Column Arrays Research Articles

Ultrasonic detection method based on flexible capillary water column arrays coupling

Conventional water immersion ultrasonic testing faces limitations due to factors such as environmental conditions, workpiece dimensions, corrosion, and resource wastage. Contact-based coupling methods, which employ coupling media or specific coupling structures, offer a convenient approach to coupling acoustic waves and reduce signal attenuation. However, these methods are time-sensitive and lack adaptability to uneven surfaces, particularly when dealing with workpieces featuring subtle undulations, resulting in significant signal decay. This paper presents an ultrasonic coupling method based on a flexible capillary water column array. By employing a stable and flexible water column array within the micro-channels as the coupling medium, stable contact-based transmission of ultrasonic signals is achieved. The influence of water column array unit dimensions and array structures is explored through theoretical analysis and experimentation, demonstrating lower energy attenuation compared to reductions in water column area. Notably, the tests revealed the method’s adaptability at oblique angles below 20 degrees, which surpasses the performance of submerged detection at similar angles. This research presents an innovative and stable approach for contact-based ultrasonic coupling testing, particularly in scenarios involving dynamic contact scanning between ultrasonic waves and workpieces.

Solute-particle separation in microfluidics enhanced by symmetrical convection.

The utilization of microfluidic technology for miniaturized and efficient particle sorting holds significant importance in fields such as biology, chemistry, and healthcare. Passive separation methods, achieved by modifying the geometric shapes of microchannels, enable gentle and straightforward enrichment and separation of particles. Building upon previous discussions regarding the effects of column arrays on fluid flow and particle separation within microchips, we introduced a column array structure into an H-shaped microfluidic chip. It was observed that this structure enhanced mass transfer between two fluids while simultaneously intercepting particles within one fluid, satisfying the requirements for particle interception. This enhancement was primarily achieved by transforming the originally single-mode diffusion-based mass transfer into dual-mode diffusion-convection mass transfer. By further optimizing the column array, it was possible to meet the basic requirements of mass transfer and particle interception with fewer microcolumns, thereby reducing device pressure drop and facilitating the realization of parallel and high-throughput microfluidic devices. These findings have enhanced the potential application of microfluidic systems in clinical and chemical engineering domains.

Flexible and Transparent Electronic Skin Sensor with Sensing Capabilities for Pressure, Temperature, and Humidity

Inspired by the interlocked biological geometry of human skin, herein, we design a flexible and transparent sensor with interlocked square column arrays with composites of Ag nanoparticles (AgNPs), citric acid (CA), and poly(vinyl alcohol) (PVA), which exhibit multisensory capabilities for pressure, temperature, and humidity. As a flexible pressure sensor, the interlocked AgNPs/CA/PVA sensor possesses a high sensitivity (-1.82 kPa-1), low detection limit (10 Pa), fast response (75 ms), and outstanding stability due to the high sensitivity of the contact resistance of the interlocked square column arrays to pressure. Because of the rigid dependence of the resistance of the AgNPs/CA/PVA composite on temperature, the interlocked AgNPs/CA/PVA sensor can also act as a temperature sensor, which exhibits high resolution (0.1 °C) and reliability in detecting ambient temperature. In addition, it is found that the amount of water molecules adsorbed by PVA and CA changes with the ambient humidity. Therefore, the interlocked AgNPs/CA/PVA sensor is also able to detect humidity in real time. This work proposes a simple but useful route to fabricate a flexible and transparent electrical skin sensor, which has great potential in the perception of pressure, temperature, and humidity.

High-Voltage Bias-Switching Electronics for Volumetric Imaging using Electrostrictive Row-Column Arrays.

