Gelatin yarns inspired by tendons--structural and mechanical perspectives

Area of Science:

• Biomaterials Science
• Materials Engineering
• Textile Science

Background:

• Natural tendons exhibit remarkable robustness and complex microstructures, like crimp patterns, contributing to their mechanical properties.
• Mimicking natural tendon structures at the microscale offers a pathway to developing advanced composite materials.
• Gelatin, a biocompatible polymer, presents potential as a base material for bio-inspired micro-yarns.

Purpose of the Study:

• To investigate the mechanical properties of gelatin micro-yarns fabricated with varying numbers of filaments and twisting configurations.
• To explore the potential of elasto-plastic gelatin filaments in enhancing material toughness, drawing parallels with natural tendon mechanics.
• To establish a reliable method for assessing the toughness of individual filaments through yarn-level testing.

Main Methods:

• Gelatin monofilaments were produced using casting and spinning techniques.
• Filaments were assembled into yarns with parallel or 15° twisted configurations, with up to ten filaments per yarn.
• Mechanical testing, including tensile tests and numerical simulations, was performed to evaluate yarn properties and toughness.

Main Results:

• Yarn mechanical properties were primarily influenced by the number of filaments, with no significant advantage observed from 15° twisting.
• Elasto-plastic gelatin yarns demonstrated a substantial increase in toughness, up to fivefold for a ten-filament yarn, compared to purely elastic materials.
• A novel, dependable method for measuring single filament toughness was developed, utilizing yarn-level testing.

Conclusions:

• Gelatin micro-yarns can achieve significantly enhanced toughness due to their elasto-plastic behavior, offering a biomimetic approach to material design.
• The study highlights the importance of filament material properties over specific micro-architectural features like twisting for toughness enhancement in this context.
• The developed testing procedure provides a more efficient and reliable means of characterizing the toughness of micro-scale filaments.