Metal Grid Research Articles

Electrochemical Nanoimprinting of Colored Infrared Reflective Patterns for Radiative Heating

AbstractMetallic nanostructures hold immense promise for radiative heating technology because of their distinctive capability to simultaneously achieve high mid‐infrared reflectance and generate vibrant colors through structural or plasmonic effects. However, fabricating metallic nanostructures remains challenging using traditional top–down techniques. Here, the solid‐state superionic stamping (S4) process is demonstrated as a scalable and economical tool to electrochemically imprint metallic grid nano‐patterns onto flexible substrates. With precise control over grid width and length at the nanoscale, the S4 approach enables the fabrication of nano‐patterned grid coatings exhibiting a spectrum of colors. These coatings also show high mid‐infrared reflectance exceeding 80% at 9.5 µm, leading to radiative heating effects of 5.9 and 3.1 °C compared to bare skin and cotton, respectively. This work introduces a viable strategy for creating colored infrared‐reflective patterns, paving the way for diverse thermal management applications.

Stretchable liquid metal grid/metallized polyurethane composites with switchable electromagnetic interference shielding and efficient infrared stealth performance

Intelligent electromagnetic interference (EMI) shielding materials with tunable electromagnetic shielding properties becomes a significant and urgent concern for information society. Hence, a switchable and low-reflectivity EMI shielding composite is fabricated by electroless nickel plating on the surface of polyurethane nonwoven fabric (Ni@TPU), and followed by combining with liquid metal (LM) grid. The synergistic combination of Ni@TPU and LM grid effectively facilitates the rational construction of hierarchical impedance matching. Meanwhile, it promotes destructive interference between electromagnetic waves reflected from Ni@TPU and the LM grid. As a result, an excellent low-reflectivity EMI shielding performance can be achieved. More importantly, the switchable EMI shielding performance can be easily realized by repeatedly stretching Ni@TPU/LM. In addition, the fluffy nonwoven fabric and LM grid with low infrared emissivity endow it with an outstanding infrared stealth performance. Such excellent low-reflectivity EMI shielding switch performance incorporated with flexible infrared stealth makes it possible to become smart EMI shielding material with a great promise to be employed in the application scenario of window in camouflage container.

In-situ cured gel polymer/ecoflex hierarchical structure-based stretchable and robust TENG for intelligent touch perception and biometric recognition

Gel-based sensors for next generation touch panels have been acknowledged for their exceptional sensitivity and flexibility. However, these sensors typically depend on a metal grid connection, which is susceptible to structural deformation under heavy stress applications and necessitates external power. Here, we report a novel in-situ cured gel polymer electrode-based triboelectric nanogenerator (GPE-TENG) that is stretchable, semi-transparent, and durable, designed to enable a self-powered touch panel for intelligent touch perception. The in-situ curing of the hierarchical structure of the ionic polymer gel encapsulated within the ecoflex ensures robust adhesion of the ionic conductive polymer gel (PEO/LiTFSI) to the ecoflex layers, addressing the issue of delamination in TENG components under mechanical stress. As a result, the GPE-TENG demonstrates high durability, enduring under stretching of approximately 375 % and sustaining heavy mechanical deformations (under folding, twisting, and rolling) over a long period (approximately 2 months) without loss of functionality. Remarkably, the GPE-TENG exhibits outstanding energy harvesting capabilities with a peak power density of 0.36 W m-2. Notably, the GPE-TENG generates electrical signals through simple device stretching, thus serving as a self-powered wearable sensor for human activity monitoring. Moreover, a 9-digital arrayed (3 × 3) flexible, semi-transparent, and self-powered touch panel based on the GPE-TENG shows multifunctionality, including touch track/pattern recognition (i.e. touch and sliding mode) and a highly accurate (∼98 %) deep learning assisted smart biometric system for user identification.

Processing and Characterization of Spent Nickel-Metal Hydride Type AA Batteries to Recover Valuable Materials (Cobalt, Nickel and Rare Earth Elements).

The experimental research was focused on the investigation of valuable material from spent Ni-MH type AA batteries, namely the metal grid anodes and the black mass material (anode and cathode powder). The materials of interest were analyzed by X-ray fluorescence spectroscopy (XRF), ICP-OES (inductively coupled plasma optical emission spectrometry), optical microscopy, scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), electron backscatter diffraction (EBSD), and X-ray diffraction (XRD). The analyzed grids have a high Fe content, but some of them correspond to the Invar alloy with approx. 40% Ni. In the black mass material, round particles and large aggregations were observed by SEM analysis, showing a high degree of degradation. The XRD analysis reveals the presence of only three compounds or phases that crystallize in the hexagonal system: La0.52Ce0.33Pr0.04Nd0.11Co0.6Ni4.4, Ni(OH)2, and La5Ni19. The obtained results provide useful and interesting information that can be used for further research in the recycling and economic assessment of metals from spent Ni-MH batteries.