Top Orthogonal to Bottom Electrode (TOBE) arrays, also known as row-column arrays, hold great promise for fast high-quality volumetric imaging. Bias-voltage-sensitive TOBE arrays based on electrostrictive relaxors or micromachined ultrasound transducers can enable readout from every element of the array using only row and column addressing. However, these transducers require fast bias-switching electronics which are not part of a conventional ultrasound system and are non-trivial. Here we report on the first modular bias-switching electronics enabling transmit, receive, and biasing on every row and every column of TOBE arrays, supporting up to 1024 channels. We demonstrate the performance of these arrays by connection to a transducer testing interface board and demonstrate 3D structural imaging of tissue and 3D power Doppler imaging of phantoms with realtime B-scan imaging and reconstruction rates. Our developed electronics enable interfacing of bias-switchable TOBE arrays to channel-domain ultrasound platforms with software-defined reconstruction for next-generation 3D imaging at unprecedented scales and imaging rates.

Evaluation of finger millet (Eleusine coracana (L.) Gaertn.) in multi-environment trials using enhanced statistical models.

Spatial variation and genotype by environment (GxE) interaction are common in varietal selection field trials and pose a significant challenge for plant breeders when comparing the genetic potential of different varieties. Efficient statistical methods must be employed for the evaluation of finger millet breeding trials to accurately select superior varieties that contribute to agricultural productivity. The objective of this study was to improve selection strategies in finger millet breeding in Ethiopia through modeling of spatial field trends and the GxE interaction. A dataset of seven multi-environment trials (MET) conducted in randomized complete block design (RCBD) with two replications laid out in rectangle (row x column) arrays of plots was used in this study. The results revealed that, under the linear mixed model, the spatial and factor analytic (FA) models were efficient methods of data analysis for this study, and this was demonstrated with evidence of heritability measure. We found two clusters of correlated environments that helped to select superior and stable varieties through ranking average Best Linear Unbiased Predictors (BLUPs) within clusters. The first cluster was chosen because it contained a greater number of environments with high heritability. Based on this cluster, Bako-09, 203439, 203325, and 203347 were the top four varieties with relatively high yield performance and stability across correlated environments. Hence, scaling up the use of this efficient analysis method will improve the selection of superior finger millet varieties.

Performance Enhancement of Electrochemiluminescence with the Immunosensor Controlled Using Magnetized Masks for the Determination of Epithelial Cancer Biomarker EpCAM.

The performance of an electrochemiluminescence (ECL) immunosensor was improved with a particle gradient. SiO2-coated magnetic beads were adopted as nanocarriers for gradient manipulation and immobilized with the primary antibody. Cadmium telluride quantum dots were coated with a layer of protein G for conjugation and orientation of the secondary antibody as signal labels. ECL immunosensor gradients on the electrode were formed by magnetolithography (ML) with magnetized nickel masks of column and stripe arrays. The immunosensor generally aggregated as an island on the substrate, leading to a decrease of efficiency in the characteristic signals. Stripe arrays of magnetized nickel were designed to generate cylindrical magnetic flux on the substrate to improve the particle manipulation with the gradient. Various gradients of the sandwich-structured immunosensor substantially affected the electrochemical performance. Compared to the gradient-free immunosensor, the gradient of the immunosensor generated by ML using a 3 μm stripe array mask enhanced the ECL intensity ∼2.2 times. The results of quantification of epithelial cell adhesion molecules (EpCAM) with the gradient immunosensor showed a broad linear range (15-420 pg mL-1), a low limit of detection (5.5 pg mL-1), and high reliability for EpCAM-spiked serum samples, indicating that the immunosensor gradient substantially enhances the performance of the ECL assay.

Anatomic and Functional Imaging Using Row-Column Arrays.

