Method for enhanced adhesion across fully encapsulated metal-ceramic interfaces in additive manufacturing processes

Abstract

Methods are disclosed for integrating a temperature-sensitive electronic component securely into an additively manufactured metal structure, without damaging the component due to heat generated by the additive manufacturing process. The methods include providing a metal base, constructing an attachment site in the metal base for securing the sensitive electronic component, securing the component in the attachment site, coating the component with a ceramic slurry, heating the slurry until dry, depositing a layer of metal onto the ceramic by a cold spray process, and continuing the additive manufacturing process at a temperature between about 1000 and about 2000 °C, thereby embedding the electronic component into the additively manufactured metal structure.

Description

105095-201METHOD FOR ENHANCED ADHESION ACROSS FULLY ENCAPSULATED METALCERAMIC INTERFACES IN ADDITIVE MANUFACTURING PROCESSESCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to commonly assigned Provisional Applications No. 63 / 749,107, filed January 24, 2025, and 63 / 966,612, filed January 23, 2026, the disclosures of which are hereby incorporated by reference in their entireties.BACKGROUND

[0002] Metal additive manufacturing (AM) processes typically require high process temperatures in the range of 1000 to 2000 °C. Integrating temperature-sensitive electronic components such as sensors and sensor arrays into metal components formed by high temperature metal AM requires protecting such components from the high heat generated by the high temperature metal AM. Previous attempts to provide protective ceramic layers to shield such sensitive electronic components have suffered from poor adhesion between the metal and ceramic interfaces. In addition, wire-arc additive manufacturing (WAAM) of a metal surface over a ceramic layer requires establishing electrically conductive paths over the ceramic layer. As a consequence, there remains a critical need for a manufacturing method that enables reliable, thermally safe, and electrically compatible integration of sensors and other sensitive components within metal structured produced by high-temperature metal AM processes such as WAAM.

[0003] Needed is a method of embedding sensors and other temperature-sensitive electronic components during high temperature metal additive manufacturing, while maintaining electrically conductive paths.SUMMARY

[0004] This disclosure addresses the challenges of interface adhesion, thermal protection, and electrical functionality, enabling reliable embedding of functional electronics and sensors within additive manufacturing processes.

[0005] A method is disclosed of embedding an electronic component into a metal structure of an electronic device. According to some embodiments, the method includes the steps of 1) preparing a surface of a metal base with an attachment site for securing the electronic component on the metal base, the metal base comprising a first metal, 2) attaching133060352.1105095-201the electronic component to the attachment site, 3) coating the electronic component with a ceramic slurry, 4) heating the ceramic slurry until dry, 5) depositing a layer of a second metal onto a surface of the ceramic slurry using a cold spray process at relatively low temperatures between about 300 °C and about 400 °C and 6) depositing a third metal by a first high temperature additive manufacturing process at a temperature of between about 1000 °C and about 1300 °C to cover the second metal and at least a portion of the metal base, thereby embedding the electronic component in the electronic device.

[0006] According to some embodiments, preparing the surface includes smoothing the surface to reduce roughness. According to some embodiments, the attachment site is formed by creating a localized region of micro-roughness on the surface of the smoothed metal base. According to other embodiments, the attachment site is formed by subtractive manufacturing of a sensor cavity through the surface of the metal base.

[0007] According to exemplary methods, the layer of the second metal layer is between about 0.1 mm and about 1 mm thick. For some exemplary methods, the electronic component is attached to the attachment site with an adhesive bonding agent. For some such methods, the adhesive bonding agent is an epoxy compound.

[0008] According to some embodiments, the electronic component is encased in a polymer. For some embodiments, the metal base is formed by a second high temperature additive manufacturing process by depositing the first metal at a temperature between about 1000 °C and about 1300 °C. For some such embodiments, the first high temperature additive manufacturing process is the same as the second high temperature additive manufacturing process.

[0009] According to some embodiments, the first and optionally the second high temperature additive manufacturing processes are selected from the group consisting of wirearc additive manufacturing (WAAM), laser powder bed fusion (LPBF), directed energy deposition (DED), and combinations thereof. For some embodiments, the second high temperature additive manufacturing process is selected from the group consisting of wire-arc additive manufacturing (WAAM), laser powder bed fusion (LPBF), directed energy deposition (DED), and combinations thereof.

