Localized Electrochemical Deposition Research Articles

Machine Learning-Enhanced Fabrication of Three-Dimensional Co-Pt Microstructures via Localized Electrochemical Deposition

This paper presents a novel method for fabricating three-dimensional (3D) microstructures of cobalt–platinum (Co-Pt) permanent magnets using a localized electrochemical deposition (LECD) technique. The method involves the use of an electrolyte and a micro-nozzle to control the deposition process. However, traditional methods face significant challenges in controlling the thickness and uniformity of deposition layers, particularly in the manufacturing of magnetic materials. To address these challenges, this paper proposes a method that integrates machine learning algorithms to optimize the electrochemical deposition parameters, achieving a Co:Pt atomic ratio of 50:50. This optimized ratio is crucial for enhancing the material’s magnetic properties. The Co-Pt microstructures fabricated exhibit high coercivity and remanence magnetization comparable to those of bulk Co-Pt magnets. Our machine learning framework provides a robust approach for optimizing complex material synthesis processes, enhancing control over deposition conditions, and achieving superior material properties. This method opens up new possibilities for the fabrication of 3D microstructures with complex shapes and structures, which could be useful in a variety of applications, including micro-electromechanical systems (MEMSs), micro-robots, and data storage devices.

3D fabrication of complex copper microstructures with path planning by localized electrochemical deposition

3D fabrication of complex copper microstructures with path planning by localized electrochemical deposition

Enhancing microscale additive manufacturing: Electrolyte-column localized electrochemical deposition for microwire and microdevice substrate connection

Electrochemical deposition is a microscale additive manufacturing technology. Due to the excellent performance of electrodeposited coating layers which exhibit no thermal stress, low porosity, and minimal microcracks, electrodeposition has been used in the connections of microdevices to solve the problems of shrinkage and deformation of microparts caused by thermal stress generated by conventional connections. Due to the low efficiency of Meniscus-Confined electrodeposition, a novel connection process for microwires and microdevice substrate using electrolyte-column localized electrochemical deposition (ECL-ECD) is proposed. The connecting mechanism is determined through simulation and experimentation. Simulation results indicated that the current density in the connection area exhibited a Gaussian distribution and the deposition layer preferentially grew at the interface between the microwire and the substrate. A high-speed camera was used to observe the liquid beam throughout the experiment, the results indicated that the microwires didn’t affect the stability of the liquid beam, and the ECL-ECD had excellent domain fixation. Smooth and dense surfaces on the connection area of the microwire and substrate were obtained at a current density of 50–60 A/dm2. Performance testing results showed that the connection point has excellent corrosion resistance and electrical properties. When the deposition time was short, the microwire was detached from the deposition area due to relatively thin deposition layer thickness and the tensile strength was only 133.82 MPa during the tensile testing. When the appropriate deposition process parameters were chosen, the fracture occurred on the microwire under tensile load and the fracture strength was 198.84 MPa, which equals the tensile strength of the microwire and indicated that the connection point can provide sufficient strength. The experimental results demonstrated that ECL-ECD can provide an effective and reliable connection process for the microwires interconnection.

Fabrication of Cu-Ni Alloy Microcomponents using Localized Electrochemical Deposition

With the rapid development of electronics, additive manufacturing of complex three-dimensional microscale metal and alloy structures has emerged as one of the future directions for advanced technologies. In this study, a localized electrochemical deposition technique was developed which enables the fabrication of microscale three-dimensional metal structures in an ambient environment. Notably, we investigated the effects of voltage, initial electrode gap, and electrolyte composition on the deposition of Cu-Ni alloy. Furthermore, we successfully fabricated Cu-Ni equiatomic micro-columns, providing possibilities for the micro/nanoscale fabrication of commercial K-Monel copper. Finally, based on these foundations, we successfully shaped overhanging structures with various angles as well as an “H” structure using a rotating cathode substrate, demonstrating their potential in the fabrication of Cu-Ni alloy micro components.

