Ultra-wide Range Research Articles

Nanomechanical Resonators: Toward Atomic Scale.

The quest for realizing and manipulating ever smaller man-made movable structures and dynamical machines has spurred tremendous endeavors, led to important discoveries, and inspired researchers to venture to previously unexplored grounds. Scientific feats and technological milestones of miniaturization of mechanical structures have been widely accomplished by advances in machining and sculpturing ever shrinking features out of bulk materials such as silicon. With the flourishing multidisciplinary field of low-dimensional nanomaterials, including one-dimensional (1D) nanowires/nanotubes and two-dimensional (2D) atomic layers such as graphene/phosphorene, growing interests and sustained effort have been devoted to creating mechanical devices toward the ultimate limit of miniaturization─genuinely down to the molecular or even atomic scale. These ultrasmall movable structures, particularly nanomechanical resonators that exploit the vibratory motion in these 1D and 2D nano-to-atomic-scale structures, offer exceptional device-level attributes, such as ultralow mass, ultrawide frequency tuning range, broad dynamic range, and ultralow power consumption, thus holding strong promises for both fundamental studies and engineering applications. In this Review, we offer a comprehensive overview and summary of this vibrant field, present the state-of-the-art devices and evaluate their specifications and performance, outline important achievements, and postulate future directions for studying these miniscule yet intriguing molecular-scale machines.

Permittivity measurement of the substrate by using the corrected differential phase method and quick-press test fixture.

Permittivity is critical for analyzing electromagnetic propagation in the substrate. The differential phase method is desirable to measure the permittivity of the substrate. The actual measurement is usually required to be started at a low frequency to avoid the S21-phase ambiguity problem. To get rid of this problem, the unwrapped S21-phase is calculated accurately at any measurement frequency range. In the classical method of calculating the real permittivity from the effective permittivity, the calculation error increases gradually with increasing frequency, especially in an ultra-wide frequency range. To effectively reduce the error, the ratio of the calculated and real permittivity is used in the permittivity correction, which is a function with respect to frequency, dimension, and permittivity of the microstrip line. A two-step fitting process is proposed to reduce the dimension of the ratio function from three-dimension to two-dimension. Furthermore, a quick-press test fixture is designed for a more convenient measurement, which is characterized by no soldering requirement and ultra-wide frequency range. Compared with the stripline resonant method, in the proposed method, the maximum deviations of the four substrates are 0.035, -0.04, 0.07, and 0.13, in the frequency range of 1-40GHz.

Improved sintering behavior and microwave dielectric properties of SnO2-based ceramics and their LTCC materials with ultrawide temperature stability

Microwave dielectric ceramics with simple composition, a low permittivity (εr), high quality factor (Q × f) and temperature stability, specifically in the ultrawide temperature range, are vital for millimetre-wave communication. Hence, in this study, the improvements in sintering behavior and microwave dielectric properties of the SnO2 ceramic with a porous microstructure were investigated. The relative density of the Sn1-xTixO2 ceramic (65.1%) was improved to 98.8%, and the optimal sintering temperature of Sn1-xTixO2 ceramics reduced from 1525 °C to 1325 °C when Sn4+ was substituted with Ti4+. Furthermore, the εr of Sn1-xTixO2 (0 ≤ x ≤ 1.0) ceramics increased gradually with the rise in x, which can be ascribed to the increase in ionic polarisability and rattling effects of (Sn1-xTix)4+. The intrinsic dielectric loss was mainly controlled by rc (Sn/Ti–O), and the negative τf of the SnO2 ceramic was optimised to near zero (x = 0.1) by the Ti4+ substitution for Sn4+. This study also explored the ideal microwave dielectric properties (εr = 13.7, Q × f = 40,700 GHz at 9.9 GHz, and τf = −7.2 ppm/°C) of the Sn0.9Ti0.1O2 ceramic. Its optimal sintering temperature was decreased to 950 °C when the sintering aids (ZnO–B2O3 glass and LiF) were introduced. The Sn0.9Ti0.1O2-5 wt% LiF ceramic also exhibited excellent microwave dielectric properties (εr = 12.8, Q × f = 23,000 GHz at 10.5 GHz, and τf = −17.1 ppm/°C). At the ultrawide temperature range (−150 °C to +125 °C), the τε of the Sn0.9Ti0.1O2-5 wt% LiF ceramic was +13.3 ppm/°C, indicating excellent temperature stability. The good chemical compatibility of the Sn0.9Ti0.1O2-5 wt% LiF ceramic and the Ag electrode demonstrates their potential application for millimetre-wave communication.

