Pivoting colloidal assemblies exhibit mechanical metamaterial behaviour

Area of Science:

• Physics
• Materials Science
• Nanotechnology

Background:

• Biological machines leverage Brownian fluctuations for actuation, but synthetic counterparts lack this capability due to stiffness.
• Existing systems with thermal conformation changes are either uncontrollable or require external manipulation.

Purpose of the Study:

• To develop synthetic metamaterials driven by thermal fluctuations with controllable deformation modes.
• To create Brownian mechanical metamaterials using DNA-based colloidal pivots.

Main Methods:

• Utilized DNA-based sliding contacts to construct colloidal pivots, enabling free fluctuation around a pivot point.
• Employed a hierarchical assembly strategy to create Brownian metamaterials with specific deformation characteristics.
• Incorporated magnetic particles into colloidal pivots for external control and precise shape manipulation.

Main Results:

• Successfully realized archetypal rotating diamond and rotating triangle (kagome) geometries.
• Quantitatively demonstrated that thermal fluctuations drive predicted auxetic deformations in these structures.
• Achieved externally controllable colloidal metamaterials that utilize Brownian fluctuations for precise shape changes.

Conclusions:

• Introduced a novel strategy for fabricating Brownian mechanical metamaterials.
• Demonstrated the creation of metamaterials with easily actuatable and precisely controlled deformation modes.
• Bridged the gap between biological and synthetic machines in utilizing thermal fluctuations for actuation.