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Electromagnetic interference (EMI) poses significant challenges to modern electronic systems and devices, garnering increasing attention as technology advances. EMI shielding methods have emerged as a crucial solution to mitigate the associated problems. The primary objective of shielding is to deflect or absorb electromagnetic waves emitted from a source. Traditionally, metals have been used for shielding materials due to their excellent conductivity. However, the high weight and cost of metals have spurred research into alternative materials. Carbon fiber materials have gained prominence in recent years due to their exceptional mechanical and electrical properties. These materials find diverse applications across industries, including defense, automotive, aviation and space. One approach to enhance the conductivity of carbon fibers is the application of metallic coatings. This study investigates the electromagnetic shielding properties of nickel-coated and uncoated polyacrylonitrile-based (PAN-based) carbon fiber fabrics at the frequency ranges of "300–1500 MHz," "2170–3300 MHz" and "3300–4900 MHz" offering valuable insights into their applications. Additionally, microstructure analysis and energy-dispersive X-ray spectroscopy (EDS) were conducted. The results demonstrated that nickel coating significantly improves EMI shielding effectiveness within the specified frequency ranges. Notably, the Ni-electroplated sample, treated at a current density of 8.7 A/dm2 for 30 min, exhibited the highest shielding effectiveness at "300–1500 MHz." Moreover, the most noteworthy performance was observed in electroless nickel-coated carbon and nickel-electroplated (at a current density of 7.3 A/dm2 for 45 min) fiber specimens within the "2170–3300 MHz" and "3300–4900 MHz" frequency ranges. Absorption and reflection values were calculated to clarify the underlying mechanisms governing EMI shielding behavior. The findings reveal that absorption mechanisms predominantly contribute to the observed EMI shielding behavior. [ABSTRACT FROM AUTHOR]

Electroplating nickel-63, a radioactive isotope used in betavoltaic batteries and random number generators, requires precise control due to its limited availability and the generation of radioactive waste. To minimize waste and ensure effective plating, small plating baths are employed, optimizing the process within constrained conditions. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were utilized to determine the optimal plating conditions and limiting conditions for nickel electroplating in a small plating bath. This study focuses on the use of low-concentration nickel solutions and small plating equipment, in contrast to the common industrial practice of using high concentrations of nickel. Here, it is important to optimize the plating parameters, especially the nickel concentration, current density, and bath temperature. An average thickness of 1.8 μm was found when plating with a nickel concentration of 0.06 M, a current density of 5 mA/cm2, and a solution temperature of 40 °C, while ideal conditions were found to achieve the theoretical maximum energy and 90% release rate when plating with nickel-63 instead of Ni. [ABSTRACT FROM AUTHOR]

In this paper, we present a rapid and straightforward method for producing graphene material in the liquid phase using a high-power-density ultrasonication technique. The graphene exfoliation process was considered with varying ultrasonication times, ranging from 1 to 5 h. The obtained results indicated that graphene nanoflakes, exfoliated under a power density of 1600 W/L for a short duration (5 h), exhibited a thickness of fewer than 10 layers, with an average flake size of ~ 300 nm. The production yield measured 30.6 mg h−1, and the dispersed concentration reached 0.459 mg ml−1. Furthermore, the exfoliated graphene nanoflakes displayed remarkable stability, as evidenced by a zeta potential value exceeding 30 mV. The resulting graphene material was used directly as a reinforcing element in nickel electroplating without the need for any additional surface modification steps. The results demonstrated a significant 53% increase in microhardness compared to the nickel coating. Structural characterizations of the few-layers graphene and nanocomposite coatings were elaborately investigated and presented. [ABSTRACT FROM AUTHOR]

