Mxene-coated polymers as waveguiding components in microwave regime

Abstract

MXene-coated antennas, and associated devices and methods of manufacture, are described herein. In one aspect, an antenna may include an antenna body, where the antenna body has a coated region with a MXene film conformally coated thereon. The implementation of MXene-based waveguide components provides an example of a facile, convenient realization of 3D-printed polymer devices with performance levels as high as metallic waveguides. The waveguide and other conductive components can be additively manufactured using commonly available 3D printers and commercially available polymers. Dip-coating of MXene provides a general solution for realizing geometrically complex metal-like 3D structures. The disclosure provides herein the implementation of thru, bent, twisted, and discontinuous filtering waveguides, each of which can be utilized to manipulate the propagation of electromagnetic waves.

Description

MXENE-COATED POLYMERS AS WAVEGUIDING COMPONENTS IN MICROWAVE REGIMERELATED APPLICATIONS

[0001] The present application claims priority to and the benefit of United States patent application no. 63 / 530,109, “3D Printed MXene-Coated Lightweight Polymers as Waveguiding Components in Microwave Regime” (filed August 1, 2023). All foregoing applications are incorporated herein by reference in their entireties for any and all purposes.TECHNICAL FIELD

[0002] The present disclosure relates to the fields of MXene materials and to the field of waveguides.BACKGROUND

[0003] The impact of additive manufacturing has been significantly increasing in the advancing technological domains, such as aerospace technology, where unique and application-dependent geometries are employed in aerial vehicles and satellites. Quick production of a limited number of components for low-volume manufacturing and rapid prototy ping is critical. Metal additive manufacturing (AM) offers the potential to fabricate hollow components that are relatively lightweight, with complex geometries increasingly demanded by new aerial vehicles and satellite designs that are outside the reach of traditional metallurgy. Still, the mass density of metals, along with the cost and complexity' of laser sintering, limits the utility of metal AM, especially in space. The usage of polymeric components through AM processes, on the other hand, has great cost and weight-related benefits. However, polymeric materials often do not meet certain property requirements, such as high electrical conductivity, that are integral to the functionality of modem communication systems.

[0004] With satellite technology marking new advancements through the commercialization of Low Earth Orbit (LEO) launches, communication devices are increasingly demanded to allow for low-latency telecommunication capability and extensive coverage. To date, five primary constellations (companies) have launched -15000 LEOsatellites that utilize microwave frequencies (in particular, Ku-Ka bands) in the communication devices. To guarantee low loss of microwave signals and to handle high- power transmission, bulky metallic components, such as waveguides are utilized. To lower the mass load of fully-metal components, thin layers of metals can be deposited on polymer structures. Application of thin metal coatings onto planar, non-conductive substrates (e.g., polymers or ceramics) enables microwave structures that introduce various functionalities, such as resonators or sensors, that be used as part of modem communication devices. However, such techniques as electroless deposition of metals onto polymer substrates presents challenges, including but not limited to a restricted selection of metal s / substrates, thermal stability of substrates and process temperature control, as well as adverse environmental effects. Metal paints, including those containing silver flakes, nanoparticles, or nanowires, have been explored. However, stabilizing metal particles — crucial for solution processing like dip coating — requires a complex mixture of stabilizers, additives, organic solvents, and binders. Since these components are nonconductive, they have a detrimental impact on electrical conductivity . Moreover, typically used solvents, such as N-methyl-2- pyrrolidone (NMP), are toxic and necessitate high-temperature removal (typically at 120-150 °C) after the paint / ink is applied to a substrate. This places constraints on the choice of polymers. Accordingly, there is a long-felt need in the art for improved antenna designs.SUMMARY

[0005] MXene-coated antennas, and associated devices and methods of manufacture, are described herein. In one aspect, an antenna may include an antenna body, where the antenna body has a coated region with a MXene film conformally coated thereon. The implementation of MXene-based waveguide components provides an example of a facile, convenient realization of 3D-printed polymer devices with performance levels as high as metallic waveguides. The waveguide and other conductive components can be additively manufactured using commonly available 3D printers and commercially available polymers. Dip-coating of MXene provides a general solution for realizing geometrically complex metallike 3D structures. The disclosure provides herein the implementation of thru, bent, twisted, and discontinuous filtering waveguides, each of which can be utilized to manipulate the propagation of electromagnetic waves.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various aspects discussed in the present document. In the drawings:

[0007] Fig. 1 : Performance and weight comparison of MXene-coated thru waveguide with conventional metallic waveguides. (A) Weight comparison of an uncoated nylon structure, a MXene-coated thru waveguide, and a metallic waveguide on a digital scale. Inset shows a TEM image of a ~l-nm thin MXene flake. (B) The measured and simulated transmission coefficient of electromagnetic waves propagating through different mediums including MXene waveguide, metallic waveguide, 3D printed uncoated structure and free space (no waveguiding structure). (C) The illustration of waveguiding functionality using Ti3C2TrMXene coated walls.

[0008] Fig. 2: Parametric performance optimization using MXene dispersions of different flake sizes and consecutive dip coating cycles. (A) Electrical conductivity, sheet resistance and flake size distribution of MXene dispersions of 3 different flake sizes. (B) MXene loading (mg cm’2) on 3D printed coupons with 1 to 5 dips in MXene dispersions of 3 different flake sizes. Insets include the optical microscopy pictures of a pristine coupon and the coated coupons after 5 dips in MXene dispersions of 3 different sizes. (C) Microwave reflected power of the dip-coated coupons (D). Microwave reflected power versus estimated MXene coated thickness of the coupons based on MXene loading, roughness-counted coating surface area and vacuum-assisted film densify of 3500 kg m’3. (E) Measured transmission coefficient after every coating cycle in a dispersion of medium-sized MXene flakes (~ 500 nm) and the calculated thickness of MXene for coated coupons at each cycle. (F) Simulated transmission coefficient (dB and linear scale) for coating thicknesses ranging from 1 pm to 12 pm (The transmission coefficients were averaged over the monitored spectra and inset shows the structure of the through waveguide).

[0009] Fig. 3: Measurements and simulations of various implemented geometries, including the repeated measurements after three months of fabrication. The plots represent the magnitude and phase of the transmission coefficient in the measured spectra. (A), and(B): Resonating (filter) section. (C) and (D) twisted, polarization rotating section, (E) and (F) bent (90°) section.

[0010] Fig. 4: Evaluation of MXene waveguides for high power (>20 dBm) handling capability. The power handling capability is demonstrated through the transmission coefficient of the MXene waveguides, at levels currently in use in LEO satellite systems.

[0011] Fig. 5: Demonstration of MXene waveguides operating at different frequency bands, currently in use for (LEO) satellite communications. (A) Photograph of developed X-band. Ku-band, and K / Ka band waveguides, covering an operation range of 8 GHz to 33 GHz. (B) The measured transmission coefficient of X-band, MXene waveguide.(C) The measured transmission coefficient of Ku-band, MXene waveguide. (D) The measured transmission coefficient of K / Ka-band, MXene waveguide.

[0012] Fig. 6: (A) thru waveguide section dip coated in MXene dispersion (inner and outer walls). (B) A cross-sectional scanning electron microscopy (SEM) image of an MXene coating after 3 dips with large T13C2 flakes. The image was captured by enabling the waveguide in epoxy and cutting it with a rotating diamond saw. The image illustrates that a compact MXene stacking can be formed simply by dip coating and air drying, resulting in high electrical conductivity. (C) A Transmission electron microscopy (TEM) image of a T13C2 MXene flake of approximately 2 pm width supports the successful etching and exfoliation during Ti3C2 synthesis and the formation of single flake dispersions.

[0013] Fig. 7: Weight comparison of MXene coated thru waveguide with conventional metallic waveguides. Photo of (a) uncoated waveguide structure, weighing 14.7 grams, (b) MXene-coated (one cycle) thru waveguide, weighing 14.8 grams, and (c) metallic waveguide, weighing 126.9 grams on a digital scale.