Microscale Structure Additive Manufacturing Control Method Using Localized Electrochemical Deposition

Micro‐nano scale 3D printing is attracting attention as an alternative manufacturing method for a variety of applications in electronic information, biomedical, and sensing devices. Localized electrochemical deposition (LECD) based on nanopipettes is naturally superior and economical for the manufacturing of high‐freedom, impurity‐free metal conductors. However, flexible printing sacrifices roughness and straightness. Therefore, the present study initially establishes a simulation model for LECD and subsequently analyzes the key factors that influence the quality and stability of the deposited structure. Furthermore, an effective solution is proposed to enhance the surface quality. Second, a constant deposition current control method based on fuzzy proportional–intergral–derivaite (PID) is proposed to effectively suppress the fluctuation and improve the stability and quality of the deposited structure. Finally, compared with the open‐loop control method, the proposed constant current control method can reduce the radial fluctuation of the copper pillar structure by 87%, and effectively improve the surface quality of the structure. The proposed method provides a new idea to carry out LCED‐based 3D printing with high resolution at the micro‐nano scale.

Additive Manufacturing of Multi‐Metal Microstructures by Localized Electrochemical Deposition Under Hydrodynamic Confinement

AbstractThis study presents a device and method for multi‐metal printing of microscale structures. The method is based on combining hydrodynamic confinement of electrolytes with localized electrochemical deposition (HLECD), allowing rapid switching of the deposited metal. The device used in HLECD integrates a micro‐anode on a vertical microfluidic chip containing two open‐ended channels that control the flow of electrolytes surrounding the anode. When placed on top of a conducting surface, a localized electrochemical reaction is initiated, wherein the deposited metal composition is dictated by the electrolyte in the confinement. A range of electrolytes, which are used to deposit copper, tin, silver, and nickel, are used to fabricate multiple structures involving more than 60 material changes within a single printing process. The structures are analyzed using electron microscopy, showing the ability to achieve sharp transitions between pure metals. The constant replenishment of electrolytes also eliminates the problem of ion depletion commonly occurring in localized electrochemical deposition, and enables printing rates that are nearly an order of magnitude greater.

Localized Electrochemical Deposition Using Copper Pyrophosphate-Based Electrolyte

Additive manufacturing (AM) has gained popularity across various industries due to its cost-effectiveness, low material consumption, and minimal environmental impact. Localized electrochemical deposition (LECD), as one of the AM methods, has the capability to produce microcomponents or structures at an microscale in a specific position as designed, without the need for any mask or support material[1]. By reducing copper ions in the local area according to the position of the micro-wire, 3D structures could be produced. This electrochemical deposition process has a significant advantage in that it is a low-temperature process and has lower costs compared to other processes[2].Using the LECD process, the micrometer of copper columns was conventionally deposited in copper sulfate-based electrolyte[3]. However, this electrolyte has the possibility to cause damage to the metal substrate used as the cathode due to its low pH, resulting in metal dissolution. The utilization of copper pyrophosphate-based electrolyte, which is a solution with a pH close to neutral, can solve this problem. Also, copper pyrophosphate-based electrolyte offers an advantage over conventional alkaline-based electrolytes in that it removes cyanide pollution of the environment and hazards to human health.[4]In this study, the microanode was employed using a platinum wire(100 μm in diameter), while a copper substrate was employed as the cathode in the electrochemical deposition process. The micrometer copper columns were deposited using copper pyrophosphate-based electrolyte by varying the main electrochemical deposition factors, such as applied potential and pulse duty cycle. In addition The surface morphology of the deposited micrometer-scale copper columns was observed through scanning electron microscopy.REFERENCES[1] Suryavanshi, Abhijit P., and Min-Feng Yu. "Probe-based electrochemical fabrication of freestanding Cu nanowire array." Applied Physics Letters 88.8 (2006): 083103.[2] Madden, John D., and Ian W. Hunter. "Three-dimensional microfabrication by localized electrochemical deposition." Journal of microelectromechanical systems 5.1 (1996): 24-32.[3] Lin, J. C., et al. "Localized electrochemical deposition of micrometer copper columns by pulse plating." Electrochimica Acta 55.6 (2010): 1888-1894.[4] Chen, C-C. "A New Process for Cyanide-Free Copper Plating."Electroplating and Pollution Control 23.4 (2003): 10-11.

