Electrochemical Additive Manufacturing Research Articles

A comprehensive study on the jet electrodeposition method for fabricating 3D structures with overhangs

Electrochemical additive manufacturing (ECAM) is gaining increasing attention in the fabrication of micro/nano-scale metal structures due to its advantages, such as high forming accuracy, low porosity, absence of thermal stress, etc. Among various ECAM techniques, interest is increasingly enhanced in jet electrochemical deposition (Jet ECD) approach due to its ultra-high deposition rate. Despite its inherent advantages as a high-efficiency ECAM process, Jet ECD still faces challenges for automated fabrication of complex 3D structures due to suitable control of the jetted flow. In the present study, a step-delay method based on Jet ECD is proposed. This approach allows for the automation of the fabrication process using commonly employed stepper motor translational stages, seamlessly integrating it into the current 3D printing framework. By adjusting the moving time of the stages and the delay time between two successive steps, agreement between the movement of the stages and the temporally nonlinear electrodeposition rate can be achieved. Consequently, complex 3D copper structures with overhangs, such as 3D helical structures, are successfully obtained. It is found the deposition rate can be as high as ∼25 µm/min, and the maximum overhanging angle that can be achieved by the automated step-delay method is ∼60°. The mechanical properties of the deposited copper using the proposed approach have been thoroughly characterized by various techniques. The average grain size of the deposited copper can be as small as 0.5 µm without preferred orientation. It also shows that highly dense structures with porosity of less than 0.1% can be obtained, and the elastic modulus of the deposited copper ranges from 3 - 20 GPa. In future studies, it is anticipated that larger overhanging angles can be achieved by incorporating image recognition techniques in the step-delay method.

High Performance Cooling for Power Electronics Via Electrochemical Additive Manufacturing

High Performance Cooling for Power Electronics Via Electrochemical Additive Manufacturing

Electrochemical Additive Manufacturing of Binary and Ternary Alloys at the Mircon Scale by Electrohydrodynamic Redox 3D Printing

The need for miniaturisation throughout many different industries brings classical subtractive manufacturing techniques to their limits. Additive manufacturing is able to overcome these limits which has made it a topic of interest in many scientific fields. This additional geometric freedom becomes increasingly important if feature sizes on the micron- or even nano-scale are desired. Multiple different techniques to fabricate device-grade metals at such length-scales have been reported [1]. As one of these techniques, electrohydrodynamic redox printing (EHD-RP) has shown promise to be a versatile fabrication tool [2, 3, 4] depositing dense, pure metallic structures at high deposition rates.In this contribution, we present our work on additively manufactured alloys. First, we introduce a novel EHD-RP approach using aqueous metal salt electrolytes instead of sacrificial anodes as ion sources. The use of metal salts not only expands the range of manufacturable metals, but also enables the fabrication of metal alloys with precise compositional control without the need for additives or a surplus of the less noble metal. We demonstrate this control by fabricating binary and ternary Cu-Ag, Cu-Zn and Cu-Ag-Zn alloys. The composition of the fabricated alloy exactly mirrors the composition of the aqueous metal salt solutions. These systems were chosen as a representative immiscible and miscible system, in order to study different growth mechanisms. Microstructural analysis of Cu-Ag alloys reveals the formation of a metastable mixed phase. Cu-Ag alloys were successively dealloyed to produce nano-porous Ag structures. The compositional control over the Cu-Ag alloy enables precise control of porosity in the dealloyed structures. These nano-porous Ag structures have also been tested as substrates for surface enhanced Raman spectroscopy.(1) L. Hirt, A. Reiser, R. Spolenak & T. Zambelli, Adv. Mater 2017, 29, 1604211(2) A. Reiser, M. Lindén, P. Rohner, A. Marchand, H. Galinski, A. S. Sologubenko, J. M. Wheeler, R. Zenobi, D. Poulikakos & R. Spolenak, Nat. Comm. 2019, 10, 1853(3) M. Nydegger, A. Pruška, H. Galinski, R. Zenobi, A. Reiser & R. Spolenak, Nanoscale 2022, 14, 17418(4) M. Menétrey, L. Koch, A. Sologubenko, S. Gerstl, R. Spolenak & A. Reiser, Small 2022, 18, 2205302

