US-12619003-B2 - Multistable elastic pixel (mep)-based reversibly reconfigurable metasurfaces

US12619003B2US 12619003 B2US12619003 B2US 12619003B2US-12619003-B2

Abstract

Provided are new classes of reconfigurable, multistable metasurfaces using the physics of colloids confined within nematic liquid crystals (NLCs). The colloids are physically moved from one stable location to another as defined by NLC-colloid interactions by external switching fields. These colloids can be scatterers within reconfigurable metasurfaces with electromagnetic (EM) responses that change with colloid location. because the colloids are moved between stable loci, these metasurfaces are also multistable, and require energy input only when changing colloid position. Furthermore, because the colloids can be returned to their original positions by simply reversing the switching field, all changes in EM responses are entirely reversible. Also provided are reconfigurable, multistable metasurfaces that utilize colloids disposed within a field of protrusions extended from a surface, with interactions between the colloid and the protrusions and the application of external fields operating to move the colloids between stable states.

Inventors

Nader Engheta
Kathleen J Stebe
Nasim Mohammadi Estakhri
Tianyi YAO
Jed-Joan Edziah

Assignees

THE TRUSTEES OF THE UNIVERSITY OF PENNSYLVANIA

Dates

Publication Date: 20260505
Application Date: 20230906

Claims (20)