8663 Sex differences in delayed fear incubation in mice

Abstract Disclosure: M. Littlepage-Saunders: None. M. Rusnak: None. M. Tsuda: None. T. Wu: None. Post-traumatic stress disorder (PTSD) has a lifetime prevalence of 1 in 13 people. It is not fully understood why some are more vulnerable to developing PTSD whereas others are more resilient. Among those who develop PTSD, about a quarter have delayed-onset PTSD where onset of symptoms occur at 6 months or later after experiencing a traumatic event. While there is recognition of this type of PTSD, the underlying mechanism is poorly understood. The development of PTSD is more prevalent in women than men. However, previous preclinical and clinical studies have focused mainly on males. Thus, there lacks an understanding of this sex difference. To enhance our understanding of the causal mechanisms, we designed a study with mice to compare the effect of sex on delayed fear incubation. We expected the female mice to show increased fear responses that would suggest more chronic delayed fear incubation than the male mice. To test this, we evaluated distance travelled, freezing, and latency until the first freezing episode in adult male and female C57Bl/6J mice (7-8 weeks of age; n=8/group) using a delayed fear incubation behavioral assay. Animals were placed in a fear conditioning chamber for a 198 s acclimation period and then administered a single 2 s scrambled footshock of 1.5 mA via the metal grid floor. After an additional 60 s, animals were returned to their home cage. At specific time after shock application, animals underwent a fear recall test where the animals were placed back in the shock chamber for a total of 180 s without any additional footshocks and then returned to their home cage. The study was based on a 2X2 factorial design comprising of sex (male vs female) and recall time (1 day and 14 days post shock). The data showed an increasing freezing trend (p=0.08) at d 14 compared to their recall d 1 counterparts. There was no effect of time or sex on distance travelled or latency until the first freezing episode. Interestingly, female mice showed less freezing when compared to the male mice. Ongoing experiments will look more into circuitry-level changes by comparing neuronal activation through cFos expression in different brain regions that are a part of the limbic system and/or have been associated with fear: the amygdala, hippocampus, prefrontal cortex, and paraventricular nucleus. Presentation: 6/2/2024

Multi-mode non-diffraction vortex beams enabled by polarization-frequency multiplexing transmissive terahertz metasurfaces

In terahertz (THz) wireless communication systems, non-diffraction vortex beams carrying an orbital angular momentum (OAM) have attracted extensive attention due to their ability to transmit information over long distances with high capacity. However, existing metasurfaces can only generate a single OAM mode non-diffracting vortex beam at reflection space for circular polarization (CP) incidence, limiting practical applications. To address this issue, we propose and design a polarization-frequency multiplexing transmissive THz metasurface to realize multi-mode non-diffracting vortex beams at linear polarization (LP) incidence. The meta-atom of this metasurface is composed of three anisotropic rectangular metallic structures embedded in vanadium dioxide (VO2) square rings, two circular aperture metallic grid layers, and four dielectric layers. By reasonably designing the size of the metal patch and the state of VO2, the designed metasurface can achieve polarization multiplexing and frequency multiplexing for LP incidence. Based on the phase response of the proposed meta-atoms, the transmissive metasurface can implement not only multi-mode non-diffraction vortex beams but also their space separation at two frequency ranges of 0.80–0.90 THz and 1.50–1.80 THz by changing the state of VO2. Therefore, the proposed multiple multiplexing metasurfaces can effectively shape the wavefront of non-diffraction vortex beams, which have broad application prospects in 6G THz communication.

Enhanced adhesion strength of copper metallization on silicon heterojunction solar cell due to improved electrochemical reduction uniformity of ITO

Copper electroplating is an ideal technique for the metallization of highly efficient silicon heterojunction (SHJ) solar cells due to the unique advantage in the low cost, strong adhesion, and low contact resistance. Achieving these characteristics depends strongly on the seed layer before Cu electroplating. This work reports a potential economical and effective route for electrochemically reducing ITO to assist electroplating of Ni seed layer and increase the adhesion of the metallization grids. Good wettability of electrolyte solution to ITO and the low temperature account for the reduction uniformity. A uniform In,Sn/SnO mixed metal layer is formed on ITO surface after electrochemical reduction. With the assistance of the uniform reduction the adhesion strength of the metallization grid reaches to 9.9 N mm⁻1. Although it is conducted on a small-size ITO-coating Si plate, the present plating is convenient and low-cost for the metallization, which is expected to be suitable for the large-scale commercialization of SHJ solar cells.