Sensitivity enhancement of nanoparticle localized surface plasmon resonance pressure sensor based on the MoS2 monolayer for ultra-wide range pressure detection

The next generation of optical pressure sensors should be highly sensitive, and have wide-ranging pressure sensing detection. The monolayer MoS2 has been considered as an excellent material with exceptional mechanical, physical, electronic and chemical properties, which is significantly different from the properties of graphene. In this paper, the properties of the MoS2 monolayer according to the placement of silver nanoparticles on the surface have been used to design a pressure sensor that can act based on localized surface plasmon resonance. The MoS2 monolayer sensitivity to stress and variations the properties in proportion to the applied pressure, increases the possibility of using it as a pressure sensor. High pressure range, nanoscale and integration capabilities are important features of this sensor. In this sensor the change in the resonance frequency is proportional to the pressure range which the structure parameters including the shape of the nanoparticles, the material and radius of the nanoparticles, the angle of the incoming light and the presence of the mos2 monolayer by considering and optimizing are provided. For mechanics section calculation, we used the FEM method, and for optical behavior, the FDTD method. Measurable pressure range is less than 1 Gpa with 11 nm/GPa sensitivity for this sensor.

Outside Front Cover: Volume 3 Issue 3

Outside front cover image: In the field of catalysis, the intentional introduction of defects is an advanced material design strategy. In this work, plasma functionalized defective MoSe2 is prepared for electrochemical sensing of H2O2. The tailored Se vacancies and N dopants generate new active sites, expose more edge active surfaces, narrow the bandgap, and strengthen binding with •OH. The sensor delivers competitive sensing performance in an ultra-wide pH range and a portable SPE sensor is developed to demonstrate the significant commercial potential. This work provides insights into plasma surface modification of 2D catalytic materials. (DOI: 10.1002/smm2.1089)

Characteristics of 22 nm UTBB-FDSOI technology with an ultra-wide temperature range

The performance of the ultra-thin body and buried oxide fully-depleted silicon-on-insulator metal-oxide-semiconductor field-effect-transistors based on a 22 nm technology node is investigated in this paper over an ultra-wide temperature range from 6 K to 550 K. The current–voltage (I–V) characteristics under wide temperature range conditions are shown, including the influence of the back-gate bias (V bg). The important electrical parameters, such as threshold voltage (V t), subthreshold swing, ON-state current (I on), and OFF-state current (I off), are extracted with temperature changes. From 550 K to 6 K, V t increased by 0.21 V, I off decreased nearly six orders of magnitude, and the gate-induced drain leakage current decreased by nearly eight orders of magnitude. The main physical mechanisms for the changing electrical performance with temperature are the variation of carrier concentration, mobility, and energy band. By utilizing a technology computer-aided design simulation, the temperature dependence of the device performance is discussed and analyzed.

Flexible Pressure Sensors with Combined Spraying and Self-Diffusion of Carbon Nanotubes.

High-performance wearable sensors are required for applications in medical health and human-machine interaction, but their application has limited owing to the trade-off between sensitivity, pressure range, and durability. Herein, we propose the combined spraying and self-diffusion process of carbon nanotubes (CNTs) to balance and improve these parameters with the CNTs spontaneously diffusing into the film surface before the film curing. The obtained sensor not only achieves high sensitivity (155.54 kPa-1) and ultrawide pressure detection range (0.1-500 kPa) but also exhibits exceptional durability (over 12,000 pressure cycles at a high pressure of 300 kPa). In addition, the sensor exhibits a fast response (25 ms), good stability, and full flexibility. This process is a general approach that may improve the performance of various types of thin film piezoresistive sensors. Besides, the fabricated sensors can be flexibly scaled into sensor arrays and communicate with smart devices to achieve wireless smart monitoring. At present, the sensor shows broad application prospects in the fields of intelligent medical health and motion sensing.