To ensure the quality and performance of arc-sprayed coatings and reduce the cost of metal wires, Zn-Al alloy wires were electroplated successively with a copper strike and a nickel layer of different thicknesses, and then used to form Zn-Al-Ni-Cu composite coatings on the surface of Q235 steel by arc spraying technology. The properties of the Zn-Al-Ni-Cu composite coatings were compared with those arc-sprayed with the conventional Zn85Al15 and Ni95Al5 wires. The microstructures of the electroplated wires, as well as the phase constitutions, element compositions, and surface morphologies of the arc-sprayed coatings were characterized by X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and scanning electron microscopy (SEM). The results showed that the electroplated coatings had strong adhesion on the alloy wire, and no obvious holes were observed at the coating/substrate interface. The coating prepared with a nickel-coated ZnAl wire is mainly composed of Zn phase, Al phase, and their compounds. The X-ray diffraction peaks of Zn-Al compounds in Zn-Al-Ni-Cu composite coatings were enhanced as compared with those in the ZnAl coating. The friction and wear behavior, electrochemical properties, and neutral salt spray resistance of the coatings were studied. As compared with NiAl and ZnAl coatings, Zn-Al-Ni-Cu composite coatings had a lower friction factor and better resistance to seawater and salt spray corrosion. [ABSTRACT FROM AUTHOR]

The scope of this study is to estimate the composition of the nickel electrodeposition bath using artificial intelligence method and optimize the organic additives in the electroplating bath via NSGA-II (Non-dominated Sorting Genetic Algorithm) optimization algorithm. Mask RCNN algorithm was used to classify the coated hull-cell panels based on their appearance. The coated plate was divided into 5 classes as "Full Bright", "Full Fail", "HCD Fail", "LCD Fail" and "Metallic impurity". The intersection over union (IoU) values of the Mask RCNN model was ascertained between 89 and 98%. Machine learning (ML) algorithms, MLP, SVR, XGBoost, GP and RF, were trained using the images classified by the Mask RCNN. The additives in the electrodeposition bath and operating parameters were specified as an input and the classes of the coated panels as an output in the ML study. Among the trained models, RF model imparted the highest F1 scores for all classes. The F1 scores of RF model for" Full Bright", "Full Fail", "HCD Fail", "LCD Fail" and "Metallic impurity" are 0.99, 1.00, 1.00, 1.00 and 0.94 respectively. NSGA-II genetic algorithm was employed to optimize the content of the bath. The trained RF model was defined as the objective function in the optimization process. The organic additives and operating parameters for full bright coating surface were optimized and the direction and importance of features (factors) impacting the output were delineated. [ABSTRACT FROM AUTHOR]

Copyright of Electroplating & Finishing is the property of Electroplating & Finishing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electroplating & Finishing is the property of Electroplating & Finishing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electroplating & Finishing is the property of Electroplating & Finishing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electroplating & Finishing is the property of Electroplating & Finishing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To solve the problems appearing in electroplating of grooved needle, such as the nonuniform distribution of coating thickness at the groove and the burning defect of coating at the hook, the process of electroplating on grooved needle was simulated numerically by COMSOL, a finite element software. The variations in distribution of coating thickness and power line on the surfaces of groove and hook caused by addition of a shielding plate and a dummy bar to the jig as well as their different positions were discussed. The simulation results showed that the coating on the surface of grooved needle was the most uniform when the spacing of grooved needle to shielding plate and dummy bar was 2 mm and 8 mm, respectively. The nickel coating electroplated experimentally under the above conditions was bright without burning defect at the hook. The thickness of coating electrodeposited experimentally at the groove was consistent with that simulated numerically, indicating that the simulation model was reliable. [ABSTRACT FROM AUTHOR]

Nickel electroplating was conducted on the surface of copper heat exchanger from a bath containing nickel sulfate hexahydrate 200 g/L, boric acid 40 g/L, saccharin 3 g/L, and sodium dodecyl sulfate 0.1 g/L at pH 4-5, temperature (60 ± 5) °, and current density 1.5 A/dm2 for 20-50 min. The nickel coating electroplated for 50 min was bright and silvery white, had a thickness of 9.30 μm and a microhardness of 149 HV, and showed good adhesion and high-temperature oxidation resistance. [ABSTRACT FROM AUTHOR]