Vitrification of Ovarian Cortex Tissue to Achieve a Glassy State of Aggregation.

Ovarian tissue cryopreservation (OTC) is an important option for fertility preservation. For patients whose gonadotoxic treatments cannot be postponed or for pre-pubertal girls, it is often the only option for fertility protection. Cryopreservation can be performed either by vitrification or by slow freezing. Slow freezing is currently the standard approach. An increasing number of studies indicate that vitrification can replace slow freezing in the state-of-the-art in vitro fertilization (IVF) laboratories, significantly improving thawing survival rates and simplifying the technical aspects of cryopreservation. A metal grid-based, high-throughput protocol for rapid vitrification of ovarian cortex tissue, suitable for clinical routine, is described. The sterilization of metal grids and liquid nitrogen ensures high quality, meeting good manufacturing practice (GMP) standards. Vitrification was conducted to ensure ultra-rapid cooling rates. Instead of slowly thawing, samples were rapidly warmed. To assess follicular viability, calcein staining was performed both prior to cryopreservation and after rapid warming. The successful application of vitrification and rapid warming using metal grids is reported. No significant differences in follicular viability were observed prior to vitrification and after rapid warming. These results substantiate the high capacity of tissue vitrification for clinical routine applications as a potential substitute for the widely used slow-freezing method.

Flexible Epitaxial Lift‐Off InGaP/GaAs/InGaAs Triple‐Junction Solar Cells Integrated with Micro/Nanostructured Polymer Film

Epitaxial lift‐off (ELO) InGaP/GaAs/InGaAs inverted metamorphic triple‐junction solar cells are encapsulated with a micro/nanostructured polydimethylsiloxane (PDMS) film. The microprism array (MPA) is realized on the PDMS film to redirect the light incident on the metal grid line to the active area. Subwavelength structures (SWSs) are also introduced onto the PDMS film to suppress the Fresnel optical reflection loss. Triangular and hemicylindrical shapes are considered for the MPA. The optical responses of the two MPAs are calculated by using ray‐tracing methods. The triangular MPA performs better than the hemicylindrical MPA in terms of light‐redirection efficiency. It is confirmed that 82.0% of the light incident on the metal grid can be harvested by the effect of the triangular MPA and the Fresnel optical reflection loss is reduced effectively by the SWSs. These effects contribute to photocurrent enhancement. The short‐circuit current density and power conversion efficiency of the flexible ELO triple‐junction solar cells integrated with the micro/nanostructured PDMS film improve by 7.0% and 7.1%, respectively, compared with those of the solar cells without the PDMS film. By using the flexible PDMS film for light management, the flexibility of the ELO solar cells is preserved.

Band-Pass and Band-Stop Filter Frequency Selective Surface with Harmonic Suppression

This study investigated a frequency-selective surface (FSS) that is used to suppress harmonics affecting the performance and accuracy of radar systems. One side of the FSS features a metal grid structure, and when converted into an equivalent circuit model, it exhibits the characteristics of a band-pass filter with an L and C parallel structure. The other side of the FSS features a metallic loop structure and when represented as an equivalent circuit model, it exhibits the characteristics of a band-stop filter with an L and C series structure. The reflection coefficient (S11) and transmission coefficient (S21) of the FSS designed based on theory are compared using a CST studio suite and Keysight’s Advanced Design System. In addition, the transmission coefficients are verified through actual measurements, wherein the measured transmission coefficient is −0.1 dB at 3.0 GHz and approximately −50 dB at the harmonic frequency of 6.0 GHz. The designed FSS is attached to an actual radar system, and the 2D radiation pattern and maximum gain are measured during steering in boresight, azimuth (30∘) and elevation (30∘) directions. At 3.0 GHz, the maximum gain in boresight is 17.25 dB without the FSS and 17.12 dB with the FSS. At 6.0 GHz, the maximum gain is 12.79 dB without the FSS and 2.69 dB with the FSS. At 3.0 GHz, the maximum gain during azimuth steering is 16.13 dB without the FSS and 16.68 dB with the FSS, and the maximum gain during elevation steering is 15.74 dB without the FSS and 15.90 dB with the FSS.

Liquid Metal Grid Patterned Thin Film Devices Toward Absorption-Dominant and Strain-Tunable Electromagnetic Interference Shielding

Multiple internal reflection-based absorption-dominant stretchable electromagnetic shielding thin film by incorporating liquid metal grid structure is developed.The device demonstrates high electromagnetic shielding effectiveness (SE) (SET of up to 75 dB) with low reflectance (SER of 1.5 dB at the resonant frequency).The shielding properties of the device can be tuned by adjusting the liquid metal patterned grid spaces upon strain.

