Method and system for multi-material 3D printing

Abstract

A manufacturing system is configured to control a 3D printing process and a selective metallization process of a part, the part being on the build platform during the 3D printing process and selective metallization process, thereby enabling fabrication of non-metal / metal hybrid structures. A computer-controlled method of manufacturing includes performing a 3D printing process and a selective metallization process, in which a part is 3D printed by the 3D printing process and one or more selected areas of the part are electroplated by the selective metallization process, the part being supported by a same build platform throughout the 3D printing process and the selective metallization process.

Description

METHOD AND SYSTEM FOR MULTI-MATERIAL 3D PRINTING RELATED APPLICATION

[0001] This patent application claims benefit of priority to the Singapore patent application no. 10202500441V, filed on February 18, 2025, the contents of which are hereby incorporated by reference in entirety for all purposes.TECHNICAL FIELD

[0002] The present disclosure relates to additive manufacturing and in particular to an additive manufacturing system for selective metallization of 3D printed substrates of non-metal materials and for fabrication of non-metal / metal hybrid structures.BACKGROUND

[0003] The development of cutting-edge technologies in informatics has put forward higher requirements for electronic device (structure) fabrication technologies. Electronic devices can be abstracted as micro multi-heterogeneous material hybrids, including polymer-metal hybrids and ceramic-metal hybrids. Conventional manufacturing methods are hampered by the lack of metallization methods that can achieve stable coatings on curved surfaces and internal cavities without thermal damage. For many practical applications, dense, continuous metal layers with robust interfaces are required in order to achieve reliable performance in standard adhesion and electrical tests.SUMMARY

[0004] The present disclosure addresses the issues in conventional manufacturing. Additionally, the present disclosure provides a viable solution for selective metallization of 3D printed substrates of non-metal materials and for the manufacturing of non-metal / metal hybrid structures to be carried out at in a scalable manner, including but not limited to mass production. In one aspect, various embodiments of the present disclosure include a manufacturing system. The manufacturing system includes: a host subsystem, the host subsystem including: avat; and a build platform configured to be disposed in the vat; and a computing device, the computing device being configured to execute instructions stored in a memory, the computing device being configured to control a 3D printing process and a selective metallization process of a part, the part being on the build platform during the 3D printing process and selective metallization process.

[0005] In another aspect, various embodiments of the present disclosure include a method of manufacturing implemented by a computer configured to execute instructions stored in a memory, the method including: performing a 3D printing process and a selective metallization process, wherein a part is 3D printed by the 3D printing process and one or more selected areas of the part are electroplated by the selective metallization process, the part being supported by a same build platform throughout the 3D printing process and the selective metallization process.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Various embodiments of the present disclosure will be described with reference to the appended figures.

[0007] FIG. 1A and FIG. 1B are schematic block diagrams of a manufacturing system according to embodiments of the present disclosure.

[0008] FIG. 1C is a schematic diagram of a control system architecture of the proposed manufacturing system.

[0009] FIG. 2A schematically illustrates an example of the manufacturing system integrating mechatronics, materials, equipment, and processes.

[0010] FIG. 2B is a schematic diagram of an example of a parts manufacturing process of FIG. 2A.

[0011] FIG. 3 schematically illustrates an implementation and system architecture for in-situ electroplating during multi-material PpSL printing.

[0012] FIG. 4 schematically illustrates the micro-hybrid additive manufacturing system configured to enable multi-material switching, cleaning and modularity in many scalable ways. Part (a) illustrates one example of multi-material switching achieved by a peristaltic pumping unit mounted in a cassette in conjunction with a fluid piping subsystem. Part (b) shows components coated with Teflon or other nonstick materials to provide resistance to contamination. Part (c) shows a slopedbottom of the printing cassette, configured to enable materials in the printing cassette to form a vortex when the materials are being extracted or removed via a base of the printing cassette. Part (d) illustrates an example of a quick-plug interface to enable quick scaling up or scaling down.

[0013] FIG. 5 schematically illustrates an embodiment of an integrated microhybrid additive manufacturing and electrochemical processing system of the present disclosure.

[0014] FIG. 6 schematically illustrates the electrodes control subsystem according to embodiments of the present disclosure.

[0015] FIG. 7 schematically illustrates the architecture and auxiliary structures for artificial intelligence-enabled control of the electrodes.

[0016] FIG. 8 shows an example of in-situ electrolytic plating during multimaterial PpSL 3D printing to realize high metal ratio structures.

[0017] FIG. 9 schematically illustrates a material-switching workflow of the proposed manufacturing system.

[0018] FIG. 10 illustrates synthesis route and applications of the proposed active precursors.

[0019] FIG. 11 schematically illustrates the proposed manufacturing system according to an embodiment manufacturing 3D-printed ceramic electronics by nano-active-anchor-induced non-invasive 3D selective metallization.

[0020] FIG. 12A to FIG. 12D present experimental verification of the 3D selective metallization mechanism driven by internal chemical reactions.

[0021] FIG. 13 shows cross-sectional characterization and elemental analysis of the metal-Ni-ALOs ceramic interface fabricated via nano-active-anchor-induced electroless plating in accordance with embodiments of the present disclosure.

[0022] FIG. 14A to FIG. 14F illustrate 4D electronic structures with topology of 3D TSMP / M hetero in terface that can be manufactured in accordance with embodiments of the present disclosure.DETAILED DESCRIPTION

[0023] The following detailed description is made with reference to the accompanying drawings, showing details and embodiments of the presentdisclosure for the purposes of illustration and to aid understanding, and not to be limiting. Features that are described in the context of an embodiment may correspondingly be applicable to the same or similar features in the other embodiments, even if not explicitly described in these other embodiments. Additions and / or combinations and / or alternatives as described for a feature in the context of an embodiment may correspondingly be applicable to the same or similar feature in the other embodiments.

[0024] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0025] The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0026] As used herein, the singular ‘a’ and ‘an’ may be construed as including the plural “one or more” unless apparent from the context to be otherwise.

[0027] The terms "about" and "approximately" as applied to a stated numeric value encompasses the exact value and a reasonable variance as will be understood by one of ordinary skill in the art, and the terms “generally” and “substantially” are to be understood in a comparable manner, unless otherwise specified.

[0028] Some processes may be described in terms of steps merely to aid understanding and / or for convenient reference. The delineation between one step and another step may be described as such merely for convenient reference in the present disclosure. It will be understood that in actual implementation there may not be a clear division or transition from one step to another subsequent step. There may be a certain amount of overlap among the steps and / or more than one step may occur or be performed concurrently in time, etc.

[0029] As used herein, the term “concurrent”, or “concurrently”, is used loosely to refer to two or more occurrences (or events) that at least partially overlap in time. The occurrences may or may not start at the same time instant and / or end at the same time instant.

[0030] Terms such as “first” and “second” are used in the description and claims only for the sake of brevity and clarity, and do not necessarily imply a priority or order, unless required by the context.

[0031] Manufacturing system

[0032] Conventional additive manufacturing may be useful for high-mix low-volume manufacturing where a relatively small number of similar articles are 3D printed one by one, e.g., a hearing aid or a prosthetic device, each customized to suit the individual user. The method of multi-material 3D printing and selective metallization described herein was found to be fairly time-consuming using a conventional 3D printer in a laboratory setting. It is currently not possible to achieve the production efficiencies of conventional mass production using conventional 3D printing apparatus. In the case of high volume manufacturing of multi-material devices (also referred to as multi-heterogeneous material devices), it would be even more difficult for additive manufacturing apparatus to achieve comparable economies of scale. In conventional manufacturing, each 3D printed layer would require at least one cycle of removing the 3D printed workpiece from the 3D printer for plating and remounting the workpiece in the 3D printer. These and other technical issues that would have to be addressed in order to implement the entire manufacturing line at an industrial or volume manufacturing level.

[0033] The present application discloses a manufacturing system 100 (e.g., a computer-controllable equipment) and method that can implement micro-hybrid additive manufacturing (MHAM) at an industrially scalable or volume manufacturing level. The manufacturing system 100 may alternatively be described as a micro-multi-heterogeneous material additive manufacturing system 100. The manufacturing system 100 may be described as a multi-material projection microstereolithography (PpSL) system. The proposed manufacturing system 100 includes a projection microstereolithography printer adapted to enable metal-plastic or metal-ceramic hybrid micro-architectures, including enabling selective metal deposition at any layer in a multi-material projection microstereolithography (SMD-PpSL) 3D printing process with in-situ plating at any layer in the process.

[0034] As an example, embodiments of the proposed manufacturing system 100 will first be described with respect to the making of devices of plastic-metal hybrid microarchitectures.

[0035] FIG. 1A is a schematic block diagram of a manufacturing system according to embodiments of the present disclosure.

[0036] According to one aspect, the manufacturing system 100 may be described as a modular system that includes a host subsystem 110 and an auxiliary subsystem 120 that are operably connected by a link subsystem 130. In some embodiments, the manufacturing system 100 further includes a co-sintering subsystem 140. The manufacturing system 100 integrates a metallization subsystem 150, which may be implemented as an in-situ electroless plating subsystem and / or electrolytic plating subsystem.

[0037] The link subsystem 130 includes one or more pipelines and wireless / wired connections for operable signal communication between the host subsystem 110 and the auxiliary subsystem 120. The mechanical and electrical interfaces in the link subsystem 130 are preferably and optionally based on international standards to facilitate the assembly or disassembly of the host system and the auxiliary subsystem 120, to enable flexible adaptation to manufacturing needs.

[0038] The modular configuration allows the host subsystem 110 and the auxiliary subsystem 120 to work in an integrated manner to produce a multi-material device (interchangeably referred to as an article or part), while being configurable to simultaneously perform different processes simultaneously for greater efficiency. For example, as illustrated schematically in FIG. 1B, the structural features and the control configuration of the proposed manufacturing system 100 enables integration of multi-material PpSL printing with in-situ electrochemical processes such as electroless nickel plating, electrolytic processes, etc. Different stages of the integrated manufacturing process, including a 3D printing stage and an in-situ metallization stage can be performed using the same build platform, same vat or bath, same materials delivery subsystem, as well as the same control and actuator subsystems, so as to realize greater precision and manufacturing efficiencies.

[0039] Advantageously, the auxiliary subsystem 120 may be scaled up to handle more types of materials or scaled down to handle fewer types of materials in asimultaneous printing process. Such a functionality may be described as being capable of arbitrarily expandable or adaptable performance. For example, the host subsystem 110 may be performing a UV polymerizing step while the auxiliary subsystem 120 may be concurrently preparing to switch from one material to another material.

[0040] FIG. 1C is a schematic diagram of a control subsystem or control system architecture of the proposed manufacturing system. FIG. 2A schematically illustrates an example of the integrated nature of the proposed maufacturing system integrating mechatronics, materials, equipment, and processes. FIG. 2B is a schematic diagram of an example of a parts manufacturing process of FIG. 2A.

[0041] Control Subsystem

[0042] Referring to FIG. 1C - FIG. 2B, the proposed manufacturing system 100 is controllable by a control subsystem. The control subsystem may be configured with an overall architecture that includes a higher level computing device (e.g., a PC-based upper computer), a lower level controller (e.g., a microcontroller-based lower computer), and a plurality of actuators and sensors. After obtaining the slicing data of the multi-heterogeneous material parts, the slicing data is read into a database by a digital processing software, the G-code of the drive subsystem and each actuator after calculation can be compiled. The drive subsystem drives each actuator under the command of the data commands thus obtained, including the motor, the DLP components, and the peristaltic pump subsystem.

[0043] CAD Processing

[0044] The manufacturing system 100 proposed herein may be implemented with a CAD modeling of the device be manufactured, in which the model corresponds to the device as a single whole entity. The CAD model may be sliced to obtain slicing data (also referred to slice data) corresponding to one layer to be built by 3D printing. From the slicing data, the shape and topology can be obtained for each of the different materials to be formed in the layer. The slicing data for the corresponding topologies of the different materials are obtained separately. The topologies corresponding to the different materials that make up a multi-heterogenous material part is modeled as a single entity and then assembled into a target part according to the topological fit between the different materials.

