistance is attributed to a multiscale mechanism involving dynamic fiber behavior, bond dynamics, and reorientation.
• The developed biohybrid hydrogel achieved a high fatigue threshold (>3000 J·m^{- 2}) and antifouling properties.

Conclusions:

• Biological soft tissues possess sophisticated design principles for fatigue resistance.
• The "compliance for resistance" mechanism offers a viable strategy for enhancing soft material durability.
• This research provides a generalizable approach for engineering fatigue-resistant soft materials for demanding applications.