Thin Copper Layer Research Articles

Tripartite Detection and Sensing of Toxic Heavy Metals Using a Copper-Based Porphyrin Metal-Organic Framework.

The detection of heavy metals in water sources is a critical concern for environmental preservation and public health. However, current electrochemical heavy metal sensors suffer from high sensing limits, cross-sensitivity, and poor selectivity. In this work, we present the possibility of an electrochemical sensor based on a copper (Cu) metal-organic framework for the detection of lead, cadmium, and mercury by replacing Cu metal nodes. The working electrode consists of a ∼5 μm thin layer of copper- tetracarboxyphenylporphyrin (Cu-TCPP) sheets that are adsorbed on a glassy carbon electrode (GCE). Upon interaction with Pb2+, Cd2+, and Hg2+, these ions are adsorbed on and incorporated into the metal nodes of the MOF. The adsorbed metallic species can be oxidized to the ionic form (Pb → Pb2+) electrochemically, which results in an oxidation response and enables the quantitative detection of these metals. The oxidation peak currents follow a (mostly) bimodal linear regression with a sensing range of up to 30 μM dependent on the deposition time and an ultralow limit of detection (LoD) of up to 5 nM. The system displays robust and selective sensing in saturated solutions of counterions and interfering metal ions (low error margins of <10%). This work represents the first report of a Cu-TCPP-modified GCE anode as an effective electrode for the sensitive detection of multiple heavy metals and an in-depth study into the Cu replacement kinetics of the Cu-MOF.

Electro-discharge machining using copper-coated additively-manufactured AlSi10Mg electrodes

Customized fabrication of electrodes for electro-discharge machining (EDM) is considered as a useful emerging application of metal additive manufacturing technologies for building complex shaped tools in a short period of time. This approach of producing electrodes not only effectively addresses the design flexibility and complexity issues of the tools but also enables the use of various materials so as to ingrain the desired properties in them. The current study explores the production of laser powder bed fusion (LPBF) AlSi10Mg tools for machining of titanium alloy. Moreover, it explicitly assesses the machining performance of additively manufactured electrodes when the tools are subjected to a thin layer of copper coating. Three types of acidic baths are used for electroless coating of tools. The machining performance of the tools in terms of material removal rate, tool wear rate, surface crack density, surface roughness, white layer thickness, and microhardness of the white layer is compared for different electroless copper coating processes. It is observed that the coated tools significantly enhance material removal rate; however, uncoated LPBF tools exhibit superior surface morphology and surface roughness.

The antibacterial activity of the copper for Staphylococcus aureus 124 and Pseudomonas aeruginosa 18 depends on its state: metalized, chelated and ionic

The hypothesis that the antibacterial effect of copper depends on its state was tested. It was studied the antibacterial effect of copper applied to the fabric, copper in chelated and free (ionic) forms on the growth intensity of Staphylococcus aureus 124 and Pseudomonas aeruginosa 18 in the in vitro system after a single or “primary” contact. Classical microbiology methods were used. Copper was applied to the fabric by magnetron and arc planar discharge systems, and the culture of microalgae Dunaliella viridis, resistant to the action of high concentrations of copper, was used to obtain copper in chelated form. It was shown that a thin layer of copper (3 μm) applied to the fabric showed pronounced antibacterial activity against Staphylococcus (85 % compared to the antibiotic meropenem) and less pronounced activity against Pseudomonas, which is resistant to meropenem. Copper in ionic form inhibited the growth of Staphylococcus aureus 124 as well as the antibiotic, and also effectively inhibited the growth of Pseudomonas aeruginosa 18 i.e., copper ions did not have species specificity like the antibiotic. Components of Dunaliella viridis microalgae cells had weakly expressed antibacterial effect to these types of bacteria, and supplementary addition of copper sulfate to the biomass of microalgae led to an increase of their antibacterial activity and this is more pronounced for microalgae culture in which the ratio « chelated/ionic » forms of copper is shifted to the ionic form. It was shown that the antibacterial activity of microalgae biomass after the first introduction into the tested bacterial cultures depends on the amount of free or “weakly bound” with cell components copper ions. It is suggested that the antibacterial effect of fabric with a thin layer of copper may be determined by two mechanisms: the action of copper ions and mechano-bactericidal effects, while chelated forms of copper may have a prolonged effect on bacterial cultures.

