Silver Layer Research Articles

Fabrication of superhydrophobic surfaces for applications in total internal reflection effects

Superhydrophobic surfaces have attracted significant attention in the applied science community. This paper presents three different methods for fabricating superhydrophobic surfaces, which can be applied in liquid light guides with the total internal reflection effect playing a central role. The selective bi-polymer etching only produces a hydrophobic porous poly(methyl methacrylate) surface but is simple and versatile for use on an arbitrary surface. In metal-assisted chemical etching, wet etching of a silver layer on a silicon sample creates porous silicon with superhydrophobicity, characterized by a water contact angle of 160°. The metal-assisted chemical etching method modified with the presence of polystyrene nanoparticles further improved the water contact angle to 164° by creating a nanopillar silicon structure. The metal-assisted chemical etching methods are more complicated but can produce superhydrophobic surfaces with very high water contact angles. These results show that superhydrophobic surfaces fabricated by methods in this study can be used for total internal reflection effect at the interface between water with huge potential applications in liquid light guides.

Targeted Deposition in a Lithiophilic Silver‐Modified 3D Cu Host for Lithium‐Metal Anodes

Lithium‐metal batteries are regarded as the “Holy Grail” of next‐generation batteries. However, lithium dendrite and anode volume expansion in cycles seriously hinders lithium‐metal battery applications. Herein, we propose a precise and efficient strategy for stabilizing lithium‐metal batteries via a lithiophilic Ag‐modified Cu current host (Li@CuM/Ag). By applying the magnetron sputtering method, the lithiophilic silver layer can be anchored homogeneously on the Cu mesh. The lithiophilic silver layer effectively guides uniform Li deposition in the 3D host and realizes spatial control over Li nucleation. In addition, a dendrite‐free lithium anode is successfully realized, which has been proven by in situ optical dynamic tests and Li deposition simulations. The symmetrical cell can maintain a low overpotential (230 mV) and long cycle life (90 h) at a large current of 10 mA cm−2 for a plating amount of 3 mAh cm−2. Furthermore, Li@CuM/Ag||LiCoO2 cells exhibited a high‐capacity retention rate (86.39%) after 150 cycles at 2 C. Lithiophilic hosts based on magnetron sputtering provide a feasible strategy for applications of lithium‐metal batteries.

Highly Flexible Electroluminescent Devices Based on Super Durable AlN‐Dispersed Ag Ultrathin Films

AbstractHigh performance and durable electrodes are prerequisites for the stable operation of various optoelectronic devices, such as alternating current electroluminescence (ACEL) applications. As for the flexible electrodes based on ultrathin metals, which have attracted much attention in recent years, stability problems as evidenced by optically lossy and electrical degradation of the silver (Ag) layer in the service environment are the key issues to be solved before its practical application. This work prepares ultrathin and stable doped silver films by introducing a small amount of AlN during the sputtering process. The Ag‐AlN thin films exhibit a comprehensive stability promotion in terms of high temperature (250 °C in the air) and damp‐heat (85 °C, 85% relative humidity (RH) for 12 h) test compared with pure Ag counterpart. In addition, flexible ACEL devices based on AZO/Ag‐AlN/AZO/polyethylene terephthalate (PET) films with a luminance of 176.1 cd m−2 at 300 V and 400 Hz and excellent luminescence performance and mechanical flexibility under operating conditions are developed. Such ACEL devices based on these ultrathin and durable Ag‐AlN films are up‐and‐coming in practical, flexible electronics applications.

Flexible Microplasma Discharge Device for Treating Multidrug-Resistant Fungal and Bacterial Infections

Multi-drug resistant (MDR) pathogens are becoming a serious global threat in the treatment of burn wounds, surgical site infections and chronic wounds, driving the need for the development of new sterilizing techniques to disinfect the wounds. To address this, a novel and flexible microplasma discharge device (MDD) was fabricated using additive print manufacturing process for the eradication of pathogens such as <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Candida albicans</i> , an opportunistic pathogenic yeast (fungus), and three bacterial species from the ESKAPE group including <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Enterococcus faecium</i> , <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Klebsiella pneumoniae</i> , and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Acinetobacter baumannii</i> using ambient air as the sterilization agent. To fabricate the MDD, silver ink (Ag) was deposited on flexible polyethylene terephthalate (PET) films in circular design consisting of a honeycomb pattern using a screen-printing process to fabricate the top and bottom electrodes. An average thickness and roughness of ~9 μm and ~2 μm were measured for the screen-printed silver layer, respectively. Then the MDD was assembled by attaching the top and bottom electrodes using a two-sided Kapton tape (dielectric layer). The antifungal and antibacterial efficacies of the MDD were investigated by varying applied voltage (6, 8, and 10 V). The antifungal and antibacterial efficacies of 100% were achieved at an applied voltage of 10 V for a treatment time of 1 min. In addition, the surface temperature of the MDD was measured from 25 to 68 °C at the applied voltages ranging from 6 V to 10 V, respectively. The MDD performs similarly both in flat and bent conditions (on surfaces with 25 mm and 50 mm radius of curvatures), indicating that it is flexible. This flexible and printed MDD can be potentially applied as a wearable bandage in hospitals to sterilize burn wound injuries which mostly contains <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C. albicans</i> and ESKAPE pathogens, and accelerate wound healing process.