Copyright of Electroplating & Finishing is the property of Electroplating & Finishing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electroplating & Finishing is the property of Electroplating & Finishing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Corrosion mostly occurs on carbon steel which is applied for automotive components and household needs. This natural phenomenon is impossible to be avoided. However, it can be set by escalating its corrosion initiation time. Electroplating is a method that can be used to give protection to slower the corrosion initiation time by forming a layer on the specimen surface, additionally, this method is simple and low cost. One of the most commonly used metals for electroplating is nickel, nickel electroplating is suitable for automotive component coating. For these reasons, this study is focused on analyzing the effect of current and coating time on the layer thickness and corrosion rate of AISI 1045 carbon steel with nickel electroplating. The current variations used were 0.5; 1.0; and 1.5 A and the coating time variations were 5, 10, and 15 minutes. AISI 1045 was used as the cathode, nickel was as the anode, and nickel chloride was the electrolyte solution. The specimen with a current of 1.5 A and a coating time of 15 minutes shows the thickest coating and the lowest corrosion rate, with values of 0.0205 mm and 0.94 mpy, respectively. This study indicates that the increase of the current and coating time enhances the layer thickness and declines the corrosion rate.

A nickel electrode was obtained by electroplating nickel on pure copper in a bath (pH = 3.8) comprising NiCl2·6H2O 10 g/L, NH4Cl 30 g/L, and Ni(NH2SO3)2·4H2O (nickel sulfamate) 310-390 g/L at temperature 35 °C and current density 3 A/dm² for 30 minutes. The effect of mass concentration of nickel sulfamate on surface morphology of the nickel coating and its catalytic activity for hydrogen evolution reaction was studied. The results showed that the nickel coating electroplated with nickel sulfamate 350 g/L was the finest and most compact with the best catalytic activity and stability in hydrogen evolution reaction. [ABSTRACT FROM AUTHOR]

Copyright of Electroplating & Finishing is the property of Electroplating & Finishing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electroplating & Finishing is the property of Electroplating & Finishing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The authors have studied water-repellency technology using a roughness structure fabricated by electroplating. This paper examined the relationship between surface morphology and water-repellency of two-layered nickel structures obtained by changing the electroplating parameters using a simple nickel chloride-based electroplating bath. As a result, it was confirmed that the surface morphology of the deposit could be transformed by electroplating the second layer at a bath temperature different from that of the first layer. The contact angle in two-layered roughness plating also tended to be higher under conditions of greater Sdq value (root mean square slope). In particular, both the Sdq value and contact angle were high for the second-layer deposited at a bath temperature of 80°C and applied electrical-quantity of 1500 C dm−2 or more. In this study, a relatively high relationship between Sdq value and contact angle was observed, and it was found that changing each layer's electroplating conditions can control the water-repellency. [ABSTRACT FROM AUTHOR]

The surface of rolled copper foil was blackened by electroplating in a cyanide-free bath comprising nickel sulfate 40-60 g/L, sodium citrate 20-30 g/L, boric acid 30-50 g/L, ammonium sulfate 5-15 g/L, and surface active additive 5-15 g/L. It was found from the surface and cross-sectional morphologies of the nickel coating by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) that the grain spacing and grain height have a decisive influence on the color of the nickel coating. When the grain spacing exceeds 0.7 µm and the grain height exceeds 0.8 µm, the nickel coating will turn black. The energy-dispersive spectroscopic (EDS) analysis confirmed that the surface of the blackened nickel coating do not contain any sulfides, indicating that the blackening of nickel coating was not induced by substances, but due to the formation of a "light trap" structure. [ABSTRACT FROM AUTHOR]

The effect of a composite buffer comprising boric acid and sodium citrate for nickel electroplating of diamonds on the stability of electroplating bath, as well as the adhesion and composition of nickel coating was discussed. The results showed that the performance of the composite buffer in stabilization of bath pH and boric acid concentration was better than that of boric acid alone. Nickel coatings with improved adhesion and reduced inclusion of boron could be obtained by using the composite buffer. [ABSTRACT FROM AUTHOR]