[0010] For some exemplary methods, the low temperature process is a cold spray process. For some exemplary methods, the first high temperature additive manufacturing process is WAAM.

[0011] According to some embodiments of the method, the electronic component is a sensor. For some such embodiments, the sensor is selected from the group consisting of a 233060352.1105095-201thermocouple, a strain gauge, an accelerometer, a radio-frequency identification (RFID) sensor, a surface acoustic wave sensor, and combinations thereof.

[0012] According to some embodiments, an electronic device is disclosed, the electronic device including a metal base comprising a first metal, one or more electronic components attached to an attachment sit on a surface of the metal base, a ceramic layer covering each electronic component of the one or more electronic components, a second metal layer at least partially interpenetrating the ceramic layer to form an interpenetrated boundary region extending about 100 pm to about 200 pm into the ceramic layer, the interpenetrated boundary region forming a bond between the second metal layer and the ceramic layer, and a third metal covering the second metal layer and at least a portion of the metal base.

[0013] For some embodiments, the attachment site is localized on a region of microroughness on the surface of themetal base. For other embodiments, the attachment site is a sensor cavity in the surface of the metal base.

[0014] For some such embodiments, one or more of the one or more electronic components is a sensor. According to some embodiments, the one or more electronic components form a sensor network comprising multiple sensors. For some such metal structures, each sensor of the multiple sensors is selected from the group consisting of a thermocouple, a strain gauge, an accelerometer, a piezoelectric sensor, a radio-frequency identification (RFID) sensor, a surface acoustic wave sensor, and combinations thereof.

[0015] According to some embodiments, the electronic device is manufactured using the exemplary methods described above.BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Fig. 1 provides an illustrative embodiment of a method of embedding a sensor element in a metal structure using WAAM.

[0017] Fig. 2 shows a metal base formed by WAAM, with a sensor cavity prior to attachment of a sensor in the cavity.

[0018] Fig. 3 shows the metal base of Fig. 2 with a sensor attached within the sensor cavity.

[0019] Fig. 4 shows the metal base and attached sensor of Fig. 3 after coating of the attached sensor with a ceramic paste.

[0020] Fig. 5 shows the ceramic paste coated sensor of Fig. 4, now dried and coated with a cold-spray metal film.333060352.1105095-201

[0021] Fig. 6 shows the structure of Fig. 5 following embedding of the sensor by WAAM to form an additive metal manufactured structure with embedded sensor.

[0022] Fig. 7A shows an exploded view of the structure in Fig. 6, for which the sensor is attached by epoxy.

[0023] Fig. 7B shows the sensor element with epoxy, ceramic, and metal coating as embedded in the additive manufactured structure of Fig. 7 A.

[0024] Fig. 8 shows an exemplary a two-layer sensor network, with sensors embedded by the methods of this disclosure.

[0025] Fig. 9 shows a method of embedding sensor elements in a metal structure comprising a sensor network. For this method, no sensor cavity is required; the sensor attachment site is formed by creating a localized region of micro-roughness on a surface of a metal base.DETAILED DESCRIPTION

[0026] Some embodiments of the disclosed technology provide a method of producing fully encapsulated metal-ceramic interfaces with enhanced adhesion and electrical conductivity. According to some such embodiments, following attachment of a temperaturesensitive electronic component such as a sensor onto a surface or into a cavity of a metal base, the component is coated with a green body ceramics paste, followed by coating the green body ceramics paste with a thin layer of metal applied to form a metal film by a coldspraying process. Following cold-spraying the metal film, a high temperature additive manufacturing process such as WAAM, laser powder bed fusion (LPBF), or directed energy deposition (DED), is carried out in order to form a metal structure having the temperaturesensitive electronic component embedded therein. The cold-spray process is optimized so that the metal film interpenetrates the green ceramic layer, while also serving as an electrically conductive metal layer for the follow-on high temperature metal AM deposition. During the high temperature metal AM deposition melting of the metal film and the effective sintering of the green body ceramic layer forms an exceptionally strong bond between the deposited metal AM layer and the ceramic layer, while the ceramic layer protects the temperaturesensitive electronic component from damage due to excessive heat. This in situ sintering feature allows for the use of minimal ceramic thickness values for the heat shield, thereby minimizing the parasitic effects to the overall metal AM structure.433060352.1105095-201