Electrochemical Additive Manufacturing of Living Bioelectrodes Having Intimate Electronic Couplings between Exoelectrogens and Electrodes

Engineered living materials (ELMs) combine living organisms with nonliving components to create responsive functions, improving traditional materials and devices. By incorporating electrochemically active microorganisms into a redox‐active matrix, ELMs merge microbial processes with environmental cleaning and sustainable energy on a scalable level. This technology faces challenges in merging the living and nonliving, and ensuring consistent manufacturing. The research introduces highly efficient living bioelectrodes, made using advanced biomanufacturing and a special 3D printing process with a microbe‐infused ink. A custom 3D printer with electropolymerization creates these organic bioelectrodes without templates, marking a significant advancement in ELM technology. The material used, poly(3,4‐ethylenedioxythiophene), is key for electron transfer between the active microorganisms and external systems without harming bacterial function. The ELM structure allows light and gas permeability and maintains thermal gradients, promising major innovations in bioelectronics, bioenergy, and biosensors.

Electrochemical Deposition of Micro- and Nanostructures of Any Shape

Meniscus-confined electrochemical deposition (MCED) is a promising method for the fabrication of micro- and nanostructures with high precision and resolution. The success of MCED depends on the optimization of several parameters, including duty cycle, voltage, frequency, electrolyte concentration, anode movement speed, anode shape, electrolyte circulation, and additives. Porosity, structure, hardness, yield strength, and composition are the critical factors that determine the quality of deposited structures. This article summarizes the effects of various factors on the outcome of the MCED process, which involves controlled deposition of voxels to create an object. Optimizing these parameters can lead to high-quality structures with good resolution and size. The article points out the relationship between these factors and the resulting properties of the deposited object, which may be useful for future research in this area. It also points to different types of approaches for the preparation of these structures through electrochemical additive manufacturing (ECAM) and its detailed mechanism.

Fabrication of Ni-microstructure through electrochemical deposition using 3D printed solution flow type microdroplet cell

Electrochemical 3D printing of electrical conductors with microscale fabrication grasps large capacities for future industrial applications. Low-cost, and eco-friendly electrochemical additive manufacturing techniques for high-speed printing metals are required. In this work, 3D-printed solution-flow type microdroplet cell (SF-MDC) is proposed as a novel electrochemical deposition technique for fabricating of Ni microstructures on the Cu substrate in localized areas. The influence of current density on the morphology and grain size of Ni electrodeposition was studied. The effect of scanning speed on the deposition thickness was also examined. The surface morphology and crystal structures of the deposited Ni layers were analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD) techniques. The results showed that as the current density increased, large nodule grain size microstructures with heterogeneous morphology were obtained. The XRD result showed that the deposited Ni crystal was characterized by face-centered cubic (FCC) structure. A thickness of 93.1 µm, 63.5 µm, and 46.3 µm were printed at scanning speeds of 3 µm s−1, 5 µm s−1, and 10 µm s−1, respectively. Free-standing 3D Ni micro-rods were fabricated on a Cu substrate using SF-MDC.

(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.

How Anionic Dopants Impact the Electrochemical Additive Manufacturing of Polypyrrole

How Anionic Dopants Impact the Electrochemical Additive Manufacturing of Polypyrrole

Patterned polypyrrole for reversible zinc anodes via electrochemical additive manufacturing

This investigation addresses the need for surface modification and stabilization of the Zn anode for Zn-ion batteries. The approach is based on the use of the electrochemical additive manufacturing (ECAM) technique, which offers multiple benefits for the stabilization of metallic Zn. ECAM allows controlled electropolymerization of pyrrole on Zn substrates by a meniscus-guided deposition and facilitates the formation of patterned films. Another key advantage of ECAM is the possibility of binder-free processing. It is found that the porosity of polypyrrole deposits is increased due to the resettlement of the meniscus. The patterned electrode exhibits improved cyclic stability and reduced overpotential for Zn2+ stripping//plating processes compared to pristine Zn. The electrochemical tests demonstrate that α-MnO2//Zn cells exhibit a reversible capacity of 131.9 mAh/g at 2C by the implementation of patterned polypyrrole.