1 . A reconfigurable multistable metasurface component, comprising: a substrate, the substrate defining a first confinement volume; the first confinement volume containing therein a single first element; and the first confinement volume and the first element are configured such that: (a) in the absence of applied energy to the first element, the first element maintains a first mechanically stable state within the first confinement volume or maintains a second mechanically stable state within the first confinement volume; and (b) application of an energy reversibly encourages the first element from one of the first mechanically stable state within the first confinement volume or the second mechanically stable state within the first confinement volume to the other mechanically stable state, wherein a state refers to at least one of a positional state and a rotational state.
2 . The reconfigurable multistable metasurface component of claim 1 , wherein the first confinement volume and the first element are configured such that: (a) in the absence of applied energy, the first element maintains a third mechanically stable state within the first confinement volume, and (b) application of an energy reversibly encourages the first element from the third mechanically stable state to the first mechanically stable state within the first confinement volume or to the second mechanically stable state within the first confinement volume.
3 . The reconfigurable multistable metasurface component of claim 1 , wherein the first confinement volume defines at least two lobes or at least two apices.
4 . The reconfigurable multistable metasurface component of claim 1 , wherein the first element defines a circular cross-section, an elongate cross-section, or is characterized as ellipsoidal.
5 . The reconfigurable multistable metasurface component of claim 1 , further comprising a fixed element positioned such that a spatial relationship between the first element and the fixed element is changed when the first element is at one of the first mechanically stable state within the confinement volume or the second mechanically stable state within the first confinement volume so as to form a dimer between the first element and the fixed element.
6 . The reconfigurable multistable metasurface component of claim 1 , wherein the substrate defines a second confinement volume, and wherein a second element is disposed within the second confinement volume, and wherein the second confinement volume and the second element are configured such that: (a) in the absence of applied energy to the second element, the second element maintains a first mechanically stable state within the second confinement volume or a second mechanically stable state within the second confinement volume; and (b) application of an energy reversibly encourages the second element from one of the first mechanically stable state within the second confinement volume and the second mechanically stable state to the other mechanically stable state within the second confinement volume.
7 . The reconfigurable multistable metasurface component of claim 6 , wherein the first confinement volume defines a major axis, wherein the second confinement volume defines a major axis, and wherein the major axes of the first and second confinement volumes are parallel.
8 . The reconfigurable multistable metasurface component of claim 1 , further comprising an energy source configured to apply an energy that reversibly encourages the first element from one of the first mechanically stable state and the second mechanically stable state to the other mechanically stable state within the first confinement volume.
9 . The reconfigurable multistable metasurface component of claim 1 , wherein the reconfigurable multistable metasurface component is positioned so as to filter a signal applied to the reconfigurable multistable metasurface component.
10 . A reconfigurable multistable metasurface component, comprising: (a) a set of first confinement volumes and a set of first elements disposed within the set of first confinement volumes, each first confinement volume containing a single first element, the set of first confinement volumes and the set of first elements being configured such that: (1) in the absence of applied energy to the set of first elements, the first elements maintain first mechanically stable states within their respective first confinement volumes or maintain second mechanically stable states within their respective first confinement volumes; and (2) application of an energy reversibly encourages the set of first elements from their first mechanically stable states or their second mechanically stable states to the other mechanically stable state; and at least one of (b1) a plurality of fixed elements; and (b2) a set of second confinement volumes and a set of second elements disposed within the set of second confinement volumes, the set of second confinement volumes and the set of second elements being configured such that (1) in the absence of applied energy to the set of second elements, the second elements maintain first mechanically stable states within their respective second confinement volumes or maintain second mechanically stable states within their respective second confinement volumes, and (2) application of an energy reversibly encourages the set of second elements from the second mechanically stable states or the second mechanically stable states to the other mechanically stable state.
11 . The reconfigurable multistable metasurface component of claim 10 , comprising a plurality of fixed elements wherein the fixed elements are positioned such that a spatial relationship between a first element and a fixed element is changed when the first element is at one of the first mechanically stable state within the confinement volume or the second mechanically stable state within the first confinement volume so as to give rise to a plurality of dimers, each dimer comprising a first element and a fixed element.
12 . The reconfigurable multistable metasurface component of claim 10 , comprising a plurality of fixed elements wherein the fixed elements are positioned such that when a first element is at one of the first mechanically stable state within the confinement volume or the second mechanically stable state within the first confinement volume, the first element is placed into register with one or more other first elements and one or more fixed elements so as to define a chain whereby a line drawn along the chain intersects (i) at least two first elements and at least one fixed element or (ii) at least one first element and at least two fixed elements.
13 . The reconfigurable multistable metasurface component of claim 10 , comprising a set of second confinement volumes and a set of second elements disposed within the set of second confinement volumes, the set of second confinement volumes and the set of second elements being configured such that (a) in the absence of applied energy to the set of second elements, the second elements maintain first mechanically stable states within their respective second confinement volumes or maintain second mechanically stable states within their respective second confinement volumes; and (b) application of an energy reversibly encourages the set of second elements from the second mechanically stable states or the second mechanically stable states to the other mechanically stable state.
14 . The reconfigurable multistable metasurface component of claim 13 , wherein the first elements and the second elements are positioned such that a spatial relationship between a first element and a second element is changed when the first element is at one of its first mechanically stable state within the confinement volume or its second mechanically stable state within the second confinement volume so as to give rise to a plurality of dimers, each dimer comprising a first element and a second element.
15 . The reconfigurable multistable metasurface component of claim 13 , wherein the first elements and the second elements are positioned such that when a first element is at one of the first mechanically stable state within the confinement volume or the second mechanically stable state within the first confinement volume, the first element is placed into register with one or more other first elements and one or more fixed elements or one or more second elements so as to define a chain whereby a line drawn along the chain intersects (i) at least one first element and two second elements, or (ii) at least two first elements and one second element.
16 . The reconfigurable multistable metasurface component of claim 13 , comprising a plurality of fixed elements and comprising a set of second confinement volumes and a set of second elements disposed within the set of second confinement volumes, the set of second confinement volumes and the set of second elements being configured such that (a) in the absence of applied energy to the set of second elements, the second elements maintain first mechanically stable states within their respective second confinement volumes or maintain second mechanically stable states within their respective second confinement volumes; and (b) application of an energy reversibly encourages the set of second elements from the second mechanically stable states or the second mechanically stable states to the other mechanically stable state, and wherein the fixed elements are positioned such that a spatial relationship between a first element and a fixed element is changed when the first element is at one of its first mechanically stable state within its confinement volume or its second mechanically stable state within its confinement volume so as to give rise to a plurality of dimers, each dimer comprising a first element and a fixed element, or wherein the fixed elements are positioned such that a spatial relationship between a second element and a fixed element is changed when the second element is at one of its first mechanically stable state within its confinement volume or its second mechanically stable state within its confinement volume so as to give rise to a plurality of dimers, each dimer comprising a second element and a fixed element.
17 . A reconfigurable multistable metasurface component, comprising: a first plurality of elements disposed within a first confinement volume so as to form a first multimer that comprises the first plurality of elements in register with one another; a second plurality of elements disposed within a second confinement volume so as to form a second multimer that comprises the second plurality of elements in register with one another; and the first confinement volume and the first element are configured such that: (a) in the absence of applied energy to the first plurality of elements, the first plurality of elements maintains the first multimer in a first mechanically stable state within the first confinement volume; and (b) application of an energy reversibly encourages at least one of the first plurality of elements within the first confinement volume so as to remove that at least one element from the first multimer, wherein a state refers to at least one of a positional state and a rotational state.
18 . A reconfigurable multistable metasurface component, comprising: a plurality of protrusions extending from a surface, each protrusion having a first concavity facing a first direction and having a second concavity facing a second direction, and the plurality of protrusions optionally being periodically arranged; a plurality of fixed pillar resonators extending from the surface, the plurality of fixed pillar resonators optionally being periodically arranged; and a plurality of moveable elements, the plurality of moveable elements configured such that application of an external field reversibly converts the component from one of a first mechanically stable state and a second mechanically stable state to the other of the first mechanically stable state and the second mechanically stable state, wherein (a) in the first mechanically stable state, each of the plurality of moveable elements associates with the first concavity of a first protrusion such that a periodic lattice is defined by the resonators and the moveable elements; and (b) in the second mechanically stable state, each of the plurality of moveable elements associates with the second concavity of a second protrusion so as to define a multimer comprising protrusions and moveable elements in register with one another, wherein a state refers to at least one of a positional state and a rotational state.
19 . The component of claim 18 , wherein the protrusion defines a maximum cross-sectional dimension, wherein the moveable element defines a maximum cross-sectional dimension, and wherein the maximum cross-sectional dimension of the protrusion is greater than the maximum cross-sectional dimension of the moveable element.
20 . The component of claim 18 , wherein the protrusion defines a maximum cross-sectional dimension, wherein the moveable element defines a maximum cross-sectional dimension, and wherein the maximum cross-sectional dimension of the protrusion is less than the maximum cross-sectional dimension of the moveable element.