[0027] Embodiments of the present technology offer the following unique advantages over existing approaches:1) Design of tailored green-body ceramic slurry for sensor packaging.Various high-temperature ceramic slurries can be utilized to suit specific applications.2) Selective surface metallization of ceramic slurry using the Cold Spray Additive Manufacturing (CSAM) - a solid-sate process where high-speed metal particles bond on impact, forming a dense metal layer on the ceramic without melting. CSAM enhances adhesion strength between the ceramic and metal particles while establishing an electrically conductive pathway on the ceramic surface.3) Versatility in feedstock powders and ability to achieve improved metal layer thickness onto the ceramic surface using CSAM process settings.4) Seamless compatibility with high-temperature AM processes (viz., LPBF, DED, WAAM) to enable resumption of metal AM on the as-metallized ceramics layer.5) Minimized defects (viz., porosity, residual stress, distortion, delamination, cracking) in the resulting AM build).

[0028] Building on these advantages, some embodiments have potential applications in sensor packaging, embedded sensors, electronics, printed circuit boards, and ceramic compounds within AM builds. As shown in Fig. 1, an exemplary process comprises six steps to embed functional sensors or other sensitive electronic components into a 3D metal AM build.

[0029] Step 1: A metal base is fabricated. According to some embodiments, the metal base is fabricated using a high temperature additive manufacturing process. Exemplary processes include wire-arc additive manufacturing (WAAM), laser powder bed fusion (LPBF), and directed energy deposition (DED).

[0030] Step 2: As exemplified in Fig. 2, an attachment site in the form of a sensor cavity 115 is machined into the metal base 110. Alternatively, as exemplified in Fig. 9, and discussed below, the surface is prepared for attachment, for example by machining a surface 910 and sandblasting an attachment region 920, without creating a sensor cavity 115.

[0031] Step 3: A sensor 120 is attached to an attachment site. As exemplified in Fig.3, and as detailed in Figs. 7A and 7B, the attachment site may comprise a sensor cavity 115. Alternatively, as discussed below, and as exemplified in Fig. 9, the attachment site may be a localized region of micro-roughness 920 on the surface of the metal base 110. An exemplary process involves attaching the sensor 120 with an adhesive bonding agent 145, for example with a layer of epoxy. As shown in Figs. 3 and 7A, according to some embodiments, the 533060352.1105095-201sensor is connected to an electrode / wiring 125, providing the means for a connection to a circuit.

[0032] Step 4: As exemplified in Fig. 4, the sensor 120 is coated with a layer of a green body ceramic paste 130. In exemplary processes, the ceramic paste 130 is tailored to the specific application.

[0033] Step 5: As exemplified in Fig. 5, a thin metal layer 135 is deposited by a cold spray process onto the ceramic paste 130. During this process, high speed metal particles bond to the ceramic paste 130 without melting, interpenetrating the layer formed by the ceramic paste 130, while establishing an electrically conductive pathway on the ceramic surface. According to an exemplary embodiment, the thin metal layer 135 has a thickness of between about 0.1 mm and about 1.0 mm.

[0034] Step 6: As exemplified in Fig. 6, 7A, 7B, and 9, metal AM is performed, by WAAM, or other high temperature process, thereby embedding the sensor in a metal structure comprising a top portion 140 and the metal base 110. Heat from the metal AM effectively sinters the ceramic paste 130 to form a sintered ceramic layer 150 and melts the metal particles interpenetrating the sintered ceramic layer, thereby enhancing adhesion strength between the sintered ceramic layer 150 and the thin metal layer 135.

[0035] Collectively, steps 1-6 provide a manufacturing process to produce a metal structure 140 with embedded sensing capabilities. Fig. 7A shows an exploded view of the embedded sensor 120, held in place by an adhesive bonding agent 145, coated in turn with a sintered ceramic layer 150 and a cold spray deposited thin metal layer 135, embedded between the metal base 110 and the top portion 140. 7B shows a close-up of the structure directly embedding the sensor element 120, including an adhesive bonding agent 145, the sintered ceramic layer 150 directly contacting the sensor, and a thin metal layer 135 deposited atop and interpenetrating the ceramic layer 150. This close-up also shows the wiring / electrodes 125 configured to connect the sensor to an electronic sensor network.