[0014] Fig. 8. The experimental setup for measuring the transmission and reflection coefficients of the waveguiding and resonator structures. A) The resonator section. B) The X-band thru section. C) The Ku-band twisted section. D) The K / Ka-band thru section. E) The Ku-band thru section. F) The Ku-band bent section.

[0015] Fig. 9. The measurement results for the phase parameter of the transmission coefficient within the thru waveguide section. The second measurement was conducted after three months of fabrication.

[0016] Fig. 10: Flake-size distribution of MXene dispersions of different sizes. The size is represented as hydrodynamic diameter (d, nm) in nanometers.

[0017] Fig. 11 : Digital images of 3D printed coupons with 1 to 5 dips in MXene dispersions of 3 different flake sizes.

[0018] Fig. 12: Optical microscopy of 3D printed coupons with 1 to 5 dips in MXene dispersions of 3 different flake sizes.

[0019] Fig. 13: Surface profile of 3D printed coupons with 1 to 5 dips in MXene dispersions of 3 different flake sizes.

[0020] Fig. 14: surface development ratio as represented by surface area / cross sectional area on 3D printed coupons with 1 to 5 dips in MXene dispersions of 3 different flake sizes.

[0021] Fig. 15: Microwave reflected power versus estimated MXene thickness of dip coated coupons and vacuumed assisted films made from MXene dispersions of different sizes.

[0022] Fig. 16: Surface profile of a partially coated 3D printed substrate obtained through optical profilometer OLS5000 (red grids indicate the surface profile).

[0023] Fig. 17: Simulated study of the impact of conductivity on the transmission coefficient in the thru waveguide section.

[0024] Fig. 18: Detailed dimensions of the A) WR-90 thru part, B) WR-62 thru part, C) WR-34 thru part, D) Bent WR-90-part, E) Resonator part, F) Twisted part. G) Shorting walls (coupons).

[0025] Fig. 19: Sn (reflection coefficient at port) measurements of Ku-band structures, including (A) Thru section (B) resonator (C) twisted section, and (D) bent section.

[0026] Fig. 20: ANSYS HFSS design models for (A) Thru section (B) Resonator section (C) Bent section, and (D) Twisted, polarization rotator section. E) The simulated electric field (E-field) distribution at the ports of the twisted section, illustrating a 90° rotation in E-field vectors' direction (i.e., polarization). These results were obtained in ANSYS HFSS by simulating the MXene-based twisted section at 15 GHz and provide further evidence on the rotation of polarization using MXene-based twisted section.

[0027] Fig. 21 : Measured reflection coefficients for MXene-based waveguides operating at various frequency bands and different input power levels.

[0028] Fig. 22: Evaluation of MXene waveguide performance for varying humidity’, high power (>20 dBm) transmission, and for different coating cycles. (A), (B), and (C) demonstrate the monitored resonant amplitude, resonant frequency, and resonant quality7factor of a MXene waveguide resonator operating under extreme humidity levels (~0-80%) in ten time cycles.

[0029] Fig. 23: The experimental setup for performance stability tests under alternating humidity conditions. The waveguide was placed inside a sealed chamber with inlet of H2O vapor, N2, and humidity probe sensor. The relative humidity7level inside the chamber was controlled by automating the MFCs and simultaneously setting the mass flow of H2O vapor (i.e., water vapor) and N2 (i. e.. air) into the chamber. To measure the %RH inside the chamber, a BK precision humidity sensor was utilized. The time-based microwave measurements were conducted using a Keysight N5222B Vector Network Analyzer (VNA) automated using a custom LabView program.

[0030] Fig. 24: Measurements of Ku-band waveguide fabricated using Ti3C2Tx MXene with different flake sizes. The small flake had an average size distribution of 130 nm, while the large flake sample had an average size distribution of 612 nm.

[0031] Fig. 25: Repeated measurements of MXene-coated structures, 6 months after the fabrication; (A) and (B) Thru section; (C) and (D) the resonator, (E) and (F) the bent section. Repeated measurements of MXene-coated structures. 6 months after the fabrication; (G) and (H) The twisted section.

[0032] Table 1 : A comparison of microwave transmission and loss, w hen employing nanomaterials such as Graphene and CNTs.DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0033] The present disclosure may be understood more readily by reference to the follow ing detailed description of desired embodiments and the examples included therein.

[0034] Unless otherw ise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the present document, including definitions, will control. Preferred methods and materials are described below , although methods and materials similar or equivalent to those described herein can be used in practice or testing. All publications, patent applications, patents and other references mentioned herein are incorporated by reference in their entirety. The materials, methods, and examples disclosed herein are illustrative only and not intended to be limiting.

[0035] The singular forms “a,” “an,’‘ and “the” include plural referents unless the context clearly dictates otherwise.

[0036] As used in the specification and in the claims, the term "comprising" can include the embodiments "consisting of and "consisting essentially of.” The terms “comprise(s),” “include(s),” “having,” “has,” “can,” “contain(s),” and variants thereof, as used herein, are intended to be open-ended transitional phrases, terms, or words that require the presence of the named ingredients / steps and permit the presence of other ingredients / steps. However, such description should be construed as also describing compositions or processes as "consisting of and "consisting essentially of the enumerated ingredients / steps, which allows the presence of only the named ingredients / steps, along with any impurities that might result therefrom, and excludes other ingredients / steps.

[0037] As used herein, the terms “about” and “at or about” mean that the amount or value in question can be the value designated some other value approximately or about the same. It is generally understood, as used herein, that it is the nominal value indicated ±10% variation unless otherwise indicated or inferred. The term is intended to convey that similar values promote equivalent results or effects recited in the claims. That is, it is understood that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but can be approximate and / or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art. In general, an amount, size, formulation, parameter or other quantity or characteristic is “about” or “approximate” whether or not expressly stated to be such. It is understood that where “about” is used before a quantitative value, the parameter also includes the specific quantitative value itself, unless specifically stated otherwise.

[0038] Unless indicated to the contrary, the numerical values should be understood to include numerical values which are the same when reduced to the same number of significant figures and numerical values which differ from the stated value by less than the experimental error of conventional measurement technique of the type described in the present application to determine the value.

[0039] All ranges disclosed herein are inclusive of the recited endpoint and independently of the endpoints. The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value; they are sufficiently imprecise to include values approximating these ranges and / or values.

[0040] As used herein, approximating language can be applied to modify any quantitative representation that can vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as "about" and “substantially,’’ may not be limited to the precise value specified, in some cases. In at least some instances, the approximating language can correspond to the precision of an instrument for measuring the value. The modifier “about” should also be considered as disclosing the range defined by the absolute values of the two endpoints. For example, the expression “from about 2 to about 4” also discloses the range “from 2 to 4.” The term “about” can refer to plus or minus 10% of the indicated number. For example, “about 10%” can indicate a range of 9% to 11%, and “about 1” can mean from 0.9-1. 1. Other meanings of “about” can be apparent from the context, such as rounding off, so, for example “about 1” can also mean from 0.5 to 1.4. Further, the term “comprising” should be understood as having its open- ended meaning of “including,” but the term also includes the closed meaning of the term “consisting.” For example, a composition that comprises components A and B can be a composition that includes A, B, and other components, but can also be a composition made of A and B only. Any documents cited herein are incorporated by reference in their entireties for any and all purposes.

[0041] Any embodiment or aspect provided herein is illustrative only and does not limit the scope of the present disclosure or the appended claims. Any part or parts of any one or more embodiments of aspects can be combined w ith any part or parts of any one or more other embodiments or aspects.

