In an article published in the journal Electronics, the evolution of MEMS-tuned metamaterials has been examined and evaluated using different kinds of actuation mechanisms such as electrostatic actuation (ESA), electrothermal actuation (ETA), electro-magnetic actuation (EMA), and flex actuation mechanisms.
Study: Actively MEMS-Based Tunable Metamaterials for Advanced and Emerging Applications. Image Credit: agsandrew/Shutterstock.com
An Introduction to Metamaterials
Owing to their distinct electromagnetism characteristics, metamaterials – synthetic periodic micro-structured or nanostructured materials used to influence the transmission of electromagnetic (EM) waves, have received a lot of interest.
The permeability and permittivity of metamaterials may be actively adjusted by carefully designing the geometric parameters and material contents of their subwavelength recurring unit cells. As a result, metamaterials are extensively researched in stealth technologies, power harvests, diagnostic imaging, negative refractive index, and other applications.
By physically expanding their geometry, metamaterials' working wavelength range may be extended throughout the whole electromagnetic spectrum, from the visible region to infrared (IR), terahertz (THz), and microwaves.
Tuning Metamaterials using MEMS Technology
Several optical instruments based on metamaterials have shown impressive performance. Nonetheless, once built, these inflexible gadgets cannot be actively adjusted.
By externally applying an input, programmable metamaterials assist to enhance flexibility. Many strategies for adjustment mechanisms have been suggested to meet this need, such as the micro-electro-mechanical systems (MEMS) technique, thermo-annealing, state-transitioning materials, 2D materials, liquid crystals and laser pumps.
Because of its capacity to actively adjust metamaterial component cells, the MEMS technique is a viable solution for actively adjustable metamaterials. Furthermore, MEMS tuning techniques may offer an appropriate platform for metamaterials since they are not restricted by the nonlinear properties of natural substances and have a wide tuning range of resonant frequencies.
Recent Developments
Active MEMS-based adjustable metamaterials have been a focus in optoelectronics research in the last few years because it allows for human manipulation of electromagnetic waves.
The metamaterial may be directly modified and has a broad range of applications by leveraging MEMS technology. Because metamaterials can be strongly incorporated with the MEMS technique, they can be installed in actuation devices.
Reconfigurable properties allow the creation of customizable metamaterials with increased intelligence. The tunable property of MEMS-based metamaterials has received a lot of attention because of its important uses, such as sensing and logic operation.
Furthermore, elastic substrates may be used to efficiently regulate the metamaterial mechanical aspects. These seminal advances in active MEMS-based metamaterials add significantly to the vast range of uses of customizable optical electronics, including logic operation, sensors, energy harvesting, displays, and so on.
Crux of the Research
MEMS-based metamaterials in optoelectronic applications have been rapidly developed in the past decade, and the article presents a roundup of the actively tunable metamaterials that use different MEMS tuning mechanisms, along with the salient features of each mechanism.
The main emerging applications of these metamaterials include highly efficient sensing and logic operation.
Considering the fast advancement of metamaterials in optoelectronics, MEMS-tuned metamaterials are being extensively explored in order to accomplish active control of electromagnetic waves and meet the needs of practical uses.
The actuation mechanism is a major aspect in determining the functionality of these instruments, such as range of tuning, driving force, operational frequency, and manufacturing suitability.
Actuation techniques are broadly classified as ETA, EMA, ESA, and stretching mechanisms. While every actuating technique has evident benefits and downsides, adjustment method selection in metamaterials for diverse purposes must be carefully evaluated.
MEMS-based metamaterials have enabled the modification of incoming electromagnetic waves in terms of frequency, amplitude, polarization condition, and phase.
Meanwhile, the operational frequency spectrum spans from visible to IR and THz spectra, allowing for numerous effective optoelectronic implementations, such as logic operation and sensors.
Although sophisticated applications of MEMS-based metamaterials are productive, large power losses and poor integration with the present IC production processes remain significant difficulties that impede the commercialization of MEMS-based metamaterial technology.
The formation of MEMS-based metamaterials that address these weaknesses by incorporating novel structures, materials, and adjustment mechanisms appears promising in the future.
As a result, MEMS-based metamaterial technologies may be incorporated into existing optoelectronic systems to significantly improve functionality, such as optoelectronic modulators, optical computers, on-chip sensors, and others.
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Reference
Xu, R.-J., & Lin, Y.-S. (2022). Actively MEMS-Based Tunable Metamaterials for Advanced and Emerging Applications. Electronics, 11(2). Available at: https://www.mdpi.com/2079-9292/11/2/243
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