[0045] For example, the proposed manufacturing system 100 may be configured to mass manufacture a target part with a variety of heterogeneous materials, e.g., a transparent resin, Ni coated wire, and a black resin. When the part coordinate system X-Y-Z for the target part is defined, the position of the topology corresponding to the different materials in this coordinate system is uniquely determined. Different 3D models can be separately built using available 3D modeling software. At this point, each structure may be described with reference to a part coordinate system X'-Y'-Z' of its own.

[0046] A proposed slicing method for multiple heterogeneous material parts may include the following. The modeled different structural models may initially be in a chaotic state. The structures may be assembled according to the correspondence of different material topologies in the target part and labeled with its corresponding material properties respectively. This step ensures that the relative positions of the respective structures in the assembly coordinate system X"-Y"-Z" are related to their positions in the target part coordinate system X-Y-Z. The assembled structure is then sliced separately according to different materials and their slicing parameters, and corresponding materials are obtained separately. When a layer of the target part is arbitrarily extracted, and the slicing data after slicing the different topological materials is extracted separately, it was found that they correspond consistently. At this point, slicing data that uniquely describes a multi-heterogeneous target part and processing data that can be recognized by a 3D printer can be obtained.

[0047] Integrated System

[0048] After the CAD model of the target device (e.g., target multi-heterogeneous material structure) is created, the slicing data of different materials and the set 3D printing process parameters can be obtained after slicing. The process data (including slicing and process parameters) may be processed by the control subsystem (e.g., the higher level computing device executing instructions according to a software stored in a memory of the higher level computing device and sending signals or commands to the 3D printer control subsystem (e.g., the host control subsystem).

[0049] In response to the commands, the manufacturing system is configured to execute the manufacturing. At the actuator layer, the DLP components are coupled with the auxiliary subsystem 120 (e.g., multi-material switching subsystem) to enable the fabrication of different materials.

[0050] FIG. 2A further shows a molding process of a part layer-S. The target part of this layer is displayed in the upper right corner of the FIG. 2A. The slicing information of Layer-S shows that the target part of this layer includes four structures corresponding to four materials. In this example, three of the structures are plastic structures and the other is a metal-coated plastic structure (the structure after the active precursor metal). According to the proposed manufacturing method, the 3D printer will manufacture the layer by first manufacturing the plastic 1 structure, manufacturing the plastic 2 structure after cleaning, and manufacturing the active precursor structure after cleaning.

[0051] At this point, the auxiliary subsystem 120 will activate and feed the plating solution into the 3D printing cartridge to achieve metallization (selective metal deposition) of the active precursor of the layer. Finally, after cleaning, the 3D printer completes the fabrication of the outermost layer of plastic 3. At this point, Layer-S fabrication is complete, and the 3D printer automatically jumps to the next layer (Layer-S+1) and loops until the final fabrication is complete.

[0052] Apparatus

[0053] Referring to FIG. 3, the host subsystem 110 is configured to carry out PpSL-based micro 3D printing processes and in-situ patterned metal deposition.

[0054] As an overall view, the apparatus for in-situ electroplating during multimaterial PpSL printing is an integrated system configured to facilitate deposition of high-metal-ratio structures suitable for fabricating metal-plastic hybrid microarchitectures with enhanced functional capabilities. Part (a) of FIG. 3 is an overview of the in-situ electrolytic plating subsystem integrated with a PpSL-based micro 3D printer, illustrating the plating principle, electric field distribution, and various components such as electrodes, printing platform, and materials supply. Part (b) of FIG. 3 shows a structure of the electrodes capable of three degrees of freedom enabled by servos at Joint 1, Joint 2, and Joint 3, respectively, and linkages (Rod 1, Rod 2, and Rod 3), enabling precision position and electrical contact of theelectrodes. Part (c) of FIG. 3 depicts a mathematical abstraction of the coordinate systems, e.g., machine coordinate system (XM, YM, ZM), workpiece coordinate system (Xp, Yp, Zp), and electrode coordinate system (XE, YE, ZE), configured to enable precision motion control and synchronization. Part (d) of FIG. 3 illustrates motion decomposition and path planning of the electrodes, illustrating rotational motions of the joints and dimensions of the linkages for precision trajectory execution.

[0055] The host subsystem 110 may include a mechanical structure as a mainframe supporting a host control subsystem (e.g., including a computing device or controller). The host subsystem 110 may include a host platform to support various other components of the host subsystem 110. The host subsystem 110 includes a vat and a printing cassette (also referred to as a 3D printing cassette or 3D printing cartridge). The vat and the 3D printing cassette may be disposed in an enclosable space defined by a host shell. The host shell may be made of ultra-violet (UV) isolation glass. According to various embodiments of the present disclosure, the host subsystem 110 includes only one vat in which the 3D printed device is formed, including the deposition of different materials to form the same 3D printed device. The 3D printing cassette is configured to deliver / deposit materials to / in the vat. The 3D printing cassette is configured to deliver / deposit materials on a build platform or on a previously printed layer supported by the build platform.

[0056] The printing cassette may be configured with an inlet and an outlet. The inlet may be connected to the multi-material switching subsystem in fluidic communication. As the multi-material switching subsystem switches from one to another container to draw only one material from the plurality of containers at any one time, only one material is directed into the printing cassette via the inlet, at any one time. The printing cassette is configured to eject or discharge the material out of the printing cassette via the outlet. To avoid cross-contamination, the computing device may be programmed to operate the multi-material switching subsystem to deliver a cleaning fluid to flush out the printing cassette in between delivering different 3D printing materials or plating solutions. The printing cassette has an outlet that can be directed towards the build platform (e.g., to output polymer resin for 3D printing) or the vat (e.g., to output a plating solution).

[0057] The bottom of the 3D printing cassette may be shaped with a 105° bevel to facilitate removal of liquid. The bevel in the bottom surface helps to create a vortex (force) when a liquid is being discharged from the outlet at the bottom of the 3D printing cassette. The vortex force helps to improve removal of the liquid, i.e., to better clean the interior surfaces of the 3D printing cassette and reduce the possibility of cross-contamination.

[0058] A humidity sensor and a temperature sensor may be provided in the enclosure defined by the host shell, and the sensor readings may be acquired by the host control subsystem. The host control subsystem may include one or more memories configured to store machine-readable instructions that can be executed by the computing device to perform dynamic positioning of electrodes (also referred to as 3D smart electrodes) and path optimization, enabling and / or improving precision and adaptability during in-situ plating. The host control subsystem may be operable according to artificial learning-driven algorithms.

[0059] The computing device may be configured to perform methods for computer-aided design (CAD) modelling, slicing, and data generation for multi-heterogenous materials, enabling relatively accurate and efficient fabrication of complex devices or structures. The computing device may include a processor and a processor-readable memory storing instructions, in which the processor is configured to

[0060] The host subsystem 110 may include a positioning mechanism, such as a three-axis precision subsystem supported by the host mainframe, configured to support and / or position the build platform and the 3D printing cartridge with respect to the vat and / or to one another. The host subsystem 110 may be configured to use orthogonal reference axes (e.g., with a z-axis representing a vertical displacement).

[0061] In the prototype manufacturing system 100, the DLP subsystem used to produce high-precision UV masks was driven by a Tl 0.47" 1080P DMD chip (available from Texas Instruments, USA), in cooperation with precision optical devices. The Z axis used to achieve layer-by-layer stacking was completed by a three-axis precision subsystem with an accuracy of 1 pm. A comprehensive printing resolution of up to 2.5 pm and an accuracy of more than 94% was achieved. Theparameters of the prototype manufacturing system 100 are shown below for illustrative purposes.Table 1. Parameters of a prototype manufacturing system 100"< >

[0062] The proposed manufacturing system 100 is configured to use only one 3D printing cassette to complete one build, the one 3D printing cassette being configured to be fed by materials from a plurality of containers (also referred to as smart material containers or smart material boxes). Advantageously, in the proposed manufacturing system, multi-material switching is realized by the use of several containers (smart material boxes) to feed different materials at different times to the one printing cassette. This does away with the need to perform recalibration or re-alignment as in the case of conventional equipment where multiple 3D printing cassettes are required to complete one build. This enables greater precision as compared to conventional equipment.

[0063] The manufacturing system 100 may be configured for a down-forming process. For example, the printing platform may be configured to displace vertically downwards (e.g., along the z-axis) by a displacement equivalent to a thickness of the layer. After each layer of the sliced pattern has been processed, the printing platform is moved downward by one layer distance (or by a vertical displacement determined at the stage of slicing).

[0064] The host subsystem 110 may include a leveling subsystem based on a laser distance-sensing sensor. The host subsystem 110 may also include an optical window distance adjustment subsystem enable adjustment of an optical window distance (H) between a resin plane (plane defined by the surface of the resin in the vat) and a digital light projector (DLP) component (e.g., digital micromirror device DMD chip) configured to provide light or UV irradiation. During the printing process, leveling may be realized by the laser displacement sensor mounted on the printing cartridge. A scraper may be horizontally mounted on the host platform and configured to allow the ink plane to be scraped flat between sequential 3D printed layers. The DLP components may be mounted in the optical window subsystem and are driven by micromotors to allow fine and automatic adjustment of the optical window distance (UV mask projection focal length. The scraper may also be actuated in a reciprocating manner over a surface of a part or in the plating solution, during the metallization stage.

[0065] The auxiliary subsystem 120 is configured to enable multi-material switching, cleaning, and (material) recycling. The auxiliary subsystem 120 may include an auxiliary shell to provide an enclosable space defined by an auxiliary shell. The auxiliary subsystem 120 may include a plurality of containers to hold the different materials to be incorporated into the multi-material device formed by the present manufacturing system 100. The auxiliary subsystem 120 may include an interface group to receive signal instructions from the host control subsystem, and to responsively and selectively open or close the containers (smart material box group). The smart material box group or smart material container subsystem is configured to support multiple instances of multi-material transitions and cleaning in one 3DP manufacturing process. Each of the smart material boxes or containers may be loaded or unloaded independently of the others for convenient replenishment of specific materials, as needed. Each of the smart material boxes or containers may output its contents at different times as controlled via the interface group.

[0066] The auxiliary subsystem 120 provides a multi-material switching subsystem that provides fluid piping or fluid pathways from respective containers to printing cassette of the host subsystem 110. FIG. 4 schematically illustrates the micro-hybrid additive manufacturing system configured to enable multi-material switching, cleaning and modularity in many scalable ways. Part (a) of FIG. 4 illustrates one example of multi-material switching achieved by a peristaltic pumping unit mounted in a cassette in conjunction with a fluid piping subsystem. Part (b) of FIG. 4 shows components coated with Teflon or other non-stick materials to provide resistance to contamination. Part (c) of FIG.4 shows a sloped bottom of the printing cassette, configured to enable materials in the printing cassette to form a vortex when the materials are being extracted or removed via a base of the printing cassette. Part (d) of FIG. 4 illustrates an example of a quick-plug interface to enable quick scaling up or scaling down.

[0067] The auxiliary subsystem 120 can be in the form of a smart material box group with a standardized quick interface. A quick plug interface or connector may be used to facilitate easy assembly and dis-assembly of each of the smart boxes. The auxiliary subsystem 120 can be configured in a modular manner, with eachauxiliary module including a smart material box (container) individually integrated with a precision peristaltic pump, an electronic subsystem, and a standard interface. Each auxiliary module can be quickly assembled or disassembled to form various combinations of multiple materials. The auxiliary subsystem 120 not only feeds or extracts photosensitive polymers into the 3D printing cassette according to instructions from the computing device but also provides other materials such as one or more plating liquids and one or more cleaning liquids or cleaning solutions. Each peristaltic pump can be controllably operable to deliver a liquid to the 3D printing cartridge by alternately compressing and releasing the piping, thereby transporting the liquid along the piping. To minimize cross-contamination between the different materials and for cleaning effectiveness, all surfaces in the 3D printer that may come into contact with the build materials are coated with Teflon to confer good hydrophobic and oleophobic properties.

[0068] The manufacturing system 100 may include a waste material handling module (also referred to as a scrap box group) that is configured to recycle inorganic waste liquid and organic waste liquid separately after each cleaning process to avoid cross contamination between the different materials.