[0042] Two-dimensional (2D) transition metal carbides and nitrides, MXenes, have attracted significant attention due to their distinctive properties, particularly high electrical conductivity, solution processibility at ambient conditions, and thermal shock stability. In contrast to metals (e.g., copper), the 2D morphology’ with functional surface terminations allows MXenes to form stable colloids in water and polar organic solvents, without the need for additives or surfactants, enabling their easy processibility. MXenes have been demonstrated as an additive-free coating material that can be applied to a variety of substrates of any shape (e.g., foams, glass, textiles). They conformally cover substrate surfaces.

[0043] Here we have demonstrated, for the first time, the application of electrically conductive MXene from a water-based MXene (colloidal) solution to polymeric AM components (nylon channels) through a straightforw ard dip coating process. Dip coating ispreferred over spray coating because it allows for the use of more concentrated (viscous) MXene solutions, can be used to coat narrow channels of complex shape, and does not require any special equipment. It should be understood, however, that the examples described herein using nylon and Tis^Tv are illustrative only and do not limit the scope of the present disclosure or the appended claims. TnCLT was synthesized by selective chemical etching of the Al atoms from the parent TisAlC2 MAX phase using a mixed acids method. The formation of single-flake MXene dispersions was confirmed by transmission electron microscopy (Fig 1 A inset), demonstrating successful etching and exfoliation. The substrate chosen for coating was commercially available Nylon PA- 12. Without being bound to any particular theory, one can select a polymer and a MXene that will exhibit bonding between one another; such bonding can be, for example, covalent interactions.

[0044] A selective laser sintering (SLS) printing method was adopted with the selection of a rougher printing resolution (on the micrometer scale) for enhancing MXene coating adhesion through mechanical entrapment. Correlations were observed between the thickness of the MXene layers and microwave performance. The facile MXene coating enables a highly efficient, three-dimensional manipulation of electromagnetic waves within channels. The microwave-associated functionalities were demonstrated at different power levels and in the frequency span of 8 GHz to 33 GHz, covering the already-in-use operation range in LEO satellite communication. Various MXene dip-coated geometries, including thru, bent, twist, and resonator sections were implemented and repetitively measured using microwave equipment.

[0045] 2. Results and Discussion

[0046] Fig. 1 demonstrates the performance and weight comparison of the MXene- coated and metallic structures for a thru waveguiding section operating at the Ku band (12.4 - 18 GHz). In Fig. 1A, the weights of a Nylon through waveguide before coating, the same waveguide after one cycle of MXene coating, and a commercial waveguide made of aluminum (measurements in Fig. 7) are compared. The waveguide coated with MXene exhibited a significantly lower (8.2 times lower) w eight compared to the conventional aluminum waveguide. Comparing the weights before and after coating, a single cycle of dip coating added only 0. 1 g or 0.62 % of the weight of the uncoated Nylon structure. Investigating electromagnetic pow er transmission and reflection within a thru rectangular waveguiding channel establishes a performance merit comparison between the MXene-coated guides and metallic waveguides. A total weight of the antenna may include the weight of the MXene coating(s), and the body of the antenna, which may be the polymer (e.g., Nylon) structure. Therefore, the transmission coefficients of the MXene-coated thru waveguide were compared to a metallic one in Fig. IB. The waveguiding performance was analyzed by measuring the transmission coefficient of electromagnetic waves, propagating from port 1 of the structure to port 2 (Fig. IB inset and Fig. 8). The magnitude of S21 (dB) measurements was used as an equivalent parameter to the transmission coefficient (relation to insertion loss is reported in the Supplementary Information). MXene coated through waveguide showed only -2.3% decrease in the electromagnetic waveguiding performance (- 0. 1 dB reduction in transmission coefficient). After only one cycle of MXene coating, the experimentally measured transmission coefficient was -0.9 dB, indicating an 81% efficiency for guiding the electromagnetic waves between two excitation terminals (Fig. IB). The stability of the guides was experimentally investigated after three months of environmental exposure showing a negligible reduction in performance (Fig. 9).

[0047] It is understood that the guiding of electromagnetic waves is affected by each incidence of waves on the conducting MXene walls. At each incidence, a portion of power will penetrate and dissipate in a conductor, leading to a loss. The remaining portion of EM power at each incident would be reflected by the conducting boundary (as illustrated by red and blue dashed lines in Fig. 1C) giving rise to the guiding mechanism. The conductivitydependent loss of MXene-coated structures can be described through the mechanism of wave penetration into a body with finite uniform conductivity. The power penetrated into the body of a conductor, Plossis correlated with a dissipative term defined as the “surface resistance”,

[0049] where f is the frequency of an incident wave on the waveguide walls, with o and n representing the conductivity and permeability of the conductor, respectively. Eq. 1. indicates the increase in the conductivity' of the conductor walls (i.e., thicker coatings) decreases the dissipative loss, Rs, minimizing the loss of energy' (heat dissipation) for a wave propagating in the guide. An ideal medium (or material) exhibiting infinitely high bulk conductivity becomes lossless at micro wave frequencies. This can then lead to a perfect reflection of waves from surfaces, particularly useful for guiding applications. The relationsof Eq. 1 also imply a frequency-dependent loss mechanism upon wave guiding, where the waves carrying a higher frequency ( ) propagate with the characteristics of higher dissipated power. The higher the ratio of reflection, the less penetration and dissipation inside the conductor body.

[0050] A parametric study was conducted to optimize the MXene coating and examine the impact of MXene size and dip coating on reflection performance (Fig. 2). The hypothesis is that MXene flake size and coating thickness influence the reflection performance. Larger MXene flake sizes can result in 1) higher electrical conductivity, leading to more effective reflection, and 2) increased viscosity, resulting in thicker MXene deposition. MXene dispersions with three different flake sizes (1300 nm, 500 nm, and 200 nm) were prepared at the same 20 mg / ml MXene content through sonication-assisted size reduction and processed into freestanding films of the same weight (20 mg) via vacuum- assisted filtration for electrical conductivity measurements (Fig. 2 A and Fig. 10). The electrical conductivities of the three films decreased with flake size from approximately 13100 S / cm to 11500 S / cm and 5400 S / cm. Identical 3D printed coupons with representative roughness for 3D printed nylon parts were prepared, and they underwent up to five dip coating cycles in the MXene dispersions. No surface modification was performed before MXene dip coating due to the chemical compatibility between nylon and MXene. Each coupon was immersed in the designated MXene dispersion for one minute and allowed to dry completely before the next dip coating cycle (Fig. 11). It is worth noting that as the MXene size increased, longer waiting times (less preferable for production) were required for the coating to dry, ranging from 10 minutes to 2 hours and 18 hours for small, medium, and large-sized MXene flakes respectively. As anticipated, the MXene loading increased with both the MXene flake size and the number of dip coating cycles (Fig. 2B). Although all flake sizes provided complete coverage of the nylon coupons from the first dip, the effect of increasing viscosity due to flake size was evident in the smoother film-like coating morphology of the large MXene dip coated coupons, compared to the rougher and more conformal coating provided by the medium and small-sized coupons (Figure 2B inserts and Fig. 12). To understand the effect of flake size and dip coating cycles on MXene coating deposition, the ratio between the actual surface area and the projected area was calculated using the Developed Interfacial Area Ratio (Sdr) obtained from laser confocal scans (Fig. 13). Distinct trends were observed for MXene flakes of different sizes. While small flakeshad little effect on the surface area, indicating a highly conformal coating, large flakes provided a decrease in surface area due to MXene coating forming films that leveled the rough surface. To our surprise, medium-sized MXene flakes exhibited the largest increase in surface area and changes in roughness throughout the five dip coating cycles (Fig. 14). We speculate that medium flakes had difficulty in flake packing on substrates of this particular roughness, leading to chaotic flake alignment on the surface and an increase in surface area.