Different concentrations of Citrus aurantium with deoxyribonucleic acid as additive (Citrus aurantiumDNA) were co-deposited with nickel via electrodeposition. The coatings were formed in an aqueous nickel bath with the incorporation of Citrus aurantiumDNA concentrations at different temperatures, and the influence of the acid and the temperature on the microstructure of the coatings was studied. The data via adsorption isotherms were also analyzed. The characteristics of the morphological structure of the coatings were examined by scanning electron microscopy. The results demonstrated that Citrus aurantiumDNA additives were evenly dispersed on the mild steel surface during the nickel coatings deposition; a current density of 1.5 A/dm3 used during the electrolysis process was favourable in attaining the maximum coating efficiency (~70%) at 25°C and 20 mg/L of Citrus aurantiumDNA. The optimum temperature for electroplating was found to be 25°C. The data spawned from the adsorption Freundlich and Langmuir isotherms showed two preferred temperatures: i.e. 25 and 40°C via the former and 55 and 70°C via the latter. The thermodynamic assessment confirms that the adsorption mechanism of the Citrus aurantiumDNA additive in a Ni electrolyte solution on mild steel in an HCl solution is physisorption at the investigated temperatures. X-ray diffraction revealed some broad peaks signifying an amorphous structure at all Citrus aurantiumDNA concentrations. [ABSTRACT FROM AUTHOR]

• A new route of purification/revalorization of Ni electroplating wastewaters is proposed. • The novel chemical treatment of wastewaters is achieved with potassium polytitanate. • The operational parameters were identified for a range of wastewaters. • The resulting solids show photocatalytic properties in the visible range of solar light. A new route of purification/revalorization of nickel electroplating wastewaters is proposed. It is shown that chemical treatment of different nickel-electroplating wastewaters with aqueous dispersion of layered structure amorphous potassium polytitanate (PPT) successfully removed the nickel from the effluents. Moreover, the resulting solid products, obtained with optimal PPT doses, showed excellent and consistent photocatalytic properties in the visible range of solar radiation, which are independent on the characteristics of the wastewater i.e. pH, nickel contents or the presence of other heavy metals. On the other hand, after proper dilution, the resulting treated effluents can be returned to the municipal wastewater collectors. The mechanisms of the processes taking place during the treatment are analyzed. [ABSTRACT FROM AUTHOR]

Composite nickel coatings on a brass substrate were produced from suspensions consisted of a conventional nickel sulphate bath and fine TiO2 particles (dp < 0.35 μm). Characterization of coatings surface was performed by using optical and SEM micrographs, by EDS analysis and by determining the surface roughness parameters. Metallographic analysis has also been done in order to get an insight about particles distribution throughout the thickness of the coating layer. Presence of TiO2 particles in electrodeposited metal affected the surface morphology. Particles were embedded as smaller or bigger agglomerates within the coatings, as well as the individual particles. Metallographic analysis showed uniform distribution of particles and their agglomerates within the coating. Surface roughness parameters of the composites have had up to 35 times higher values than the ones of the pure nickel coatings. Roughness maxima appeared at the concentration of particles between 10 and 20 g dm-3. Then it drops down and remains constant for concentrations > 40 gdm-3. SEM micrographs showed irregularities like single-nodule, or beads of nodules on the surface. Relationship between surface roughness and current density has not been noted. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. OI 172060]

In this work, defect-free and high mechanical strength nickel films are deposited at a high growth rate using a high concentration sulfamate bath for applications in fabrication of MEMS components. Effects of the applied current density on the morphology, average grain size, Vickers hardness, micro-mechanical property, and thickness distribution are studied. The average grain size is refined to a minimum value when the current density is increased from 10 to 20 mA/cm2. The finest grain size obtained is 349.8 nm. The grain refinement effect is a result of the promoted nucleation rate as the applied current density increased. When the current density is beyond 20 mA/cm2, overpotential of the nickel reduction reaction is lowered because of the promoted hydrogen evolution and causes coarsening of the average grain size. The film electroplated at 20 mA/cm2 shows a high growth rate at 0.296 μm/min, the highest Vickers hardness at 371 HV, and the yield stress evaluated by micro-compression test is 1.3 GPa. Relationship between the average grain size and the applied current density follows the Hall-Petch relationship well. Unlabelled Image • Defect-free Ni films were electroplated at a high growth rate using sulfamate bath. • The finest grain size at 349.8 nm was obtained when 20 mA/cm2 was used. • Ni with the finest grain size had hardness of 371 HV and yield stress of 860 MPa. • Grain size and strengths of the films followed the Hall-Petch relationship well. • Films plated at 10 & 20 mA/cm2 had uniform thickness distribution on the substrate. [ABSTRACT FROM AUTHOR]