Satellite Vibration Isolation Using Periodic Acoustic Black Hole Structures With Ultrawide Bandgap

Abstract A lightweight whole-spacecraft vibration isolation system with broadband vibration attenuation capability is of great significance to the protection of satellites during the launch phase. The emergence of metamaterials/phononic crystals provides new ideas for the design of such isolation systems. This letter reports a new type of satellite isolation system to isolate shock and vibrations in an ultrawide frequency range. The labyrinth design of this system integrates acoustic black holes (ABHs) as microstructures, which leads to a significant impedance mismatch and enhances the bandgap effect. The ultrawide vibration and shock attenuation ability of the proposed design is confirmed through band structure and transmission analyses as well as the hammer and falling tests, showing the potential for vast isolation applications.

Research and Application of Terahertz Response Mechanism of Few-Layer Borophene.

The terahertz stealth and shielding performance of a new type of two-dimensional material, borophene, has been studied theoretically and experimentally. Studies have shown that borophene materials have good terahertz stealth and shielding properties. First-principles calculations show that compared with single-layer borophene, few-layer borophene has good terahertz stealth and shielding performance in the range of 0.1~2.7 THz. In the range of 2~4 layers, the terahertz stealth and shielding performance of few-layer borophene increases with the increase of the number of layers. The finite element simulation calculation results also confirmed this point. Using the few-layer borophene prepared by our research group as a raw material, a PDMS composite was prepared to verify the terahertz stealth and shielding performance of the few-layer borophene. In the ultra-wide frequency range of 0.1~2.7 THz, the electromagnetic shielding effectiveness (EMI SE) of the PDMS material mixed with few-layer borophene can reach 50 dB, and the reflection loss (RL) can reach 35 dB. With the concentration of few-layer borophene increasing, the terahertz stealth and shielding effectiveness of the material is enhanced. In addition, the simultaneous mixing of few-layer borophene and few-layer graphene will make the material exhibit better terahertz stealth and shielding performance compared with mixing separately.

Dual two-color method: A new concept of ultra-wide temperature range thermography (200-3600 °C) for ITER divertor infrared thermography.

A new temperature measurement method-the dual two-color method-was developed to accurately measure the temperature over an ultra-wide temperature range (200-3600 °C) for ITER divertor infrared thermography. This novel method introduces a third wavelength filter to the conventional two-color method by replacing the shorter single wavelength bandpass filter with a customized dual-bandpass filter having two transmission bands, without having to add a third infrared camera. The dominant wavelength band of the total radiance through the dual-band filter changes automatically as the temperature increases and, consequently, either the shorter or longer wavelength band of the dual-bandpass filter is used to establish the two-color combination at both low and high temperatures. The dual two-color method increased the acceptable measurement error of the two-color radiance ratio for the temperature measurement requirement of the ITER divertor infrared thermography to 9.45% from that of 4.3% when using the conventional two-color method.

A novel umami electrochemical biosensor based on AuNPs@ZIF-8/Ti3C2 MXene immobilized T1R1-VFT

The bioelectronic tongues based on taste receptors have been emerging with human-like taste perception. However, the practical applications of the receptor-based biosensors were restricted by their narrow and low dynamic ranges. Here, a novel immobilization strategy based on AuNPs@ZIF-8/Ti3C2 MXene was developed to immobilize the umami ligand binding domain (T1R1-VFT), to fabricate an umami biosensor for umami substances detection. Through the synergic effect of AuNPs@ZIF-8 and Ti3C2 MXene, the capacity to load T1R1-VFT was effectively increased, and the response signal was also amplified by approximately 3 times. The proposed biosensor showed an ultrawide dynamic range of 10−11–10−3 M, and a high upper limit of detection, which was closer to the human taste threshold and suitable for detecting foods rich in umami substances. Additionally, the biosensor was successfully applied to detect real samples and analyze the synergistic effects of binary umami substances.