[0051] Microwave measurements of the coupons were performed using a WR-90 Keysight waveguide calibration kit (8.2-12.4 GHz). The system was calibrated for one-port measurements. Fig. 2C shows that large and medium-sized MXene coatings exhibited significantly higher reflected power compared to small-sized MXene. With just one dip coating cycle, large and medium-sized MXene resulted in reflected power greater than 0.95. Moreover, large-sized MXene flakes showed a steady increase in reflected power with dip coating cycles, while small and medium-sized MXene coated samples exhibited small fluctuations in reflected power over the dip coating cycles. The performance fluctuation was attributed to the higher surface roughness of medium and small-sized MXene coated coupons, leading to less stable contacts between flakes. The reflected power of the coupons was plotted against the surface-normalized coating thickness in Fig. 2D. It is to be noted that despite the higher MXene loading (mg / cm2) from the medium-sized dispersion, the coating thickness was comparable due to the increased surface area. Nevertheless, medium-sized MXene offered better power, indicating the importance of MXene flake size and electrical conductivity on performance. To benchmark the performance, the reflected power of six vacuum-assisted films made from 0.5 ml and 1 ml of the three different MXene dispersions was measured (Fig. 15). All films exhibited nearly perfect reflection, outperforming the coatings at comparable thicknesses with the performance gap increasing with decreasing flake size. This suggests that the rough surface substrate disrupts the alignment and contacts between flakes, resulting in a realized electrical conductivity lower than that of films (vacuum assisted filtered films are used to approximate the optimal flake alignment and contacts of a given MXene flake size). For the purpose of this study, to use MXene coating (Fig. 16) as fast, cost-effective method to impart electrical conductivity to 3D printed parts, medium-sized MXene flakes is recommended as they provided sufficient reflection performance with a faster drying time (processing time) compared to large MXene flakes, while also providing a thin conformal coating with low MXene consumption. Subsequently,actual thru waveguides were dip coated in a 20 mg / ml MXene dispersion of medium size (-500 nm), and the transmission coefficient was measured.

[0052] The functionality and performance of the MXene-coated structures were parametrically investigated through experiments and finite element method (FEM) simulations, observing a relation between the number of dip coating cycles and measured microwave performance (transmission coefficient) (Fig. 2E). This was then hypothetically tied to the thickness of the MXene coating and the effective electrical conductivity of a layer. The results depicted in Fig. 2E indicate the increasing number of dip-coating cycles resulted in a mass increase of the coated coupon. The observed mass change was perceived as a buildup of the MXene with increasing layer thickness. Furthermore, it was observed that, with increasing the number of dip coating cycles from one to four, the average transmission coefficient over the monitored frequency range improved by 14% (+ 0.7 dB), with the highest measured efficiency of 95 % (-0.2 dB). Simulating the performance MXene-based waveguides (using a FEM method) provided additional support on performance enhancement through increasing thickness or electrical conductivity in the layer (Fig. 2F, Fig. 2E, Fig. 17 and the related text).

[0053] To demonstrate the wide applicability of the proposed method for manipulating electromagnetic wave behavior, four different MXene-coated structures with complex geometries were manufactured and studied in the microwave regime (Fig. 3). These geometries are difficult for metal AM. Our measurement results demonstrated the suitability of the proposed method for producing a variety of MXene-based components with varying geometries (Fig. 18 - Fig. 20) and operation conditions (Fig. 22-23 and related text) after one dip coating cycle. To show the feasibility of a relatively complex geometry', a two- dimensional twist was 3D-printed, MXene-coated and its transmission response was measured (Fig. 3C and 3D). The twisted sections are generally utilized to rotate the wave polarization in microwave signals (Fig. 20), physical equivalence of orientating waveguide apertures. In an optimized scenario, the twist should be gradually applied over a distance of two times the wavelength (the lowest operating frequency in this case, i.e., 12.4 GHz). Passing the stall frequency, the twist functioned as an effective guiding medium, with a low insertion loss of -0.27 dB, corresponding to a 6% loss (relative to the input power) of transmitted electromagnetic power. The microwave oscillation phenomenon (Fig. 3A and 3B) and bent waveguiding (Fig. 3E and 3F) were also experimentally investigated with MXene-coated polymeric waveguides and The longevity of coating on these structures was investigated over three months and assessed as excellent (Fig. 3).

[0054] The power handling capability of MXene guides was studied by adjusting the input power of the signal source from +20 dBm to +40 dBm, covering the typical power levels utilized in LEO satellite communications. At each input power level, measurements were taken after one hour of signal propagation through the waveguide. Fig. 4 shows the magnitude of the transmission coefficient for the varied power levels, and Fig. S16 includes the reflection coefficients and phase measurements for the transmission coefficient. The waveguides efficiently handled an input power level of 30 dBm (equivalent to 1 watt) and 40 dBm (equivalent to 10 Watts), with no decline in performance. The frequency dependence of the transmission coefficient (Fig. 4, zoomed-in) shows that the transmission of electromagnetic power remains nearly identical across various input power levels, with a maximum change of 0.002 dB, equivalent to a relative difference in power transmission of 0.05%. The insignificant variation observed across input power levels can be attributed to the minimal resolution of the microwave instrumentation utilized for detecting these power levels at the second port of the waveguide.

[0055] Finally, MXene-based waveguides for operation in different frequency bands, including LEO frequencies, were manufactured and measured. Fig. 5A demonstrates three MXene-coated waveguides for operation at different frequencies: X-band (WR-90 8.2- 12.4 GHz range), Ku-band, and the K / Ka-band (WR-34 in 22-33 GHz range), which were manufactured using the proposed method (dimensions in Fig. 18). The X-band waveguide (Fig. 5B) demonstrated a -0.06 dB reduction in the transmission, compared to a metallic waveguide. This w as equivalent to ~2 % of additional losses as a result of replacing metal with MXene in the same geometry. The K / Ka-band waveguide demonstrated increased losses in the 22-33 GHz range. Fig. 5D shows the measured transmission coefficient for a w aveguide with operation frequency covering K and Ka bands (WR-34 waveguide) (dimensions and performance in Fig. 18). The reduced guiding performance of K / Ka-band waveguides is attributable to higher frequencies having a higher loss of microw aves within conductor bodies (relation to Eq. 1 described in the Supplementary Information). This indicated that the MXene coating thickness and conductivity should be further optimized for use in the high-frequency K / Ka range. Furthermore, the observed differences between simulated and measured waveguide performances (~I%, ~2%, and ~6%, for X, Ku, and K / Kabands, respectively) are atributed to fabrication-related parameters, such as film conductivity, roughness, and film thickness, and indicate the significance of parameter optimization for increasing the transmission coefficient of MXene-based waveguides.

[0056] The longevity of MXene-coated waveguiding components was verified through tests conducted six months after the coating, as shown in Fig. 25. The MXene-based waveguides w ere kept unsealed and stored under standard room conditions in a laboratory seting. The MXene guide had a slightly lower performance than its metallic counterpart, with a difference of -0.25 dB (equivalent to 6% underperformance). For space applications, where components might experience extreme low temperatures, the electrical conductivity of TisC2 exhibits a slight increase down to at least -100K (typical for metallic conductors). Therefore, excellent performance of the MXene-coated communication components is anticipated.

[0057] Over the past several decades, efforts have been made to reduce the w eight in aerospace and satellite components by developing novel materials and manufacturing procedures and aiming for a certain level of operational efficiency. Moreover, with the recent expansion in satellite communications and extended space missions, the considerations for w eight reduction has become crucial. Graphene, carbon nanotubes (CNTs), and conducting polymers (particularly, PEDOT: PSS) were also used as conducting materials in microwave technology7in aerospace applications. How ever, only a limited number of structures based on graphene and CNTs have been reported for purposes other than absorption and EMI shielding, specifically for transmission and radiation applications. A comparison of performance and manufacturability between MXene-based 3D waveguides and other nanomaterials in Table 1 shows that the MXene films offer higher shielding effectiveness and conductivity compared to films and coating based on graphene, CNTs, and PEDOT: PSS. Graphene and CNT-based materials may be used for microwave absorption and signal dissipation.Table 1:

[0058] Furthermore, the reported non-reciprocal characteristics of graphene may not be suitable for applications such as microwave guiding and transmission, which rely on reciprocity. Because solution-processable CNTs, reduced graphene oxide and polymer films do not offer sufficient conductivity and shielding effectiveness, and chemical vapor deposition of graphene onto polymers or transfer inside waveguide channels of a complex shape is not possible, MXenes are an attractive material for 3D waveguides.