Row-column (RC) arrays have the potential to yield full 3-D ultrasound imaging with a greatly reduced number of elements compared to fully populated arrays. They, however, have several challenges due to their special geometry. This review article summarizes the current literature for RC imaging and demonstrates that full anatomic and functional imaging can attain a high quality using synthetic aperture (SA) sequences and modified delay-and-sum beamforming. Resolution can approach the diffraction limit with an isotropic resolution of half a wavelength with low sidelobe levels, and the field of view can be expanded by using convex or lensed RC probes. GPU beamforming allows for three orthogonal planes to be beamformed at 30 Hz, providing near real-time imaging ideal for positioning the probe and improving the operator's workflow. Functional imaging is also attainable using transverse oscillation and dedicated SA sequence for tensor velocity imaging for revealing the full 3-D velocity vector as a function of spatial position and time for both blood velocity and tissue motion estimation. Using RC arrays with commercial contrast agents can reveal super-resolution imaging (SRI) with isotropic resolution below [Formula: see text]. RC arrays can, thus, yield full 3-D imaging at high resolution, contrast, and volumetric rates for both anatomic and functional imaging with the same number of receive channels as current commercial 1-D arrays.

Patterning the surface structure of transparent hard-brittle material β-Ga2O3 by ultrashort pulse laser

Femtosecond laser direct writing technology offers a powerful and advantageous tool for precise three-dimensional (3D) micro/nanofabrication of transparent hard and brittle materials. In this paper, micro-craters, micro/nano-rectangular columns, and microchannels structures with different spatial characteristics are achieved after irradiation of crystalline (100) β-Ga2O3 via an optical-fiber femtosecond laser (515/1030 nm, 285 fs, 100 kHz) with different processing parameters in air ambient. Laser scanning confocal microscope, atomic force microscopy, and Raman spectroscopy are employed to characterize the roughness and constitutive property of the surface structure under tightly focused laser conditions. The influences of different pulse numbers and different pulse energies on the morphology of the pits were investigated. Through precise control and optimization of processing parameters, the formation of cracks and chipping can be effectively avoided. Crack-free ablation holes with smooth edges were fabricated under low-energy (E = 22 nJ) single-pulse conditions. Furthermore, the effects of different laser processing parameters (single-pulse scanning interval, pulse number and scanning repetition times) on the microchannel morphology were also explored. From this work, high-precision micro-hole arrays, micro-nano rectangular column arrays, and microchannels were successfully fabricated on (100) β-Ga2O3 substrates. Due to the interaction of single-pulse femtosecond laser with β-Ga2O3 materials, this fast fabrication method of 3D submicron structures has potential applications in sensing, photonics, or electronics.

Analysis of electromechanical characteristics of the 1-3-2 piezoelectric composite and 1-3-2 modified structural material

In this study, a piezoelectric material with a modified structure was designed and fabricated based on a 1-3-2 piezoelectric composite, in an attempt to improve the thickness vibration electromechanical coupling coefficient of the piezoelectric sensitive element of transducer. No polymer was injected into the ceramic column arrays, and the upper surface of the ceramic column was covered with a metal plate, thereby reducing the lateral coupling among the piezoelectric columns. Thus, reducing the loss, and effectively improving the thickness vibration electromechanical coupling coefficient. The thickness vibration modes and electromechanical coupling coefficient of the 1-3-2 piezoelectric composite and 1-3-2 modified structural material were studied by theoretical analysis, simulation, and experiment. The results show that for the thickness vibration, the electromechanical coupling coefficient of the modified structural material increases by about 6% compared with the 1-3-2 piezoelectric ceramic/epoxy composite.

High crack self-healing efficiency and enhanced free-edge delamination resistance of carbon fibrous composites with hierarchical interleaves

Carbon nanotube (CNT), poly(ethylene-co-methacrylic acid) (EMAA) and epoxy (EP) are used to prepare a hierarchical interleaf, consisting of [CNT/EP/EMAA]s sandwich structure with periodic EP column arrays, which can act as crack self-healing interface within carbon fiber reinforced plastic (CFRP) by in-situ electrical-heating the CNTs. Results show that the introduced [CNT/EP/EMAA]s interleaf has little effect on the free-edge delamination initiation stress (<±3.2%) and the in-plane strength (<±1.2%) of the baseline CFRP. But, the interleaved CFRP shows high self-healing efficiencies of 99.1–111.3% to the delamination initiation stress and 97.9–99.4% to the elastic modulus, respectively, from two delamination initiation-healing circles activated by electrical-heating the embedded CNTs, as well as with a maintenance of 92.6–99.7% to the tensile ultimate strength. This study reveals that the [CNT/EP/EMAA]s interleaf and the electrical-heating activated self-healing method are promising to effectively restore the initial damage of CFRP without decreasing the in-plane strength, unlike the traditional pure EMAA interleaf.