Self-Organizing Sub-μm Surface Structures Stimulated by Microplasma Generated Reactive Species and Short-Pulsed Laser Irradiation.

Catalysts are critical components for chemical reactions in industrial applications. They are able to optimize selectivity, efficiency, and reaction rates, thus enabling more environmentally friendly processes. This work presents a novel approach to catalyst functionalization for the CO2 reduction reaction by combining the reactive species of an atmospheric pressure plasma jet with the electric fields and energy input of a laser. This leads to both a nanoscale structuring as well as a controllable chemical composition of the surface, which are important parameters for optimizing catalyst performance. The treatment is conducted on thin copper layers deposited by high power pulsed magnetron sputtering on silicon wafers. Because atomic oxygen plays a key role in oxidizing copper, two photon absorption fluorescence is used to investigate the atomic oxygen density in the interaction zone of the COST plasma jet and a copper surface. The used atmospheric pressure plasma jet provides an atomic oxygen density at the surface in a distance of 8 mm to the jet nozzle of approximately or a flux of . Pulsed laser-induced dewetting is used to form nanoparticles from the deposited copper layer to enhance catalytic performance. Varying the layer thickness allows control of the size of the particles. A gas flow directed on the sample during the combined treatment disturbs the particle formation. This can be prevented by increasing the laser energy to compensate for the cooling effect of the gas flow. Investigating the surface using X-ray photoemission spectroscopy reveals that the untreated copper layer surface consists mostly of metallic copper and Cu(I) oxide. Irradiating the sample only with the laser did not change the composition. The combination of plasma and laser treatment is able to produce Cu(II) species such as CuO, whose concentration increases with treatment time. The presented process allows the tuning of the ratio of C2O/CuO, which is an interesting parameter for further studies on copper catalyst performance.

Phosphate and Nitrate Electrochemical Sensor Based on a Bifunctional Boron-Doped Diamond Electrode.

Phosphorus and nitrogen are important elements in both environmental cycles and biological growth, and their imbalance can lead to serious environmental and biological problems. It is important to be able to monitor the concentration of nitrate and phosphate in the water online. In this paper, a bifunctional boron-doped diamond (BDD) electrode with repeatable electrochemical renewal and modification ability has been developed and used as a shared working electrode for the determination of nitrate and phosphate. First, phosphate can be detected directly with a bare BDD electrode. After a thin copper (Cu) layer was electrodeposited on the BDD electrode, nitrate could be determined. The copper layer is then removed under a positive voltage, and the BDD electrode is renewed and can be used again for phosphate detection. This method enables the detection of both phosphate and nitrate while also improving the stability and repeatability through the renewal of the electrode surface. The segmented linear ranges for phosphate were 0.02-0.4 and 0.4-3 mg/L with a detection limit of 0.004 mg/L. The sensor detected nitrate in a wide concentration range, with segmented linear relationships in the ranges of 0.07-3 and 3-100 mg/L, with a detection limit of 0.065 mg/L. The electrochemical sensor based on the BDD electrode has a good reproducibility for phosphate and nitrate detection. The relative standard deviation (RSD) values of the current responses were 2.98, 2.79, 1.66, 1.81, and 1.23%, respectively, for 35 consecutive tests in 0.05, 0.2, 0.5, 1, and 1.5 mg/L phosphate solution. The RSD values of the current responses were 2.00, 0.97, and 1.03%, respectively, for 25 consecutive tests in 5, 7, and 10 mg/L nitrate solution.

Analyzing and mitigating parasitic capacitances in planar transformers for high-frequency operation

Planar magnetic components are compact and less susceptible to skin effect due to their thin copper layers. However, the increase in parasitic capacitance has been a challenge in high-frequency operation of planar transformers (PTs). Parasitic capacitances resonate with inductance and may damage switch devices. Thicker printed circuit board (PCB) and reconfigured windings are suggested in this paper to mitigate the parasitic capacitances. A detailed analysis of the parasitic capacitances is performed with a prototype PT. The resonant frequency increased from 1.27 to 1.63 MHz with a 0.4 mm thicker PCB. The reconfigured PT was 1.38 MHz, 0.3 MHz higher than the original PT.