[0059] 4. Conclusions

[0060] This work showed that MXene coatings supported on additive-manufactured polymeric components can replace traditionally -manufactured channels of metallic waveguides. The benefits of the method include not only weight and cost of manufacturing, but also the feasibility of creating complex 3D-printed shapes that are much more difficult to make with metal. The manufacturability and processability of MXenes allows for adjustment of microwave performance and manufacturing of a large variety of devices of waveguides of any size and complexity. MXene coating can be accomplished by several methods and the choice of the substrate (the 3D-printed material) is not restricted to nylon but can include a variety of plastics, polymers, and composites. Further, the broad range of MXenes allows the integration of thin films wi th different optical and structural properties for a multitude of industries, beyond waveguides and aerospace.

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[0114] Additional Disclousre

[0115] Materials and Methods

[0116] Additive manufacturing of waveguiding structures

[0117] The structure of the waveguiding components was fabricated by a Fusion additive manufacturing (3D) method. The filament material used for the 3D printing was NYLON PA12, a commercially available nylon-based material.

[0118] The high-frequency simulations and MXene modeling

[0119] The performance of the MXene-coated waveguiding structures was simulated in ANSYS HFSS.

[0120] To model MXene, a finite conductivity layer boundary condition was applied to the inner and outer walls of the waveguide structures (resembling a conductive coating on nylon channels).

[0121] Parametric ANSYS HFSS simulations were performed with the followingMXene-related setings as it provided a very good agreement between the observed measurement results and simulated structures.

[0122] Conductivity sweep: 5000 S / cm to 25000 S / cm

[0123] The thickness of the MXene layer: 1 pm to 12 pm

[0124] To account for the roughness of the coated layers, a local (defined in the software environment) surface roughness parameter, termed the Groiss model, was used, and the value of this parameter was set to 5 pm, corresponding with the physical thickness of the MXene coating.

[0125] The MXene-based waveguide structures were designed and simulated in ANSYS HFSS to investigate the transmission characteristics for each geometry. The structures were modeled by Nylon PA 12 (incorporated 3D printed filament), and a finite conductivity boundary7condition was imposed on the outer surfaces of each geometry to account for the coated layers of TitybTx MXene. The finite conductivity boundaries take into account the effect of MXene layer thickness and roughness.

[0126] Frequency response measurement of the waveguides and coupon:

[0127] A Key sight N5222B Vector Network Analyzer (VNA) was used to measure the MXene-based structures scattering parameters (S -parameters). For the two-port measurements, a standard TRL (thru-response-load) calibration procedure (based on a Keysight Pl 1644A mechanical kit) was used.

[0128] The measured S21 (dB) values have the following relation to the insertion loss (dB) of each waveguiding component:

[0129] Insertion loss (dB) = — S21 dB)

[0130] Coupon performance was measured with Keysight N5247A Performance Network Analyzer (PNA-X). XI 1644A Keysight calibration kit was used to measure MXene coupon performance in the X-band (8.2-12.4 GHz) frequency range. To increase the accuracy, a 1-port calibration procedure was performed before the coupon measurements.

[0131] Cyclic Humidity measurements setup

[0132] The humidity measurement setup was composed of a B&K Precision meter for monitoring the chamber’s humidity and temperature. LabVIEW program was used to record the active MXene-based resonator’s time-based frequency response. An Alicat mass flow controller was used to control the humidity injection into the chamber, while a second mass flow controller was used for purging the humidity by pumping synthetic air into the chamber. The MXene-based sensor was located inside a sealed chamber.

[0133] XRD & SEM / EDS

[0134] TisC2Txwith an average flake size of 600 nm was selected as the representative medium of the full range of available MXene sizes and was obtained with probe sonication. Scanning electron microscopy (SEM) images of Fig. 6 confirmed a conformal MXene coating to the nylon waveguide.

[0135] The first demonstration of the concept involved dipping a 3D-printed nylon thru waveguide in a colloidal MXene dispersion (details in the SI) just once, followed by 48 hours of drying at ambient temperature.

[0136] Without being bound to any particular theory or embodiment, an increase in the thickness of the MXene layer, flake size, and flake alignment improves the electrical conductivity of coatings, enhancing the microwave guiding performance.

[0137] On the details of waveguide efficiency measurements within different mediums, the transmission distance of Ku-band waveguides was 3 inches (same for the case of free space).

[0138] Power handling study of MXene waveguides

[0139] On the power handling study, as a result of the maximal input power restriction of the employed instrument (VNA), the power levels were limited to 40 dBm during the performed tests. Investigating higher power levels (>40 dBm=10 watts) necessitates sophisticated instrumentation and facilities that exceed the scope of this work and the intended application. The results of Fig. 4 confirmed that the developed MXene guides are suitable for LEO satellite communication transponder system, in which the average satellite transmission power varies from 20 dBm to 40 dBm. Our interpretation from the unaffected transmission coefficients is that the MXene’ s outstanding electrical conductivity enables the coatings to offer sufficient thermal capacity, potentiating the use MXene based components for high power, communication systems.

[0140] Further details and descriptions

[0141] To investigate the effect of solution-processed MXene’s flake size on the performance of dip-coated structures, a WR-62 waveguide was dip-coated (single coating) in a colloidal solution of TiaCTTx MXene with smaller flakes sizes (130 nm size distribution). Based on the visual observation in the first dip coating cycle, the adhesion of MXene onto the surface of Nylon structures was not as strong as in the case of large flakes. The transmission coefficient and the reflection coefficient for the waveguide fabricated using the small flake MXene solution were measured, and the results are shown in Fig. 24. The transmissioncoefficient is compared to the transmission coefficient of a thru waveguide fabricated by a single dip into a larger flake (-612 nm) MXene solution. It is evident that the small-flake solution did not allow for sufficient conductivity’, as a thru waveguide had -20 dB loss (equivalent to 99% loss) in power transmission. Our observation indicated that the large-flake MXene solution had higher adhesion on Nylon and formed a highly conductive thin boundary on the waveguide walls that ensured outstanding microwave performance.

[0142] For coupon coating study, MXene dispersions with three different flake sizes (1300 nm, 500 nm. and 200 nm) were prepared with the same 20 mg / ml MXene content through sonication-assisted size reduction (size distribution is shown in Fig. 10. As shown in Fig. 2A, to study the effects of dip coating cycles and MXene flake sizes, as a simplified model for larger waveguides, flat coupons (with dimensions in Fig. 18), were fabricated with the same material / manufacturing parameters as the aforementioned thru waveguide. The coupons were identical and underwent up to five dip-coating cycles following the same dipcoating protocol. (Fig. 11). It was observed that, as the MXene size increased, longer waiting times were required for the coating to dry, ranging from 10 minutes to 2 hours and 18 hours for small, medium and large-sized MXene flakes respectively.

[0143] To estimate the thickness of MXene coatings and the effects of the surface roughness, change in mass between coated and uncoated samples is used. The thickness of the coating depends on surface area of the sample (S), density’ of the MXene (p=3500 kg / rn3) Eq. 2. Increase in surface area due to the roughness of the Nylon substrate is accounted for by coefficient k. It is measured using optical profilometry and is defined as k = Sdr + 1.

[0145] Surface areas of coupons and waveguides were calculated based on CAD models (Surface area of coupons - S = 4.3 x 10-3m2, Surface area of WR-62 waveguide - S = 1.3 x 102m2).