Synergistically Microstructured Flexible Pressure Sensors with High Sensitivity and Ultrawide Linear Range for Full‐Range Human Physiological Monitoring

AbstractHigh sensitivity and wide linear range are core performances for flexible pressure sensors in practical applications. Due to the trade‐off between sensitivity and linear range, developing high‐performance flexible pressure sensors with both high sensitivity and wide linear range through a facile method is still a great challenge. Herein, a synergistically microstructured flexible pressure sensor with fibrous and microdomed (FMD) structure composed of a fibrous conductive layer sandwiched between a microdome‐structured PDMS layer and an interdigital electrode is proposed. Ascribed to the synergistic effect of the FMD structure possessing multiple deformations, the resistance of the sensor varies sensitively and continuously under pressure. Consequently, the pressure sensors perform a high sensitivity (6.31 kPa−1), an ultrawide linear range (4.6 Pa–800 kPa), short response time (72 ms) and relaxation time (88 ms), and remarkable stability during 10 000 loading/unloading cycles under 127.4 kPa. These high performances allow the sensors to detect full‐range human psychological signals from low to high pressures, such as pulse, phonation, joint moments, and plantar pressure. Moreover, the synergistically microstructured sensors can be integrated into large‐area and crosstalk‐free sensor array to map the spatial pressure distribution, demonstrating their viable applications in personal physiological parameters monitoring and human–machine interfaces.

Design of a Compact UWB-MIMO Antenna with Isolation Enhancement through Extended Elliptical Ground Plane

This paper deals with the design of a Multiple Input Multiple Output (MIMO) antenna for UWB applications. It is composed of two identical radiating elements (parallel monopoles) symmetrically arranged on a FR-4 substrate. The monopoles are closely spaced (about 0.2 Lambda, center to center). A decoupling mechanism based on vertical extension of the Ground plane with elliptical edges (stub) allows to achieve high isolation (>20 dB). Further, the designed system presents good diversity performance, as the obtained Envelope Correlation Coefficient is less than 0.01. The antenna array is compact (36x30 mm2), with ultra-wide operating frequency range (2.6 to 10.8 GHz). Simulations and measurements demonstrate good agreement. The obtained results make the proposed structure a good candidate for any UWB applications and modern wireless communications systems thanks to its wide frequency band, compactness and performance.

Ultra-wide range and wavelength fixed trace gas detection technology based on single chamber multiplexing

The all-fiber photo-thermal interference (PTI) system based on hollow-core photonic crystal fiber (HC-PCF) has the advantages of wide dynamic range, ultra-sensitivity, and small volume, which is of great significance in gas trace analysis. Most of the previous PTI systems obtain the relationship between gas concentration and phase modulation by wavelength scanning and extracting the second harmonic signal absorbed by the gas. However, the residual modulation caused by the asynchronism between wavelength and modulation signal seriously affects the signal-to-noise ratio (SNR) and dynamic detection range of the system. In addition, wavelength scanning has limitations for detecting gas with irregular absorption lines. This paper proposes an all-fiber photo-thermal interference system with pump intensity external modulation. The system is not limited by the gas absorption line and has a high SNR. The factors affecting the dynamic range of the system are analyzed theoretically and experimentally. It is verified that increasing the injection gas pressure can significantly increase the detection limit of the system compared with increasing the pump light power. The redshift of the pump light can dramatically increase the detection limit of the system. A C2H2 gas trace system with the pump wavelength redshifted to 1530.41 nm was demonstrated. The detection lower limit of 9.24 ppm and an extensive dynamic detection range of five orders of magnitude were obtained.

Underwater gradient metalens for broadband subwavelength focusing

Broadband effectiveness and impedance mismatching in fluid-structure coupling remain significant obstacles in the pursuit of broadband high-efficient high-symmetrical subwavelength underwater acoustic devices by using metamaterials. Here, we systematically propose a microstructure-macrostructure-functionality integrated design of underwater gradient metalens, which facilitates the realization of broadband, high-efficient, high-gain, and high-symmetry acoustic focusing. To improve the focusing capabilities of the metalens, an optimization approach of gradient index profile is presented. The square-latticed mode metamaterial is proven to support perfect single polarization characteristic and high customizability of the effective properties. The single polarization mode and optimized index contribute the metalens to presenting an excellent acoustic high-efficient subwavelength focus behavior. The sound pressure field shows that the meta-device can convert plane waves to subwavelength focusing with FWHM ≤ 0.5λ over an ultra-wide frequency range of 5∼33 kHz, even FWHM ≤ 0.4λ of 10∼24 kHz. The metalens can amplify sound intensity over 6 times at focal spots within 10∼22 kHz, when the efficiency is above 80% in 6∼20 kHz. Meanwhile, environmental adaptability evaluation reveals good hydrostatic pressure resistance (∼1.5 MPa) of lightweight porous underwater metalens. The present design strategy and the realized high-performance underwater metalens have application potential in the fields of acoustic transmission, harvesting, and communications.