[0069] In-situ Metallization

[0070] The proposed manufacturing system 100 is configured with an in-situ metallization module, enabling selective metallization to take place without the need to remove the article or workpiece from the 3D printer. In preferred embodiments, the in-situ metallization module is switchable between operating as an in-situ electroless plating module and operating as an in-situ electrolytic plating module.

[0071] In-situ Electrolytic Plating

[0072] The proposed in-situ electrolytic plating subsystem is particularly adapted for seamless integration with projection micro-stereolithography (PpSL) to produce high-metal-content, metal-plastic hybrid microstructures.

[0073] The in-situ electrolytic plating subsystem includes a pair of electrodes operable by an actuator subsystem, a printing platform, a hollow anode electrode (fixed electrode), a material pool, and an intelligent material supply unit.

[0074] The electrodes is configured with a three degrees-of-freedom (3-DOF) actuator subsystem, enabling precise positioning and contact with targeted regionson the printed substrate. The electrodes may be positioned out of the way or controllable positioned to contact selected areas of the 3D printed article or workpiece.

[0075] The hollow anode electrode serves as a source of metal ions. The intelligent material supply unit provides automated delivery and switching of the plating solution, facilitating electrolytic plating at any stage of the printing process. The plating solution is delivered to the vat in which the 3D printed article or workpiece is disposed. There is no need to remove the 3D printed article or workpiece from the 3D printer. This integration significantly enhances the efficiency and precision of hybrid structure fabrication.

[0076] Electrolytic plating relies on electrochemical reactions for metal deposition. At the anode, metal atoms undergo oxidation, releasing metal ions into the plating solution. The ions migrate toward the cathode. At the cathode, which is the 3D printed article or workpiece (e.g., a plastic substrate), the metal ions gain electrons under the influence of an electric field and are reduced to form a solid metal layer. The electric field generated by the electrodes is controllable to provide a generally uniform deposition of metal ions. It was found that a strong adhesion between metal and plastic can be formed.

[0077] Electrodes for In-situ Electrolytic Plating

[0078] The proposed manufacturing system 100 includes a pair of electrodes (also referred to as dual 3D smart electrodes). The electrodes are adapted to enable in-situ electrolytic plating in several aspects.

[0079] For example, in one aspect, during the 3D printing stage or electroless plating stage, the electrodes are positioned spaced apart from the article or the workpiece, in which the electrodes may be described as being in a rest state. During electrolytic plating stage, the electrodes are controllably actuated until they are in predetermined positions in contact with parts of the article or workpiece, in which the electrodes may be described as being in an operation state. The electrodes may be repeatedly controllably actuated between the rest state and the operational state along the course of one manufacturing run, and controllable actuated between different positions during the course of an electrolytic plating process, depending on the target configuration of the multi-material part being formed.

[0080] For example, in another aspect, three degrees-of-freedom (3 DOF) actuator subsystem, enables precise positioning of the electrodes relative to the article or workpiece, and enables formation of a stable electric field at designated regions on the surface of the article or workpiece. This promotes a uniform deposition of metal ions during the electrolytic plating process

[0081] For example, in another aspect, the proposed manufacturing system 100 is configured to execute automated path planning and synchronizable motion control of the electrodes. The manufacturing system 100 is configured to dynamically adjust the positions of the electrodes during the electrolytic plating stage and hence adjust the electric field strength to achieve precision metal deposition. That is, the areas to be plated or metallized can be more precisely formed.

[0082] For example, in yet another aspect, the material supply subsystem is configured to deliver and switch between different plating solutions. A first plating solution suitable for electroless plating can be first provided during the electroless plating stage, followed by a second plating solution for carrying out the electrolytic plating stage. Cooperating with the positionable electrodes, the manufacturing system 100 is configured to plate different parts of the same layer with different metals. At the same time, chemical stability can be maintained throughout different stages of the manufacturing process. Metal content and deposition efficiency can be effectively increased. It was also found that the reduced manual intervention while carrying out the different processes on the same platform enables enhanced automation and reproducibility, which in turn significantly improves the uniformity, and adhesion of metal deposition.

[0083] Referring again to part (b) of FIG. 3, the electrodes operable by the actuator subsystem include a first electrode and a second electrode (also referred to as a left electrode and a right electrode, respectively). The two electrodes are configured to be positioned independently of one another. Each electrode is configured three degrees-of-freedom (3 DOF), being controllable by three servo motors (Joint 1, Joint 2, and Joint 3, respectively) configured to drive electrode rotation and other movement. The linkage structure (Rod 1, Rod 2, and Rod 3, respectively) is configured to coordinate the actions of the servo motors, allowingthe respective electrode tip of each electrode to be precisely disposed at respective target designated regions on the 3D printed substrate (also referred to as the 3D printed article, workpiece, or part). The actuator subsystem further include a bracket. The bracket may be fixed to serve as a stable support, to enable precision and to provide stability during operation. The electrode tips may be made of silver. The electrode tips may be spherical to provide a single point contact for accurate surface contact and efficient current transmission. The connecting rod and electrical interface further ensure stable current flow.

[0084] In some embodiments, one of the electrodes (e.g., the first electrode) may be fixed and the other electrodes (e.g., the second electrode) may be dynamically positioned and re-positioned throughout the process. The fixed electrode may be an insoluble anode.

[0085] In some embodiments, as illustrated in FIG. 5, the proposed manufacturing system 100 includes a scraper. The scraper may be used during the in-situ electroplating process (e.g., the electroless plating or electrolytic plating).

[0086] Part (a) of FIG. 5 shows a modular configuration of the proposed system with electrodes, a motion axis system, and an additional fixed electrode to enable dynamic electrochemical deposition. Part (a) of FIG. 5 schematically illustrates that different processes being carried out on a single platform. This method enables a rapid formation of polymer materials and facilitates the subsequent addition of metallic functional layers (or other electrochemical processes to achieve specific functionalities). Such a combined strategy enables the fabrication of plastic-metal hybrid microstructures, addressing the requirements of multifunctional devices for electrical conductivity, mechanical strength, and multi-material integration.

[0087] The modularity of the proposed manufacturing system 100 enables flexible adjustments to accommodate various manufacturing needs. For instance, users can opt for in-situ electroless plating or electrolytic plating after 3D printing or opt for dynamically switching between multiple steps.

[0088] Part (b) of FIG. 5 shows a set-up for in-situ electroplating, operable on direct current power supply, with a left electrode, a fixed electrode, a material tank, and a scraper. The scraper is configured to perform a reciprocating motion to improve coating uniformity through agitating the plating solution, preventing bubbleadhesion, promoting electrolyte circulation, removing foreign particles, and enhancing bonding strength of the plating with the substrate.

[0089] The scraper is supported and actuable by a reciprocating mechanism, as shown in part (b) of FIG. 5, During electroplating, the scraper reciprocates across the part’s surface. The dynamic reciprocating motion of the scraper effectively agitates the electrolyte, facilitating a uniform metal ion distribution and reducing local concentration variations caused by uneven electric field distribution. This agitation promotes consistent metal deposition, preventing thickness irregularities, especially along edges, recesses, or complex geometries. Additionally, the scraper’s motion helps to eliminate air bubbles adhering to the part’s surface, which is very helpful for avoiding plating defects and to promote coating integrity, particularly in recessed areas.

[0090] Further, the scraper’s reciprocating motion enhances electrolyte circulation and helps to maintain a stable local metal ion concentration. This circulation facilitates the delivery of fresh metal ions to the part’s surface, preventing ion depletion that can compromise coating quality. The scraper’s movement also removes impurities from the part’s surface, reducing defects and improving coating purity. Continuous mild scraping or surface agitation activates the part’s surface, enhancing the adhesion strength between the metal coating and the substrate. Experiments demonstrated that integrating a scraper into the manufacturing system 100 and method significantly improves coating uniformity, density, and bonding strength.

[0091] Referring to part (c) of FIG. 5, the proposed manufacturing system 100 is configured to perform electrochemical polishing using the same apparatus or system. Electrochemical polishing involves removing microscopic protrusions on metal surfaces through electrochemical reactions, resulting in a polished surface characterized by a greater brightness and smoothness.

[0092] The scraper may be configured with a reciprocating motion to facilitate dynamic electrolyte agitation, removal of gas bubbles and impurities, and improve surface finish to a mirror-like smooth polished surface.

[0093] In the electrochemical polishing process, a direct current voltage is applied to create an electric field between the workpiece (anode) and the fixedelectrode (cathode), causing the micro-protrusions on the metal surface to dissolve, forming a uniform surface. The scraper may be configured to concurrently reciprocate along the workpiece surface. As shown in the figure, electrochemical polishing significantly improves the workpiece surface microstructure, reducing roughness and achieving a high degree of flatness and mirror-like gloss. This method is particularly suitable for metal components with complex geometries, microstructures, or high-precision requirements, such as microelectronic devices, medical implants, and optical components. Compared with traditional mechanical polishing, electrochemical polishing offers advantages including no mechanical damage, no residual stress, high processing efficiency, and superior surface quality. Furthermore, process parameters, such as voltage, current density, scraper speed, and electrolyte composition, can be adjusted to meet the requirements of different materials and applications.

[0094] Modelling of Electrodes

[0095] To achieve high-precision control of the 3D dual smart electrodes, a mathematical model of relevant parts of the manufacturing system 100 was developed. The mathematical model included establishing a comprehensive spatial coordinate system to describe the printer material tray, the pair of electrodes, and the relative motion of the electrodes. The coordinate system enables accurate positioning, path planning, motion control, and electric field generation. The printer material tray coordinate system provides a spatial reference framework for the entire 3D printing platform. This coordinate system defines the position and orientation of the printed substrate in three-dimensional space, offering a clear spatial baseline for subsequent metal deposition operations. It determines the initial position of the printed part and the features of each printed layer, laying the groundwork for in-situ electrolytic plating processes. Further, the establishment of the 3D dual smart electrode coordinate system enables a precise description of the electrode system’s spatial movement. The dual smart electrodes possess three degrees-of-freedom (3 DOF), including rotations and displacements along different axes. An independent electrode coordinate system was used to represent the dynamic position, orientation, and contact point between the electrode tips, and the printed substrate. Introducing this coordinate system provides mathematicalsupport for electrode path planning, automated control, and electric field generation. By linking the printer material tray coordinate system with the electrode coordinate system, spatial mapping and motion coordination between the two can be achieved. This relationship facilitates dynamic adjustments to electrode positions and electric field distribution during the printing process, ensuring uniform metal ion deposition at designated locations. Additionally, it provides a precise spatial coordinate system which significantly enhances system automation and repeatability, reducing deposition defects caused by positioning errors.

[0096] Reference is made again to part (c) of FIG. 3 which illustrates the spatial coordinate systems of the 3D printer material tray and the electrodes subsystem, including the machine coordinate system (XM, YM, ZM) and the workpiece coordinate system (Xp, Yp, Zp). The machine coordinate system is referenced to the material tray origin OM, with the XM axis extending horizontally to the right along the platform, the YM axis extending inward parallel to the platform surface, and the ZM axis extending vertically upward. The workpiece coordinate system is referenced to the printed substrate origin OP, with the Xp and Yp axes parallel to the XM and YM axes, respectively, and the Zp axis extending vertically upward from the substrate. A fixed spatial transformation relationship is established between these two coordinate systems, useful for describing the precise movement of the electrodes relative to the printed substrate.