"EFFECT OF PRECOATING ON PROPERTIES OF FUNCTIONAL COATING AND ELECTRICAL CONDUCTIVITY OF INKJET-PRINTED ELECTRONICS"

"In the present work, various surface treatments of base paper were investigated in order to make it suitable for application in printed electronics. A functional coating based on silica pigment was preceded by PVOH-containing precoating, and differently surface treated papers were characterized in terms of surface roughness, relative area of surface pores, wettability, printability and by FTIR spectroscopy. The precoating had a significant effect on the constriction of through-pores, the reduction of their number, and on the permeability of the functional coating, and it increased the dynamic contact angle of the liquids. Analysis of FTIR spectra of precoated and functionally coated paper confirmed a higher content of polyvinyl alcohol binder and cationic polymer in the functional coating, compared to that of functionally coated paper, without precoating. SEM analysis showed that the silver layer of the RFID antenna printed by inkjet on the precoated and functionally coated paper was continuous. Better printability of the precoated and functionally coated paper, compared to the functionally coated paper, without precoating, was also confirmed by higher electrical conductivity of the dipole of the RFID antenna, which reached the level of the antenna printed on a commercial inkjet PET film."

Observation of polarization-dependent optical Tamm states in heterostructures containing hyperbolic metamaterials in the near-infrared region

In the heterostructure composed of metal and one-dimensional photonic crystal (1DPC), the optical Tamm state (OTS) can be excited directly without the coupling of prism or grating, but it is strongly dependent on the photonic band gap (PBG) of the 1DPC. In particular, the PBG of the all-dielectric 1DPC as well as the corresponding OTSs shift toward shorter wavelengths for both transverse magnetic (TM) and transverse electric (TE) polarizations as the angle of incidence increases, making it impossible to achieve a high-performance polarization selection. In a heterostructure consisting of a silver layer and an ITO-based one-dimensional photonic hypercrystal (1DPHC), we experimentally observe for the first time that the OTSs are red-shifted for TM polarization and blue-shifted for TE polarization with increasing incident angle. The ITO-based 1DPHC possesses a large red-shifted PBG in the near-infrared region, which guarantees the full excitation of the OTSs at different angles. Our work provides a potential direction for improving the sensitivity, polarization selection and operating angle range of the Tamm sensor.

Enhanced MOKE Via Tunable Plasmon Resonance Field in the Otto Configuration

Here, we demonstrate the enhancement of the transverse magneto-optical Kerr effect (TMOKE) signal, due to surface plasmon resonance in the Otto configuration, where the low index dielectric has a variable thickness. This constitutes a demonstration that, in principle, a separation of the magnetic sample from the plasmonic device and the modulation of the plasmon resonance with an enhancement of the MOKE signal is possible. We have achieved this by using air as a low index dielectric where the evanescent wave extends, preceding to excitation of surface plasmons. The magnetic sample under consideration is a thin layer of cobalt coated by an ultrathin silver layer, on a silicon substrate (Ag/Co/Si). The sample is brought close enough to the prism/air interface, allowing surface plasmon excitation in the air/Ag interface. This leads to an increase of the TMOKE signal up to ~ 2 ‰ with respect to the incident light. This is about 7 times the traditional MOKE signal in the absence of plasmons. This is comparable with previous works using the Kretschmann-Raether configuration. Furthermore, the fact that the plasmon field generated at the metal-air interface substitutes the laser light used in traditional MOKE allows new functionalities such as controlling the penetration depth of the plasmonic field into the sample. This should find applications in magnetometry and related technology.