(Invited) An Overview of Electrochemistry Application to Additive Manufacturing

Additive manufacturing (AM) is the process of creating three-dimensional (3D) objects from digital models through the sequential deposition of material in layers. This talk will highlight how researchers have used electrochemical research in additive manufacturing and will provide insights into how technology can be exploited to formulate novel microstructures and optimize the manufacturing process. Electrochemical 3D printing is a relatively new form of AM that creates metallic structures through the electrochemical reduction of metal ions from solutions onto conductive substrates. It involves localized electrochemical deposition of metals combined with additive manufacturing principles to achieve Electrochemical Additive Manufacturing (ECAM). The talk will also focus on the formulation of metal precursor inks to produce novel metallic microstructures and nanoalloys containing multiple metals. These inks are used with AM techniques to fabricate 2D and 3D printed conductive structures directly onto a substrate. Examples include aligned nickel nanowires over large areas, which provide opportunities to produce structures with enhanced anisotropic electrical and magnetic properties. Nanoalloy films printed using metal precursor inks have a variety of important applications involving local control of alloy composition in AM part. Examples include the facile formation of layered nanostructures and electrical conductivity with oxidative stability. The talk will conclude with current research on electropolishing of AM parts. AM while capable of producing complex-shaped metal parts with intricate internal geometries and lattice structures struggles to make parts with the smooth surface finish required for many applications. Polishing interior surfaces inaccessible to traditional surface polishing methods is a challenge. Electropolishing is increasingly being used as a post-treatment option for metal AM parts due to its non-contact nature and ability to finish complex internal features.

High-efficiency localized electrochemical deposition based on ultrafast laser surface modification

Localized electrochemical deposition is a promising technology that allows for additive manufacturing of micro-nano structures in designated areas with high precision and controllability. However, ultra-low printing speed of current localized electrochemical deposition hinders its practical applications, especially the manufacturing of large-scale and complex devices. Here we propose a strategy combining ultrafast laser surface modification with traditional electrochemical deposition to achieve high-efficiency and large-scale printing. With using a focused ultrafast laser, arbitrary large-scale patterned structure can be efficiently scratched on substrate surface. Since the laser scratched region has formed nano-sized surface relief structures which experience local field enhancement when subjected to a voltage, the electrochemical deposition rate in the laser scratched region can be significantly improved, resulting in equivalent localized electrochemical deposition under traditional electrochemical deposition conditions. Such parallel electrochemical deposition can significantly shorten the printing time for large-scale devices. As for the processing of microstructure arrays with a size of 16 mm2, the printing time is compressed within 10 min, among which the electrochemical deposition process is compressed to 10 s. The results demonstrate the potential for improving the efficiency and scalability of localized electrochemical deposition through this combined approach.

Fabrication of n-shaped micro copper structures through localized electrochemical deposition

Localized electrochemical deposition is a cost-effective technique for fabricating 3D microstructures. In this study, to fabricate a complete n-shaped micro copper structure, multi-layer deposition was adopted, and the v-groove was removed by an asymmetric trajectory. Thereafter, the merging mechanism of the n-shaped structure was analyzed using COMSOL simulations. The results demonstrated that multilayer deposition was suitable for connecting the copper column in different directions; the optimized layer was 15 layers with a height of 15 μm. The simulation showed that the v-groove was caused by the speed difference between the column and bumps, and an asymmetric trajectory with a height difference of 55 μm could suppress vertical deposition and remove the v-groove.