[0036] As exemplified in Fig. 8, the process can be extended to embed multiple sensors and other temperature-sensitive electronic components of various types into a metal structure. In the example shown in Fig. 8, a two-layer sensor network 150 was designed, with each layer containing three strain gauges 155 (SGT-2 / 350-XY43, Omega Engineering, Inc.) and three temperature sensors 160 (5RTD-F3105, Omega Engineering, Inc.). As detailed in the Example discussed below, a smart sensor network 150 of Fig. 8 was successfully manufactured using WAAM, with all sensors remaining functional. This outcome633060352.1105095-201demonstrates the effectiveness of the developed fully encapsulated ceramic-metal interface in protecting sensors during high temperature metal AM processes.

[0037] Fig. 9 displays all steps in an embodiment for which, in step 1, the metal base 110 is manufactured by WAAM. In step 2, a surface 910 of the metal base 110 is surface machined to reduce roughness and create a uniform, flat surface for sensor attachment, and attachment regions 920 are formed on the surface by creating localized micro-roughness. According to some such embodiments, the micro-roughness is created by sandblasting.According to some such embodiments, surface machining is performed by computer numerical controlled (CNC) milling, and the sandblasting uses particles (e.g. aluminum oxide particles) applied through a mask. Steps 3-6 correspond to steps 3-6 in Fig. 1. Notably, however, for the process of Fig. 9, in contrast to the process of Fig 1, no sensor cavity 115 is formed. Bypassing sensor-cavity machining according to the embodiment of Fig. 9 effectively preserves mechanical integrity, as machined cavities act as stress concentrators, especially in architectures involving dense sensor networks.

[0038] Embodiments of the processes described above can be used to embed a variety of sensor types and other temperature-sensitive electronic components in metal structures. Examples of such sensor types include but are not limited to strain gauges, thermocouples, accelerometers, radio-frequency identification (RFID), and surface acoustic wave sensors. The metal structures into which the sensors are embedded can be produced by additive manufacturing processes including directed energy deposition (DED), laser powder bed fusion (LPBF), and WAAM. Such structures provide the basis for the additive manufacturing of smart metallic structures for advanced structural health monitoring applications.Example: A convergent manufacturing pathway for smart metallic structures with embedded sensors.1. Convergent manufacturing of smart metallic structures

[0039] Smart structures are structural components integrated with sensors that enable continuous monitoring of structural health, environmental conditions, and operational states. These systems facilitate real-time data acquisition and analysis, enhancing safety, performance, and reliability. In recent years, growing interest in embedding sensors within metallic components has driven the development of smart metallic structures (SMS), which have found broad applicability across aerospace, defense, automotive, robotics, energy systems, and related fields. Metal additive manufacturing (MAM) has emerged as a733060352.1105095-201promising platform for producing next-generation SMS with enhanced functionality, robustness, and scalability.

[0040] For some embodiments of this disclosure, as in the process of Fig. 1, MAM with subtractive machining to create sensor cavities is used to embed sensing elements. For other embodiments, as in the process of Fig. 9, sensor cavity machining is bypassed. While both processes have advantages over currently available methods, bypassing sensor-cavity machining has additional advantages for some applications with respect to preserving mechanical integrity, as machined cavities can act as stress concentrators, especially in architectures involving dense sensor networks.

[0041] Figure 9 shows an embodiment of a convergent manufacturing pathway for embedding functional sensors within additively manufactured metal structures. According to this embodiment, the pathway consists of six sequential steps: (Step 1) WAAM to fabricate the host structure; (Step 2) Surface preparation for sensor attachment (i.e., machining and sandblasting); (Step 3) Sensor integration; (Step 4) Application of a ceramic shielding layer; (Step 5) Surface metallization; (Step 6) Resumption of WAAM deposition to realize the SMS. The following subsection provides a detailed description of each step, and Table 1 summarizes the operational settings for each process.Step 1: WAAM to build the host structure