[0097] Building upon the machine coordinate system and the workpiece coordinate system, an electrode coordinate system (XE, YE, ZE) and joint coordinate systems (XEI, YEI, ZEI; XE2, YE2, ZE2; XES, YES, ZES) are further established to achieve high-precision end-point control of the electrodes as shown in part (d) of FIG. 3.The origin OE of the electrode coordinate system is located at the electrode base. The XE axis extends forward along the electrode body, the YE axis is perpendicular to the XE axis and extends inward, parallel to the electrode base surface, while the ZE axis extends vertically upward from the electrode base. The system includes three joints (Joint 1, Joint 2, Joint 3) that control the electrode's rotations and displacements. These joints are connected by three links (Rod 1 : 52 mm, Rod 2: 45 mm, Rod 3: 59.2 mm), forming a mechanism with three degrees of freedom. Joint 1 rotates around the ZE axis, Joint 2 adjusts the angle of the middle link, andJoint 3 fine-tunes the final orientation of the electrode tip. By applying kinematic equations and coordinate transformation matrices, the rotation angles of the joints and the lengths of the links can be mapped to the precise position and orientation of the electrode tip within the electrode coordinate system. These coordinates can then be transformed into the machine coordinate system and the workpiece coordinate system. As an example, in the prototype, the three joints of the 3D smart electrode utilize A0090 and MG90S servomotors as driving devices. The rotational axis of Joint 1 aligns with the Z-axis of the overall coordinate system and is driven by the A0090 servomotor, providing the primary rotational force. Joint 2 and Joint 3 have rotational axes parallel to the Y-axis of the overall coordinate system and are driven by MG90S servomotors, enabling two-dimensional rotational control. This configuration endows the 3D smart electrode with high flexibility, allowing it to achieve a relatively large working range within a limited space. Precision-machined interfaces connect the servomotors, ensuring accurate torque transmission and minimizing cumulative errors caused by prolonged use. The joint drive system is configured with considerations for load capacity, response speed, and reliability. The A0090 servomotor (available from Guohua) and MG90S servomotor (available from Towerpro) provide high torque output and stable control performance, enabling the electrodes to maintain precise attitude control even under high-load conditions. Other makes of servomotors may be used. Additionally, the servomotor system incorporates high-precision angular encoders for closed-loop feedback, enhancing the repeatability and accuracy of the electrodes' positioning.

[0098] As an example, in the prototype, each electrode’s linkages include three aluminum alloy segments: Link 1 (52 mm), Link 2 (45 mm), and Link 3 (59.2 mm). Each linkage is made from aerospace-grade 8086 aluminum alloy and coated with polytetrafluoroethylene (PTFE). This combination of material and surface treatment provides a lightweight mechanism with corrosion resistance and surface smoothness, effectively reducing friction. The use of aluminum alloy provides structural rigidity, allowing the 3D smart electrode to exhibit excellent dynamic response characteristics and minimizing precision loss caused by vibration during motion.

[0099] As an example, in the prototype, for the end-effector, the tip of Link 3 is made of silver-plated aluminum alloy, further improving bending stiffness and wear resistance. This provides a stable support structure for high-precision operations, making it suitable for applications requiring precise end-point positioning. The joints and servomotor components of the electrodes are connected through precision-machined brackets to ensure overall rigidity and resistance to deformation. The brackets are made of 8086 aluminum alloy, which offers strength and durability, making it suitable for supporting the high-frequency and high-load movements of the electrodes. The mounting interfaces between the brackets and servomotors were calibrated to ensure assembly accuracy, minimizing mechanical deviations caused by assembly errors. The overall assembly architecture of the prototype manufacturing system 100 followed the principles of modularity and maintainability, with each joint module being independently detachable and replaceable. This modular configuration facilitates maintenance and supports future upgrades. For instance, servomotors with different load capacities or linkages made of various materials can be exchanged to meet specific task requirements, allowing adaptation to diverse application scenarios.

[0100] Electrodes Control

[0101] According to embodiments of the present disclosure, the control subsystem for the electrodes includes four layers: a software layer, a hardware layer, an executor layer, and a mechanical system layer, as illustrated in FIG. 6.

[0102] The electrode control subsystem may be organized in four distinct layers: an electrode software layer, an electrode hardware layer, an electrode executor layer, and an electrode mechanical system layer. The electrode software layer is executed by a computing device (e.g., PC) configured to plan motion paths, issue control commands, monitor system status, and process real-time feedback. The electrode hardware layer includes the servo drive and the signal processor configured to convert digital signals into pulse and electrical signals for servo motor control. The electrode executor layer includes six servo motors (e.g., Servo 1 to Servo 6), a direct current power supply, and a signal generator. The electrode executor layer is configured to drive the electrodes (also referred to as the dual 3D smart electrodes) along predefined paths and generate the required electric fieldfor electrolytic plating process. The electrode mechanical layer includes the pair of electrodes (also referred to as the left 3D smart electrode and the right 3D smart electrode) which can achieve three degrees of freedom motion control via the servo motors. The electrode control subsystem also includes a contact status detection mechanism, showing the transition from the disconnected state (e.g., red indicator) to the contact state (e.g., green indicator) when the electrodes contact the 3D printed part, triggering electric field generation and initiating the electrolytic plating process.

[0103] The proposed manufacturing method can be combined with various postprocessing techniques. For example, through chemical dissolution, polymer materials can be removed from the workpiece to obtain a purely metal structure. For example, the multi-material article formed using the proposed manufacturing method can serve as the basis for further additive manufacturing processes to create more complex metallized hybrid structures. For example, the multi-material article can be subjected to a sintering process to fabricate inorganic-metal hybrid structures with high thermal resistance.

[0104] The control subsystem can be configured to support a selection of operational mode from a plurality of available operational modes, e.g., a manual mode, a programmed mode, and an artificial intelligence (Al)-driven mode.

[0105] In the manual mode, operators directly control the electrodes’ positions and contact processes in real time via an interface. The electrodes have multiple degrees of freedom, with each joint capable of rotating in the forward direction (w+) and backward direction (w-), enabling precise control of the contact position. The contact status detection function may be operational in the manual mode to ensure there is the required contact between the electrodes and the workpiece. The control subsystem provides data transmission and feedback signals, e.g., via the servomotors, to facilitate real-time monitoring and operational adjustments.

[0106] In the programmed mode, automated electrode motion control is achieved through predefined path planning and command codes, as described above, ideal for repetitive tasks and high-precision path control.

[0107] In the Al-driven mode, artificial intelligence algorithms autonomously adjust electrode positions and contact points based on real-time sensor data andenvironmental feedback, enabling intelligent and adaptive control in complex and dynamic environments.

[0108] Programmed Mode

[0109] In the programmed mode, the electrodes operates under automated control based on predefined path planning and instruction codes. The operator inputs the movement path, contact point positions, and process parameters into the control system. The system then drives the electrodes along the specified path to contact the target part according to these preset instructions. This mode supports closed-loop control with data transmission and feedback signals, ensuring precise electrode positioning along the planned path. The 3D smart electrodes possess multiple degrees of freedom, enabling high-precision contact control. Programmed mode is characterized by short connection times and high connection accuracy, making it suitable for executing complex electrode contact and electrolytic plating tasks without real-time human intervention.

[0110] Al-Driven Mode

[0111] In the Al-driven mode, the dual 3D smart electrode system achieves autonomous control through artificial intelligence vision algorithms. The system relies on real-time sensor data, primarily images captured by a camera, to dynamically identify electrode positions, contact points, and the geometric features of the target component. These image data are transmitted to the signal processor and servo drivers, where the Al vision model analyses them to make decisions. Based on the recognition results, the system automatically optimizes electrode paths and contact parameters, enabling high-precision contact and electrolytic plating operations.

[0112] The Al vision model advantageously enables intelligent adaptive control by dynamically identifying contact status and geometric features, allowing flexible adjustments to electrode paths and adapting to complex and dynamically changing environments. The Al-driven mode can deliver precision and real-time feedback. Through image recognition and closed-loop feedback control, it can significantly reduce contact errors and improve plating quality. Furthermore, this mode operates without real-time human intervention, reducing workload and minimizing human-induced errors. The Al-driven mode also exhibits rapid response capabilities,enabling real-time electrode path adjustments during operation, making it suitable for non-standard components and unexpected scenarios. Continuous learning and data accumulation further optimize path planning and contact control, enhancing overall system performance and stability.

[0113] Al Model for Positioning and Connection of Electrodes

[0114] To achieve Al-driven mode, an artificial intelligence model named the “Al Model for Positioning and Connection of Dual 3D Smart Electrodes” was developed. The system’s architecture as illustrated in part (a) of FIG. 7 includes three primary modules: Data Acquisition and Transmission, Al Model Training, and Path Planning and Control Execution. These modules work collaboratively to achieve high-precision autonomous positioning and dynamic connection of the electrodes, ensuring adaptability to complex environments and real-time variations in working conditions. The Data Acquisition and Transmission Module captures real-time spatial position data and geometric features of the electrodes and target components (primarily auxiliary structures). This is accomplished through high-resolution images obtained by a camera, coupled with sensor feedback. The acquired data undergo preprocessing, annotation, and augmentation to build the training dataset (Drosophila dataset). After processing, the dataset is divided into training and testing sets, which are then transferred to the Al model training phase. This process ensures the system accurately identifies electrode positions and target features across different operating scenarios, providing reliable input for subsequent path planning and control.

[0115] The Al Model Training Module utilizes the You Only Look Once (YOLO) deep learning network for real-time object detection and localization. The YOLO model comprises a Backbone (P5) for feature extraction and a Head for object recognition. Using convolutional layers (Conv), pooling layers, and fully connected layers, the model accurately identifies the electrodes and auxiliary structures. Upon completing training, the model outputs real-time trajectory coordinates of the electrodes and the location of auxiliary structures. This information guides path planning and contact point control, enabling the electrodes to quickly and accurately complete connection tasks in dynamic environments. The Path Planning and Control Execution Module employs positional data from the Al model to preciselycontrol the motion of the dual 3D smart electrodes through a servo-driven system (comprising six drives: Drive 1 to Drive 6). The electrodes possess multiple degrees of freedom, allowing flexible rotations in various directions to meet diverse operational requirements. A closed-loop feedback mechanism continuously monitors electrode motion and contact accuracy, making real-time adjustments to optimize performance.

[0116] For high-precision positioning and connection of the electrodes in Al-driven mode, an auxiliary structure is provided, as illustrated in parts (b) and (c) of FIG. 7 The auxiliary structure can be provided as part of the auxiliary subsystem 120. The auxiliary structure includes a functional resin framework and a metal coating, with the metal layer deposited on the resin surface via an in-situ electroless plating process. The electroless plating offers a stable contact point for the dual 3D smart electrodes, ensuring reliable electrolytic plating connections with the target part and enabling the fabrication of complex multi-material, high-precision structures. The functional resin framework is produced using multi-material projection micro-stereolithography (PpSL) 3D printing technology. This framework can be flexibly tailored based on the geometric features of the target part. It exhibits excellent mechanical strength and stability, allowing it to endure repeated electrode contacts and operations while maintaining structural integrity and connection stability in dynamic environments. The dimensions, shapes, and spatial configurations of the resin framework can be adjusted to meet specific requirements, ensuring precise alignment with the electrode geometry and improving positioning accuracy and operational reliability. A uniform, highly conductive metal coating is formed on the resin framework's surface through in-situ electroless plating. This metal coating enhances the conductivity of the auxiliary structure and provides a reliable contact interface for the pair of electrodes. It serves as an electrical bridge between the electrodes and the target part, enabling uniform current distribution and stable metal deposition during electrolytic plating. The coating thickness can be adjusted to meet specific process requirements, accommodating various current densities and deposition rates. The specific dimensions and shape of the auxiliary structure may be customized to match the structural characteristics and size of the target part, to enable precise alignment with the contact points of the electrodes.

[0117] According to various embodiments of the present disclosure, the auxiliary structure may be adapted based on the proposed technical framework, incorporating high-precision positioning, adaptive path planning, and closed-loop feedback control to provide for the Al-driven mode's effectiveness and stability in practical applications.

[0118] Part (c) of FIG. 7 illustrates a coupling method and application principles of the auxiliary structure with the target part, using two exemplary embodiments (auxiliary structure 1 for a left electrode and auxiliary structure 2 for a right 3D smart electrode) to demonstrate reliable electrical connections and structural compatibility. This configuration provides an optimal or operational balance between mechanical stability and electrical conductivity. In practical applications, the auxiliary structure may be configured to closely match the geometric features of the target part, facilitating precise electrode positioning and contact. During electrode contact, the metal coating would form a conductive bridge between the auxiliary structure and the target part, ensuring uniform current conduction and stable electrolytic plating.

[0119] The auxiliary structure is preferably configured with the following in view, e.g., customized dimensions and shapes based on the target part’s specific requirements, accommodating various operational scenarios and process demands.