Benchmark experimental study on wave run-ups of fixed four-rounded-square-column array in regular waves

Wave run-up on surface-piercing columns is an important phenomenon in offshore engineering. Previous studies have mainly focused on a single column and circular column arrays. This study is concerned with the wave run-up ratio and the wave force on a fixed array of four rounded square columns. A series of regular wave tests were conducted, and the effects of wave periods and steepness were investigated. The nonlinearity of the wave run-up under incident waves with a small period is more sensitive to wave steepness. Utilizing empirical mode decomposition (EMD) and fast Fourier transform (FFT) methods, the measured signals were separated into three components representing characteristics of the incident wave component (IMF1), near-field interference (IMF2), and far-field low frequency reflected wave (IMF3), respectively. The proposed methods are helpful for studying the mechanism of near-field interference, and the experimental data are essential benchmarks for validating further numerical simulations of wave run-ups on rounded square columns.

A dual-stimulation strategy in a micro-chip for the investigation of mechanical associative learning behavior of C. elegans

During the past decades, few micro-devices for analysis of associative learning behavior have been reported. In this work, an agarose-PDMS hybridized micro-chip was developed to establish a new associative learning model between mechanosensation and food reward in C. elegans. The micro-chip consisted of column arrays which mimicked mechanical stimulation to C. elegans. After trained by pairing bacterial food and mechanical stimuli in the chip, the worms exhibited associative learning behavior and gathered in the regions where there was food during training. The key research findings include: (1) Associative learning behavior of C. elegans could be generated and quantitatively analyzed by this developed micro-chip. (2) Associative learning behavior could be enhanced by extending the training time and developmental stage. (3) Mechanosensation-related genes and neurotransmitters signals had effects on the learning behavior. (4) The associative learning ability could be strengthened by exogenous dopamine in both wild type and mutants. We validated that the design of the micro-chip was useful and convenient for the study of learning behavior based on mechanosensation.

Maximum size limit of Au nanoparticle applicable for surface enhanced infrared absorption

The particle size limit for enhanced infrared absorption on metal nanostructures was identified using an infrared spectrometer and microscope accessory for well-defined periodic gold square column (SC) arrays with various nanoparticle sizes on silicon wafers fabricated by electron beam lithography. The sizes of SC arrays are compatible with those of vacuum evaporated thin metal films, which are used conventionally for surface-enhanced infrared absorption. The experimental results revealed that the particle size limit for the enhancement was about one-tenth of wavelength of infrared radiation. It indicates that this ratio limits the applicability of effective medium approximation in the SC model.

Imaging Performance for Two Row-Column Arrays.