[0146] The surface area of the WR-62 waveguide (S = 1.3 x 10-2m2) as calculated and the surface roughness of the 3D printed Nylon, obtained through optical profilometry. was accounted in the calculations. The increase in the surface area due to the roughness (£=1.82) of the surface was estimated as a relationship between the surface area of the Nylon substrate relative to the sampling area of the microscope.

[0147] The results of Fig. 2E demonstrate the relation between the number of dip coating cycles and the microwave performance of a thru section. In addition, this figureincludes the estimated thickness of MXene coating on the coupons, after each dip coating cycle. It was hypothesized that the increasing mass and thickness increase had an impact on the microwave performance. The estimation of coating thickness was based on relating mass change (Am) of coated pieces before and after each coating cycle. The thickness of the MXene layer on the coupon after the initial coating cycle in the MXene solution was calculated to be 1.8 pm. The optical profilometry (image) shown in Fig. 16 for a waveguide component (partially) coated with one cycle of MXene, suggest a distinction between the profiles (red-gridding) of MXene-coated and (un-coated) Nylon regions.

[0148] Regarding the investigation of coating aging in addition to device performance, the practicality' of the MXene coating weighs heavily on its environmental stability'. Therefore, to evaluate the effect of potential oxidation and humidity absorption, the S21 measurements were repeated after 3 months subsequent to initial fabrication (coating). Only 0.05 dB reduction was observed in the transmission of waves which indicates the excellent environmental stability' of Ti3C2Txcoatings. Furthermore, the changes in the propagation time of microwaves after three months of fabrication was assessed from S21 phase measurements. Our results showed almost identical phase parameters in the transmission coefficient of the MXene guide (Fig. 9), implying an unchanged time of propagation for microwave power flowing within a MXene-coated thru section.

[0149] ANSYS HFSS Simulations were performed sweeping thickness values from 1-12 m to obtain the average transmission coefficient, as shown in For MXene thickness in the 2-3 [im range, the transmission coefficient ranged from -0.1 dB to -0.5 dB (- 0.64 dB and -0.43 dB for 2 and 3 m values), which was in close range to measured values at corresponding coating cycles. Parametrically increasing MXene’ s thickness in these simulations up to 12 m, a highest of -0.2 dB transmission coefficient resulted (equivalent to -95% power transmission efficiency). These results were in very good agreement with the experimentally measured transmission coefficients of Fig. 2E. Furthermore, the settling of performance for (coatings thicker than 6 pm) indicated the importance of bulk coating’s conductivity after each coating cycle. This was demonstrated by assigning a constant thickness for the MXene layer (1 pm) and increasing bulk conductivities from 5000 S / cm to 25000 S / cm, where the simulated transmission coefficient was improved by 20 % equivalent to +1 dB, as shown in Fig. 17.

[0150] The simulated and fabricated MXene waveguides showed near-identical phase parameters of the transmission coefficient for the simulated and fabricated MXene guides (Fig. 9). implying an unchanged time of propagation for microwave energy flowing in an MXene-based guide. For the phase angles of S21 parameters for the simulated and the measured MXene guides (Fig. 9), there was only a 6° difference, which can be considered negligible. At the frequency of 13.5 GHz, a 6° of phase difference means the effective electrical length of the fabricated MXene waveguide was only 0.016 Xo (wavelength) shorter than the simulated one.

[0151] The variously designed and fabricated structures included (dimensions are in Fig. 18): the aforementioned thru waveguiding section, a 90° bend thru waveguiding section, a twisted waveguiding section, and a resonator section with discontinuities in the channel. To evaluate the performance of each structure, the transmission coefficients and reflection coefficients (S21 and Si 1) were measured at both ports of these structures. Fig. 3 shows the measurements that include both magnitude and phase, represented in the frequency domain. To benchmark a base level for the full transmission of microwaves within each structure, the transmission characteristics were compared to a commercially available metallic thru section. Only one dip-coating cycle was performed to enable the following micro wave functionalities.

[0152] On the operation of microwave twists, if a twist is applied over a shorter distance, the microwaves will not have sufficient time 'distance to adapt to the gradually changing geometry, resulting in increased losses of transmission. For a (relatively) short, twisted section, the transmission losses can be observed in the high-pass frequency response of the two-port microwave structure (i.e., a high-pass waveguide filter). In our design, the length of the twisted section was maintained short to illustrate the capability of MXene- enabled manipulation of microwaves, resulting in dual, polarization-rotation and high-pass filtering functionalities. As shown in Fig. 3C, the twisted section demonstrated a high pass frequency response, with a 3 dB cut-off frequency (for the loss factor) of 13.06 GHz. The implemented twist also indicated a high-pass frequency response with a 3 dB cut-off frequency of 13. 13 GHz. The simulated and measured transmission phase for the short twist indicated a good consistency, with slight differences attributable to the dip-coating fabrication procedure and differences in the surface roughness values. After three months ofmanufacture, there was only a 3.2% decrease in the transmission performance of the twisted waveguide.

[0153] As indicated by the results of Fig. 3A, microwave resonance (i.e., oscillation) was also generated inside a (MXene-coated) channel with discontinuities. These results show the measured and simulated band-pass response of the designed MXene-based resonator. This resonant section was created using two rectangular discontinues (slits) introduced inside the waveguide section (Fig. 18) to cause a resonant reaction in the waveguiding medium. Observing S21 (dB) results of the MXene-based waveguide resonator and a thru metallic / MXene guide (Fig. IB and Fig. 3 A), this structure clearly demonstrates a frequency band-pass response around 13.82 GHz, compared to the all-pass behavior of a thru section with no discontinuities in the channel. This bandpass MXene waveguide fdter had a measured peak transmission amplitude of -11.18 dB, associated with a -3 dB quality factor of 149. Furthermore, the simulation results for this MXene-based band-pass waveguide filter indicated a resonant frequency of 13.67 GHz, a peak transmission magnitude of -12.6 dB that was associated with a -3 dB uality factor of 155. We assume that the slight difference of 150 MHz, equivalent to 1% of the design frequency in the simulated and fabricated waveguide’s resonant frequencies are due to the fabrication faults, that can effectively change the length and the geometry of the cavity between the discontinuities from an ideally modeled cavity7in the simulations. The measured and simulated reflection coefficients of the resonator waveguide (Fig. 19) were in accordance with the observed bandpass transmission response. Similar to the thru waveguide section, the bandpass resonator guide exhibited excellent stability over the course of three months after the fabrication, with only a 0.3 dB reduction of transmission (equivalent to 6.6%).

[0154] By illustrating the electromagnetic field distribution within the twisted channel by ANSYS HFSS simulations (Fig. 20), the polarization rotating capability is preserved for the MXene-based twist section. The simulation results also indicated a high- pass frequency response yvith a 3 dB cut-off frequency of 13. 13 GHz. The simulated and measured transmission phase for the short twist indicated a good consistency, with a slight difference that can be attributed to the dip-coating fabrication procedure and differences in the surface roughness values. After three months of manufacture, there was only a 3.2% decrease in the transmission performance of the twisted yvaveguide.

[0155] A bent MXene-based waveguide section was implemented, with transmission coefficient results shown in Fig. 3E. Only a -4% reduction in the transmission performance was observed for the bent waveguiding section. The MXene-coated bent section showed an excellent transmission performance compared to a metallic waveguide, by demonstrating an additional negligible loss of -0.05 dB. The observed transmission loss of the bent MXene guide was in the frequency range of 12-15 GHz, with the highest value of 0.5 dB. This corresponded to -11% loss of the transmitted power throughout the bent, guiding section. The transmission characteristics of the MXene bent waveguide were further compared to the simulation results in Fig. 3E. The simulations have demonstrated a consistent loss of transmission in the monitored frequency range (12.4-18 GHz). Yet, the measurements indicated a higher loss of transmission from 12-15 GHz. We hypothesize this difference is due to the slight variations in the uniformity of the MXene coating on the bent surface, affecting the achieved electrical conductivity in the final coating. S21 phase results for simulated and measured bent guides, demonstrated excellent matching, where the slight deviation of phase quantities can be attributed to differences in the surface roughness of fabricated and simulated structures. The reflection coefficient of the MXene-based bent section was measured, and the results (Fig. 19) were consistent with the obtained transmission coefficients.