[0120] Data Acquisition and Model Training

[0121] In the practical implementation process, the Al-driven mode can be divided into two stages: dataset extraction, annotation, and construction; and model training and deployment. The first stage is required for preparing the dataset, while the second stage enables the trained Al model to perform its intended function. To achieve high-precision positioning and connection of the electrodes in the Al-driven mode, a training dataset was constructed, as illustrated in part (d) of FIG. 7. The dataset construction process included feature extraction, annotation, and augmentation. High-resolution cameras captured images of the target components, from which key feature points were identified and labeled with their central positions. These feature points served as identification markers for auxiliary structures, providing reference points for accurate electrode positioning. The extracted features were labeled to generate feature tags, enabling the Al model to recognize the geometric features and spatial locations of the target parts. The preprocessedand augmented data formed a diverse training dataset covering various operational scenarios, establishing a robust foundation for efficient Al model training.

[0122] Once the dataset has been constructed, it could be used for Al model training, as shown in part (e) of FIG. 7. The Al model employed the YOLO (You Only Look Once) deep learning network for real-time object detection and localization. In the prototype, the model used convolutional layers to extract features and fully connected layers to identify and locate auxiliary structures, generating the positional information required for the electrodes. During application, the Al model processed real-time images to obtain the positional data of target parts, outputting coordinates for feature points (e.g., Position 1 (x1 , y1) and Position 2 (x2, y2)). Based on this information, the left electrode and the right electrode sequentially performed positioning and contact operations, achieving high-precision connections with the target parts. Simultaneously, a closed-loop feedback mechanism monitored (e.g., continuously over a period of time or intermittently over a period of time) the connection status of the electrodes, to maintain stability and accuracy in dynamic environments.

[0123] In-situ Electroless Plating

[0124] Conventionally, use of electroless plating is typically limited to plating relatively small areas. This is due to the comparatively slower metal deposition rate of electroless plating. In fact, electroless plating is traditionally not preferred for fabricating parts with a high metal content or hybrids with a high percentage of metal structures.

[0125] The proposed manufacturing system 100 is however configured to integrate metal plating relatively in a feasible and efficient manner. The proposed manufacturing system 100 is configured to provide seamless integration as the manufacturing process switches between 3D printing and selective metal plating. The plating carried out by the proposed manufacturing system 100 is referred to as "in-situ", i.e., the plating is carried out in the same host subsystem 110 in which the 3D printing was carried out. According to some embodiments of the present disclosure, the manufacturing includes the hardware and corresponding control subsystem to switch between different types of in-situ metal plating, e.g., between in-situ electroless plating and in-situ electrolytic plating. This ability to switchbetween 3D printing and metal plating in-situ, as well as the ability to switch between alternative plating processes without the need for equipment downtime, enables a broader selection of materials without sacrificing manufacturing efficiency. In one aspect, in-situ metal plating may be described as metal plating that is carried out without removing the 3D printed part from the printing platform. This helps to enable the fabrication of metal structures with precise patterns and avoids the need to reposition or realign the 3D printed part. The method proposed herein also promotes homogeneity and strong metal-plastic adhesion.

[0126] FIG. 8 shows the structural features of a target part with a high percentage of metal structures, which includes a plastic substrate and a number of conical microneedles comprising pure metal Ni. The cross-sectional schematic demonstrates the difference between this type of structure (achieved by conventional methods) and the structure of the metal-coated active precursor obtained by in situ electroless plating (achievable using embodiments of the present disclosure).

[0127] Part (a) of FIG. 8 shows structural features of a target part having a hybrid structure with pure metal structures.

[0128] In contrast to electroless plating, electroplating is a technique that utilizes an applied current to reduce and deposit metal ions on the surface of a substrate. The controllable nature of the metal deposition rate allows electroplating to make up for the shortcomings of electroless plating in building pure metal 3D structures. In order to realize in-situ electrolytic plating, the proposed manufacturing system 100 includes an in-situ electrolytic plating auxiliary system (or plating subsystem) that can be directly mounted on the host system. As shown in part (b) of FIG. 8, the in-situ electrolytic plating subsystem includes two electrodes with three degrees of freedom in the form of micromechanical arms mounted on the outside of a magazine. The electrode may be a multi-axis microelectrode, configured as a multiaxis robotic arm, mounted on a 3D printing cassette to enable in-situ electrolytic plating.

[0129] In operation, the method of manufacturing may include an electroless metal plating step to form electrically conductive regions on the 3D printed part, followed by an electrolytic plating step. The two electrodes of the electrolytic platingsubsystem (also referred to as the electrolytic plating auxiliary system) are configured to automatically contact electrically conductive regions on the part to form the electric field required for electrolytic plating and to complete the in-situ electrolytic plating.

[0130] More generally described, an article with a substantially high metal content can be manufactured efficiently using the proposed manufacturing system 100 and method. According to embodiments of the present disclosure, in-situ electrolytic plating can be performed in any layer of a multimaterial process, and in conjunction with sacrificial structures, to form 3D structures of pure metal. Part (c) of FIG. 8 illustrates a working principle of the proposed in-situ electrolytic plating and the fabrication process for realizing a hybrid with a pure metal 3D structure, using a sacrificial resin (the target part shown in part (a) of FIG. 8. First, a structure comprising a sacrificeable resin and a sacrificeable active precursor was fabricated as a mold for electroplating a large amount of metal (electroforming mold). Thereafter, an in-situ electroless plating process is implemented to form a patterned metal layer (electrically conductive layer) on the designed 3D surface. After cleaning, the in-situ electrolytic plating subsystem (also referred to as the in-situ plating auxiliary subsystem 120) is activated so that the electrodes automatically contact the part in the designed positions. At this point, the electroplating power supply is switched on, allowing the part to begin electroplating metal deposition in the electrolyzer where the plating solution is provided. Once metal deposition is completed, the electrodes can be automatically retracted, and the manufacturing process can continue on to cleaning and PpSL 3D printing of the next layer.

[0131] In one aspect, the proposed manufacturing system 100 is configured to provide seamless transition between three process states of in-situ electroless plating, in-situ electrolytic plating, and PpSL 3D printing.

[0132] Sacrificial structures

[0133] It is also possible to form multi-heterogeneous material devices involving sacrificial structures that are removed to obtain the final target device. This is an advancement that enables large scale manufacturing of complex multi-material devices.

[0134] Part (d) of FIG. 8 illustrates various ways of removing sacrificial structures, according to the properties of the materials used.

[0135] In one example, the sacrificial resin is selected to be an alkaline-soluble resin (a corresponding sacrificial reactive precursor may be obtained by adding reactive UV monomers to the sacrificial resin). After 3D printing, the 3D printed article can be soaked in an alkaline solution to remove the sacrificial structures (also referred to as sacrificeable structures).

[0136] In another example, as schematically illustrated in part (d) of FIG. 6 (middle figure), the sacrificial structure may be fabricated from a wax-loss UV resin. The 3D printed article can be heated to about 200°C to about 300°C to melt and remove the sacrificial structure.

[0137] In yet another example, if the non-sacrificial structure is made from a resin that is resistant to high temperatures (e.g., high-temperature-resistant resin), the 3D printed article can be sintered at about 500°C to about 600 °C degrees to remove most of the sacrificial UV resin. A tube sintering may be used, as schematically illustrated in part (d) of FIG. 8 (right figure).

[0138] Material Switching Workflow

[0139] As illustrated in FIG. 9, the manufacturing system 100 includes multiple containers for different material pools (e.g., Material Pool 1 to Material Pool 7), such as but not limited to contain different polymer resins. A material-switching subsystem, e.g., resin-switching subsystem may use a single pipeline to draw a resin from one of the multiple containers and to deliver the resin to the printing platform.

[0140] In some embodiments, a single pipeline is used to draw resins from any of a plurality of containers (multiple material pools), facilitating rapid and efficient switching between various resins during printing. During material switching, the manufacturing system 100 is configured to inject the selected resin while simultaneously extracting the unwanted resin from the printing platform, enabling precise material control and preventing cross-contamination. Additionally, an alcohol-based cleaning module may be provided to maintain platform cleanliness during transitions, avoiding residual resin contamination and preserving print quality.

[0141] Metallized Polymer Hybrids / Metallized Ceramic Hybrids

[0142] The proposed manufacturing system 100 can be used with a wide variety of materials and different combinations of materials. Solely to aid understanding and for illustrative purposes, and not to be limiting, the preparation of suitable materials are described below.

[0143] Providing Active UV Monomers

[0144] FIG. 10 illustrates synthesis route and applications of the proposed active precursors. Part (a) of FIG. 10 shows the molecular structures of maleic acid, methacrylic acid, and acrylic acid used in synthesizing active UV monomers. Part (b) of FIG. 10 illustrates an overall strategy for synthesizing active UV monomers utilizing direct neutralization reactions of maleic acid, methacrylic acid, and acrylic acid with palladium hydroxide to obtain respective complexes. Part (c) of FIG. 10 shows the molecular formulae and 3D molecular structures of the proposed active UV monomers (Pd-based complexes) of palladium maleate, palladium methacrylate, and palladium acrylate, respectively. Part (d) of FIG. 10 illustrates a proposed strategy for the preparation of different active precursors with different functionalities, by combined addition of active UV monomers, polymers (prepolymers), photoinitiators, and functional additives (or fillers).

[0145] Palladium Maleate

[0146] Palladium maleate activated UV monomer was processed as follows: first, Maleic acid (CAS Number: 110-16-7, ^99% (HPLC), powder) was dissolved in a certain amount of deionized water to obtain a certain concentration (molar concentration) of maleic acid solution. A certain amount of Palladium hydroxide on carbon (CAS Number:12135-22-7, 20 wt. % loading (dry basis), matrix carbon) was gradually added to the dilute hydrochloric acid solution, during which the dilute hydrochloric acid solution was continuously stirred and kept gently heated (usually at 60°C -80°C) to promote the reaction. After the reaction was completed, the reaction mixture was filtered with filter paper and funnel to separate the unreacted palladium hydroxide and carbon carrier to obtain the PdCll~ solution. A certain amount of the PdCZ^solution was added dropwise to the maleic acid solution to obtain palladium maleate active UV monomer.

[0147] Palladium Methacrylate

[0148] The process for Palladium methacrylate reactive UV monomer is as follows: first, a certain amount of Palladium hydroxide on carbon (CAS Number: 12135-22-7, 20 wt. % loading (dry basis), matrix carbon) is gradually added to a dilute hydrochloric acid solution. During the process, the dilute hydrochloric acid solution was stirred continuously and kept gently heated (usually at 60°C -80°C) to promote the reaction. After the reaction was completed, the reaction mixture was filtered by filter paper and funnel to separate the unreacted palladium hydroxide and carbon carrier to obtain the PcZCZ^solution. A certain amount of the PcZCZ^solution was added dropwise to methacrylic acid (CAS Number: 79-41-4, 99%, liquid) to obtain palladium methacrylate active UV monomer.

[0149] Palladium Acrylate

[0150] The process of Palladium acrylate reactive UV monomer is as follows: first, a certain amount of Palladium hydroxide on carbon (CAS Number: 12135-22-7, 20 wt. % loading (dry basis), matrix carbon) was gradually added to the dilute hydrochloric acid solution, during which the dilute hydrochloric acid solution should be constantly stirred and kept mildly heated (usually 60°C -80°C) to promote the reaction. During the process, the dilute hydrochloric acid solution was stirred and kept gently heated (usually at 60°C -80°C) to promote the reaction. After the reaction was completed, the reaction mixture was filtered with filter paper and funnel to separate the unreacted palladium hydroxide and carbon carrier to obtain the PcZC 4-solution. A certain amount of the PcZCZ^solution was added dropwise to acrylic acid (CAS Number: 79-10-7, 99%, liquid) to obtain acrylic acid active UV monomer.

[0151] Active Precursors

[0152] After obtaining the reactive UV monomer, the reactive precursors can be prepared according to the desired function, performance, and / or properties of the target device. A UV curing system (reactive UV inks or inks reactive to UV irradiation) may include monomers, polymers (pre-polymers), photoinitiators and some functional fillers. Depending on the performance and functionality of the target device, different active UV monomers, different polymers (prepolymers), photoinitiators and functional fillers can be mixed.