Metal Mesh Design for Dynamic Windows Based on Reversible Metal Electrodeposition

Dynamic windows, which allow electronic control over visible light and solar irradiation, enable responsive environments free of glare and unwanted heat. Electronic control over visible light transmittance and solar heat gain coefficients will allow dynamic windows to be integrated with algorithms to optimize for energy efficiency and comfort. The implementation of this technology increases building energy efficiency by up to 20% compared to traditional, static low-emissivity windows.[ 1] Furthermore, worker productivity can be increased by 2% due to reductions in eye strain, headaches, and drowsiness.[ 2] Dynamic windows based on reversible metal electrodeposition (RME) represent an exciting, new class of electrochromic devices. These RME windows function like a battery by electrochemical movement of metallic ions dissolved in a nearly colorless aqueous electrolyte between a transparent conducting working electrode and a metal mesh or ion-intercalation counter electrode (see Figure). Metals are ideal light-modulators for dynamic windows because they can be color neutral, inert, photostable, and opaque at 20-30 nanometer thicknesses. Our team has most recently demonstrated metal-based dynamic windows that boast a dark state below 0.001% visible light transmittance in less than 10 minutes, an ultrawide range for optical and solar modulation (ΔTvis=0.76 and ΔSHGC=0.56) with uniform and color neutral (C*<5) tinting in prototypes >900 sq. cm.[ 3] To achieve a dark state transmission <0.1%, which has been defined as privacy state, ~150 mC/sq. cm of charge must be shuttled between the working electrode and counter electrode. We first outline the counter electrode design parameters for these high-contrast RME dynamic windows: high transparency, capacity, and surface area while maintaining low haze, sheet resistance, and cost. We show that metal meshes are a leading candidate for the counter electrode material based on these design parameters. Metal meshes also keep the design simple by having the same reversible electrochemical reaction on both electrodes (in opposite directions).We then analyze the material composition of the metal mesh to ensure cycling durability in a Cu-Bi electrolyte. This analysis shows that previously used Cu mesh in as the counter electrode material increases [Cu2+] over cycling (~200 privacy cycles) which results in degradation optically and electrochemically. We then develop a transparent mesh using an inert core with a thin metal coating that enables a high capacity (1.5 C/sq. cm) Cu-Bi layer for a metal mesh counter electrode. Finally, we incorporate this custom designed mesh in an RME dynamic window and demonstrate 250 privacy cycles.Developing a strong understanding of reversibly electroplating metals using multivalent metallic ions with variable sizes yields valuable insight to batteries where reversible plating is critical for operation and durability, particularly with deep cycling.

Surface modification engineering of iron-silicon-aluminum alloys: Microstructure evolution investigation and microwave absorption enhancement

Developing highly efficient electromagnetic (EM) absorbers with a broad bandwidth remains a major challenge for reducing EM pollution originating from the ever-rising electronic and telecommunication devices. Designing core-shell structures containing a magnetic core and dielectric shell could be an effective strategy to tackle this problem. Herein, we report a surface modification strategy to synthesize the FeSiAl/phosphate core-shell materials with unique rodlike structure through a facile surface passivation process. Multilevel phosphate shells are in situ introduced for significantly facilitating the EM absorbing performance by inducing multiple interfacial polarizations and obtain ideal impedance matching. Direct evidence of the morphology and microstructure evolution of resultant FeSiAl/phosphate composites correlated to the EM properties has been systematically investigated. Due to intense synergistic effects between magnetic and dielectric loss, exceptional microwave dissipation capacity can be achieved over an ultra-wide absorption bandwidth of 9.8 GHz at 2.5 mm. • The microstructure evolution at high temperatures has been elaborated at different scales by the focused ion beam technology. • Core-shell structure enhanced the dielectric loss ability by inducing multiple interfacial polarizations and achieved ideal impedance matching. • Superb dissipation capacity has been achieved over an ultra-wide range of 9.8 GHz attributed to the magnetic-dielectric synergistic effects.

Proposal for collinear integrated acousto-optic tunable filters featuring ultrawide tuning ranges and multi-band operations.