[0156] The waveguides operating at different frequency bands were constructed using identical Nylon PAI 2 material and were dip coated in the TisC2TxMXene solution by a single dip cycle, similar to previous fabrication procedures. The measured and simulated transmission coefficients of the MXene-based X-band waveguide, along with the results of the metallic waveguide are shown in Fig. 5B. As the thickness of the MXene layer and the bulk conductivity of the layer were assumed to be greater than their real (post-fabrication) values, the simulated transmission coefficient exhibited better performance with only -0.02 dB reduction in the transmission coefficient. Additionally, the observed frequencydependence of microwave losses further confirms the metallic nature of MXene’s electrical conductivity. MXene layers behave similarly to conventionally studied metals in terms of micro wave loss analysis and micro wave guiding mechanisms. For both X-band and K / Ka- band waveguides, the reflection coefficients were measured (Fig. 21), showing agreement with the transmission coefficients (Fig. 5). The simulated high-frequency waveguide (22 GHz to 33 GHz) demonstrated improved performance with reduced losses (Fig. 5). This can beattributed to the higher assigned conductivity of the MXene layer within the simulation environment (than the achieved conductivity on fabricated MXene-coated walls), as well as the increased impact of rough waveguide walls on microwave transmission at higher frequencies.

[0157] The WR-34 waveguide showcased excellent guiding performance in 22 GHz-33 GHz, with only 0.4 dB reduction (equivalent to 9% loss) from the full transmission case (thru metallic).

[0158] The observation of increased loss with frequencies agrees with the theoretical prediction of Eq. 1, which states that a higher frequency can result in larger sheet resistances, corresponding to an increased portion of microwave energy' being dissipated in the conductor.

[0159] We extended the investigation of MXene-based resonator to evaluate their performance both in humid and dry environments, with details in the supplementary materials. It was found that the MXene-based structure had negligible (<1%) fluctuations in performance. To assess the performance under alternating humidity levels, the MXene-based resonator section was used as a resonant micro wave component for monitoring humidity. Fig. 22 A, B, and C demonstrate the resonant characteristics of the MXene-based resonator in ten consecutive cycles of high (-80%) and low relative humidity (<1%) levels. These measurements were performed at (room) temperature of 22 ± 0.1 °C, where the waveguide was positioned in a sealed chamber (Fig. 23), and the humidity levels were controlled by mass flow controllers that regulated the flow of water vapor (to increase %RH) and synthetic air (to decrease %RH) in the chamber. Fig. 22 A, B, and C illustrate the alterations of resonant characteristics from their initial (start of the experiments) value. With the increasing relative humidity from 1% to 80% inside the chamber, the highest observed peak-to-peak shift in the resonant amplitude (AA) was <0.015 dB. The range of alteration was equivalent to a negligible 0.35% loss in transmission for highly humid environments (-80% RH). Similarly inconsequential, the resonant frequency exhibited a maximum alteration of 0.002 GHz from its original value, which corresponded to a 0.016% alteration. Throughout ten cycles of extremely high and low relative humidity levels, the quality factor of the resonator, which is defined as the ratio of power stored to power loss at resonance, changed by only 0.8%. In addition, the results of Fig. 22C revealed that the quality factor for the resonatorreturned to its initial value of -170 after the waveguide’s exposure to ten consecutive high- low humidity cycles.

[0160] The implementation of MXene-based waveguide components provides an example of a facile, convenient realization of 3D-printed polymer devices with performance levels as high as the metallic ones. The waveguide and other conductive components can be additively manufactured using commonly available 3D printers and commercially available polymers. The dip-coating of MXene provides a general solution for realizing geometrically complex metal-like 3D structures. We demonstrated the implementation of thru, bent, twisted, and discontinuous filtering waveguides, each of which can be utilized to manipulate the propagation of electromagnetic waves.

[0161] For this MXene-based demonstration, we reviewed the reported high- frequency transmission and absorption of microwaves within structures that employed nanomaterials such as graphene, CNTs, and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT: PSS), as shown in Table SI. MXene offers several advantages, including but not limited to, higher achievable conductivity in a film processed from a solution. This is combined with better reflectivity and shielding effectiveness, and a fabrication procedure, which is a room-temperature deposition from solution. Some have demonstrated waveguiding losses >two orders of magnitude in a 80 pm planar transmission line structure based on graphene. Additionally, chemical vapor deposition (CVD) of graphene onto polymers is not possible. Transfer of graphene inside 3D waveguide channels w ould not be possible either. In a microstrip line topology implemented in section by a PEDOT: PSS -based strip, reported a significant - 4.2 dB additional loss (i.e., >half power loss), and the fabrication procedure included a heat treatment of samples for better adhesion. The comparison (in Table 1) reveals a much higher electrical conductivity and reflectivity of MXene coatings, in agreement with published data for MXene films.

[0162] Furthermore, the shielding effectiveness parameter of MXene-based films, is much higher (+ >30 dB - orders of magnitude higher shielding) than other carbon-based materials such as CNTs, graphene, or PEDOT:PSS. The higher electrical conductivity7of MXene films in comparison to CNTs and graphene materials lead to the higher reflection of microwaves at the first incidence of a ray. Thereby, a 3D microwave channel based on MXenes (T CiT in this w ork) has greatly superior transmission characteristics with significantly reduced loss factors and comparable performance to metals. The loss ofmicrowave power is also increased in a single-layer, 2D planar structure due to the absence of additional walls that confine (and guide) electromagnetic waves (e.g., a 3D channel). It should be noted that the power loss values in Table 1 were selected from the values reported at the modem microwave communication bands.

[0163] Most of the graphene and CNT-based structures reported tailored dissipative performance at microwave frequencies, where nanocomposites (carbon dispersed in polymers) cause the dissipation of electromagnetic waves, in contrast to near-perfect guiding from aligned MXene flakes forming a coating. There were also reports of manipulations in the wave polarization of incident waves, indicating that graphene-based structures can realize non-reciprocal components, whereas reciprocal transmission components are required for waveguiding (3D channels) and transmission line components (strip and microstrip topology).

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[0019] D.L. Sounas, C. Caloz, Gyrotropy and nonreciprocity of graphene for microwave applications, IEEE Trans. Microw. Theory Tech. 60 (2012) 901-914. https: / / doi.org / 10.1109 / TMTT.2011.2182205.EXEMPLARY EMBODIMENTS

[0184] The following embodiments are exemplary only and do not serve to limit the scope of the present disclosure of the appended claims. It should be understood that any part of any one or more Embodiments can be combined with any part of any other one or more Embodiments.Embodiment 1

[0185] An antenna, comprising: an antenna body, the antenna body having a coated region with a MXene film conformally coated thereon.Embodiment 2

[0186] The antenna of Embodiment 1, wherein the antenna body comprises any or more of a rectangular waveguide, a double-ridge waveguide, or a circular waveguide. Embodiment 3

[0187] The antenna of Embodiment 1 or 2, wherein the antenna body comprises any one or more of a twisted section, a thru section, and a bent section.Embodiment 4

[0188] The antenna of any one of Embodiments 1-3, wherein the antenna body comprises a cavity having the coated region therein.Embodiment 5

[0189] The antenna of any one of Embodiments 1 -4, wherein the antenna body comprises a channel having the coated region therein.Embodiment 6