Influence of polarization curve slope on the accuracy of local copper electrodeposition from sulphate electrolyte

Local electrochemical deposition is an emerging technique, used in the field of additive manufacturing. The advantage of electrochemical additive manufacturing lies in the utilization of room temperature electrolyte and permits to manufacture microscale objects with high precision. The increase in deposition current increases the deposition area, so measures are to be taken to focus the electric field. This work describes the influence of polarization curve slope on the accuracy of local deposition, both experimentally and by computer modelling. The copper was deposited using rotating anode on the surface of stainless steel from sulphate electrolyte. The influence of electrolyte composition on the accuracy of deposition was investigated. The profile of deposited parts was analyzed by profilometry and microscopy. The increased amount of sulfuric acid and presence of the additive in the electrolyte was shown to increase the accuracy of deposition by changing the slope of cathodic polarization curve from 320 to 1100 mA V–1cm–2).

Beginner's Guide to Micro- and Nanoscale Electrochemical Additive Manufacturing.

Electrochemical additive manufacturing is an advanced microfabrication technology capable of producing features of almost unlimited geometrical complexity. A unique combination of the capacity to process conductive materials, design freedom, and micro- to nanoscale resolution offered by these electrochemical techniques promises tremendous opportunities for a multitude of future applications spanning microelectronics, sensing, robotics, and energy storage. This review aims to equip readers with the basic principles of electrochemical 3D printing at the small length scale. By describing the basic principles of electrochemical additive manufacturing technology and using the recent advances in the field, this beginner's guide illustrates how controlling the fundamental phenomena that underpin the print process can be used to vary dimensions, morphology, and microstructure of printed structures.

Simulation Study on Microstructure of Magnetic Field Assisted ECAM

Electrochemical additive manufacturing (ECAM) technology is a non-thermal metal additive manufacturing technology that is widely used in microfabrication. The quality of additively manufactured moulded parts can be improved by applying magnetic fields with unknown effects of process parameters on additively manufactured microstructures. Therefore, a multi-physical field coupling model for magnetic field-assisted ECAM was developed. The results show that increasing the applied voltage and magnetic field strength can increase the cathode current density and improve the deposition rate and deposition height, but after the applied voltage increases to 4 V, the ion concentration decreases too fast and the concentration polarization occurs, which affects the deposition rate instead. The ion flux reached the maximum at the magnetic field strength of 0.2T. However, the cathode current density is affected by the electrode gap, and the deposition rate decreases with the increase of the electrode gap, and the deposition rate stabilizes after the electrode gap increases to 50 μm. The increase in current density with increasing electrode size may be related to the applied magnetic field.

Meniscus-confined electrochemical additive manufacturing of copper microstructures: Design, fabrication, characterization, and decorative art technology

For the first time, a room-temperature meniscus-confined electrochemical additive manufacturing (MC-ECAM) process is evaluated as a potential decorative art technology for fabricating copper metal. The MC-ECAM has proven to be an excellent method for large-scale printing of decorative copper artworks such as warli art, plant leaves, and paintings. The inherent nature of the MC-ECAM process has the potential to eliminate the traditional time-consuming route to producing such copper microstructures and provide a one-step and efficient solution. The TEM and FE-SEM results revealed that well-oriented microstructures are prepared without surfactant, indicating the ECAM self-assembly mechanism. A small amount of zinc is added to the copper system to prevent corrosion. The XRD analysis also revealed the formation of copper metal, which barely changed even after 10 months of atmospheric ageing with the addition of 2% zinc. The XPS results show that zinc provides excellent stability for the ECAM-printed copper microstructure, further examined by an electrochemical corrosion study. Zinc act as a barrier to corrosion, and the results show that the Cu-Zn 2% exhibits excellent corrosion resistance than the pure copper microstructures.