[0153] In some examples, the photoinitiators can be free radical photoinitiators such as TPO, Irgacure 184 and cationic photoinitiators such as Irgacure 369. In some examples, the prepolymers may contain a number of different materials with different properties and functionalities that can be cured under UV radiation, such as acrylates and epoxy polymers. In some examples, functional fillers may optionally be added to obtain active precursors with more properties. For example, ceramic powders may be dispersed in the mixture to obtain active ceramic precursors with both active and ceramic precursor functions. In some other examples, piezoelectric materials may be added to the mixture to obtain piezoelectric active precursors with both piezoelectric and catalytic activities. Various types of active precursors may be provided and used with the proposed manufacturing system 100, e.g., hydrogel-based active precursors, photosensitive resin-based active precursors, composite photosensitive ink-based active precursors.

[0154] Ceramic-Metal Composites

[0155] FIG. 11 schematically illustrates the proposed manufacturing system according to an embodiment manufacturing 3D-printed ceramic electronics by nano-active-anchor-induced non-invasive 3D selective metallization. Part (a) of FIG. 11 illustrates a material phase evolution during the fabrication of AI2O3-S and AI2O3-AS-Ni hybrids. Amorphous AI2O3and MgO particles were uniformly dispersed in a UV polymer comprising TPO, HDODA, and TMPTA to form AI2O3-UV-CPS, which was further converted to AI2O3-A-CPS by the addition of Pd2+ions. AI2O3-UV-CPS and AI2O3-A-CPS were fabricated into AI2O3-PS and AI2O3-APS hybrid structures, respectively, using multi-material DLP 3D printing. Both materials embedded AI2O3and MgO particles within the UV polymer crosslinked network, with Pd2+ions uniquely incorporated into AI2O3-APS. After integrated debinding and sintering in a high-temperature furnace, the hybrid structures transformed into AI2O3-S and AI2O3-AS. During this process, amorphous AI2O3particles densified into characteristic AI2O3ceramics, and the UV polymer network dissipated. In AI2O3-AS, Pd2+ions were reduced to metallic Pd, imparting catalytic activity for electroless plating. A homogeneous and dense Ni coating was selectively depositedon the surface of AI2O3-AS following treatment with an electroless Ni plating solution.

[0156] Part (b) of FIG. 11 illustrates the proposed nano-active-anchor-induced non-invasive 3D selective metallization process for 3D-printed ceramic electronics integrates multi-material DLP 3D printing, sintering, and selective electroless plating. Multi-material DLP 3D printing produces AI2O3-PS and AI2O3-APS hybrids, which transform into AI2O3-S and AI2O3-AS hybrids after sintering, culminating in AI2O3-based electronics after the selective electroless plating process.

[0157] Part (c) of FIG. 11 shows fabrication of arbitrarily complex ceramic-based electronic structures in accordance with embodiments of the present disclosure. Parts (c)(l) - (c)(l 11) illustrate the fabrication process of a lattice-structured AI2O3-based electronic device, progressing from AI2O3-PS and AI2O3-APS hybrids to AI2O3-S and AI2O3-AS-Ni hybrids. Parts (c)(VI) - (c)(X) showcase four representative structures of AI2O3-based electronic devices: (VI) a ceramic-based electrode device, (VII) a solid electronic device with a complex 3D shape, (VIII) a typical 3D electronic structure (3D-MID), and (IX) a microstructured ceramic electronic structure, demonstrating the high resolution achievable by the proposed manufacturing system.

[0158] Sample Preparation for Experiments

[0159] For experimental verification, AI2O3-UV-CPS and AI2O3-A-CPS were prepared and placed in material vats A and B respectively.

[0160] Alcohol was added to cleaning container A-1 and cleaning container B-1.

[0161] Sodium chloride solution was added to cleaning container A-2 and cleaning container B-2.

[0162] The articles were printed slice by slice. For the AI2O3-UV-CPS resin, the single layer exposure time (i.e. , exposure time per layer) was in a range from about 6 seconds to about 11 seconds, with each slice having a slice thickness of about 0.05 mm or about 0.1 mm. For AI2O3-A-CPS, the single layer exposure time (i.e., exposure time per layer) was in a range from about 8 seconds to about 12 seconds, with each slice having a slice thickness of about 0.05 mm or about 0.1 mm.

[0163] After multi-material slicing and multi-material 3D printing, the ceramic electronics yielded AI2O3-PS hybrids and AI2O3-APS hybrids. The hybrids may then undergo post-processing.

[0164] The 3D printed article underwent an integrated sintering process according to a pre-determined temperate profile over time. The sintering was carried out in a furnace, for example but not limited to a KJ-T1600-80 sintering furnace available from Kejia Vacuum Furnace (kejia-furnace.com).

[0165] Example of a Sintering Temperature Profile

[0166] One example of a sintering temperature profile includes an initial heating. The initial heating may include an increase from room temperature to about 800°C (degrees Celsius) at a rate of 1 °C per minute, with a 30-minute hold at every 100°C interval to promote uniform heat distribution and to reduce thermal stress in the structure of the article. This may be described as a relatively gradual increase in temperature.

[0167] The sintering temperature profile may further include a decrease in temperature over 600 minutes to 900 minutes (or approximately 3 hours) to release internal stresses that may have been generated during the initial heating.

[0168] The sintering temperature profile may further include a rapid temperature increase at a rate of 5°C per minute to a peak temperature of 1450°C. The article was held at the peak temperature of 1450°C for about 2 hours. This process was found to promote densification and sintering of the ceramic material.

[0169] The sintering temperature profile may further include a decrease in the temperature at a controlled rate of 10°C per minute. This controlled rate was found to be sufficiently low to prevent or deter thermal shock and cracking.

[0170] Both AI2O3 PA and AI2O3 APS were subject to the same thermal treatments described above. It was found that use of the sintering profile described above was useful for obtaining articles having an enhanced ceramic microstructure with few or minimal defects.

[0171] Selective Metallization Based on Electroless Plating

[0172] After the sintering described above, the sintered articles were cleaned and dried. The articles were then directly immersed in a chemical plating solution for selective electroless plating.

[0173] As one example, the plating bath composition and plating conditions of selective electroless nickel plating of some of the sintered articles are shown below.Table 2. Electroless Ni Plating Bath Composition and Operating Conditions

[0174] The reactions may be represented by the following equations.H2PO2 + H2O HP0 ~ + H++ 2H (1) H2PO2 + H++ 2H 2H2O + P (2)2H H2T (3) Ni2++ 2H Ni + 2H+(4)

[0175] As another example, the plating bath composition and plating conditions of selective electroless copper plating of some of the sintered articles are shown below.Table 3. Electroless Cu Plating Bath Composition and Operating Conditions>

[0176] As another example, the plating bath composition (silver plating solution) and plating conditions of selective electroless silver plating of some of the sintered articles are shown below.Tabl34. Electroless Ag Plating Bath Composition and Operating Conditions>

[0177] In the experiments an active precursor containing uniformly dispersed (or substantially uniformly dispersed) Pd2+ions were deposited in a predetermined three-dimensional topology on a ceramic substrate forming part of the 3D printed article. The exposed Pd2+ ions on the surface of the substrate were initially reduced to Pd. The palladium acts as a catalytically active metal nucleus. During the plating process, the electroless plating reaction was initiated in the areas where palladium was deposited. It was observed that there was hardly any deviation between the regions intended to be plated and the regions actually plated. The results were consistent with the idea that the palladium would be bound to the surface of an active precursor component, i.e. , the palladium would be prevented from migratingduring the electroless plating process. That is to say, the experimental results confirmed the usefulness of the present method to avoid overflow of the plating caused by catalyst migration during the electroless plating process. It is believed that the palladium nano-anchors catalyze the reduction of metal ions, selectively depositing metal in active areas, while no metal is deposited in inactive areas.

[0178] The reactions represented by the following equations describe the mechanism by which the reactive precursor catalyzes the directed deposition of Ni metal. In this process, hypophosphite was oxidized in solution to generate adsorbed hydrogen atoms on the surface of the substrate. Immediately thereafter, these hydrogen atoms reduce Ni ions in the solution. Because hydrogen atoms were adsorbed on the surface of the substrate, the reduced Ni became deposited on the same surface after five to 10 minutes to form a coating. In addition, because the Pd2+ ions were embedded on the surface of the active precursor portions of the substrate, there was no overflow or deviated deposition of the plating layer since there was no migration of the catalyst during the electroless plating process. This means that a time-consuming pretreatment of the substrate surface would not be required, the original surface morphology could be maintained, and yet a more accurate plating pattern could be achieved.H2PO2 + H2O HP0 ~ + H++ 2H (5) H2PO2 + H++ 2H 2H2O + P (6)2H - H2T (7) Ni2++ 2H Ni + 2H+(8)

[0179] The results of the electroless plating process were then rinsed with deionized water and dried to produce the desired ceramic electronic components.

[0180] Nano-Active-Anchor-Induced Non-invasive 3D Selective Metallization

[0181] FIG. 12Ato FIG. 12D present experimental verification of the 3D selective metallization mechanism driven by internal chemical reactions.

[0182] FIG. 12A shows XRD spectra of samples at different stages and regions and the formation of Pd nano-active anchors during processing. The samples show the main phase of a-AI2O3, and the metal diffraction peak appears only in the activezone, demonstrating that the metal deposition is consistent with the voxel zoning. Samples #1 and #3 exhibit y-AhOs characteristic peaks, indicating unsintered precursors, and samples #2 and #5 display a-AhOs peaks corresponding to the thermodynamically stable phase achieved after sintering. The Pd peaks in samples #3 to #7 indicate the transformation from ionic Pd2+to metallic Pd nanoparticles and subsequent coverage by No or Cu plating layers in samples #6 and #7.

[0183] FIG. 12B is a schematic diagram of the reduction deposition of Ni2+induced by Pd (0) nano-anchors in an electroless plating solution, emphasizing its autocatalytic effect and interfacial conversion pathway. Embedded Pd nanoparticles act as catalytic active sites for the reduction of Ni2+in the electroless plating bath, promoting selective deposition via electron transfer and H2PO2' decomposition.

[0184] FIG. 12C shows a full XPS spectra of different samples, combined with surface / internal contrast, show that Pd2+is converted to Pd (0) after sintering, triggering characteristic peaks of Ni or Cu in the metallized samples. In particular, Pd signals in samples #5 and #6 indicate successful reduction to Pd(0), and Ni and Cu signals confirm selective plating on Pd-activated surfaces.

[0185] FIG. 12D shows XPS spectra of typical elements, including Pd 3d, Ni 2p, Cu 2p, and O 1s, reveal the surface enrichment of Pd at the interface and the deposition signals of Ni and Cu are confined to the active zone.

[0186] FIG. 13 shows cross-sectional characterization and elemental anaylsis of the metal-Ni-ALOs ceramic interface fabricated via nano-active-anchor-induced electroless plating in accordance with embodiments of the present disclosure.

[0187] Part (a) of FIG. 13 is a SEM cross-sectional image of the interface showing the metal layer, intermediate layer, and ceramic layer. Part (b) of FIG. 13 is a magnified view of the interface highlighting the distinct transition regions and Ni and Pd migration trends. Part (c) of FIG. 13 shows a multi-elemental mapping of Al, Pd, and Ni, illustrating their spatial distribution across the interface. Part (d) of FIG.13 shows element-specific EDS mapping: Part (d)(l) shows Al element, uniformly distributed in the ceramic layer; part (d)(ll) shows Pd element, enriched in the intermediate layer, indicating catalytic activation; part (d)(lll) shows Ni element, predominantly in the metal layer with partial diffusion into the intermediate layer.Part (e) of FIG. 13 shows the elemental composition in the ceramic, intermediate, and metal layers, demonstrating Pd enrichment (19.2-23.8 wt%) in the intermediate layer and limited Ni diffusion (0.2-4.6 wt%). Part (f) of FIG. 13 is a schematic representation of Ni and Pd migration trends, elucidating the formation of a chemically and structurally robust intermediate layer that enhances the metalceramic interface adhesion and functionality.

[0188] Multi-material 4D Printing and 3D Patterned Metallization Enables Smart Architectures

[0189] It can be appreciated from the foregoing description that the proposed manufacturing system 100 include an electrode subsystem (some embodiments also referred to as an Al-controlled dual 3D smart electrode system), a scraper subsystem (also referred to as an integrated dynamic scraper system), an auxiliary subsystem 120 (also referred to as a modular multi-material switching system), and optionally a co-sintering subsystem 140 (also referred to as an integrated ceramic co-sintering system).