Quantifying thiolated chemical additives for copper electroplating process

BackgroundCopper foil, a thin layer of high-purity metallic copper, having excellent conductivity, ductility, and corrosion resistance, is extensively applied in various electronic applications. Thiolated (SH-containing) chemical additives (i.e., accelerator and inhibitor) in copper electroplating solution are known to be critical for optimizing the copper foil manufacturing processes. Due to the high ionic strength and acidity of copper electroplating solution, proper and accurate characterization of the thiolated chemical additives is a critical concern. ResultsIn this study, a facile, accurate approach is developed for quantitative characterization of thiolated additives in the copper electroplating solution. Firstly, gold nanoparticles (AuNPs) were employed as an adsorbent for separating the thiolated chemical additives, namely, poly(ethylene glycol) methyl ether thiol (PEG-SH) as inhibitor, and 3-mercaptopropionic acid (MPA) as accelerator from other interfering chemicals present in the copper electroplating solution. Subsequently, quantitative analysis of the AuNPs in the form of thin particle film was performed using attenuated total reflection-Fourier transform infrared spectroscopy. Electrospray-differential mobility analyzer was employed orthogonally for the quantitative analysis of the amount of thiolated additives adsorbed on AuNP. Interestingly, the results indicated that the detection concentration ranges of 5 μM–100 μM for PEG-SH and 10 μM–200 μM for MPA, respectively. SignificanceOverall, this work demonstrates a successful separation and analysis methodology for the thiolated chemical additives in copper electroplating solution which enables the precise control over the copper foil manufacturing process.

Metalized Plastic Current Collectors Incorporated with Halloysite Nanotubes toward Highly Safe Lithium‐Ion Batteries

AbstractMetalized plastic current collectors (MPCCs) have shown potential in improving the energy density and safety of lithium‐ion batteries (LIBs). However, the poor mechanical strength, weak interfacial adhesion force, and surface metal corrosion have impeded the practical application of MPCCs. Here, an innovative engineering of MPCCs is proposed by incorporating halloysite nanotubes (HNTs) as fillers into polyimide (PI) polymer layer, which is further coated with two thin copper (Cu) layers. Because of the strong bonding between HNTs surface and the PI precursor, HNTs improve the mechanical strength of PI‐HNTs composite film, reinforce the interfacial adhesion force between the PI‐HNTs film and the coated Cu layer, and suppress the Cu corrosion by electrolyte. The prepared MPCCs exhibit a low mass density and only account about one‐fifth of the density of commercial Cu CCs. Furthermore, the PI‐HNTs‐Cu composite demonstrates significantly enhanced interfacial adhesion force doubled to 4 N cm−1 along with prolonged stability under electrolyte immersion and electrochemical reaction conditions, and delivers a high fracture strength of 125 MPa. LIBs assembled with MPCCs deliver a twice higher discharge capacity compared to battery with Cu CCs and reach a long‐term cycle capacity retention as high as 92.9% at 0.5 C after 500 cycles.

Bipolar Current Collectors of Cu/polymer/Al Composite for Anode‐Free Batteries

AbstractThe all‐in‐one design of cathode and anode is a promising strategy to improve energy density and assembly efficiency for lithium batteries. However, it is an important prerequisite to combine negative and positive current collectors in a single sheet. Here, an asymmetric structure of bipolar composite current collector (BCCC), thin copper (Cu) and aluminum (Al) metal layers respectively deposited on each side of a thin polyethylene terephthalate (PET) polymer substrate is developed. Unlike conventional metal foils, the electronically insulative polymer blocks electron transfer between the cathode and anode coated on each side of BCCC. Buckling‐based mechanics measurement and molecular simulation are conducted to quantitatively evaluate the interfacial strength of metal/polymer, which is enhanced by introducing an intermediate chromium (Cr) layer. For applications in anode‐free wound batteries, the integrated sheet of separator/cathode/BCCC can simplify the alignment of the electrodes during the winding process. Without special surface and electrolyte optimizations, a higher Coulombic efficiency (99.1%) and larger capacity retention (50.0%) are achieved after 100 cycles in the LiNi0.8Co0.1Mn0.1O2 anode‐free battery than the battery using Cu foils.