Experimental investigation of localized electrochemical deposition-based micro-additive manufacturing process

ABSTRACT Localized Electro-chemical Deposition (LED) is a non-thermal additive manufacturing process for fabricating micron-sized 3D metallic parts. In the present LED study, the process parameters, namely, applied voltage, frequency of current, inter-electrode gap (IEG), and scanning speed, are varied to determine their effect on layer height and width. An Analysis of Variance (ANOVA) study based on the statistical design of experiments (DOE) is conducted to determine the most significant process parameters and their impact on the percentage contribution of output responses. Response Surface Methodology (RSM) is utilized to determine the optimum values of the process parameters while achieving maximum and minimum values of the layer height and width, respectively. A single bead of 5 mm length is deposited over a brass substrate for all experiments during DOE. It is observed that a uniform deposition can be achieved up to a critical voltage of 4 V, and beyond that, the deposited structure becomes nonuniform.

Fabrication of an X-shaped micro-copper structure containing a merging joint based on localized electrochemical deposition

Local electrochemical deposition (LECD) has proved to be an efficient and economical method for fabricating three-dimensional micron structures. Realizing complex structures that join up when deposited using LECD has been complex; therefore, the fabrication of an X-shaped joining structure was investigated in this study. A horizontal trace model was proposed, and the effects of the number of deposition layers and the horizontal sweep width on the merging joint were studied. The horizontal trace model could complete the merging joint. Multiple deposition layers and a large horizontal sweep width could stabilize and better connect the X-shaped structure containing merging joints. The merging mechanism of the X-shaped structure was also investigated using COMSOL. The stable deposition of the joining structure enables the LECD method to have a broader range of applications in micro-nano manufacturing.

The Roles of Microprobe in Localized Electrodeposition: Electrolyte Localized Transport and Force-Displacement Sensitivity.

Facing the rapid development of 6G communication, long-wave infrared metasurface and biomimetic microfluidics, the performance requirements for microsystems based on metal tiny structures are gradually increasing. As one of powerful methods for fabrication metal complex microstructures, localized electrochemical deposition microadditive manufacturing technology can fabricate copper metal micro overhanging structures without masks and supporting materials. In this study, the role of the microprobe cantilever (MC) in localized electrodeposition was studied. The MC can be used for precise deposition with electrolyte localized transport function and high accuracy force-displacement sensitivity. To prove this, the electrolyte flow was simulated when the MC was in bending or normal state. The simulation results can indicate the influence of turbulent flow on the electrolyte flow velocity and the pressure at the end of the pyramid. The results show that the internal flow velocity increased by 8.9% in the bending probe as compared with normal. Besides, this study analyzed the force-potential sensitivity characteristics of the MC. Using the deformation of the MC as an intermediate variable, the model of the probe tip displacement caused by the growth of the deposit and the voltage value displayed by the photodetector was mathematically established. In addition, the deposition of a single voxel was simulated by simulation process with the simulated height of 520 nm for one voxel, and the coincidence of simulation and experimental results was 93.1%. In conclusion, this method provides a new way for localized electrodeposition of complex microstructures.

Effects of applied potential, initial gap, and megasonic vibrations on the localized electrochemical deposition of Ni-Co microcolumns

This study demonstrates the localized electrochemical deposition (LECD) of nickel–cobalt (Ni-Co) alloy microcolumns and investigates the effects of the experimental parameters on the deposition process. The results revealed that the applied potential significantly affected the surface morphology, deposition rate, and compositions of the Ni-Co microcolumns. Although a high potential significantly improved the deposition rate of the microcolumns, the deterioration of the surface morphologies of the microcolumns was observed. The microcolumns were also deposited at different initial gaps, and smoother surface morphologies were achieved with a relatively larger initial gap. The addition of megasonic vibrations was shown to significantly increase the deposition rate, due to the accelerated ion mass transfer and bubble elimination. Furthermore, the compositions of deposited samples confirmed the anomalous co-deposition behavior of Ni-Co alloys. This study lays the experimental groundwork for potential applications such as micro actuators and magnetic helical microrobots.