Studies of surface plasmon resonance effect on different metallic layers of silver (Ag) and copper (Cu) with molybdenum trioxide (MoO3) for formaldehyde sensor

This paper reports the implementation of surface plasmon resonance in optical fiber sensor for formaldehyde detection. The studies involve comparison effects of different metallic layer of silver (Ag) and copper (Cu) to enhance evanescence wave in optical fiber sensor (OFS). We integrate the MoO3 materials due to its natural advantage where it can be used as high-activity metal oxide catalyst. The sensor will be focusing on sensing formaldehyde which is an environmental pollutant and is considered hazardous if more than 0.1 ppm is inhaled. MoO3 contributes to the sensitivity enhancement and improvement of the oxidation resistance on the metal films. The independent variables are the different metal films namely Ag and Cu at 40 nm thickness obtained from previous work. Formaldehyde sensing using bare Cu film, bare Ag film and the combination of Cu/Ag-MoO3 is compared via transmission-wavelength graphs to check if there is sensitivity enhancement in the Cu/Ag-MoO3 combination. Ag-MoO3 displays a better red shift with formaldehyde, by 10 nm at a resonant wavelength of 350 nm where Cu shows highest responsive metallic layer in formaldehyde detection.

Designing Optical Coatings with Incorporated Thin Metal Films

In the world of nanomaterials and meta-materials, thin films are used which are an order of magnitude thinner than historically used in optical thin film coatings. A problem stems from the island structure that is seen as the film nucleates and grows until there is coalescence or percolation of the islands into a nearly continuous film. The application problem is that the indices of refraction, n and k, vary with thickness from zero thickness up to some thickness such as 30 or 40 nanometers for silver. This behavior will be different from material to material and deposition process to deposition process; it is hardly modeled by simple mathematical functions. It has been necessary to design with only fixed thicknesses and associated indices instead. This paper deals with a tool for the practical task of designing optical thin films in this realm of non-bulk behavior of indices of refraction; no new research is reported here. Historically, two applications are known to have encountered this problem because of their thin metal layers which are on the order of 10 nm thick: (1) architectural low emittance (Low-E) coatings on window glazing with thin silver layers, and (2) black mirrors which transmit nothing and reflect as little as possible over the visible spectrum with thin layers of chromium or related metals. The contribution reported here is a tool to remove this software limitation and model thin layers whose indices vary in thickness.

Artificial neural network based optimization for Ag grated D-shaped optical fiber surface plasmon resonance refractive index sensor

This study reports the optimization of fiber optic SPR refractive index sensor parameters with the simulation of finite element method (FEM) and artificial neural network (ANN) model. To demonstrate the applicability of the algorithm, we examined an Ag-grated D-shaped fiber optic sensor configuration with 4 basic input parameters with the aim of reaching the highest sensitivity. Through the conventional optimization, the best parameter set appeared to be a 10 nm air gap distance between the gratings (a), 20 gratings (N), 50 nm residual cladding thickness (d), and 70 nm silver layer thickness (Ag_th) at the indices of 1.35 and 1.39 yielding a sensitivity of 3775 nm/RIU. A close match is found between the actual and predicted sensitivity. 199 input data obtained from FEM are used for training by Leave One Out Cross-Validation (LOOCV) approach with R-squared value of 0.98, and the trained model with R-squared value of 0.97 is implemented in the Genetic Algorithm. We achieved the sensitivity of 3890 nm/RIU at the predicted a, N, d, and Ag_th of 10 nm, 20, 50 nm, and 75 nm, respectively. Future studies may further improve these results by integrating other algorithms. This method may apply to different and more complex structures to observe the correlation between the parameters, cover an entire range of parameters, and get more accurate results, especially with a high number of inputs requiring less time and computing effort. The proposed method carries great potential to improve the sensing ability and bring a new perspective to the literature.

Preparation and Characterization of Stable Superhydrophobic Copper Foams Suitable for Treatment of Oily Wastewater

A simple two-stage chemical solution process is reported, to deposit a superhydrophobic film on copper foams with a view to be employed in oil absorption or filtration procedures. The first stage includes the growth of a silver layer to increase micro roughness and the second one evolves the modification of the film using stearic acid. The whole process is time-saving, cost effective and versatile. UV-Vis spectroscopy was employed to determine optimum deposition durations and detect potential film detachments during the synthesis process. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to examine the film structure and elemental analysis. Surface functional groups were detected by Fourier transform infrared (FTIR) spectroscopy. An adherent superhydrophobic silver coating was achieved under optimum deposition durations. A leaf-like structural morphology appeared from silver deposition and spherical, microflower morphologies stemmed from the stearic acid deposition. The influence of process conditions on wettability and the obtained silver film morphology and topography were clarified. Thermal stability at several temperatures along with chemical stability for acidic and alkaline environments were examined. Oil absorption capacity and separation efficiency were also evaluated for the optimum superhydrophobic copper foams. The results showed that the produced superhydrophobic copper foams can potentially be used to oil/water separation applications.