CubeSat-Based Observations of Lunar Ice Water Using a 183 GHz Horn Antenna: Design and Optimization

Technological advancements have revolutionized the space industry, facilitating deep space exploration using CubeSats. One objective is to locate potential life-support elements, such as water, on extraterrestrial planets. Water possesses a distinct spectral signature at 183 GHz, useful in remote sensing and environmental monitoring applications. Detecting this signature provides crucial information about water and ice presence and distribution on celestial bodies, aiding future exploration and colonization efforts. Mostly in space remote sensing uses corrugated horn antennae due to high gain and radiation patterns but fabrication of corrugated antenna is very challenging or even impossible in some cases. To ease this challenge, in our research we propose ideas to transform a corrugated horn antenna into a smooth-walled design by using MATLAB Cubic smoothing Splines algorithms. We compare simulation results between smooth-walled and corrugated antennas, and we can see some improvements in insertion losses, Voltage Standing Wave ratio (VSWR), and gain. We also manufactured this 183 GHz antenna using a commercially available 3D printer by utilizing Acrylonitrile Butadiene Styrene (ABS) material. The antenna surface was then coated with a thin layer of copper using conductive paint. In the end, we practically evaluate smooth-walled antenna functionality and compare it with the theriacal results. Validating the antenna’s functionality proposes a cost-effective and accessible production method to be used in a CubeSat engineering model or university students’ project.

Research on the possibility of controlling the growth of thin copper layers deposited by DC magnetron sputtering

This paper addresses the influence of the sputtering time and hence thickness of thin copper (Cu) layers on the grain size, surface morphology and electrical properties. Cu layers 54–853 nm thick were deposited by DC magnetron sputtering at room temperature from a Cu target with a sputtering power of 2.07 W × cm−2 in an argon atmosphere at a pressure of 8 × 10−3 mbar. The structural and electrical properties were determined on the basis of four-contact probe measurements, stylus profilometry, atomic force microscopy (AFM), scanning electron microscopy (SEM) with an X-ray microanalysis (EDS) detector, and X-ray diffraction (XRD). The results of the conducted experiments show that the structure of thin copper layers can significantly change depending on the thickness and deposition process parameters. Three characteristic areas of structural changes and growth of copper crystallites/grains were distinguished. Ra and the RMS roughness linearly increase with increasing film thickness, while the crystallite size significantly changes only for copper films thicker than 600 nm. In addition, the resistivity of the Cu film is reduced to approximately 2 μΩ × cm for films with a thickness on the order of 400 nm, and a further increase in their thickness does not have a significant effect on their resistivity. This paper also determines the bulk resistance for the Cu layers under study and estimates the reflection coefficient at the grain boundaries.

Invited: Investigation of Carbon/Copper Multilayer to Examine the Influence of Copper Coating on the Li-Storage Performance of Carbon

