In this work, sensor abilities of the metamaterial absorber based on swastika shaped resonator are developed both theoretically and experimentally at X-band frequency range. The structure is ...consisted of a swastika shaped resonator on the top of dielectric layer and have an air gap to fill chemicals liquids between the copper plate and backside resonator. In this study, a full-wave EM solver CST Microwave Studio (Computer Simulation Technology) based on finite integrate technique has been used to simulate and investigate the absorption of the metamaterial structure with chemicals liquids depending on the electrical properties. A vector network analyzer 85070E probe kit has been used to measure the relative dielectric constants and loss tangent of some chemical liquids (ethanol content, methanol content, acetone, methanol, ethanol, Polyethylene Glycol 300, water) in the related frequency range. Absorption value of the sensor structure for selected chemicals placed in the air gaphas been investigated. It is obtained that there is a significant difference in absorption ratios between each chemicals and overall resonance frequency shifts have been observed which provides information to accurately estimate density rate of the sensed liquids. The absorption mechanisms of the metamaterial has been explained by using electric field, magnetic field and surface current distributions. Furthermore, the resonance absorption properties of the metamaterial based absorber sensor can be modified and adjusted easily by varying the dimensions of the resonator.
Experimental and simulated results demonstrate that the resonance frequency of the swastika metamaterial based sensor is linearly related to the permittivity of selected chemicals which creates an appropriate approach for multipurpose sensor devise and electrochemical sensor.
•Physical mechanism of absorption investigated by simulating surface current, electric and magnetic field distribution.•The dimensions effect of the resonator has been carried out.•Simulated and measured values for the absorption are in a good agreement.•The proposed metamaterial sensor is highly sensitive to the considered chemical liquids.
Two dimensional materials have been widely identified as promising microwave absorbers, owing to their large surface area and abundant interfaces. Here, a novel laminated and magnetic composite ...derived from Mxene was designed and successfully synthesized via facile hydrothermal oxidization of nickel ion intercalated Ti
C
. Highly disordered carbon sheets were obtained by low temperature hydrothermal oxidization, and the in-situ produced TiO
and NiO nanoparticles embedded closely between them. This layered hybrid exhibits excellent microwave absorbing performance with an effective absorbing bandwidth as high as 11.1 GHz (6.9-18 GHz) and 9 GHz (9-18 GHz) when the thickness is 3 and 2 mm, respectively. Besides the high dielectric loss, magnetic loss and ohmic loss of the composite, the amorphous nature of obtained carbon sheets and multi-reflections between them are believed to play a decisive role in achieving such superior microwave absorbing performance.
Graphene nanoribbons (GNRs) are ultra-narrow strips of graphene that have the potential to be used in high-performance graphene-based semiconductor electronics. However, controlled growth of GNRs on ...dielectric substrates remains a challenge. Here, we report the successful growth of GNRs directly on hexagonal boron nitride substrates with smooth edges and controllable widths using chemical vapour deposition. The approach is based on a type of template growth that allows for the in-plane epitaxy of mono-layered GNRs in nano-trenches on hexagonal boron nitride with edges following a zigzag direction. The embedded GNR channels show excellent electronic properties, even at room temperature. Such in-plane hetero-integration of GNRs, which is compatible with integrated circuit processing, creates a gapped channel with a width of a few benzene rings, enabling the development of digital integrated circuitry based on GNRs.
A compact printed multiband decoupled dual-antenna system for WWAN/LTE smartphone applications is presented. The proposed dual-antenna system is composed of two groups of symmetrical bending ...structures and uses the structure of the slotted and protruded ground to reduce the coupling between elements. A measured impedance bandwidth with S 11 lower than -6 dB over 740-965 and 1380-2703 MHz is obtained. The isolation between elements is better than 10 dB within the operating bands. Based on 3-D radiation patterns, the envelope coefficient, the mean effective gain, and the diversity gain are calculated. The results show that a good diversity performance is achieved for the proposed dual antenna, which makes the antenna suitable for WWAN/LTE smartphone applications.