Post supercritical (PSC) carbon dioxide electroplating process uses the fully mixed electrolyte with CO 2 in supercritical state and then performs conventional electroplating at atmospheric pressure. The oversaturated electrolyte provides the regenerated CO 2 micro bubbles and similar improvement on the prepared coating as in the supercritical electroplating is obtained. However, after being exposed to atmosphere, the electrolyte diminishes gradually the influence of oversaturated CO 2 . In this study, monoethanolamine (MEA) was used as an additive for a Watts bath prepared for the PSC CO 2 electroplating. MEA had been employed in CO 2 capture for reducing carbon emission from power plants. The adoption of MEA in the electrolyte was intended to control the CO 2 regeneration from the post supercritical mixing and, subsequently, to assist the electroplating. The experimental results showed that the nickel coating prepared by adding 5 mL/L MEA in the electrolyte increased its hardness and corrosion potential both for conventional and PSC electroplating. Cross-sectional TEM micrograph revealed the columnar grain growth in the prepared nickel coating. Adding MEA in the electrolyte provided the PSC electroplated nickel coating with the emergence of crystalline defects such as dislocation and twin along with nano-grains. Therefore, the coating's hardness increased accordingly. Moreover, the collateral increase in internal tensile stress due to these defects produced cracking in the coating. More cracking and higher surface roughness of the coating should be responsible for the larger corrosion current measured in the polarization curves. [ABSTRACT FROM AUTHOR]

Anodizing is a widely used method for increasing the wear and corrosion resistance of aluminum alloys. However, it is known that the porous brittle alumina layer can easily crack during tribological stresses, which results in the detachment of large particles from the worn surface. Electroplating, on the other hand, can produce a compact ductile metallic coating with enough wear resistance, though a specific pretreatment like the zincate process is needed for an aluminum substrate. In this paper, a combination of the two methods, anodizing and electroplating, is applied on the surface of pure aluminum intending to improve the wear resistance. Anodizing was performed in oxalic acid by applying a constant current density of 2 A/dm2. The anodized samples were then immersed in phosphoric acid for up to 10 h to increase the diameter of the pores. Nickel electroplating was carried out on the anodized samples at a current density of 0.5 A/dm2 in a Watts solution. Cross-sectional studies show that there is an optimum pore widening time that establishes a good adhesion between nickel and anodic oxide layers, while the structure of the oxide film is largely preserved. Sliding wear tests were performed on the samples using a ball-on-disk reciprocating tribometer. The results show much higher wear life for all Ni/Al 2 O 3 composite coatings as compared with the alumina layer. The maximum wear life was obtained for the sample etched for an optimum pore widening time of 4 h. • Nickel was electrodeposited on the surface of the anodized aluminum samples. • The coefficient of friction trend was analyzed through wear surface and subsurface studies. • Nickel plating largely improves the wear life of the anodized aluminum. • The coefficient of friction was reduced once the coatings were tribologically damaged. • Alumina and nickel fragments and the aluminum substrate were mechanically mixed to form an MML. [ABSTRACT FROM AUTHOR]

As an example of the applicable process chain, a concave grating (1175 grooves/mm) with an active area of approx. 24 mm to 24 mm has been replicated by means of electroplating and further by injection moulding with polycarbonate, resulting in a surface accuracy even below 4 µm peak-to-valley (PV). The obtained moulds were further metallised with bare aluminium to obtain components for optical applications. To our knowledge, this is the first time that such a large nanostructured nonplanar surface has been manufactured by injection moulding in such an accuracy.

Composite nickel coatings on a brass substrate were produced from suspensions consisted of a conventional nickel sulphate bath and fine TiO2 particles (dp < 0.35 μm). Characterization of coatings surface was performed by using optical and SEM micrographs, by EDS analysis and by determining the surface roughness parameters. Metallographic analysis has also been done in order to get an insight about particles distribution throughout the thickness of the coating layer. Presence of TiO2 particles in electrodeposited metal affected the surface morphology. Particles were embedded as smaller or bigger agglomerates within the coatings, as well as the individual particles. Metallographic analysis showed uniform distribution of particles and their agglomerates within the coating. Surface roughness parameters of the composites have had up to 35 times higher values than the ones of the pure nickel coatings. Roughness maxima appeared at the concentration of particles between 10 and 20 g dm3. Then it drops down and remains constant for concentrations > 40 gdm3. SEM micrographs showed irregularities like single-nodule, or beads of nodules on the surface. Relationship between surface roughness and current density has not been noted. [ABSTRACT FROM AUTHOR]