Joining of carbon nanotube fiber by nickel–copper double-layer metal via two-step meniscus-confined localized electrochemical deposition

Joining of carbon nanotube fiber by nickel–copper double-layer metal via two-step meniscus-confined localized electrochemical deposition

Simulation and Experiment of Localized Electrochemical Deposition with Re‐Entrant Structures by Applying the Tip Effect

Re‐entrant structures on the metallic surface play an essential role in the surface properties of materials. However, low efficiency in the preparation of such structures decreases their presence in different application areas. Herein, a new method of localized electrochemical deposition (LECD) manufacturing of re‐entrant structures by applying the tip effect (TE) is introduced. Thanks to this method, manufacturing complex re‐entrant structures can be realized rapidly and efficiently by a simple process without any external control. First, electrochemical measurement methods are used to analyze the copper electrodeposition mechanism, and then a simulation software is adopted to simulate this method. The simulation results suggest that the deposition velocity of the four edges on the copper microcolumn is faster than that of the other position, which means that applying TE makes it feasible to prepare re‐entrant structures by localized electrodeposition. Moreover, experimental results show that the deposition potential of −0.70 V and the deposition time of 900 s are the optimal parameter combinations to obtain the best re‐entrant structures. In addition, the volumetric deposition rate of a single re‐entrant structure can reach 924.8 μm3 s−1. This method provides an opportunity for large‐area manufacturing of re‐entrant structures and lays the foundation for future applications.

An ultrasensitive bacteria biosensor using “multilayer cake” silver microelectrode based on local high electric field effect

A signal response mechanism of local high electric field effects was designed to detect bacteria using a chemically modified “multilayer cake” micro-nanostructured pillar electrode. Since the silver electrode has a strong specific electrochemical signal response to chloride ions, we choose silver as the electrode material. The microelectrode was prepared by a one-step localized electrochemical deposition method without the use of mold. Then the electrode was successively functionalized with chitosan, catechol, and aptamer. Many nano- and micro-scale protrusion tips on the electrode surface generated a local high electric field and drove the leakage of intracellular chloride ions when bacteria were captured by APT; thus, a reduced signal of the silver electrode related to chloride ions was recorded. A pseudocapacitor structure composed of chitosan, catechol, Ru3+, and Fc was constructed on an electrode surface to further amplify the signal. The electrochemical sensor based on this electrode showed excellent performance for template bacteria Staphylococcus aureus detection in terms of the detection limit (1 CFU mL−1), linear response range (1–105 CFU mL−1), and specificity. This work provides another way to design an electrochemical biosensor using the nanoeffect of the electrode rather than the conventional current response based on the electrical properties of the bacterial surface.

Additive manufacturing of three-dimensional intricate microfeatures by electrolyte-column localized electrochemical deposition

Electrochemical additive manufacturing (ECAM) based on electrochemical deposition (ECD) has been increasingly used, owing to its inspiring capacities of fabricating void-free and crack-free three-dimensional (3D) complex dense nano-and micro-sized metal geometries. In this study, a unique electrolyte-column localized electrochemical deposition (ECL-ECD) was initially proposed to manufacture 3D intricate precision micro-and mesoscale solid objects. In ECL-ECD, a dynamically stable electrolyte column is maintained between the electrolyte nozzle (anode) and cathodic surface, and metal electrodeposition is localized and guided by the electrolyte column, which is moved controllably. Its working mechanisms were determined from simulations and experimental findings, and some intricate structures such as curved columnar structures, U-shaped, Z-shaped, and spiral structures were successfully manufactured via the proposed technique using different path planning and control strategies. It was indicated that ECL-ECD has an excellent capacity in additively manufacturing micrometer-to-millimeter-scale freestanding metal geometries simultaneously with relatively high geometrical accuracy, good surface finish, and material compactness. ECL-ECD, as a novel metal additive manufacturing (AM), is significantly competitive in micro and mesoscale metal manufacturing, filling the gap in mesoscale ECAM technology.