[0042] The fabrication process begins with constructing the metal base 110 with Al 5356 alloy using WAAM, which serves as the backbone of the proposed convergent manufacturing pathway. WAAM was employed owing to its high deposition rate, excellent metallurgical bonding, and relatively low material waste compared to other AM processes (e.g., powder bed fusion, laser powder DED). In addition, the use of Al 5356 alloy provides a favorable combination of strength, ductility, and corrosion resistance, making it well-suited for structural components in SMS applications. To enhance deposition-substrate bonding, the build was deposited onto a build plate made of Al 6061 alloy featuring machined surface grooves, which increased surface roughness and promoted metallurgical adhesion.Subsequently, the WAAM process was carried out using a multi-robot WAAM architecture system integrated with 1 robot arm holding a weld torch, a wire-feed system and another robot arm integrated with a thermal camera for in-situ thermal imaging, enabling precise control of deposition, temperature, and repeatability. The wire was fed into the torch at a rate of 0.17 m / s, while the torch traversed at 4 mm / s (see Table 1). The host build (length= 220 mm, width= 70 mm, height = 18 mm) was fabricated in three WAAM layers, each833060352.1105095-201comprising 21 beads spaced 6 mm apart. To improve interlayer consolidation and reduce porosity, a 3 mm hatch spacing was applied between successive layers. This strategy was informed by a prior scan-n-print approach, where laser scanning was employed to characterize the bead geometry (width, height, and profile) and improve bead overlap and geometric consistency in WAAM builds.Step 2: Surface preparation

[0043] Following deposition of the metal base 110, a surface 910 of the metal base was smoothed via CNC milling to remove weld-induced roughness and create a uniform, flat surface for the subsequent sensor 120 attachment. Notably, machining was used solely for surface facing of the WAAM-built layer to facilitate sensor attachment on a smooth surface, and no sensor-cavity machining was performed. Sandblasting with 64-grit aluminum oxide medium was applied to the as-machined surface at 12 mm × 6 mm sensor attachment regions 920, using an aluminum mask to create micro-roughness for improved sensor bonding.Step 3: Sensor integration

[0044] In this example, commercial off-the-shelf (COTS) sensors were employed, including strain gauges (SG, OMEGA, SGT-2 / 350-XY43) and resistive temperature detectors (RTDs, OMEGA, 5RTD-F3100), which were used as procured. These sensors were selected for their small footprint, which minimized the required encapsulation volume and reduced mechanical debit. The operating temperature range of the SGs is -75-200 °C, necessitating careful sensor encapsulation to protect them from the elevated temperatures inherent to the WAAM process. Prior to attaching the sensors to the host structure, flexible printed circuit board (FPCB) packaging was applied to each sensor to provide mechanical support, protect the sensing elements during handling, and facilitate reliable electrical interfacing. This packaging also improves durability under subsequent processing steps by mitigating strain concentrations at the sensor terminals and ensuring stable signal transmission. The sensor electrodes were spot-welded (UNITEK thin-line spot welder) to ensure robust electrical connections and minimize contact resistance. Lastly, the packaged sensors were directly bonded to the surface of the host structure using an adhesive bonding agent (M-Bond 610). This adhesive was selected for its high-temperature stability, strong shear strength, and compatibility with both strain gauges and RTDs, ensuring reliable adhesion during subsequent WAAM deposition and thermal cycling. To cure the adhesive, the sensor-attached 933060352.1105095-201structure underwent a two-stage thermal cycle: 1 hour at 150 °C followed by 2 hour at 230 °C. After curing, the specimens were allowed to cool naturally to room temperature under ambient conditions.Step 4: Ceramic shielding

[0045] To protect the sensors from direct thermal exposure during WAAM deposition, a ceramic shielding layer (1 mm thick) was applied over the sensor assemblies to serve as an effective thermal barrier. In this context, a zirconia-based paste (ZrO2, Graphite Store, Ultra-Temp 516) with cement additives was applied to ensure uniform coverage and robust thermal insulation. The paste was deposited onto the sensor assemblies (i.e., sensors with FPCB packaging) through manual dispensing using a 17-gauge syringe, enabling controlled placement and consistent thickness with the aid of a masking fixture. The applied ceramic layer minimizes heat transfer to the embedded sensors, preventing thermal degradation, sensor drift, or failure during subsequent metal deposition. Following application, the ceramic was cured at room temperature for 24 hours, forming a green body with sufficient mechanical strength and dimensional stability to withstand the thermal and mechanical conditions of the over-deposition process.Step 5: Cold spray metallization

[0046] For seamless resumption of WAAM deposition over the sensor-embedded regions, a continuous electrically conductive pathway is essential to maintain arc stability and prevent process interruptions. However, the ceramic shielding layer is intrinsically insulating, necessitating the creation of a conductive intermediary layer to support stable arc initiation and propagation. To address this requirement, cold spray (CS) metallization was employed to deposit a dense, electrically conductive coating onto the ceramic surface. In this step, a mixture of metallic feedstock powders (Al + Al2O3+ Zn) was sprayed using a robotic low-pressure CS system (Titomic D523) to create a conformal, mechanically robust, and electrically continuous surface. The corresponding operational settings used for CS deposition are summarized in Table 1. The metallized layer, achieved using a single spray pass, provides sufficient electrical conductivity for stable WAAM re-deposition and strong mechanical anchoring for subsequent WAAM layers, thereby facilitating uninterrupted fabrication of the SMS.Step 6: WAAM resumption1033060352.1105095-201

