Programmable Entanglement of Granular Mechanical Metamaterials

A Rezanejad and M Mousa and CD Lorenz and M Howard and AE Forte, ADVANCED FUNCTIONAL MATERIALS, 35, e16484 (2025).

DOI: 10.1002/adfm.202516484

Entanglement between objects offers a powerful route to programmable collective behavior in granular media. Here, the concept of entangled granular metamaterials-clusters of geometrically complex grains is introduced, whose interlocking interactions drive emergent and tunable properties. The geometric features that promote entanglement are identified, distinguished from simple contact interactions, and the strength of entanglement is quantified through disentanglement dynamics. By varying the number and shape of grains, the degree of interlocking within the cluster is modulated, and its utility is demonstrated in robotic handling tasks. Using a ferromagnetic grain assembly manipulated by an electromagnet, the metamaterial is deployed onto a second, non- ferromagnetic cluster of complex targets. The grains penetrate and entangle with the targets, enabling robust collective picking and even selective retrieval of individual objects with intricate geometry. Finally, strategies for controlled separation of the grains from the targets are outlined, establishing a foundation for programmable entanglement in matter manipulation.

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