Localized electrodeposition micro additive manufacturing of pure copper microstructures

The fabrication of pure copper microstructures with submicron resolution has found a host of applications, such as 5G communications and highly sensitive detection. The tiny and complex features of these structures can enhance device performance during high-frequency operation. However, manufacturing pure copper microstructures remain challenging. In this paper, we present localized electrochemical deposition micro additive manufacturing (LECD-μAM). This method combines localized electrochemical deposition (LECD) and closed-loop control of atomic force servo technology, which can effectively print helical springs and hollow tubes. We further demonstrate an overall model based on pulsed microfluidics from a hollow cantilever LECD process and closed-loop control of an atomic force servo. The printing state of the micro-helical springs can be assessed by simultaneously detecting the Z-axis displacement and the deflection of the atomic force probe cantilever. The results showed that it took 361 s to print a helical spring with a wire length of 320.11 μm at a deposition rate of 0.887 μm s−1, which can be changed on the fly by simply tuning the extrusion pressure and the applied voltage. Moreover, the in situ nanoindenter was used to measure the compressive mechanical properties of the helical spring. The shear modulus of the helical spring material was about 60.8 GPa, much higher than that of bulk copper (∼44.2 GPa). Additionally, the microscopic morphology and chemical composition of the spring were characterized. These results delineate a new way of fabricating terahertz transmitter components and micro-helical antennas with LECD-μAM technology.

(Electrodeposition Division Research Award Address) Electrodeposition in the Era of Additive Manufacturing

In the era of additive manufacturing (AM), great interest in electrodeposition has evolved, either as a post-printing finishing stage (e.g., on cellular AM’ed structures) or as a standalone three-dimensional (3D) printing technique. Over the years, a variety of electrochemical 2D patterning and 3D printing techniques have been developed, e.g., meniscus-confined electrodeposition (MCED), localized electrochemical deposition (LECD), electrochemical fountain pen nanofabrication (ec-FPN), electrochemical dip-pen nanolithography (E-DPN), electrochemical printing (EcP), electrochemical fabrication (EFAB), and nanotransfer printing (nTP).The MCED process relies on an electrolyte-containing micropipette with a micron/submicron-size orifice. As the micropipette approaches the surface of a conductive substrate, a meniscus (liquid bridge) is established between the dispensing orifice and the substrate’s surface (Fig. 1b). Electrical current (or potential), applied between a small conductive wire inside the pipette and the conductive substrate via the meniscus, causes reduction of the reducible species on the surface confined by the meniscus. The dispensing micronozzle is then withdrawn from the substrate at a speed that should match the deposition rate, allowing continuous fabrication. The size and shape of the meniscus established between the nozzle and the growing feature are determined mainly by the shape and size of the nozzle, its moving speed, the thermodynamic properties of the electrolyte, surface wettability, and the relative humidity.We recently suggested a novel setup and procedure for 3D electrochemical deposition, combining MCED with atomic force microscope (AFM) closed-loop control (see Fig. 1a).1,2 This aforementioned combination allowed us to print freestanding vertical pillars (Fig. 1c) and overhang structures with an overhang angle as high as 80° without the need to use supports (Fig. 1d). A copper-based electrolyte was used for feasibility tests. Fully dense, uniform and exceptionally smooth features were printed (Fig. 1c), with diameters ranging from 1.5 μm down to 250 nm and a high aspect ratio (> 100). The dense deposited copper features had a polycrystalline microstructure, with submicron grain size (see Fig. 1e), and were mechanically rigid and of good electrical conductivity.Other functional metals and alloys that will be printed in the near future in our lab include pure aluminum and cobalt-phosphorous amorphous alloy. To this aim, a recipe for successful electrodeposition of these materials under potentially relevant conditions should first be developed. Here, I will summarize our ongoing work on: (1) electrodeposition of pure and dense nanocrystalline aluminum from room-temperature ionic liquids (RTILs) on copper and nickel substrates; and (2) electrodeposition of exceptionally well adhered CoP coatings on copper.I will also present our novel electrochemical processing of functional core/multi-shell ZnAl/Ni/NiP powders.3,4 This process can be used for processing of functional powders for laser-based additive manufacturing (LAM) with either reduced or increased laser absorbance, but also processing of phase change materials (PCMs) or zinc-based anodes in zinc-air batteries. Figure 1