[0047] WAAM deposition was seamlessly resumed over the sensor regions to fully integrate the sensor networks within the build. Upon completing the WAAM, the structure underwent final surface machining to achieve a near-net-shape beam geometry (180 mm x 20 mm x 13 mm). Finally, the embedded sensors were wired out through designated routing paths for signal acquisition and functional verification, enabling subsequent structural testing of the fabricated SMS. Collectively, leveraging the convergent manufacturing pathway developed in this work, dense sensor networkss of COTS strain and temperature sensors were integrated within a WAAM-built beam, as detailed in the following section.2. Sensor network and embedding strategy

[0048] According to the embodiment shown in Fig. 8, a two-layer sensor network — each layer comprising four RTDs and three SGs — was embedded within an ASTM-standard bending beam (180 mm x 20 mm x 13 mm). This multilayer, densely distributed sensor network was selected to capture the temperature and strain evolution throughout the beam, rather than relying on single-point local measurements. This design enables higher sensing resolution and provides a richer diagnostic capability for structural evaluation. Moreover, the SGs were strategically embedded asymmetrically with respect to the neutral axis (i.e., 3.5 mm away in Layer 1 and 1.5 mm away in Layer 2) to assess the strain sensitivity, gradient response, and measurement fidelity of embedded sensors under bending-dominated loading. The RTDs were also positioned at corresponding locations within each layer to capture through-thickness temperature gradients and support coupled thermo-mechanical analysis of the developed smart structure.1133060352.1105095-201Table 1: Operational settings for each, process.Fabrication Process Parameter Settings Material Aluminum (Al-5356) Wire Feed Rate Step - 1 Torch Speed 4 mm / s WAAM for Host Structure Number of Weld Beads 20 Beads (Hatch) Distance 6 mm Arc-on Temperature 140 °C–150 °C* Cutting Tool 3.175ball end mill JM • £ - 1* J ». NZS -.. Spui le Speed m Surface preparationv‘Feed Rate 2 inch / min (~50.8 mm / min) RTD SW Voltage / Current 170 V / 20 kAStep - 3 SG SW Voltage 7 Current 130 V / 35 kA Sensor Integration Bonding agent Mbond 610 adhesive agent Curing Temperature 175 °C 1 h + 300 °C 2 h Step - 4 Air Curing Humidity 40%–50% Ceramic Shielding Air Curing Time 24 hMaterial Mixture of Al, Al₂O₃, and ZnGas Temperature 400 °CGas Pressure 6 bar (0.6 MPa)Cold Spray MetallizationNozzle Transverse Speed 20 mm / sNozzle Stand-off Distance 25 mmStep - 6Same as Step - 1WAAM resumption

[0049] All sensors were first spot-welded onto the FPCB for packaging, after which the assembled sensors were bonded onto the pre-treated beam surface. This sequential approach ensured robust electrical connections, proper alignment, and reliable mechanical anchoring prior to ceramic shielding and subsequent CS-metallization. In addition, the use of an FPCB provided a flexible and stable platform for routing sensor leads, minimizing wiring clutter, and protecting junctions during handling. This integrated packaging and bonding strategy helps to maintain sensor integrity throughout the subsequent ceramic encapsulation and metal deposition steps.

[0050] To interface the embedded sensor network with dedicated data acquisition unit (National Instruments NI-9216 for RTDs and NI-9235 for SGs), side tabs were incorporated into the beam design to expose the FPCB leads, enabling electrical connection. These tabs were created by machining dedicated recesses along the beam edges after WAAM resumption, allowing the FPCB legs to be safely routed outward without interfering with the surrounding metal regions. Finally, external copper wires (28-gauge ~320 pm) were soldered to the exposed tabs to establish reliable electrical connections between the embedded sensors and the data acquisition system. This configuration provides secure access to the sensor terminals while preserving the structural integrity of the smart structure (i.e., smart beam).1233060352.1105095-2013. Microstructural characterization