Multiscale Transfer Printing via Shape Memory Polymer with High Adhesion and Modulus Switchability.

Flexible electronics have gained significant attention as an innovative solution to meet the growing need for information collection from the human body and the environment. However, a critical challenge lies in the need for a transfer printing technique that can fabricate rigid and brittle devices on flexible organic substrates. Here, we develop a multiscale transfer printing technique using an ultraviolet-curable shape memory polymer (SMP) that serves as both the stamp and the receiver substrate. The SMP demonstrates exceptional mechanical performance with toughness at room temperature and remarkable flexibility near its glass transition temperature. The SMP material exhibits an impressive shape recovery ratio and remarkable adhesion switchability. We demonstrate robust transfer printing of diverse objects with different materials and morphologies and in situ transfer of multiscale metallic structures. In addition, the in situ fabricated transparent hyperthermia patches with embedded metal grids are demonstrated, offering potential application in the field of sensors, wearable devices, and electronic skin.

Punching of Concrete Slabs Reinforced by Recycling Waste

Abstract This study aims to experimentally evaluate the mechanical properties of concrete slabs reinforced with two types of fibers: metallic fibers (MF) and grids based on polypropylene fibers (PPG). The metallic fibers, sourced from machining waste of steel parts, are randomly distributed in the concrete, while the polypropylene fibers are arranged in grids. The investigation includes punching tests conducted on slabs measuring [25x50x7] cm³, as well as compression tests on cylinders with a diameter of Ø16 cm and a height of H32 cm. Mechanical resistance and tearing characteristics of the fibers were also assessed. The concrete’s composition was determined using the experimental “Dreux-Gorisse” method. Five different metal fiber contents (MF) were studied (W=0.2%, W=0.4%, W=0.6%, W=0.8%, and W=1%), alongside a control concrete sample (BT) with no fibers (W=0%) having the same composition as the matrix. Two variants of grids based on small-mesh polypropylene fibers (PPG/SM) and large-mesh (PPG/LM) configurations were considered. The comparative analysis of the results highlights that, at a fiber content of W=0.8%, metallic fibers (MF) enhance both resistance and rigidity more effectively than polypropylene fibers in small meshes (PPG/SM) and large meshes (PPG/LM), thereby limiting the formation of puncturing cracks.

Plasma Response of a Metallic “Grating” Metasurface on a Substrate

The transmission of electromagnetic radiation through a silicon substrate with a square metallic grid deposited on one side has been studied experimentally. It has been established that the electrodynamic response of the structure is equivalent to the excitation of a transverse electromagnetic plasma mode in it with the plasma frequency determined by the geometric parameters of the grating, as well as by the thickness and relative permittivity of the substrate. A theoretical model has been developed to qualitatively describe the experimental results obtained.

Experimental investigation of electrically enhanced boiling of FC 72 using high-resolution phase-detection diagnostics

This work features the boiling of FC72 on a transparent sapphire substrate. Tests are performed using a thin ITO film (indium tin oxide) coated on the sapphire substrate as the heat source, a fast speed video camera to capture the boiling process using a technique to track the phase (liquid or vapor) in contact with the heating surface, an InfraRed video camera to capture the average temperature on the surface, and a metallic grid to impose an electric field perpendicular to the boiling surface. The maximum average electric field tested in this work is 3.3kV/mm, which led to a 18% increase of the critical heat flux. This study analyses in detail the phase distribution data showing that (1) there is no evidence of microlayer formation, and suggesting that (2) the triple contact line evaporation accounts for approximately 20% of the total heat flux, while (3) the quenching stage accounts for approximately 80%. Finally, phase distribution images are processed to characterize the size of vapor patches, showing that a boiling crisis occurs when the distribution of the vapor patches becomes scale-free, and corroborating the hypothesis that the boiling crisis can be modelled as a bubble interaction instability using a percolation model.

Controlled in-situ reduction strategy for synthesis of transparent conductive metal meshes using tannic acid-based photoresists

Transparent conductive films (TCFs) that converge high transmittance and high conductive properties are essential for many optoelectronic devices, and efforts have been made to acquire films with high transmittance as well as low resistance of the thin layer by low-cost means. Here, we introduce a novel and simple strategy for the controlled in-situ templated synthesis of a transparent conductive metal mesh by utilizing the good reducibility to silver ions of the patterned tannic acid (TA)-based photoresists. To achieve this, mesh patterns with tunable line width were first printed using the TA-based negative photoresists by laser direct writing equipment. Within the patterned domains, the phenolic hydroxyl groups could interact with metal ions and act as reducing agents, thus accelerating the in-situ growth of silver nanoparticles to fabricate silver grids. By changing the line width of the designed patterns and the PH of the plating solution, the metal grids with a high transmission (T) of 91.5% and a thin-layer resistance (Rs) as low as 4.15 Ω sq.−1 are ultimately achieved after annealing treatment. Our description demonstrates a simple and effective approach that is potentially scalable to other materials as well.

