Realization of active metamaterials with odd micropolar elasticity

Abstract

Materials made from active, living, or robotic components can display emergent properties arising from local sensing and computation. Here, we realize a freestanding active metabeam with piezoelectric elements and electronic feed-forward control that gives rise to an odd micropolar elasticity absent in energy-conserving media. The non-reciprocal odd modulus enables bending and shearing cycles that convert electrical energy into mechanical work, and vice versa. The sign of this elastic modulus is linked to a non-Hermitian topological index that determines the localization of vibrational modes to sample boundaries. At finite frequency, we can also tune the phase angle of the active modulus to produce a direction-dependent bending modulus and control non-Hermitian vibrational properties. Our continuum approach, built on symmetries and conservation laws, could be exploited to design others systems such as synthetic biofilaments and membranes with feed-forward control loops.

arXiv commentMain text, 6 figures, methods, and supplementary information

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Cited by in corpus (14)

• Topological active matter
• Odd Viscosity and Odd Elasticity
• Transient non-Hermitian skin effect
• Hybrid skin-topological modes without asymmetric couplings
• Anomalous Floquet non-Hermitian skin effect in a ring resonator lattice
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• Non-Hermitian physics of levitated nanoparticle array
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• Mechanical activity and odd elasticity of passive, 2D chiral metamaterials