Process study of copper preparation by FDM-assisted limited domain electrodeposition

A combination of Fused Deposition Modeling (FDM) and electrochemical deposition was used to prepare copper samples, and the influence of different copper anodes on the composition and microstructure of the prepared samples were investigated. It was shown that under the deposition conditions of constant current, the deposited products were mainly copper with trace impurity elements when brass, leaded brass, phosphor bronze, manganese copper, purple copper, and beryllium copper were used as anodes. The surface morphology of copper films obtained when brass was used as an anode was the flattest, and the thickness was also the largest. Electrodeposition experiments of 20 and 150 layers of copper samples were conducted using brass as the anode and the preliminary validation of FDM-assisted electrochemical additive manufacturing fabricating 3D solids.

Extruded 3D Printing Assisted Electrochemical Additive Manufacturing

This essay investigates an additive manufacturing technique of an extruded 3D printing-assisted electrochemical deposition. The effects of solutions with different additive (Cl− and brightener) concentrations on the surface micromorphology and deposition rate of the formed films were investigated by using characterization data from test tools such as an electrochemical workstation, X-ray diffractometer, and scanning electron microscope, as well as discussing the laws of interaction between these two additives during the electrodeposition process. The experimental results show that when the concentration of Cl− in the copper plating solution is 2×10−3 mol/L and the brightener concentration is 10 ml/L, the electrodeposition experiments yielded deposited copper films with a significantly preferred orientation on the (111) crystal plane, and the prepared copper film has thicker deposited film and better surface quality. To validate the additive manufacturing method for extruded 3D printing-assisted electrochemical deposition, deposition experiments of 25-layer copper samples were carried out utilizing the best process parameters.

A novel mask electrochemical additive and subtractive combined manufacturing technique for microstructures with high machining performance

In this paper, a novel mask electrochemical additive and subtractive combined manufacturing technique was proposed. This is a machining method at the atomic level, and it can be used to produce metal microstructures with high-profile accuracy and low surface roughness. Due to the accumulation of electric field lines during mask electrochemical deposition, the height of the edges of the microcolumns is usually twice or more than the height of the central position in the deposition plane. A combined machining method based on the electric-field constraint of the mask is thus proposed to improve the accuracy of the profile and its surface roughness. The feasibility of the proposed method was verified by both simulations and experiments. The height difference between the column center and the surrounding layer on the surface of nickel microcolumns was reduced from 13 to 2 µm, and the roughness of the tops of the microcolumns was also improved. Experiments to examine electrolysis leveling were carried out to verify the correctness of the results of the simulations and theoretical calculations. Finally, the parameters were optimized using orthogonal experiments, and an array of nickel microcolumns with a diameter of 200 µm and a height of nearly 50 µm was obtained using these optimal parameters. The profile accuracy and surface roughness of the high-precision microcolumn array were improved by using the mask electrochemical additive and subtractive combined machining technique, and a high-precision microcolumn array structure was manufactured.

Electrochemical additive manufacturing (ECAM): A new approach to fabricate metal nanostructures

Nanoscale printing is growing rapidly as a feasible fabrication method for a wide range of applications, including electronics and nanooptics, sensors, nanorobots, and energy storage. In today’s cutting-edge technologies, the constantly reducing dimension necessitates the production of complex conductive structures with nanometre resolution., ECAM methods can produce impurity-free metallic conductors with excellent electrical and mechanical properties; however, the true nanoscale resolution remains very challenging. Here, silver nanostructures are synthesized by an ECAM process and investigated as a substrate for surface-enhanced Raman scattering (SERS) detection of aspirin. Various characterizations such as XRD, TEM, HR-TEM, FE-SEM, EDX-mapping, optical, ultraviolet–visible, and Raman spectroscopy are used to analyse ECAM-printed nanostructured silver substrates. A remarkable enhancement factor of ∼ 107 is realized in the silver nanostructured substrates with the detected limit of 10-8 mol. ECAM printed silver nanostructured substrates can thus be used as viable substrates for SERS applications.