Integrated optical tunable filters are key components for a wide spectrum of applications, including optical communications and interconnects, spectral analysis, and tunable light sources, among others. Compared with their thermo-optic counterparts, integrated acousto-optic (AO) tunable filters provide a unique approach to achieve superior performance, including ultrawide continuous tuning ranges of hundreds of nm, low power consumption of sub-mW and fast tuning speed of sub-µs. Based on suspended one-dimensional (1D) AO waveguides in the collinear configuration, we propose and theoretically investigate an innovative family of integrated AO tunable filters (AOTFs) on thin-film lithium niobate. The AO waveguides perform as tunable wavelength-selective narrow-band polarization rotators, where highly efficient conversion between co-propagating TE0 and TM0 modes is enabled by the torsional acoustic A1 mode, which can be selectively excited by a novel antisymmetric wavefront interdigital transducer. Furthermore, we systematically and quantitatively explore the possibilities of exciting modulated acoustic waves, which contain multiple frequency components, along the AO waveguide to achieve independently reconfigurable multi-band operations, with tunable time-variant spectral shapes. By incorporating a complete set of ultrawide-band polarization-handling components, we have proposed and theoretically investigated several representative monolithic AOTF configurations, featuring different arrangements of single or cascaded identical AO waveguides. One of the present AOTF designs exhibits a theoretical linewidth of ∼8 nm (∼4 nm), a sidelobe suppression ratio of ∼75 dB, and theoretically no excess loss at the center wavelength of 1550 nm (1310 nm), with an ultrawide tuning range of 1.25-1.65 µm (from O-band to L-band), a fast tuning speed of 0.14 µs, and a low power consumption of a few mW.

Graphene Metamaterial Embedded within Bundt Optenna for Ultra-Broadband Infrared Enhanced Absorption.

Graphene is well-known for its extraordinary physical properties such as broadband optical absorption, high electron mobility, and electrical conductivity. All of these make it an excellent candidate for several infrared applications such as photodetection, optical modulation, and optical sensing. However, a standalone monolayer graphene still suffers from a weak infrared absorption, which is ≅2.3%. In this work, a novel configuration of graphene metamaterial embedded inside Bundt optical-antenna (optenna) is demonstrated. It can leverage the graphene absorption up to 57.7% over an ultra-wide wavelength range from 1.26 to 1.68 µm (i.e., Bandwidth ≅ 420 nm). This range covers the entire optical communication bands of O, E, S, C, L, and U. The configuration mainly consists of a Bundt-shaped plasmonic antenna with a graphene metamaterial stack embedded within its nano-wide waveguide that has a 1.5 µm length. The gold average plasmonic loss is ≅25%. This configuration can enhance graphene ultra-broadband absorption through multiple mechanisms. It can nano-focus the infrared radiation down to a 50 nm spot on the graphene metamaterial, thus yielding an 11.5 gain in optical intensity (i.e., 10.6 dB). The metamaterial itself has seven concentric cylindrical graphene layers separated by silicon dioxide thin films, thus each layer contributes to the overall absorption. The focused infrared propagates tangential to the graphene metamaterial layers (i.e., grazing propagation), and thus maximizes the light–graphene interaction length. In addition, each graphene layer experiences a double-face exposure to the nano-focused propagating spot, which increases each layer’s absorption. This configuration is compact and polarization-insensitive. The estimated maximum absorption enhancement compared to the standalone monolayer graphene was 25.1 times (i.e., ≅4 dB). The estimated maximum absorption coefficient of the graphene stack was 5700 cm−1, which is considered as one of the record-high reported coefficients up to date.

All-Solid-State Terahertz Phased Array Based on Graphene Metasurface for Ultra-Wide-Angle Beam Steering

In this paper, we propose an all-solid-state, electrically tunable, and reflective terahertz phased array (TPA) based on a novel graphene metasurface. By designing and optimizing the key structural parameters of graphene antenna, the metasurface can achieve close to the continuous phase curves corresponding to different deflection angles and the accurate modulation of phase over 350° by the metasurface in THz spectrum. Based on the above two elements, the designed TPA can achieve a specific deflection angle or continuous scanning in the ultra-wide range of −79.11°∼79.11° almost without side lobe interference. A key feature of our design can maintain the beam steering function in the range of incident angle less than 20°. This method holds a promising potential for versatile utilization in integrated devices such as adjustable wavefront control.