[0051] To substantiate the feasibility of the proposed manufacturing pathway prior to structural evaluations, the microstructure of the resulting deposition optical microscopy as used to demonstrate that the layer-by-layer WAAM deposition was successfully achieved without delamination or significant porosity at the WAAM-WAAM interface, thereby confirming interlayer fusion. Notably, the interface between the WAAM and the cold-sprayed layer exhibits the successful resumption of WAAM deposition on the metallized ceramic surface. However, local voids were observed at the sharp corner (edge) of the ceramic-CS-WAAM interface. This is likely due to the limited effectiveness of CS metallization at sharp edges, where the spray angle becomes non-orthogonal as the nozzle passes over the substrate, thereby limiting the metallization of the ceramic sidewalls. As sharp corners also serve as stress concentrators, such localized damage was observed in the ceramic coating in that region. Nevertheless, WAAM was able to over-deposit and completely infill this area due to the small footprint of the defect, which is smaller than the width of a single WAAM bead (6 mm x 6 mm). Notably, aside from this sharp-edge region, the overall structural integrity of the ceramic shielding was preserved throughout both the CS metallization and the subsequent over-WAAM deposition. As for the interface between the host WAAM layer, FPCB, and embedded sensors, no delamination, cracking, or interfacial damage was observed at the WAAM-FPCB-sensor junction. This confirms that the deposition process preserved the structural and functional integrity of the embedded sensors and enabled reliable mechanical bonding between the WAAM layer and the FPCB.

[0052] Scanning electron microscopy (SEM, FEI Versa) was also performed to focus on two critical interfaces: (1) the WAAM (top layer)-CS-ceramic interface and (2) the WAAM (bottom layer)-sensor-ceramic interface. The SEM images confirm strong metallurgical compatibility between the two layers. In addition, the cold-spray metallization on the ceramic surface displayed a uniform, adherent, and conformal coating morphology, demonstrating robust coating integrity and effective surface metallization. Therefore, seamless continuation of WAAM deposition (i.e., WAAM top layer) was obtained.

[0053] In the embedded sensor region, the ceramic shielding conformed tightly to the sensor surface, with no evidence of interfacial de-bonding, thereby providing effective mechanical support and thermal protection. Moreover, the FPCB and its electrode traces preserved their structural integrity, confirming the effectiveness of the ceramic layer in shielding these packaging elements from the excessive heat generated during the over- 1333060352.1105095-201WAAM. Additionally, the adhesive bonding layer (M-Bond 610 epoxy) between the sensor and the bottom WAAM surface remained intact and continuous. This is important for maintaining reliable sensor contact—particularly for SGs, which require robust bonding to accurately transfer strain from the attached surface.

[0054] Overall, the microstructural analyses revealed that the proposed convergent manufacturing approach is robust and reliable, maintaining strong interfacial integrity across all the critical interfaces. The absence of delamination confirmed stable mechanical bonding and effective thermal shielding, which validates the proposed approach for embedding sensors within additively manufactured metallic structures. The following sections present the testing and utilization of the developed Smart Beams under a series of thermal and mechanical evaluations.4. Thermo-mechanical characterization of the Smart Beam.

[0055] The fabricated Smart Beams were comprehensively evaluated to assess both mechanical integrity and sensing performance. The evaluations include: (i) thermal tests (steady-state and transient) and (ii) static mechanical tests. All embedded sensors were calibrated prior to testing using reference (control) sensors mounted on the beam surface.Thermal tests

[0056] Temperature testing assessed whether the embedded RTDs could accurately sense and track thermal variations within the beam. Two complementary tests were performed: (1) a steady-state test to calibrate the resistance-temperature relationship under equilibrium conditions, and (2) a transient test to evaluate the dynamic response under timevarying heating. Together, these tests established the spatial-temporal sensing capability of the embedded RTD network and informed subsequent thermo-mechanical evaluations.Static mechanical tests

[0057] Static three-point bending experiments were conducted to verify that the embedded strain gauges can sense the internal strain field of the Smart Beam under normal operating conditions (i.e., within the linear elastic region). In this configuration, the beams were tested under three-point bending in accordance with ASTM E290 using a universal testing machine (Instron No.8801). The results obtained confirm that the calibrated embedded SGs provide reliable through-thickness strain information and enable accurate reconstruction 1433060352.1105095-201of the flexural strain. This validated reconstruction capability underscores the suitability of the embedded sensing approach for SHM applications where direct surface instrumentation may be impractical or insufficient.5. Conclusions

[0058] The key findings are:1) The developed approach enabled reliable embedding of COTS sensors within WAAM-built structures (Al 5356) without significantly compromising interfacial integrity across the heterogeneous material interfaces.2) Embedded RTDs demonstrated high accuracy under both steady-state and transient heating conditions, maintaining temperature errors below 0.5%.3) Similarly, the embedded SGs provided consistent strain measurements, deviating by less than 0.5% from the surface-mounted reference sensors.