Thin copper and carbon coatings of electrodes of lithium-ion batteries (LIBs) have the potential to improve LIB operation by preserving electrode integrity during cycling, by developing a proper solid-electrolyte interphase (SEI) layer (e.g., by increasing the de-solvation rate), and by enhancing electric conductivity. In the structures, the thin coatings, e.g., copper thin films, must be permeable to Li+ ions in order to facilitate Li+ uptake and Li+ release in the electrochemically active material of coated electrodes beneath. The influences of copper and carbon thin coatings on LIB-electrode performance were investigated in this work by electrochemically cycling a [C(16 nm)/Cu(17 nm)] × 10 multilayer (ML) up to lithium plating. The C/Cu ML was deposited onto a copper current collector using ion beam sputtering. The rate capability and the long-time cycling were compared to the corresponding ones for the cycling of the bare copper substrate and 16 nm and 230 nm carbon single films (without Cu coating). The bare copper electrode does not store Li+ ions, which is as expected because copper is electrochemically inactive with respect to lithiation. The Li+ uptake and Li+ release in thin carbon layers capped by thin copper layers within the C/Cu ML is compared to that of uncapped carbon single thin films. All electrodes exhibited a good rate capability and long-term cycling stability. Under fast cycling, the amount of reversible Li+ uptake and Li+ release was largest for the case of the C/Cu ML, which pointed to the beneficial influence of the capping Cu layers. The higher Li kinetics in the C/Cu ML was confirmed using impedance analysis. The C/Cu ML behaves as a supercapacitor possessing a differential charge plot nearly independent of potential. At lower currents, the specific capacity of the C/Cu ML is only 20% of that of the thin carbon single films, with that of the latter being the same as that of graphite. On the one hand, this evidences a disadvantageous influence of the thin Cu layers, which block the Li+ permeation, that is necessary to reach deeper carbon layers of the C/Cu ML electrode. On the other hand, the differential capacity plots reveal that the carbon material in the interior of the C/Cu ML is electrochemically cycled. Microscopy, Raman scattering, depth profiling with X-ray reflectometry (XRR), and secondary ion mass spectrometry (SIMS) were applied to get deep insights and a comprehensive examination of the contradiction. The XRR examination revealed a non-altered ML after more than 542 electrochemical cycles, after the washing procedure, and even after 15 months of air exposure. This observation suggests that the copper layers block contamination as well as the Li insertion. The analyses of microscopy, Raman, and SIMS affirm the ML intactness but also reveal the participation of some portions of the interior of the C/Cu ML in electrochemical cycling. The low capacity of carbon in the C/Cu ML may stem from the mechanical stress inside the C/Cu ML, which reduces the Li+ uptake and Li+ release.

High Thermal Conductivity of Sandwich-Structured Flexible Thermal Interface Materials.

Thermal interfaces are vital for effective thermal management in modern electronics, especially in the emerging fields of flexible electronics and soft robotics that impose requirements for interface materials to be soft and flexible in addition to having high thermal performance. Here, a novel sandwich-structured thermal interface material (TIM) is developed that simultaneously possesses record-low thermal resistance and high flexibility. Frequency-domain thermoreflectance (FDTR)is employed to investigate the overall thermal performance of the sandwich structure. As the core of this sandwich, a vertically aligned coppernanowire (CuNW) array preserves its high intrinsic thermal conductivity, which is further enhanced by 60% via a thick 3D graphene (3DG) coating. The thin copper layers on the top and bottom play the critical roles in protecting the nanowires during device assembly. Through the bottom-up fabrication process, excellent contacts between the graphene-coated CuNWs and the top/bottom layer are realized, leading to minimal interfacial resistance. In total, the thermal resistance of the sandwich is determined as low as ~0.23mm2 KW-1 . This work investigates a new generation of flexible thermal interface materials with an ultralow thermal resistance, which therefore renders the great promise for advanced thermal management in a wide variety of electronics.

Copper plasmonics with excitons

We investigate the propagation of surface plasmons (SPPs) in a thin layer of copper surrounded by copper oxide Cu$_2$O. It is shown that particularly strong excitons in Cu$_2$O can have considerable impact on plasmon propagation, providing many opportunities for plasmon-exciton and plasmon-plasmon interactions. It is demonstrated that by the use of sufficiently thin metal layer, one can excite the so-called long range plasmons (LRSPPs) which can overcome the inherently high ohmic losses of Cu as compared to usual plasmonic metals such as silver. Analytical results are confirmed by numerical calculations.

New possibilities of using cold kinetic deposition

This work deals with the properties of the protective layer applied to the base material using the cold spray method. Aluminum plate, on which a thin layer of copper was applied, served as the basic material. The samples prepared in this way were subjected to accelerated corrosion tests. Sensors for measuring the acoustic emission signal were attached to the samples. The recording was an acute emission and was taken during the entire period of corrosion. The properties of the deposited layer were also verified using metallography.

