Plant-Like Tropisms in Artificial Muscles.

Area of Science:

• Materials Science
• Biomimetics
• Robotics

Background:

• Helical plant tropisms inspire artificial muscles, but current designs lack autonomous adaptation to environmental stimuli.
• Existing shape-mimicked actuators require artificial triggers and are unsuitable for real-world, on-demand applications.

Purpose of the Study:

• To develop novel artificial muscles with self-adaptive capabilities to environmental humidity and temperature.
• To create artificial muscles that biomimic plant hydrotropism and thermotropism at a microstructural level.

Main Methods:

• Hierarchically patterned, helically wound yarns were fabricated using a microstructural biomimicking approach.
• Individual microfilaments were inlaid with hydrogel and twisted into coil-shaped hierarchical structures to enhance actuation.

Main Results:

• The artificial muscles demonstrated large strokes and rapid actuation, with average speeds of ≈5.2% s⁻¹ (expansion) and ≈3.1% s⁻¹ (contraction).
• The developed muscles exhibited autonomous environmental responsiveness, successfully closing a window in humid conditions.
• The yarns proved washable without degradation, indicating suitability for reusable smart textiles and soft robotics.

Conclusions:

• Novel self-adaptive artificial muscles inspired by plant microstructural memories have been successfully developed.
• These artificial muscles represent a significant advancement in speed and autonomous functionality compared to existing actuators.
• The materials are suitable for developing smart, reusable textiles and advanced soft robotic devices.