[0190] The electrode subsystem is configured for executing in-situ electroplating. The electrode subsystem may include two independent electrodes, each with at least three degrees of freedom (3 DOF) in which the positioning and path optimization are controllable by Al-drive algorithms using real-time sensor data.

[0191] The scraper subsystem may be a mechanically actuable scraper integrated as part of the host system. The scraper subsystem includes a scraper that is configured to reciprocate across a part's surface during in-situ electroplating or electrochemical polishing to improve deposition uniformity and electrolyte circulation.

[0192] The auxiliary subsystem 120 may have a system architecture that is based on modular "intelligent material boxes" ("boxes" in the present disclosure may be understood to refer to "containers"). Each container can hold a volume of a material. Each container may be integrated with a pump (e.g., a peristaltic pump) and connected via a fluidic network to enable automated and precise switching between a plurality of materials. Each of the plurality of materials is disposed in a respective container. The materials may include resins, plating solutions, and cleaning solutions.

[0193] The co-sintering subsystem 140 may be configured to operate a thermal cycle that co-sinters a hybrid ceramic green body. The proposed manufacturing system 100 enables a method of mass manufacturing multi-material devices that involves co-sintering to both densify ceramic regions of a 3D printed part as well as form nano-anchors at the surface of the 3D printed part to facilitate subsequent metallization.

[0194] The method may be described as involving a non-invasive metallization process for ceramics. The method may include subjecting a 3D printed hybrid part to a co-sintering process. For example, the 3D hybrid part may include an inert region (a region that has been 3D printed using an inert material) and a Pd2+-doped ceramic region (another region that has been 3D printed using a Pd2+-doped ceramic slurry). The single thermal process of co-sintering simultaneously densifies the ceramic matrix and causes the in-situ thermal reduction of Pd2+ions into surface-concentrated Pd(0) nano-anchors without the need for external chemical reductants.

[0195] The proposed manufacturing system 100 is highly flexible in the types of products that can be mass produced thereby.

[0196] For example, the proposed manufacturing system 100 may be used to carry out a method of hybrid additive manufacturing method in which a sacrificial resin (e.g., alkaline-soluble or wax-loss resin) is co-printed within the same layer as an active precursor to form a mold. The 3D printing may be followed by in-situ plating and subsequently followed by a removal of the sacrificial resin. The resulting article can be a freestanding or hollow pure metal structure.

[0197] For example, the proposed manufacturing system 100 may be configured to manufacture a sintered, monolithic ceramic structure characterized by a chemically bonded intermediate layer at a metal-ceramic interface, in which the interface contains Pd(0) nano-anchors. The nano-anchors are in highly concentration at the surface of the structure or part ("enriched at the surface") and can act as both catalytic centers and diffusion barriers, enabling a robust bond between a metal plating and the ceramic structure.

[0198] The proposed system and method also work well for fabricating multimaterial "four-dimensional" (4D) printed devices with 3D patterned metallization.

[0199] FIG. 14A to FIG. 14F illustrate 4D electronic structures with topology of 3D TSMP / M hetero in terface that can be manufactured in accordance with embodiments of the present disclosure.

[0200] FIG. 14A illustrates 4D electronics with various complex shapes and 3D programming patterns of the TSMP / M heterointerface, in which (I) fully programmed metamaterial parts; (II) plastic-metal composite structures with three metal topologies, obtained by using the deformable feature of AP-SMR; (III) 4D electronic structure constructed by 3D programming of the TSMP / M heterointerface on rigid resin; (IV) is a 4D electronic pyramid structure, consisting of a light-emitting diode (LED) circuit developed on rigid resin and four extendable shells.

[0201] FIG. 14B illustrates a bone-meat unfolded structure wrapped in 2D metamaterials with transparent flexible polymers.

[0202] FIG. 14C illustrates finger robots implemented through various technical routes.

[0203] FIG. 14D illustrates 4D electronic structure with micro actuators inside the part; by programming the AP-SMR mechanical gripper inside the transparent hollow ball with the TSMP / M heterointerface, the internal micro actuator can be controlled offline.

[0204] FIG. 14E shows an example of a 4D electronic smart device. With doublelayer TSMP / M heterointerface's 4D electronic intelligent mechanical claw integrates drive function and strain sensing function; among them, the front pattern can radiate a thermal field to drive the mechanical claw (UV-SMR substrate) to deform after being energized.

[0205] FIG. 14F shows a 4D electronic intelligent mechanical gripper deformation process, in which the back metal will undergo a change in resistance, so as to achieve strain measurement.

[0206] Preparation of Functional Polymers Formulations and Solutions

[0207] Preparation of a Pd2+-based active solution

[0208] At room temperature (e.g., 26°C), an active precursor was prepared by dissolving 15.4 g of NH4CI in 50 ml of deionized water, to which 270 mg PdC was added and dissolved with agitation. This yielded 50 ml of a saturated activation solution containing 0.2 wt% Pd2+. After allowing this solution to stand for a while, a12ml portion of the upper and clear part of the solution was used in subsequent steps described below.

[0209] Preparation of UV-SMR

[0210] 15g of PCL granules was added to a clean, closeable beaker. 85g of chloroform was added with a glass dropper. The beaker was sealed and placed in a dark environment (at room temperature) for 2 hours in a dissolving step to allow the contents to dissolve naturally. After the dissolving step, the contents of the beaker was stirred with a glass rod to obtain 100 ml of a transparent colloidal PCL solution.

[0211] The PCL solution and an ABS-like photosensitive resin were mixed together to obtain UV-SMR. For purposes of the experiments conducted, various samples of the UV-SMR were obtained using different volume ratios of PCL to photosensitive resin, 0:100, 10:90, 20:80, 30:70, 40:60, and 50:50. For example, some samples of UV-SMR were obtained by mixing PCL and ABS-like photosensitive resin in a volume ratio of 20:80.

[0212] Preparation of AP-SMR

[0213] 38 ml of UV-SMR was transferred to a vessel with a magnetic stirrer spinning at 1000 rpm, and 12 ml of the activation solution was added dropwise. Subsequently, the mixture was stirred for another 30 minutes at 1200 rpm to obtain 50 ml of an active precursor solution (in which the concentration of Pd2+ was approximately 0.058 wt%).

[0214] Preparation of a Cleaning Solution

[0215] A cleaning solution was prepared by mixing 65% ethanol and 35% chloroform solution.

[0216] Stability Tests of the Prepared PCL solution, UV-SMR, and AP-SMR

[0217] Stability tests were conducted to test the stability of the prepared PCL solution, the UV-SMR, and the AP-SMR (for the sake of brevity, these will be referred to as "the prepared materials"). The freshly prepared materials were uniform in color. The prepared materials were placed in a dark constant temperature (26°C) drying oven for static testing. The prepared materials were removed from the drying over at hourly intervals and images (photographs) were taken. The prepared materials were observed after one hour, two hours, three hours, fourhours, five hours, six hours, seven hours, and eight hours in the drying oven, respectively. None of the prepared materials showed significant precipitation or material system chaos, showing positive stability. The 3D printing process is generally within eight hours. That is to say, the observed results indicated that the prepared materials exhibited stability sufficient for precision manufacturing and the purposes described herein. In addition, the prepared materials were found to be stable for more than 16 hours.

[0218] Polymer Flow Deformation (Viscosity) Analysis

[0219] The factors affecting the viscosity of the UV-SMR and AP-SMR include the PCL content and the Pd2+-AS content. As either the PCL content or the Pd2+-AS content increases, the viscosity of the UV-SMR or AP-SMR was found to increase. In comparison to the influence of the PCL content, the influence of Pd2+-AP on the viscosity of the UV-SMR or the AP-SMR was relatively small. With an increase in PCL content, the viscosity of the UV-SMR and the AP-SMR increased from the initial 225 MPa s to 500-750 MPa s. The UV-SMR and the AP-SMR demonstrated rheological properties and photocuring parameters suitable for processability as UV photopolymers.

[0220] Measurement of Young's Modulus

[0221] Using commercially available benchtop tensile and compression testing machines, samples of the UV-SMR and AP-SMR were subjected to tensile tests to obtain load-displacement relationship data, from which a slope of the corresponding graph (tensile curves) could be obtained and substituted into the following Young's modulus formula to calculate the Young's modulus of the sample.

[0222] In the experiments conducted, the samples were in the form of cuboids of dimensions 50 mm (length) x 50 mm (width) x 3 mm (thickness). The samples were supported at two support points 3 cm apart.

[0223] Since there are variations in the Young's modulus at different temperatures, the measurements were taken at different temperatures. For example, measurements were taken immediately after removal of the sample and fixture. Measurements were also taken after holding samples in a heated pot ofwater at the specified temperature for 10 minutes (after the samples were sealed from water). The statistical average of each set of data was taken as the final result of Young's modulus for each of the prepared materials.

[0224] Plating Conditions for 4DP / 3D Metallized Parts

[0225] Electroless Ni Plating

[0226] The same electroless Ni plating bath (nickel plating solution) composition and operating conditions described above for making ceramic electronics (Table 1 ) can be used for making multi-material 4D printed / 3D patterned metallized smart devices.

[0227] The active precursor was printed at selected portions of the substrate. Upon immersion of the substrate in the plating bath, the exposed Pd2+ ions on the surface of the substrate were initially reduced to Pd monomers by the reducing agent (sodium hypophosphite monohydrate). The Pd monomers then served as catalytically active metal nuclei, initiating the electroless plating in the selected portions (e.g., in specific microscopic regions) and thereby achieving targeted Ni metal deposition.

[0228] Electroless Cu Plating

[0229] The process of electroless copper plating is similar to that of electroless nickel plating. Table 4 below shows the main components of the plating bath used in the experiments. The pH of the copper plating solution or copper plating bath was adjusted to 12.2 by adjusting the relative amounts of sulphuric acid and sodium hydroxide. Eguations (10) and (11) describe the reaction mechanism of the electroless copper plating. Copper ions undergo a reduction reaction under the catalytic effect of palladium, thereby depositing metal that is attached to the surface of the substrate.Table 5. Electroless Cu Plating Bath Composition and Operating Conditions for 4DP substrates

[0230] The reactions may be represented by the following equations.2HCH0 + 4OH~ -> 2HC0CT + 2H2O + 2e~ + H2? (10) Cu2++ 2e~ Cu (11)

[0231] Electroless Au Plating

[0232] Au can be selectively deposited on AP-SMR, replacing Ni, to form a gold metal layer of an TSMP / M heterointerface. Gold was deposited onto the nickel surface via an immersion (displacement) process in which the less noble nickel was oxidized to provide electrons that facilitate reduction of the more noble gold in solution. The electroless gold plating solution (plating bath composition) and operating conditions, as well as the equations describing the process, are shown below.Table 6. Electroless Au Plating Bath Composition and Operating Conditions for 4DP substratesNi ^ Ni2++ 2e~ (12) 2Au++ 2e~ ^ 2Au (13)

[0233] Various Embodiments

[0234] According to various embodiments of the present disclosure, a manufacturing system includes: a host subsystem, the host subsystem including: a vat; and a build platform configured to be disposed in the vat; and a computing device, the computing device being configured to execute instructions stored in a memory, the computing device being configured to control a 3D printing process and a selective metallization process of a part, the part being on the build platform during the 3D printing process and selective metallization process.

[0235] Optionally, the computing device is configured to control: delivering a first selected material and a second selected material from respective ones of a plurality of containers at different times to the host subsystem to 3D print respective regions of the part in the 3D printing process; and performing one or both of an electroless plating process and an electrolytic plating process in the vat, in the selective metallization process.

[0236] Optionally, the computing device is configured to control: delivering a plating solution from one of the plurality of containers to the vat in the selective metallization process; and performing the selective metallization process in-situ with the part being in a same position relative to the build platform in the 3D printing process and in the selective metallization process.

[0237] The manufacturing system may further include: a positioning mechanism, the positioning mechanism being configured to controllably position a printing cassette relative to the build platform and to controllably position the build platform relative to the vat; and a multi-material switching subsystem, the multi-material switching subsystem providing a fluidic pathway from each of the plurality of containers to the printing cassette.