[0190] The antenna of any one of Embodiments 1-5, wherein the antenna body comprises a polymeric material. The polymeric material can. as described elsewhere herein, be additively manufactured. This is not a requirement, however, as the polymeric material can be molded or otherwise formed. As described elsewhere herein, the MXene film can be applied via dip coating, although other methods of application can be used.Embodiment 7

[0191] The antenna of Embodiment 6, wherein the polymeric material comprises a polyamide. Nylon is considered particularly suitable, but other polymers can be used. Embodiment 8

[0192] The antenna of any one of Embodiments 1-7, wherein the MXene film defines a thickness of up to about 20 pm.Embodiment 9

[0193] The antenna of Embodiment 8, wherein the thickness is from about 1 to about 15 pm.Embodiment 10

[0194] The antenna of any one of Embodiments 1 -9, wherein the MXene film exhibits a reflected power of from 0.9 to 1.0.Embodiment 11

[0195] The antenna of any one of Embodiments 1-10, wherein the MXene film comprises a singlelayer of MXene.Embodiment 12

[0196] The antenna of any one of Embodiments 1-11, wherein the MXene film defines less than 5% of a total weight of the antenna. The MXene film can define less than 15% of a total weight of the antenna, less than 10% of a total weight of the antenna, or even less than 5% of a total weight of the antenna.Embodiment 13

[0197] The antenna of Embodiment 12, wherein the MXene film defines less than 1% of a total weight of the antenna.Embodiment 14

[0198] The antenna of Embodiment 13, wherein the MXene film defines approximately 0.62% of a total weight of the antenna.Embodiment 15

[0199] The antenna of any one of Embodiments 1-14, wherein the MXene film weighs approximately 0. 1 grams.Embodiment 16

[0200] The antenna of any one of Embodiments 1-15, wherein the antenna exhibits at least an 80% transmission efficiency.Embodiment 17

[0201] The antenna of Embodiment 16, wherein the antenna e.xhi bi ts at least an 85% transmission efficiency.Embodiment 18

[0202] The antenna of any one of Embodiments 1-17, wherein a transmission coefficient for the antenna is less than -1.0 dB.Embodiment 19

[0203] The antenna of any one of Embodiments 1-18, wherein a transmission coefficient for the antenna is approximately -0.9 dB.Embodiment 20

[0204] The antenna of any one of Embodiments 18 and 19, wherein the transmission coefficient is an S21 transmission coefficient.Embodiment 21

[0205] The antenna of any one of Embodiments 1 -20, wherein the MXene film comprises a plurality of MXene flakes.Embodiment 22

[0206] The antenna of Embodiment 21, wherein the plurality of MXene flakes have an average cross-sectional dimension of between 200 nm and 1300 nm. The average cross-sectional dimension can be, for example, from about 200 to about 1300 nm, from about 300 to about 1100 nm, from about 500 to about 900 nm, or even from about 600 to about 800 nm, as well as all intermediate and combined ranges. The MXene flakes can, for examplecomprise multiple different populations, each of the populations having a different average cross-sectional dimension. For example, the MXene flakes can comprise two populations, each of the two populations having a different average cross-sectional dimension.Embodiment 23

[0207] The antenna of Embodiment 22, wherein the average cross-sectional dimension comprises approximately 200 nm, approximately 500 nm, or approximately 1300 nm.Embodiment 24

[0208] The antenna of any one of Embodiments 1-23, wherein the antenna is characterized as a low earth orbit (LEO) antenna.Embodiment 25

[0209] The antenna of any one of Embodiments 1 -24, wherein the antenna comprises a waveguide with an operating frequency between 8-33 GHz.Embodiment 26

[0210] The antenna of any one of Embodiments 1-25, wherein an electrical conductivity of the MXene film is between 5,000 and 14,000 S / cm.Embodiment 27

[0211] The antenna of Embodiment 26, wherein the electrical conductivity comprises approximately 5,400 S / cm, approximately 11,500 S / cm, or approximately 13,100 S / cm.Embodiment 28

[0212] An antenna, comprising: an antenna body, the antenna body having extending therein a cavity at least partially coated with a MXene film.Embodiment 29

[0213] An electronic device, the electronic device comprising an antenna according to any one of Embodiments 1-28.Embodiment 30

[0214] The electronic device of Embodiment 29, wherein the electronic device is configured as at least one of a transmitter and a receiver.Embodiment 31

[0215] A method, comprising effecting communication of a signal along an antenna according to any one of Embodiments 1-28.

Claims

What is Claimed:

1. An antenna, comprising: an antenna body. the antenna body having a coated region with a MXene film conformally coated thereon.

2. The antenna of claim 1 , wherein the antenna body comprises any or more of a rectangular waveguide, a double-ridge waveguide, or a circular waveguide.

3. The antenna of any one of claims 1-2, wherein the antenna body comprises any one or more of a twisted section, a thru section, and a bent section.

4. The antenna of any one of claims 1-3, wherein the antenna body comprises a cavity having the coated region therein.

5. The antenna of any one of claims 1-4, wherein the antenna body comprises a channel having the coated region therein.

6. The antenna of any one of claims 1-5, wherein the antenna body comprises a polymeric material.

7. The antenna of claim 6, wherein the polymeric material comprises a polyamide.

8. The antenna of any one of claims 1-7, wherein the MXene film defines a thickness of up to about 20 pm.

9. The antenna of claim 8, wherein the thickness is from about 1 to about 1 pm.

10. The antenna of any one of claims 1-9, wherein the MXene film exhibits a reflected power of from 0.9 to 1.0.

11. The antenna of any one of claims 1-10, wherein the MXene film comprises a single layer of MXene.

12. The antenna of any one of claims 1-11, wherein the MXene film defines less than 5% of a total weight of the antenna.

13. The antenna of claim 12, wherein the MXene film defines less than 1% of a total weight of the antenna.

14. The antenna of claim 13. wherein the MXene film defines approximately 0.62% of a total weight of the antenna.

15. The antenna of any one of claims 1-14, wherein the MXene film weighs approximately 0.1 grams.

16. The antenna of any one of claims 1-15, wherein the antenna exhibits at least an 80% transmission efficiency.

17. The antenna of claim 16, wherein the antenna exhibits at least an 85% transmission efficiency.

18. The antenna of any one of claims 1-17, wherein a transmission coefficient for the antenna is less than -1.0 dB.

19. The antenna of any one of claims 1-18, wherein a transmission coefficient for the antenna is approximately -0.9 dB.

20. The antenna of any one of claims 18 and 19, wherein the transmission coefficient is an S21 transmission coefficient.

21. The antenna of any one of claims 1-20, wherein the MXene film comprises a plurality of MXene flakes.

22. The antenna of claim 21. wherein the plurality of MXene flakes have an average cross-sectional dimension of between 200 nm and 1300 nm.

23. The antenna of claim 22, wherein the average cross-sectional dimension comprises approximately 200 nm, approximately 500 nm, or approximately 1300 nm.

24. The antenna of any one of claims 1-23, wherein the antenna is characterized as a low earth orbit (LEO) antenna.

25. The antenna of any one of claims 1-24, wherein the antenna comprises a waveguide with an operating frequency between 8-33 GHz.

26. The antenna of any one of claims 1-25, wherein an electrical conductivity of the MXene fdm is between 5,000 and 14,000 S / cm.

27. The antenna of claim 26, wherein the electrical conductivity comprises approximately 5.400 S / cm, approximately 11.500 S / cm, or approximately 13,100 S / cm.

28. An antenna, comprising: an antenna body, the antenna body having extending therein a cavity at least partially coated with a MXene film.

29. An electronic device, the electronic device comprising an antenna according to any one of claims 1-28.

30. The electronic device of claim 29, wherein the electronic device is configured as at least one of a transmitter and a receiver.

31. A method, comprising effecting communication of a signal along an antenna according to any one of claims 1-28.

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