This study evaluates the volumetric imaging performance of two prototyped 62 + 62 row-column-addressed (RCA) 2-D array transducer probes using three synthetic aperture imaging (SAI) emission sequences and two different beamformers. The probes are fabricated using capacitive micromachined ultrasonic transducer (CMUT) and piezoelectric transducer (PZT) technology. Both have integrated apodization to reduce ghost echoes and are designed with similar acoustical features, i.e., 3-MHz center frequency, λ /2 pitch, and [Formula: see text] active footprint. Raw RF data are obtained using an experimental research ultrasound scanner, SARUS. The SAI sequences are designed for imaging down to 14 cm at a volume rate of 88 Hz. Two beamforming methods, spatial matched filtering and row-column adapted delay-and-sum, are used for beamforming the RF data. The imaging quality is investigated through simulations and phantom measurements. Both probes on average have similar lateral full-width at half-maximum (FWHM) values, but the PZT probe has 20% smaller cystic resolution values and 70% larger contrast-to-noise ratio (CNR) compared to the capacitive micromachined ultrasonic transducer (CMUT) probe. The CMUT probe can penetrate down to 15 cm, and the PZT probe down to 30 cm. The CMUT probe has 17% smaller axial FWHM values. The matched filter focusing shows an improved B-mode image for measurements on a cyst phantom with an improved speckle pattern and better visualization of deeper lying cysts. The results of this study demonstrate the potentials of RCA 2-D arrays against fully addressed 2-D arrays, which are low channel count (e.g., 124 instead of 3844), low acoustic intensity mechanical index (MI ≤ 0.88 and spatial-peak-temporal-average intensity [Formula: see text]), and high penetration depth (down to 30 cm), which makes 3-D imaging at high volume rates possible with equipment in the price range of conventional 2-D imaging.

Response of U-Oscillating Water Column arrays: semi-analytical approach and numerical results

Nowadays, sea waves are recognized as an energy source that may contribute in the future to the global electricity demand. This fact manifests itself with the quite relevant number of proposed devices aimed at converting wave energy to electrical energy. In this context, the Oscillating Water Column (OWC) system plays a leading role, as it demonstrated flexibility, in the sense that it can work in conjunction with other marine systems, and effectiveness from a strict energy harvesting perspective. As a subclass, the U-Oscillating Water Column (U-OWC) was developed for further improving the OWC performance in mild-seas, where the natural resource is not abundant, such as in the Mediterranean Sea. This wave energy converter is composed by a water column in the lower part, an air pocket over the water column which is connected to a Power Take-Off device, and an external vertical duct connecting the water column to the open wave field. This paper deals with the problem of determining the response of a plant composed by an array of U-OWCs. This problem is relevant to the design of upright breakwaters embodying U-OWC chambers, where the interaction between contiguous U-OWCs influences the dynamics of each water column and, thus, the energy-wise performance of the whole plant. The models proposed currently in the literature are based on two-dimensional approaches neglecting three-dimensional effects and the mutual interference among the chambers. Therefore, firstly, the system of integro-differential equations describing the array dynamics is derived. Then, a semi-analytical approach is proposed for determining infinite frequency added mass and retardation function matrices. For this purpose, the wave field is described by the linear water wave theory and the boundary value problems pertaining to the determination of these hydrodynamic parameters are solved by combining Fourier transform and domain decomposition techniques.Next, numerical results are shown under the assumption of regular and irregular incident waves. It is seen that the individual U-OWC response is affected by the surrounding U-OWCs. Specifically, it is observed that the power available to the turbines decreases of about 9% with respect to the power associated with an isolated U-OWC in regular wave conditions. Although the reduction occurs over a wide range of incident wave frequencies, the numerical studies undertaken herein do not show the occurrence of frequencies leading to the sudden drop or magnification of the power output. This observation is confirmed by numerical simulations in case of irregular incident waves.

Surface enhanced perfect absorption in metamaterials with periodic dielectric nanostrips on silver film.

Integrated dielectric metamaterials with plasmonic structures can cause drastic optical resonances and strengthen the capacity of light absorption. Here, we describe the optical properties of silicon nanoarrays on a thin silver film for extreme light confinement at subwavelength nanoscales. We attain the nearly total absorption in silicon nanostrips, which support magnetic quadruple Mie-type resonances in the visible regions. The Mie resonant field of the dielectric nanostrip engages the screening response of the silver film, resulting in plasmon resonance configuration and thus achieving perfect light absorption in the dielectric nanostrip. Moreover, we can attain similar results in other nanostructures, such as silicon cylinder and rhombus column arrays. Because it can sustain hybridized plasmon modes and magnetic modes, the combined system will benefit the application of solar energy accumulation.