[0238] Optionally, the printing cassette includes: an inlet, the inlet being in fluidic communication with the multi-material switching subsystem, the multi-material switching sub-system being configured to deliver only one material to the printing cassette via the inlet at any one time; and a bottom, the bottom being shaped with a bevel surface leading to an outlet via which the material in the printing cassette delivered towards the build platform or the vat.

[0239] In some embodiments, the multi-material switching subsystem is configured to deliver a cleaning solution between delivering the first selectedmaterial and the second selected material, the cleaning solution being obtained from one of the plurality of containers, the cleaning solution being delivered to flush at least the multi-material switching subsystem and the printing cassette.

[0240] The manufacturing system may further include: a pair of electrodes; and an actuator subsystem, the actuator subsystem being coupled to the pair of electrodes and configured to controllably position each of the electrodes independently of one another, wherein the selective metallization process includes: performing the electroless plating process to form at least two spaced apart metallized areas on the part; controllably bringing the pair of electrodes into electrical contact with respective ones of the metallized areas; and performing the electrolytic plating process.

[0241] Optionally, the pair of electrodes are actuable between a rest state and an operational state, the pair of electrodes in the retracted state being in spaced apart position relative to part and the pair of electrodes in an operational state are in contact with the part, and wherein the pair of electrodes are in the rest state during the 3D printing process and the electroless plating process, and wherein the pair of electrodes are in the operational state during the electrolytic plating process.

[0242] In some embodiments, the computing device is configured with an artificial intelligence (Al) model, the Al model comprising: a data acquisition and transmission module, the data acquisition and transmission module being configured to capture a plurality of real-time spatial position data of each of the pair of electrodes and geometric features of primary auxiliary structures of a target part; a model training module, the model training module being a You Only Look Once (YOLO) deep learning network configured to output positional data based on data acquired from the data acquisition and transmission module, the positional data including real-time trajectory coordinates of each of the pair of the electrodes and corresponding locations of the primary auxiliary structures of the target part; and a path planning and control execution module, the path planning and control execution module being configured to use the positional data to controllably position each of the pair of electrodes in the selective metallization process.

[0243] The manufacturing system may further include a scraper, wherein the scraper is configured to be controllable by the computing device and mechanicallyactuable to reciprocate across a surface of the part during the selective metallization process.

[0244] In some embodiments, the computing device may be further configured to control an electrochemical polishing of the part, the electrochemical polishing being performed with the part being on the build platform.

[0245] Optionally, the manufacturing system further includes a co-sintering module.

[0246] In various embodiments, the selective metallization process comprises, in a same plating solution, metallizing a first region in preference over a second region, the first region being 3D printed using the first selected material and the second region being 3D printed using the second selected material.

[0247] In another aspect, various embodiments include a method of manufacturing implemented by a computer configured to execute instructions stored in a memory, the method including: performing a 3D printing process and a selective metallization process, wherein a part is 3D printed by the 3D printing process and one or more selected areas of the part are electroplated by the selective metallization process, the part being supported by a same build platform throughout the 3D printing process and the selective metallization process.

[0248] The method of manufacturing may further include: in the 3D printing process, delivering a first selected material and a second selected material at different times from respective ones of a plurality of containers to a host subsystem via a multi-material switching subsystem and a printing cassette, the plurality of containers being configured to contain a corresponding plurality of materials, the multi-material switching subsystem being controlled by the computing device and configured to provide a fluidic pathway from each of the plurality of containers to the printing cassette.

[0249] In various embodiments, the method of manufacturing may further include projecting an ultraviolet (UV) light from an ultraviolet light source towards the part on the build platform to cure the first selected material and the second selected material.

[0250] The selective metallization process may include one or both of an electroless plating process and an electrolytic plating process.

[0251] The selective metallization process may include: delivering a plating solution from one of the containers to a vat; and performing the selective metallization in-situ, the part being in a same position relative to the build platform in the of 3D printing process and in the selective metallization process.

[0252] The selective metallization process may include, in a same plating solution, metallizing the first region in preference over the second region, the first region being 3D printed using the first selected material and the second region being 3D printed using the second selected material.

[0253] In various embodiments of the method of manufacturing, the first region contains a catalyst configured to promote the metallization process, and the second region does not contain the catalyst.

[0254] The method of manufacturing may further include displacing the build platform relative to the vat via a positioning mechanism controlled by the computing device, the positioning mechanism being configured to controllably position the printing cassette relative to build platform and to controllably position the build platform relative to the vat.

[0255] Optionally, the first selected material and the second selected material are reactive to UV irradiation by the UV light source to respectively form a first region of the part and a second region, and only one of the first selected material and the second selected material includes an active precursor containing palladium ions.

[0256] Optionally, the first selected material includes an active precursor containing palladium ions and is used in the 3D printing stage to form a first region of the part, and the palladium is preferentially deposited in the first region in the electroless plating process.

[0257] Optionally, the first region plated with palladium is selected to be in electrical contact with one of the pair of electrodes in the electrolytic plating process.

[0258] Optionally, the second selected material is free of the active precursor and is used in the 3D printing process to form a second region of the part, and the second region remains unmetallized after the selective metallization process.

[0259] Optionally, at least one of the plurality of containers is provided with a UV reactive ink containing a palladium-doped UV reactive monomer and aphotoinitiator, the UV reactive ink optionally containing one or more functional fillers and / or polymers.

[0260] Optionally, at least one of the plurality of containers is provided with a UV reactive ink containing a palladium-doped UV reactive monomer and a photoinitiator, the UV reactive ink further containing aluminum oxide.

[0261] Optionally, at least one of the plurality of containers is provided with a UV reactive ink containing a palladium-doped UV reactive monomer and a photoinitiator, the UV reactive ink further containing a shape memory polymer.

[0262] Optionally, the plating solution delivered to the vat for the electroless plating process is one of a gold plating solution, a silver plating solution, a copper plating solution, and a nickel plating solution.

[0263] All examples described herein, whether of apparatus, methods, materials, or products, are presented for the purpose of illustration and to aid understanding and are not intended to be limiting or exhaustive. Modifications not involving inventive effort may be made by one of ordinary skill in the art without departing from the scope of the claimed invention.

Claims

CLAIMS1. A manufacturing system comprising:a host subsystem, the host subsystem including:a vat; anda build platform configured to be disposed in the vat; anda computing device, the computing device being configured to execute instructions stored in a memory, the computing device being configured to control a 3D printing process and a selective metallization process of a part, the part being on the build platform during the 3D printing process and selective metallization process.

2. The manufacturing system as recited in claim 1,wherein the computing device is configured to control: delivering a first selected material and a second selected material from respective ones of a plurality of containers at different times to the host subsystem to 3D print respective regions of the part in the 3D printing process; andperforming one or both of an electroless plating process and an electrolytic plating process in the vat, in the selective metallization process.

3. The manufacturing system as recited in claim 2, wherein the computing device is configured to control:delivering a plating solution from one of the plurality of containers to the vat in the selective metallization process; andperforming the selective metallization process in-situ with the part being in a same position relative to the build platform in the 3D printing process and in the selective metallization process.

4. The manufacturing system as recited in claim 2, further comprising:a positioning mechanism, the positioning mechanism being configured to controllably position a printing cassette relative to the build platform and to controllably position the build platform relative to the vat; anda multi-material switching subsystem, the multi-material switching subsystem providing a fluidic pathway from each of the plurality of containers to the printing cassette.

5. The manufacturing system as recited in claim 4, wherein the printing cassette comprises:an inlet, the inlet being in fluidic communication with the multi-material switching subsystem, the multi-material switching sub-system being configured to deliver only one material to the printing cassette via the inlet at any one time; anda bottom, the bottom being shaped with a bevel surface leading to an outlet via which the material in the printing cassette delivered towards the build platform or the vat.

6. The manufacturing system as recited in claim 4 or claim 5, wherein the multimaterial switching subsystem is configured to deliver a cleaning solution between delivering the first selected material and the second selected material, the cleaning solution being obtained from one of the plurality of containers, the cleaning solution being delivered to flush at least the multi-material switching subsystem and the printing cassette.

7. The manufacturing system as recited in any one of claims 2 to 6, further comprising:a pair of electrodes; andan actuator subsystem, the actuator subsystem being coupled to the pair of electrodes and configured to controllably position each of the electrodes independently of one another,wherein the selective metallization process comprises:performing the electroless plating process to form at least two spaced apart metallized areas on the part;controllably bringing the pair of electrodes into electrical contact with respective ones of the metallized areas; andperforming the electrolytic plating process.

8. The manufacturing system as recited in claim 7, wherein the pair of electrodes are actuable between a rest state and an operational state, the pair of electrodes in the retracted state being in spaced apart position relative to part and the pair of electrodes in an operational state are in contact with the part,and wherein the pair of electrodes are in the rest state during the 3D printing process and the electroless plating process, and wherein the pair of electrodes are in the operational state during the electrolytic plating process.

9. The manufacturing system as recited in claim 7 or claim 8, wherein the computing device is configured with an artificial intelligence (Al) model, the Al model comprising:a data acquisition and transmission module, the data acquisition and transmission module being configured to capture a plurality of real-time spatial position data of each of the pair of electrodes and geometric features of primary auxiliary structures of a target part;a model training module, the model training module being a You Only Look Once (YOLO) deep learning network configured to output positional data based on data acquired from the data acquisition and transmission module, the positional data including real-time trajectory coordinates of each of the pair of the electrodes and corresponding locations of the primary auxiliary structures of the target part; anda path planning and control execution module, the path planning and control execution module being configured to use the positional data to controllably position each of the pair of electrodes in the selective metallization process.

10. The manufacturing system as recited in any one of claims 2 to 9, further comprising a scraper, wherein the scraper is configured to be controllable by the computing device and mechanically actuable to reciprocate across a surface of the part during the selective metallization process.

11. The manufacturing system as recited in any one of claims 2 to 10, wherein the computing device is further configured to control an electrochemical polishing of the part, the electrochemical polishing being performed with the part being on the build platform.

12. The manufacturing system as recited in any one of claims 2 to 11, further comprising a co-sintering module.

13. The manufacturing system as recited in claim 3, wherein the selective metallization process comprises, in a same plating solution, metallizing a first region in preference over a second region, the first region being 3D printed using the first selected material and the second region being 3D printed using the second selected material.

14. A method of manufacturing implemented by a computer configured to execute instructions stored in a memory, the method comprising:performing a 3D printing process and a selective metallization process, wherein a part is 3D printed by the 3D printing process and one or more selected areas of the part are electroplated by the selective metallization process, the part being supported by a same build platform throughout the 3D printing process and the selective metallization process.

15. The method of manufacturing as recited in claim 14, further comprising: in the 3D printing process, delivering a first selected material and a second selected material at different times from respective ones of a plurality of containers to a host subsystem via a multi-material switching subsystem and a printing cassette, the plurality of containers being configured to contain a corresponding plurality of materials, the multi-material switching subsystem being controlled by the computing device and configured to provide a fluidic pathway from each of the plurality of containers to the printing cassette.

16. The method of manufacturing as recited in claim 15, further comprising projecting an ultraviolet (UV) light from an ultraviolet light source towards the part on the build platform to cure the first selected material and the second selected material.

17. The method of manufacturing as recited in claim 15, wherein the selective metallization process comprises one or both of an electroless plating process and an electrolytic plating process.

18. The method of manufacturing as recited in any one of claims 15 to 17, wherein the selective metallization process comprises: delivering a plating solution from one of the containers to a vat; and performing the selective metallization in-situ, the part being in a same position relative to the build platform in the of 3D printing process and in the selective metallization process.

19. The method of manufacturing as recited in claim 18, wherein the selective metallization process comprises, in a same plating solution, metallizing the first region in preference over the second region, the first region being 3D printed using the first selected material and the second region being 3D printed using the second selected material.

20. The method of manufacturing as recited in claim 19, wherein the first region contains a catalyst configured to promote the metallization process, and wherein the second region does not contain the catalyst.

21. The method of manufacturing as recited in any one of claims 15 to 20, further comprising displacing the build platform relative to the vat via a positioning mechanism controlled by the computing device, the positioning mechanism being configured to controllably position the printing cassette relative to build platform and to controllably position the build platform relative to the vat.

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