Description

RELATED APPLICATIONS The present application claims priority to and the benefit of U.S. patent application No. 63/374,723 (filed Sep. 6, 2022) and U.S. patent application No. 63/380,622 (filed Oct. 24, 2022). All foregoing applications are incorporated herein by reference in their entireties for any and all purposes. GOVERNMENT RIGHTS This invention was made with government support under W911NF1610288 awarded by ARO (Army Research Office). The government has certain rights in the invention. TECHNICAL FIELD The present disclosure relates to the field of multistable metasurfaces. BACKGROUND Metamaterials are engineered materials with periodic or non-periodic subwavelength (e.g., micro/nano) building blocks with distinct responses to electromagnetic waves that cannot be readily achieved in nature. One of the main research directions in this field is to develop reconfigurable metamaterials whose functionality can be tuned after fabrication with full reversibility and with little energy to maintain it at a given state. Existing reconfigurable metamaterials (e.g., metasurfaces that manipulate the transmission of electromagnetic waves) suffer from several drawbacks, including limited reversibility and the need to have energy constantly applied in order for the system to maintain a given state. Accordingly, there is a crucial need in the field for reconfigurable metamaterials that are fully reversible and do not necessarily require energy input in order to maintain a particular state. SUMMARY In meeting the described challenges, the present disclosure first provides reconfigurable multistable metasurface components, comprising: a substrate, the substrate defining a first confinement volume; a first element disposed within the first confinement volume; and the first confinement volume and the first element are configured such that: (a) in the absence of applied energy to the first element, the first element maintains a first mechanically stable state within the first confinement volume or maintains a second mechanically stable state within the first confinement volume; and (b) application of an energy reversibly encourages the first element from one of the first mechanically stable state within the first confinement volume or the second mechanically stable state within the first confinement volume to the other mechanically stable state, wherein a state refers to at least one of a positional state and a rotational state. Also provided are methods, comprising: applying an energy to a reconfigurable multistable metasurface component according to the present disclosure so as to reversibly encourage the first element from one of the first mechanically stable state within the first confinement volume and the second mechanically stable state within the first confinement volume to the other mechanically stable state. Further provided are reconfigurable multistable metasurface components, comprising: (a) a set of first confinement volumes and a set of first elements disposed within the set of first confinement volumes, the set of first confinement volumes and the set of first elements being configured such that: (1) in the absence of applied energy to the set of first elements, the first elements maintain first mechanically stable states within their respective first confinement volumes or maintain second mechanically stable states within their respective first confinement volumes; and (2) application of an energy reversibly encourages the set of first elements from their first mechanically stable states or their second mechanically stable states to the other mechanically stable state; and (b) a plurality of fixed elements; (c) a set of second confinement volumes and a set of second elements disposed within the set of second confinement volumes, the set of second confinement volumes and the set of second elements being configured such that (1) in the absence of applied energy to the set of second elements, the second elements maintain first mechanically stable states within their respective second confinement volumes or maintain second mechanically stable states within their respective second confinement volumes; and (2) application of an energy reversibly encourages the set of second elements from the second mechanically stable states or the second mechanically stable states to the other mechanically stable state; or (d) both (b) and (c). Additionally provided are methods, comprising: applying an energy to a reconfigurable multistable metasurface component according to the present disclosure so as to reversibly encourage the first element from one of the first mechanically stable state within the first confinement volume and the second mechanically stable state within the first confinement volume to the other mechanically stable state. Further disclosed are reconfigurable multistable metasurface components, comprising: a substrate, the substrate defining a first confinement volume; a first element disposed within the first