Parametric analysis to enhance the printability in metal with electrochemical additive manufacturing

• Development of in-house Electrochemical Additive Manufacturing (ECAM) setup. • Parametric study to assess printability of pure Cu metal on Ni-metallic sheets. • Rectangular and convex profiles formed on Ni-sheets at different nozzle diameters. • The average profile height varied between 2.56 µm and 30.46 µm. • The adhesion strength of the printed part was limited to a maximum force of 9 N. The work presents the parametric study to assess the printability of pure metal on Ni-sheets using Electrochemical Additive Manufacturing (ECAM) process. Layer-by-layer linear profiles are printed using an in-house developed ECAM setup. The effect of printing parameters, i.e., nozzle orifice diameter (d n ), printing time (t n ), and traverse speed of nozzle (s n ) on the profile dimensions (width and height), is studied. Results indicate the stability of features as nozzle size varies from higher to lower dimension, allowing easy formation of minuscule at its tip. The average profile width varied between 195.8 µm and 2401.4 µm, and profile height between 2.56 µm and 30.46 µm.

Localization of jet electrochemical additive manufacturing with a liquid confinement technique

Electrochemical additive manufacturing (ECAM) is a flexible additive manufacturing method to deposit metallic/metallic-alloys microstructures without any thermally induced residual stresses. The conventional ECAM process suffers from stray deposition leading to reduced dimensional accuracy. Therefore, this paper proposes a novel liquid confinement technique to improve the deposition localization in Jet-ECAM process. Dichloromethane was employed as a second liquid phase to confine and control the flow field distribution of electrolyte as well as localize electric field on the substrate. Thus, the stray deposition induced by spreading electrolyte and hence spreading electric field could be avoided, and the deposition localization was improved. Liquid-liquid two-phase flow model was developed to analyze the flow field characteristic of two-phase flow formed by electrolyte and dichloromethane. Both simulation and observation results indicated that the flow region of the electrolyte on the substrate was well confined by the dichloromethane. The experimental results showed that the deposition localization was improved about 43.84 % compared to that in traditional Jet-ECAM. The inter-electrode gap (IEG) had a significant effect on both electrolyte flow region and current density distribution on the substrate, which affected deposition quality. Additionally, high current density leads to coarsened grains and reduces the deposition quality. Moreover, increasing the reciprocating speed of nozzle could refine the grains of microstructure, but the deposition efficiency was reduced. By employing process parameters of IEG of 100 μm, electric current of 0.0015 A, and the reciprocating speed of 300 μm/s, micro-patterns including both lines and curves were well deposited with a width of 500 μm, height of 60 μm, and a radius of 2 mm (letters G and U) and 2.5 mm (letter D).

Hybrid electrochemical additive and subtractive manufacturing (HEASM) based on simultaneous mask electrochemical deposition and dissolution

This paper proposed a method for hybrid electrochemical additive and subtractive manufacturing (HEASM) to fabricate microstructures with high-dimensional accuracy and good surface quality. Electrochemical additive manufacturing is achieved by applying positive pulses between the electrodes and then negative pulses are subsequently applied to achieve electrochemical finishing of the shape and surface. In this study, the formation of irregular surface defects was investigated, and a verification experiment was carried out. The inter-electrode pulse waveform and machining process were observed to characterize the electrochemical deposition and dissolution machining. The effects of pure electrodeposition, HEASM, and excessive electrolysis on the surface morphology were compared experimentally. The results indicate that HEASM can reduce the surface roughness by 45.5% but excessive electrolysis can cause a collapse of edge regions. Finally, Taguchi optimization experiments were carried out, and an optimized parameter combination for HEASM was obtained. A microstructure manufactured with an optimized pulse number ratio 0.6 × 10−2, peak current ratio 0.5, and pulse width ratio 1.0 had the best surface morphology and dimensional accuracy. And its surface roughness and height were 0.343 μm and 33.563 μm, respectively.