In-Bath 3D Printing of Anisotropic Shape-Memory Cryogels Functionalized with Bone-Bioactive Nanoparticles.

Cryogels exhibit unique shape memory with full recovery and structural stability features after multiple injections. These constructs also possess enhanced cell permeability and nutrient diffusion when compared to typical bulk hydrogels. Volumetric processing of cryogels functionalized with nanosized units has potential to widen their biomedical applications, however this has remained challenging and relatively underexplored. In this study, we report a novel methodology that combines suspension 3D printing with directional freezing for the fabrication of nanocomposite cryogels with configurable anisotropy. When compared to conventional bulk or freeze-dried hydrogels, nanocomposite cryogel formulations exhibit excellent shape recovery (>95%) and higher pore connectivity. Suspension printing, assisted with a prechilled metal grid, was optimized to induce anisotropy. The addition of calcium- and phosphate-doped mesoporous silica nanoparticles into the cryogel matrix enhanced bioactivity toward orthopedic applications without hindering the printing process. Notably, the nanocomposite 3D printed cryogels exhibit injectable shape memory while also featuring a lamellar topography. The fabrication of these constructs was highly reproducible and exhibited potential for a cell-delivery injectable cryogel with no cytotoxicity to human-derived adipose stem cells. Hence, in this work, it was possible to combine a gravity defying 3D printed methodology with injectable and controlled anisotropic macroporous structures containing bioactive nanoparticles. This methodology ameliorates highly tunable injectable 3D printed anisotropic nanocomposite cryogels with a user-programmable degree of structural complexity.

Application of Slice Culture System for Successional Dental Lamina in Diphyodont Mammals.

Replacement teeth develop from the successional dental lamina (SDL). Understanding how SDL transitions from quiescence to initiation is crucial for preserving dental lamina stem cells in the jawbone microenvironment and for complete tooth regeneration. Miniature pigs are good models for studying human tooth replacement because of their similarities to humans. However, the molecular mechanisms and cellular composition that initiate SDL development remain unclear. One possible reason for this is the limitations of the current methods for culturing SDL in vitro, such as the inability to directly observe tooth morphological changes during culture and low tissue viability. This study aimed to improve the in vitro culture method for SDL. Using a McIlwain Tissue Chopper, we obtained mandibular slices containing deciduous canine and SDL of permanent canine. The slices were approximately 500 μm thick and were cultured on a Transwell membrane supported with metal grids over medium. The SDL developed into the bud stage on the second day and entered the cap stage on the fifth day in vitro. The expression of proliferation markers, cell death markers, and key odontogenetic genes in vitro was similar to that observed invivo. In conclusion, we successfully applied a slice culture system to the SDL of miniature pigs. This slice culture method allowed us to directly visualize SDL initiation and further elucidate the molecular mechanisms underlying the initiation of permanent tooth development.

Design of multibeam antenna with ultralow cross‐polarization

AbstractThis paper presents a design to realize extremely low cross‐polarization level in multibeam antenna. The antenna consists of two reflectors placed on top of each other. The front reflector is a panel made of metal grid, which is used to separate two orthogonal polarizations. The rear reflector serves as the actual multibeam antenna surface. The multibeam antenna and feed array operated at Ku band are designed and fabricated. The test results show that the gains of the 28 beams can be better than 40.42 dBi, and the cross‐polarization level can be lower than −40 dB. The proposed method provides a novel idea for the design of ultralow cross‐polarization multibeam antenna.

Gigahertz streaking and compression of low-energy electron pulses.

Although radio frequency (RF) technology is routinely employed for controlling high-energy pulses of electrons, corresponding technology has not been developed at beam energies below several kiloelectronvolts. In this work, we demonstrate transverse and longitudinal phase-space manipulation of low-energy electron pulses using RF fields. A millimeter-sized photoelectron gun is combined with synchronized streaking and compression cavities driven at frequencies of and , respectively. The phase-controlled acceleration and deceleration of photoelectron pulses is characterized in the energy range of -. Deflection from a transient space-charge cloud at a metal grid is used to measure a fourfold compression of electron pulses, from to pulse duration.