Surface plasmons excited from close-packed nanoring tube arrays produced by nanosphere lithography

Two-dimensional (2D) periodical close-packed nanoring tube arrays (RTAs) composed of metal and dielectric materials with unique surface plasmon properties have been investigated. A new fabrication route, which uses conventional semiconductor fabrication methods, has been developed to produce large-area highly ordered close-packed RTAs in a controllable and inexpensive way. Optical properties of this structure, as well as its replica, are investigated by both the finite-difference-time-domain (FDTD) algorithm and experiments. The simulation results show that both BW-SPP modes and coupled cavity modes at separate wavelengths are excited in RTAs, in accordance with experimental results. These modes are dependent on the geometry of RTAs. Ag RTAs with high absorption over the visible and near IR range has been experimentally demonstrated, which can be used in solar cells and as chemical/biological sensors with miniature size. The RTAs can also be employed as templates for producing other nanostructures by the nano-imprint methods, such as non-close-packed cylindrical column arrays that can be applied to surface-enhanced Raman scattering (SERS) substrates.

Multi-chamber oscillating water column wave energy converters and air turbines: A review

The oscillating water column (OWC) is a more common type of wave energy converter (WEC) that has been the subject of the study and development for several decades. Multi–chamber oscillating water column (MC–OWC) devices or arrays have the advantage of being more efficient in energy extraction compared to a single chamber system, particularly in more chaotic sea states. A variety of single and array OWC devices have been proposed and studied on a small–scale, whereas few large–scale devices have been tested under ocean wave conditions. This paper provides a concise review of the current state of MC–OWC device development in laboratory conditions. The review highlights explicitly the main stages of MC–OWC device development for one ongoing study as an example. This review was based on the available information in the literature from 2003 to 2012, in addition, further work is presented as part of the current study at the University of Technology Sydney. This study is from 2015 to 2018. The discussion shows the challenges that a device needs to overcome to be more competitive with other WECs in the global of wave energy converter area.

Broadband radar absorbing sandwich structures with enhanced mechanical properties

Abstract Foam sandwich structures reinforced with the fiber column arrays are proposed to achieve broadband absorption at microwave frequencies as well as good mechanical properties. To achieve the microwave absorption, two layers of resistive films are embedded into the sandwich structures. The results show that the proposed sandwich structure with the whole thickness of 9.73 mm can achieve broadband absorption with the reflection less than −10 dB in the frequency range of 2.6–21 GHz. The absorption mechanism has been discussed by using the equivalent circuit model. It is further indicated that introduction of the fiber column array in the sandwich structure has little influence on the absorption performance, but can remarkably enhance the mechanical properties. This has been well demonstrated experimentally by three-point bending experiment. Compared with the ordinary sandwich absorbing structures, enhanced mechanical properties make the designed structure suitable in some loading applications. It is expected that the proposed multifunctional structure may find great potentials in the applications of stealth technology, electromagnetic interferences and so on.

Interdigitated Electrode‐Based Triboelectric Sliding Sensor for Security Monitoring

AbstractSecurity monitoring and precaution for private information and property plays a key role in the smart home system. In this work, a triboelectric nanogenerator‐based active sliding sensor is demonstrated which can monitor the position, displacement, velocity, and direction of a contact sliding objects. The device consists of a mover and a stator which operate in sliding mode. Two aligned column arrays of copper electrodes are coated on the substrate as the mover, while two interdigitated copper electrode pairs with relative position shift are coated under a polytetrafluoroethylene film as the stator. The experimental results show that a single device can generate a voltage of about 5 V at a resistance load of 60 MΩ at a sliding velocity of 0.5 m s–1. The sliding sensor can detect an ultralow velocity in 0.001 m s–1 as well as the sliding direction of the mover. The sensor can be fixed on the drawer and door to detect the motion parameters which are sent to a remote client application for security monitoring in smart home systems. The proposed sliding sensor has great potential in the Internet of things, personal motion feature recognition, and meandering trajectory tracking.