Due to the wide use of iron in all kinds of areas, the design and construction of direct, fast, and highly sensitive sensor for Fe
3+
are highly desirable and important. In the present work, a kind ...of fluorescent MXene quantum dots (MQDs) was synthesized via an intermittent ultrasound process using
N,N
-dimethyl formamide as solvent. The prepared MQDs were characterized via a combination of UV–Vis absorption, fluorescence spectra, X-ray photoelectron energy spectra, and Fourier-transform infrared spectroscopy. Based on the electrostatic-induced aggregation quenching mechanism, the fluorescent MQDs probes exhibited excellent sensing performance for the detection of Fe
3+
, with a sensitivity of 0.6377 mM
−1
and the detection limit of 1.4 μM, superior to those reported in studies. The present MQDs-based probes demonstrate the potential promising applications as the sensing device of Fe
3+
.
Driven by the urgent need for adaptive infrared (IR) electrochromic devices, the improvement in electrochromic performance based on polyaniline (PANI) conducting polymers has become an outstanding ...challenge. In recent years, the acid doping strategy has been proven to increase the IR modulation ability of PANI, in particular for the Bronsted acid doping. Herein, the effects of copper ions, a Lewis acid, on the structure and electrochromic properties of polyaniline were investigated. Compared to pure polyaniline, the Cu-doped PANI porous films show better IR modulation ability. With the increasing concentration of copper ions, the Cu-doped PANI porous films exhibit a trend in volcanic patterns for the emittance variation (∆
ε
), depending on the number of polarons and bipolarons. The optimal IR emissivity (
ε
) modulation obtained on Cu-doped PANI films shows the ∆
ε
modulation of 0.35 and 0.3 in the wavelength range of 8–14 µm and 2.5–25 µm, superior to previously reported pure sulfuric acid-doped PANI. Furthermore, a flexible IR electrochromic device was fabricated with the present Cu-doped PANI porous films. The modulation of the emittance variation varied between 0.513 and 0.834 (∆
ε
= 0.32 in ranges of wavelength 8–12 µm), suggesting the great potential for applications in military camouflage and intelligent IR thermal management. We believe that the results in this work will provide a novel perspective and avenue for improving the IR modulation ability of electrochromic devices based on polyaniline conducting polymers.
The previous work on reflective linear polarization converters has mostly focused on wideband characteristics, while the out-of-band selectivity has received rare attention. To achieve wideband and ...high selectivity simultaneously, a wideband reflective linear polarization converter with quasi-elliptic filtering characteristic is proposed based on multi-mode resonant metamaterial. Through the loading of the cross-shaped slotlines and inter-unit connecting lines, the inherent degenerate modes of a square patch can be excited and separated, and two additional resonant modes and two independently controllable conversion zeros are introduced to achieve excellent wideband and quasi-elliptic filtering characteristics. After the principles of generating in-band resonant modes and out-of-band conversion zeros are revealed, the mechanism of polarization conversion is analyzed in detail from the perspective of the amplitude-phase imbalance between its polarization components. Finally, a polarization converter is designed, fabricated, and measured. The main-polarization reflection coefficient is less than − 10 dB in fractional bandwidth of 50%, wherein the polarization conversion rate is 90%, and the polarization conversion rate squareness is about 0.9. The proposed converter with excellent frequency selectivity provides great potential for applications in multi-band and multi-functionality systems for reduced isolation band.
Magnetic–dielectric composites are usually designed to develop high-performance microwave absorbers. In this paper, magnetic–dielectric Ti
3
SiC
2
/Co
2
Z ferrite composites were firstly prepared for ...application in microwave-absorbing materials. The phase structure, micro-morphology, electromagnetic response behavior, and microwave absorption performance of these composites have been investigated and subsequently discussed. The measured results showed that the introduction of dielectric Ti
3
SiC
2
into magnetic Co
2
Z ferrite can increase the complex permittivity and dielectric loss of these composites appropriately. And then, a desired stronger reflection loss peak of –38.04 dB could be achieved with a thin thickness of 1.5 mm in the Ti
3
SiC
2
/Co
2
Z composite-filled microwave-absorbing materials. It was also found that appropriately increasing the complex permittivity can improve the electromagnetic attenuation ability and the impedance-matching property simultaneously, which eventually contributes to the enhanced microwave absorption performance.
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