Degradation Mechanism of Silver Sintering Die Attach Based on Thermal and Mechanical Reliability Testing

This article investigates the degradation mechanism of sintered silver (s-Ag) layer in silicon carbide (SiC) die attach by means of thermal shocked test (TST) and nine-point bending test (NBT). TST can thermally provide out-of-plane deformation with s-Ag die layer, whereas NBT developed by the authors can mechanically provide the out-of-plane deformation. Two types of Ag paste (NP: nanopaste and NMP: nano- and micropaste) are employed, which are sintered with 300 °C for 10 min under 60-MPa pressure for SiC die attach. TSTs are conducted under thermal cyclic loading between −40 °C and 150 °C with trapezoidal waveform for 60 min per a cycle. NBTs are conducted under cyclic mechanical loading between 0 and 300 N with triangle waveform for 3 min per a cycle at 150 °C. Scanning acoustic tomography (SAT) evaluates the die-attach delamination during TST and NBT, which starts from the edge of the die. Cross-sectional scanning electron microscopy (SEM) observation demonstrates that mechanical cracking and material aging in s-Ag layer coexist after TST under the −40 °C to 150 °C conditions only. A damage parameter (DP) proposed in this study works well to fit the delamination area ratio in the cracking and cracking-aging specimens separately after 1000 cycles. Molecular dynamics (MD) simulation and classical pore growth discussion suggest that pores can grow under only tensile stress state at high temperature, which would have given rise to the difference between the two degradation mechanisms.

Surface plasmon resonance biosensor sensitivity improvement employing of 2D materials and BaTiO3 with bimetallic layers of silver

Surface plasmon resonance biosensor sensitivity improvement employing of 2D materials and BaTiO3 with bimetallic layers of silver

Aptasensors based on track-etched membranes coated with nanostructured silver layer for influenza A and B virus detection

A biosensor based on a polyethylene terephthalate track membrane coated with silver nanoparticles is proposed for the detection of influenza A and B viruses using aptamers for specific sorption of the viruses on the membrane surface, as well as for the introduction of a Raman-active or fluorescent label in the complex. The analytical signal was recorded using a Raman spectrometer, observing the effects of surface-enhancing of the intensity of optical responses from the labels.

Aptasensors Based on Track-Etched Membranes Coated with a Nanostructured Silver Layer for Influenza A and B Virus Detection

Aptasensors Based on Track-Etched Membranes Coated with a Nanostructured Silver Layer for Influenza A and B Virus Detection

Analysis of riboflavin/ultraviolet a corneal cross-linking by molecular spectroscopy

Corneal cross-linking (CXL) with riboflavin and ultraviolet A light is a therapeutic procedure to restore the mechanical stability of corneal tissue. The treatment method is applied to pathological tissue, such as keratoconus and induces the formation of new cross-links. At present, the molecular mechanisms of induced cross-linking are still not known exactly. In this study, we investigated molecular alterations within porcine cornea tissue after treatment with riboflavin and ultraviolet A light by surface enhanced Raman spectroscopy (SERS). For that purpose, after CXL treatment a thin silver layer was vapor-deposited onto cornea flaps. To explore molecular alterations induced by the photochemical process hierarchical cluster analysis (HCA) was used. The detailed analysis of SERS spectra reveals that there is no general change in collagen secondary structure while modifications on amino acid side chains are the most dominant outcome. The formation of secondary and aromatic amine groups as well as methylene and carbonyl groups were observed. Even though successful cross-linking could not be registered in all treated samples, Raman signals of newly formed chemical groups are already present in riboflavin only treated corneas.

A Green Approach for Recycling Compact Discs.

Compact discs (CDs) and digital versatile discs (DVDs) are mainly made by polycarbonate disc, a thin layer of aluminum or silver, a thin layer of a coating and a thin layer of a label of paper or PET. The recycling of these discs is difficult due to the removal of these non-polymeric layers and to our best knowledge, no industrial plants have been resent for their recycling. In this work, we propose a facile way to remove the non-polymeric layers and investigate the effect of the repetitive extrusion process on the processability and on the mechanical properties of the recycled polycarbonate. A few works have been published dealing with both the removal of the non-polymeric layers and the mechanical recycling of the disk of polycarbonate. In our approach, the removal of the non-polymeric layers is easily obtained through a thermo-mechanical treatment in a basic solution by ammonia. This process can be considered green because is made at a low temperature with a small amount of water and a very small amount of ammonia, saving energy and water. The properties of the polycarbonate remain good if the mechanical recycling is made after drying the post-consumer polycarbonate.

