Multifaceted mechanical responsive metamaterials: Mechanisms, fabrications, and applications

Abstract

Mechanically responsive metamaterials, with their unique structural and functional advantages, have emerged as a key focus in interdisciplinary research spanning materials science, mechanics, and bionics. In this review, we begin with an in-depth analysis of the fundamental materials that constitute mechanically responsive metamaterials, exploring key driving mechanisms such as thermal, electrothermal, electrochemical, photo-responsive, and magnetic responses. By elucidating these underlying principles, we aim to provide readers with a comprehensive understanding of how these responsive behaviors are achieved. The review then systematically evaluates various fabrication methods tailored to specific material properties and structural design requirements, offering a critical analysis of the unique advantages and limitations of each approach. Furthermore, the review highlights the current applications of these fabrication techniques across different fields of mechanical metamaterials, providing a comprehensive overview of their practical implementation and potential.

Keywords: metamaterials; responsive materials; 3D printing.

Graphical abstract

Figure 1

Overview of the response mechanism diagram of responsive metamaterial substrates

Figure 2

Responsive metamaterials capable of responding to thermal, electrical, and light stimuli (A) Microthermal-responsive metamaterials constructed based on the thermal bimorph effect. Reproduced with permission. Copyright 2021, The Authors, distributed under CC BY 4.0. (B) Hierarchical metamaterial with almost infinite theoretical CTE constructed based on pivotal junctions. Reproduced with permission. Copyright 2017, Elsevier. (C) Thermal-responsive metamaterials based on LCE with programmed nematic order. Reproduced with permission. Copyright 2018, John Wiley & Sons. (D) Shape memory metamaterials that can be cold programmed at room temperature and have multiple triggering temperatures. Reproduced with permission. Copyright 2023, The Authors, distributed under CC BY 4.0. (E) Electric responsive micro-origami metamaterial designed based on asymmetric electric thermal expansion structures. Reproduced with permission. Copyright 2020, John Wiley & Sons. (F) Surface electrochemical reactions actuated micro/nanoscale origami metamaterials. Reproduced with permission. Copyright 2021, The American Association for the Advancement of Science. (G) Integrated piezoelectric metamaterials for actuation and sensing. Reproduced with permission. Copyright 2022, The American Association for the Advancement of Science. (H) Photothermal-responsive LCE micro/nanochiral metamaterials with electrostatic field-induced orientation. Reproduced with permission. Copyright 2022, Elsevier. (I) Tunable elastic metamaterials activated by photochemical isomerization. Reproduced with permission. Copyright 2020, The Authors, distributed under CC BY 4.0. (J) Self-folding metamaterials with stiffness enhancement capability. Reproduced with permission. Copyright 2020, American Chemical Society.

Figure 3

Responsive metamaterials capable of responding to magnetic, liquid, and mechanical stimuli (A) 3D-printed metamaterials with programmed ferromagnetic domains. Reproduced with permission. Copyright 2018, Springer Nature. (B) Magnetic thermal-responsive mechanical metamaterials combining magnets with shape memory polymers. Reproduced with permission. Copyright 2022, John Wiley & Sons. (C) Magnetic field responsive metamaterials based on magnetorheological effects. Reproduced with permission. Copyright 2018, The American Association for the Advancement of Science. (D) Cooperative deformation of patterned hydrogel metamaterials induced by asymmetric swelling. Reproduced with permission. Copyright 2017, The American Association for the Advancement of Science. (E) Topology reconfigurable micro metamaterials driven by liquid tension. Reproduced with permission. Copyright 2021, Springer Nature. (F) Reconfigurable micro metamaterials composed of pH responsive hydrogels. Reproduced with permission. Copyright 2020, The Authors, distributed under CC BY 4.0. (G) Elastomer-cellulose composite origami metamaterials driven by air pressure. Reproduced with permission. Copyright 2012, John Wiley & Sons. (H) Origami metamaterials driven by negative pressure. Reproduced with permission. Copyright 2017, The Authors, distributed under CC BY-NC-ND 4.0. (I) Fabric metamaterials with variable Gaussian curvature capability driven by air pressure. Reproduced with permission. Copyright 2023, The American Association for the Advancement of Science.

Figure 4

Schematic diagrams of common manufacturing methods for various responsive metamaterials

Figure 5

Mechanical responsive metamaterials manufactured using different methods (A) Programmable thermally responsive metamaterials constructed by FDM printing on a rotating axis. Reproduced with permission. Copyright 2021, The Authors, distributed under CC BY 4.0. (B) Metamaterials manufactured using the multi-material DIW method. Reproduced with permission. Copyright 2019, National Academy of Sciences. (C) Micro-nano LCE metamaterials manufactured based on the MEW method. Reproduced with permission. Copyright 2023, John Wiley & Sons. (D) Shape memory metamaterials manufactured based on the multi-material DLP method. Reproduced with permission. Copyright 2022, The Authors, distributed under CC BY 4.0. (E) Self-folding metamaterials manufactured based on the g-DLP method. Reproduced with permission. Copyright 2020, American Chemical Society. (F) Shape memory metamaterials manufactured based on the PμSL method. Reproduced with permission. Copyright 2019, Royal Society of Chemistry. (G) Light-responsive metamaterials manufactured based on the TPL method. Reproduced with permission. Copyright 2023, John Wiley & Sons. (H) Negative humidity expansion metamaterial manufactured based on the material jetting 3D printing method. Reproduced with permission. Copyright 2018, The American Association for the Advancement of Science. (I) Variable Poisson’s ratio metamaterials produced by the injection molding method. Reproduced with permission. Copyright 2022, The Authors, distributed under CC BY 4.0. (J) Electrochemical-driven micro metamaterials manufactured based on micro polymer templates. Reproduced with permission. Copyright 2019, Springer Nature. (K) Multistable metamaterials constructed by assembling micro units. Reproduced with permission. Copyright 2023, Elsevier.

Figure 6

Applications of mechanical responsive metamaterials in various fields (A) Flexible grippers based on super-elastic metamaterials. Reproduced with permission. Copyright 2020, John Wiley & Sons. (B) Starfish robots based on tensegrity structures. Reproduced with permission. Copyright 2020, The American Association for the Advancement of Science. (C) A variable configuration robot with reversible plasticity. Reproduced with permission. Copyright 2022, The American Association for the Advancement of Science. (D) A self-sensing piezoelectric metamaterial robot. Reproduced with permission. Copyright 2022, The American Association for the Advancement of Science. (E) Vascular stents made of SMP-hydrogel composite metamaterials. Reproduced with permission. Copyright 2021, The American Association for the Advancement of Science. (F) LCE metamaterials used to assist in wound recovery. Reproduced with permission. Copyright 2021, John Wiley & Sons. (G) Biomimetic metamaterials for human tissue structures. Reproduced with permission. Copyright 2019, The American Association for the Advancement of Science. (H) Piezoelectric metamaterials with impact absorption and self-sensing capabilities. Reproduced with permission. Copyright 2019, Springer Nature. (I) Reproduction of encrypted information in hydrogel metamaterials by heating. Reproduced with permission. Copyright 2023, The Authors, distributed under CC BY 4.0.