This study proposed a low-temperature method to form joints between copper (Cu) and aluminum (Al) by electroplating nickel (Ni) at temperatures below 50 °C. Both the Cu/Ni and Al/Ni interfaces were characterized by transmission electron microscopy (TEM). The Cu/Ni interface was an approximately 60-nm-wide layer of an unlimited substitutional solid solution of Cu and Ni, whereas a 20-nm-wide layer of a BCC-structured AlNi intermetallic compound (IMC) was observed at the Al/Ni interface on the Ni side. The joined samples were heat-treated at 200 °C for durations of 5 h to 1000 h, and the joint strength did not degrade after isothermal aging. No further growth of the intermetallic compound was observed at the Al/Ni interface during the isothermal aging process. [ABSTRACT FROM AUTHOR]

This paper presents the design and a new low-cost process for fabrication of a second-order micromechanical filter using UV-LIGA technology. The micromechanical filter consists of two identical bulk-mode ring resonators, mechanically coupled by a flexural-mode beam. A new lumped modeling approach is presented for the bulk-mode ring resonators and filter. The validity of the analytical derivation is investigated using the finite element method by ANSYS software. The new low-cost fabrication process is used to achieve a high aspect ratio of 16 with 3 μm gap spacing. The rigid graphite serves as a low-cost primary substrate and plating base of nickel as structural material. The fabrication process needs only three UV-lithography steps with Mylar masks to fabricate the main structure and pattern the printed circuit board as a secondary substrate. The frequency response of the fabricated filter is characterized as a function of the DC-bias voltage using a fully differential drive and sense interface circuit. The experimental results demonstrates micromechanical filter with center frequency in the vicinity of 10.31 MHz and percent bandwidth less than 0.3% using a DC-bias voltage of 60 V. The detailed fabrication process can be applied as an appropriate low-cost alternative to X-ray LIGA and silicon-based micromechanical filters.

The design, fabrication, performance simulation and characterization of a piezoelectric zinc oxide (ZnO) nanowire (NW) micro-energy harvester integrated with a microelectromechanical proof-mass/spring system are presented. Low temperature hydrothermal growth of vertically aligned nanowires together with MEMS surface micromachining and UV-LIGA (Lithographie, Galvanoformung, Abformung) processes were utilized to achieve efficient coupling of environmental vibrations to the nano energy harvester. The NWs were connected in series through the membrane/proof-mass structure to achieve higher output voltage. A novel polyimide fill-in and etch-back technique was employed to embed the NW tips into the membrane, such that the NWs were compressed and stretched by the membrane/proof-mass structure in response to the external vibrations. Peak power of 70 pW was observed across an optimal 7 MΩ load when the nano energy harvester was excited with an acceleration of 1.4 g at 40 Hz, corresponding to 22 mW/cm 3 volume-normalized power output. The measured voltage between the top and the bottom electrode was 21.4 mV for this case. The output frequency spectral density with 40 Hz excitation and output voltage with varying excitation frequency are also discussed. [ABSTRACT FROM AUTHOR]

The hierarchical micro/nano structure of a real lotus leaf was successfully transferred to a nickel stamp, and it was used as a nanoimprinting stamp for superhydrophobic surface preparation. The hierarchical micro-bump/nano-tubule structure of the lotus leaf was transformed to a nano-wrinkled micro-bump in order to apply the nanoimprinting process and provide superhydrophobicity. Ag nanoparticles (AgNPs) were uniformly coated over the lotus leaf surface to form an electrically conducting seed layer, followed by a nickel electroplating process. A nickel stamp with a well-defined negative structure of a lotus leaf, including even nano-wrinkled microstructure, was thereby successfully fabricated. The micro/nano pattern of the lotus leaf was successfully reduplicated on a poly vinyl chloride (PVC) film by a nanoimprinting process using the nickel stamp. According to contact angle measurements, the nanoimprinted polymer films are rendered hydrophobic. Superhydrophobicity was then obtained by applying a self-assembled monolayers (SAM) coating over the nanoimprinted polymer film. [ABSTRACT FROM PUBLISHER]