Search

In this study, we demonstrated a new class of frequency-switchable metamaterial absorber in the X-band. Eutectic gallium-indium (EGaIn), a liquid metal alloy, was injected in a microfluidic channel engraved on polymethyl methacrylate (PMMA) to achieve frequency switching. Numerical simulation and experimental results are presented for two cases: when the microfluidic channels are empty, and when they are filled with liquid metal. To evaluate the performance of the fabricated absorber prototype, it is tested with a rectangular waveguide. The resonant frequency was successfully switched from 10.96 GHz to 10.61 GHz after injecting liquid metal while maintaining absorptivity higher than 98%.

A frequency-switchable half-mode substrate-integrated waveguide antenna is proposed. The resonant frequency of the proposed antenna is switched by injecting liquid metal (eutectic gallium indium; EGaIn) into a single vertical fluidic hole. The position and dimensions of the fluidic hole are chosen in order to maximize the tuning ratio and peak gain. The radiation performance is demonstrated through full-wave simulation and measurement. The resonant frequency is successfully switched from 2.33 to 3.35 GHz by injecting EGaIn into the vertical fluidic hole while maintaining the peak gain higher than 6 dBi.

Display Omitted THz multi-resonant metamaterial absorber using glass wafer bonding is demonstrated.Pyrex glass wafer is used as a dielectric layer for high absorptivity in THz range.Hexagonal comb-shape resonator is used to realize polarization insensitivity.Fabricated absorber shows an absorptivity of 93% and 74%, at 0.98THz and 1.55THz. We present the design, fabrication and characterization of a terahertz multi-resonant metamaterial absorber showing polarization-insensitive characteristics. The proposed absorber uses Pyrex glass as a dielectric layer for higher absorption in a terahertz range and is wafer-level fabricated by thermo-compression bonding technique using gold films as intermediate layers. In addition, an array of comb-shaped hexagonal pattern is introduced as a multi-band LC resonator and symmetric geometry is used for polarization insensitivity. The fabricated absorber shows two absorption peaks at 0.98THz and 1.55THz with the absorptivity of 93% and 74%, respectively, and almost identical responses to the different polarization angles.

In this letter, a novel frequency tunable metamaterial absorber is proposed for wireless humidity sensor applications made with natural cork. Natural cork has excellent hygroscopicity and its electrical properties can be changed depending on the moisture content. In this work, the absorption ratio of the proposed absorber are simulated and measured in different moisture content ( ${\rm M} = 0\% $ , 1.44%, 5.88%, 13.32%, 18.8%) of the cork substrate. The resonant frequency changed from 4.92 GHz in the dry ( ${\rm M} = 0\% $ ) state to 3.49 GHz in the wet ( ${\rm M} = 18.8\% $ ) state; the measured absorptivity is higher than 90% in all moisture content values. To the best of our knowledge, it is the first metamaterial absorber using natural cork.

In this paper, we propose a novel microfluidic tunable metamaterial (MM) absorber printed on a paper substrate in silver nanoparticle ink. The metamaterial is designed using a periodic array consisting of square patches. The conductive patterns are inkjet-printed on paper using silver nanoparticle inks. The microfluidic channels are laser-etched on polymethyl methacrylate (PMMA). The conductive patterns on paper and the microfluidic channels on PMMA are bonded by an SU-8 layer that is also inkjet-printed on the conductive patterns. The proposed MM absorber provides frequency-tuning capability for different fluids in the microfluidic channels. We performed full-wave simulations and measurements that confirmed that the resonant frequency decreased from 4.42 GHz to 3.97 GHz after the injection of distilled water into the microfluidic channels. For both empty and water-filled channels, the absorptivity is higher than 90% at horizontal and vertical polarizations.

This paper describes a tunable metamaterial (MM) absorber that incorporates novel microfluidic channels and is realized using inkjet printing on a photo-paper substrate. The fabricated sample demonstrated frequency-switching capability owing to distilled water flowing in the microfluidic channels. In addition, the resonant frequency was changed from 4.42 to 3.97 GHz when the empty channels were filled with de-ionized water. An analysis of the results suggests that microfluidic technology is a simpler and more effective way to achieve tuning functionality. The proposed structure is the first microfluidic absorber based on a photo-paper substrate.

In this paper, a novel flexible inkjet-printed metamaterial absorber is proposed. The unit cell of the metamaterial is designed with a modified Jerusalem-cross ring resonator and is inkjet printed with silver nanoparticle ink on a flexible polymer film. All fabrication processes are performed using a commercial printer (EPSON WF-7011). The absorber's flexibility and absorption performance are demonstrated by measuring the absorption ratio after coating the proposed absorber on a cylindrical object with a radius of 4.56 cm. An absorption rate exceeding 99% is achieved at 9.21 GHz for both flat and cylindrical surfaces. In addition, the cylindrical model attains an absorption rate higher than 96% for all polarization angles, and a high absorption rate of 95% is preserved until the incident angle is less than 30(sic). (C) 2015 Optical Society of America

In this paper, we propose a novel flexible metamaterial (MM) absorber. The conductive pattern consists of liquid metal eutectic gallium indium alloy (EGaIn) enclosed in elastomeric microfluidic channels. Polydimethylsiloxane (PDMS) material is used as a supporting substrate. The proposed MM absorber is flexible because of its liquid metal and PDMS substrate. Numerical simulations and experimental results are presented when the microfluidic channels are filled with liquid metal. In order to evaluate the proposed MM absorber's performance, the fabricated absorber prototype is tested with rectangular waveguides. Almost perfect absorptivity is achieved at a resonant frequency of 8.22 GHz. (C) 2015 Optical Society of America