Multi-physics coupling test design and failure analysis of intelligent door lock

In this paper, the multi-physical field coupling test of the intelligent door lock is firstly designed based on the actual service scenario of the product. The failure analysis of the display circuit is implemented after the multi-physical field coupling reliability test. The failure reasons and mechanism of the intelligent door lock abnormal-display widely existing in the market are proved and reproduced. The research shows that there are two main reasons for the abnormal display in the market at present. First, the mechanical cracking of the outer bonding point of the LED on the display panel leads to the failure of the LED, which in turn leads to an abnormal-display for the intelligent door lock. Second, improper three-defense technology of the display circuit system leads to sulfide corrosion failure of the silver layer of the resistance surface electrode, and the resistance of the circuit system increases or opens failure, which makes the intelligent door not display in service.

Probing the stability of perovskite solar cell under working condition through an ultra-thin silver electrode: Beyond the halide ion diffusion and metal diffusion

Perovskite solar cells (PSCs) with an excellent optoelectronic performance have intrigued mushrooming research interests, and the undesirable intrinsic stability of halide perovskite materials still remains a severe constraint for their practical application. Fortunately, the ambiguous and complicated incentives for the degradation process of PSCs under working condition can be directly reflected on the corrosion of silver electrode by halogens. Here, a new perspective for evaluating the long-term stability of PSCs is presented by the time-dependent transverse resistance of the ultrathin silver electrode under different working conditions. Being anode or cathode, the stability of ultra-thin silver layer has been systematically investigated through adjusting the external operating conditions of devices, i.e. light illumination and bias voltage. Experimental results indicate that the gradual resistance increases of silver film can be attributed to the oxidation of I− existing on the top surface of perovskite layer by non-equilibrium holes generated from light illumination or electrical injection for producing corrosive I2 gas, which will diffuse through the carrier transporting layer and attack the thin silver layer. The interaction probability of I− and non-equilibrium holes at the interface plays a critical role on the generation of I2 gas and resistance variation of the top thin silver electrode. The stability study of electrode indicator will shed light on the ambiguous degradation mechanisms of PSC under working condition, paving a path for conquering the fatal problems of the practical application.

Effect of 2-D nanomaterials on sensitivity of plasmonic biosensor for efficient urine glucose detection

This paper presents a multi-layered Kretschmann configuration-based Surface Plasmon Resonance (SPR) biosensor for the detection of urine glucose. The modelling, simulation, and analysis have been done by using Silver (Ag) and Gold (Au) layer on the low refractive index prism BK-7 separately, which created two structures: structure-I (BK7/Ag/Bio-sample) and structure-II (BK7/Au/Bio-sample). Urine samples from a non-diabetic person (0–15 mg/dL) and a diabetic person (.625 gm/dL, 1.25 gm/dL, 2.5 gm/dL, 5 gm/dL, and 10 gm/dL) with the corresponding refractive indices of 1.335, 1.336, 1.337, 1.338, 1.341, and 1.347, respectively, have been used as a bio-sample that has been put on the top layer of the sensor. An investigation was conducted to improve the performance parameters of the proposed plasmonic biosensor by layering different 2-D nanomaterials (graphene, BP) and TMDC materials (MoS2, MoSe2, WS2, and WSe2) over the silicon (Si) layer in both structures at a visible wavelength of 633 nm, using Transfer Matrix Method (TMM). With layer thickness optimization, Structure-I (BK7/Ag (56 nm/Si (3 nm)/WS2 (.8 nm)/Bio-sample) shows a sensitivity of 200 °/RIU which is enhanced up to 1.7 times that of the conventional biosensor (BK7/Ag/Bio-sample) and 1.3 times that of the BK7/Ag (56 nm)/Si (3 nm)/Bio-sample based biosensor. Whereas in Structure-II (BK7/Au (50 nm)/Si (3 nm)/BP (.53 nm)/Bio-sample) with optimised layer thickness, we obtained a sensitivity of 273.4°/RIU, which is enhanced up to 2.2 times that of the conventional biosensor (BK7/Au/Bio-sample) and 1.3 times that of the BK7/Au (50 nm)/Si (3 nm)/Bio-sample. Other performance parameters such as detection accuracy for Structure-I and Structure-II are .5617 degree−1 and .134 degree−1 respectively. The Figure of merit for Structure-I and Structure-II are 112.35/RIU and 36.89/RIU respectively. Therefore, we expect Structure-I (BK7/Ag (56 nm/Si (3 nm)/WS2 (.8 nm)/Bio-sample) and Structure-II (BK7/Au (50 nm)/Si (3 nm)/BP (.53 nm)/Bio-sample) have the potential to detect the glucose concentration with quick response and high sensitivity in terms of the resonance angle shift in SPR curves.