A novel lightweight tubular receiver for drone wireless charging system

AbstractIn the research of drone wireless charging, the lightweight design of the wireless charging device has a large impact on the overall performance of the drone. To realize the lightweight, the tubular coil, which caused by high‐frequency excitation to produce skin effect in the conductor becomes a way to optimize the weight of the receiver coil. This paper proposes an aluminum tube with a thin copper layer plated on the surface as a drone receiver coil and landing gear. This solution can not only replace the original bracket but also be lightweight and obtain high coupling coefficient. Experiments show that this novel receiver can receive power up to 30 W at 250 kHz excitation source with 78% average transmission efficiency and has good antimisalignment ability. This new tubular coupler is more suitable for the demand of lightweight wireless charging for drones.

Integrating Structural Colors with Additive Manufacturing Using Atomic Layer Deposition.

We demonstrate tunable structural color patterns that span the visible spectrum using atomic layer deposition (ALD). Asymmetric metal-dielectric-metal structures were sequentially deposited with nickel, zinc oxide, and a thin copper layer to form an optical cavity. The color response was precisely adjusted by tuning the zinc oxide (ZnO) thickness using ALD, which was consistent with model predictions. Owing to the conformal nature of ALD, this allows for uniform and tunable coloration of non-planar three-dimensional (3D) objects, as exemplified by adding color to 3D-printed parts produced by metal additive manufacturing. Proper choice of inorganic layered structures and materials allows the structural color to be stable at elevated temperatures, in contrast to traditional paints. To print multiple colors on a single sample, polymer inhibitors were patterned in a desired geometry using electrohydrodynamic jet (e-jet) printing, followed by area-selective ALD in the unpassivated regions. The ability to achieve 3D color printing, both at the micro- and macroscales, provides a new pathway to tune the optical and aesthetic properties during additive manufacturing.

Dual-functional phase change composite based on copper plated cellulose aerogel

The application of latent heat storage technology, employing phase change materials (PCMs) to realize the storage and release of energy, is hindered by the leakage problem and low thermal conductivity of the PCMs. To synchronously solve these problems, copper plated cellulose aerogel (CPCA) has been prepared by plating lightweight cellulose aerogel with thin copper layer via simple and energy-saving electroless deposition (ELD), which could encapsulate polyethylene glycol (PEG) to form composite PCM. The cellular and porous structure of cellulose scaffold could generate enough capillary force to effectively confine PCMs and provide heat and electricity transfer pathways. Therefore, the composite PCM shows enhanced thermal conductivity (1.03 W m−1 K−1 with 11.1 wt% Cu content), high PCM loading capacity (84.0 wt%) and extraordinary shape-stability. Moreover, the improved electrical conductivity of the composite PCM endows it with intriguing electromagnetic interference (EMI) shielding property (the average total shielding effectiveness is 38.2 dB), suggesting the great potential of this material in heat-harvesting, thermal management and EMI shielding systems.

Towards durable and efficient antenna with SAR reduction analysis for on-body applications

Abstract This paper is focused on providing a viable solution to wearable antenna performance disconcertment caused by the underlying human body. Direct placement of the antenna on the body yields undesired results owing to the frequency detuning effect. The simplest possible way out is to make use of a metallic reflector. Hence, a reflector backed antenna is presented for 5.8 GHz ISM band with total lateral dimensions of 28 × 28 × 13.58 mm3. The reflector makes use of a conformal high dielectric laminate coated with a thin copper layer owing to which the assembled design achieves low SAR (Specific Absorption Rate). The prototype provides excellent results at the cost of some extra volume occupation in an off-body direction. Another AMC (Artificial Magnetic Conductor) backed technique is followed and implemented separately to have the structural compactness lacking in the former case. The antenna at hand is backed by a 2 × 2 array of AMC unit cells. The overall design dimensions are reduced. The reflector backed design achieves 8.2 dB gain, above 90% efficiency, and 99% bandwidth overlap with the primary antenna. The AMC backed design provides good spectrum coverage from 5.73 to 5.94 GHz with high gain. Free space response, on-body performance, and investigation of SAR analysis of the proposed designs substantiate effective wireless data transfer in body-centric communication.

Research on the Possibility of Controlling the Growth of Thin Copper Layers Deposited by Magnetron Sputtering

Research on the Possibility of Controlling the Growth of Thin Copper Layers Deposited by Magnetron Sputtering