Fabricating and Assembling Acoustic Metamaterials and Phononic Crystals

Choi, Christabel; Bansal, Shubhi; Münzenrieder, Niko; Subramanian, Sriram

doi:10.1002/adem.202170008

Cited by 15 publications

(10 citation statements)

References 21 publications

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“…[ 3 ] The intelligent manipulation of acoustic wave through tailored structures and elastic properties enables acoustic metamaterials to have a wide range of applications in acoustic absorber, cloaking, and anomalous refraction. [ 84,85 ]…”

Section: Development and Categories Of Metamaterialsmentioning

confidence: 99%

3D Printed Graphene‐Based Metamaterials: Guesting Multi‐Functionality in One Gain

et al. 2023

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Advanced functional materials with fascinating properties and extended structural design have greatly broadened their applications. Metamaterials, exhibiting unprecedented physical properties (mechanical, electromagnetic, acoustic, etc.), are considered frontiers of physics, material science, and engineering. With the emerging 3D printing technology, the manufacturing of metamaterials becomes much more convenient. Graphene, due to its superior properties such as large surface area, superior electrical/thermal conductivity, and outstanding mechanical properties, shows promising applications to add multi‐functionality into existing metamaterials for various applications. In this review, the aim is to outline the latest developments and applications of 3D printed graphene‐based metamaterials. The structure design of different types of metamaterials and the fabrication strategies for 3D printed graphene‐based materials are first reviewed. Then the representative explorations of 3D printed graphene‐based metamaterials and multi‐functionality that can be introduced with such a combination are further discussed. Subsequently, challenges and opportunities are provided, seeking to point out future directions of 3D printed graphene‐based metamaterials.

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Section: Development and Categories Of Metamaterialsmentioning

confidence: 99%

3D Printed Graphene‐Based Metamaterials: Guesting Multi‐Functionality in One Gain

et al. 2023

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“…The integration of active microfluidic actuation techniques in liquid embedded metamaterial designs opens up new paradigms to achieve active tunability using many existing fluidic and MEMS techniques like electrophoresis, photo-electrowetting, and many more, which have never been utilized in acoustic metamaterials. [55] We conceptualized the metamaterial using a single slit and droplet, with variable control parameters like droplet contact angle, volume, position on the slit, and different electrode designs. We also established the broadband operations of MAM for 10 kHz wide range.…”

Section: Broadband Dynamicsmentioning

confidence: 99%

A Microfluidic Acoustic Metamaterial using Electrowetting: Enabling Active Broadband Tunability

Bansal

Subramanian

2021

Adv Materials Technologies

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membrane-type metamaterials, [17] recent work has shown that integrating liquids with the solid structures can dramatically assist reconfigurability. Recently a passively reconfigurable Helmholtz resonator was illustrated, where different volumes of water were filled to tune its free cavity space. [18] However, for actively tuning the liquid embedded metamaterial designs, we need active microfluidic techniques for on-chip control of liquid mobility. A number of active microfluidic control mechanisms [19] exist in literature like photo-electrowetting, electrophoresis, and surface acoustic waves. These can be used to move microscale droplets in a controlled manner, and have been explored for various applications like lab-on-a-chip, [20] printing, [21] opto-fluidic lensing, [22] and acousto-fluidics. [23] However, the field of acousto-fluidics [24] has to-date focused only upon manipulating liquid droplets using applied acoustic fields [25,26] and not vice versa. Furthermore, there are fabrication challenges in making ultra-compact tunable metamaterial designs, because of the large dimensions, low throughput, bulk geometries, and huge material costs required for incorporating active control mechanisms. Here, we propose and develop a novel ultra-compact metastructure, which we refer as a metamaterial, with an active actuation mechanism utilizing microfluidics, that will be practically significant and promote a new approach toward microfluidic acoustic metamaterials (MAMs).In this paper, we design, fabricate, and demonstrate a droplet integrated metamaterial, which derives its tunability from a digital microfluidics based active droplet manipulation technique called electrowetting-on-dielectric (EWOD). [27][28][29] We achieve dynamic control of a deep sub-wavelength slit (dimensions, length = 0.5 λ (L), width = 0.06 λ, and height = 0.02 λ) for manipulating ultrasound (40 kHz) by using microelectromechanical (MEMS) technology. Ultrathin deep subwavelength metamaterial for example, around λ/650 at the frequency of 20.9 kHz (λ denotes the wavelength of sound), where arbitrary patterns were paper-cut by hollow-out patterning on metasurfaces, seldom exist in literature. [30] Most of the reported works like ultrasonic meta-lens [31] which range within µm to mm scale are "passive," but here we propose a novel actively tunable deep subwavelength ultrathin metamaterial (200 µm in thickness, up to λ/44), establishing a record in comparison with previous works to our best knowledge. MEMS based MAM design paves While acoustic metamaterials provide extraordinary control to manipulate sound waves, their physical realization and applicability are severely impeded by the limited tunability, narrow operational frequency range, and noncompact designs. Integrating liquids with active actuation mechanism in the metamaterials provides broader material and design scope. Active microfluidic techniques for liquid actuation, never used in metamaterials before, will enable active tunability for liquid-embedded metamaterial designs, leading tow...

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“…10 Electrowetting has been explored with various liquid metals, 11 including aluminum, 12 gallium, 13 and mercury. 14 Eutectic gallium−indium alloy (EGaIn) has emerged as one of the most viable liquid metals because of its extraordinary properties such as excellent fluidity, low melting point, high conductivity, and low toxicity, marking it a promising candidate for applications such as flexible electronics, 15 microfluidic acoustic metamaterials, 16,17 and conductive printing. 18 The electrowetting of EGaIn has also been researched by controlling the surface tension of the liquid metal for active droplet manipulation.…”

Section: ■ Introductionmentioning

confidence: 99%

Electrically Induced Liquid Metal Droplet Bouncing

et al. 2022

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Liquid metals, including eutectic gallium–indium (EGaIn), have been explored for various planar droplet operations, including droplet splitting and merging, promoting their use in emerging areas such as flexible electronics and soft robotics. However, three-dimensional (3D) droplet operations, including droplet bouncing, have mostly been limited to nonmetallic liquids or aqueous solutions. This is the first study of liquid metal droplet bouncing using continuous AC electrowetting through an analytical model, computational fluid dynamics simulation, and empirical validation to the best of our knowledge. We achieved liquid metal droplet bouncing with a height greater than 5 mm with an actuation voltage of less than 10 V and a frequency of less than 5 Hz. We compared the bouncing trajectories of the liquid metal droplet for different actuation parameters. We found that the jumping height of the droplet increases as the frequency of the applied AC voltage decreases and its amplitude increases until the onset of instability. Furthermore, we model the attenuation dynamics of consecutive bouncing cycles of the underdamped droplet bouncing system. This study embarks on controlling liquid metal droplet bouncing electrically, thereby opening a plethora of new opportunities utilizing 3D liquid metal droplet operations for numerous applications such as energy harvesting, heat transfer, and radio frequency (RF) switching.

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Fabricating and Assembling Acoustic Metamaterials and Phononic Crystals

Cited by 15 publications

References 21 publications

3D Printed Graphene‐Based Metamaterials: Guesting Multi‐Functionality in One Gain

3D Printed Graphene‐Based Metamaterials: Guesting Multi‐Functionality in One Gain

A Microfluidic Acoustic Metamaterial using Electrowetting: Enabling Active Broadband Tunability

Electrically Induced Liquid Metal Droplet Bouncing

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