[0059] Collectively, the results demonstrate that the proposed convergent manufacturing method preserves both sensing functionality and mechanical integrity, establishing a viable pathway for next-generation SMS.

[0060] What has been described and illustrated herein is an example along with some of its variations. The terms, descriptions and figures used herein are set forth by way of illustration only and are not meant as limitations. Many variations are possible within the spirit and scope of the subject matter, which is intended to be defined by the following claims -- and their equivalents -- in which all terms are meant in their broadest reasonable sense unless otherwise indicated.1533060352.1

Claims

105095-201What is claimed is:

1. A method of embedding an electronic component into a metal structure of an electronic device comprising:preparing a surface of a metal base with an attachment site for securing the electronic component on the metal base, the metal base comprising a first metal;attaching the electronic component to the attachment site;coating the electronic component with a ceramic slurry;heating the ceramic slurry until dry;depositing a layer of a second metal onto a surface of the ceramic slurry by a low temperature process at temperatures between about 300°C and about 400 °C; and depositing a third metal by a first high temperature additive manufacturing process at a temperature between about 1000 °C and about 1300 °C to cover the second metal and at least a portion of the metal base, thereby embedding the electronic component in the electronic device.

2. The method of claim 1, wherein preparing the surface includes surface machining to reduce roughness.

3. The method of claim 1, wherein the attachment site is formed by subtractive manufacturing of a sensor cavity through the surface of the metal base.

4. The method of claim 2, wherein the attachment site is formed by creating a localized region of micro-roughness on the surface of the metal base.

5. The method of claim 1, wherein the layer of the second metal is between about 0.1 mm and about 1 mm thick.

6. The method of claim 1, wherein the electronic component is attached to the attachment site with an adhesive bonding agent.

7. The method of claim 6, wherein the adhesive bonding agent is an epoxy compound.

8. The method of claim 1, wherein the electronic component is encased in a polymer.

9. The method of claim 1, wherein the metal base is formed by a second high temperature additive manufacturing process.1633060352.1105095-20110. The method of claim 9, wherein the first high temperature additive manufacturing process is the same as the second high temperature additive manufacturing process.

11. The method of any one of claims 1-10, wherein the first high temperature additive manufacturing process is selected from the group consisting of wire-arc additive manufacturing (WAAM), laser powder bed fusion (LPBF), directed energy deposition (DED), and combinations thereof.

12. The method of claim 9, wherein the second high temperature additive manufacturing process is selected from the group consisting of wire-arc additive manufacturing (WAAM), laser powder bed fusion (LPBF), directed energy deposition (DED), and combinations thereof.

13. The method of any one of claims 1-10 and 12, wherein the low temperature process is a cold spray process.

14. The method of any one of claims 1-10 and 12, wherein the first high temperature additive manufacturing process is WAAM.

15. The method of any one of claims 1-10 and 12, wherein the electronic component is a sensor.

16. The method of claim 15, wherein the sensor is selected from the group consisting of a thermocouple, a strain gauge, an accelerometer, a radio-frequency identification (RFID) sensor, a surface acoustic wave sensor, and combinations thereof.

17. An electronic device comprising:a metal base comprising a first metal;one or more electronic components attached to an attachment site on a surface of the metal base;a ceramic layer covering each electronic component of the one or more electronic components;1733060352.1105095-201a second metal layer at least partially interpenetrating the ceramic layer to form an interpenetrated boundary region, the interpenetrated boundary region forming a bond between the second metal layer and the ceramic layer; anda third metal covering the second metal layer and at least a portion of the metal base.

18. The electronic device according to claim 17, wherein the attachment site is a localized region of micro-roughness on the surface of the metal base.

19. The electronic device according to claim 17, wherein the attachment site is a sensor cavity in the surface of the metal base.

20. The electronic device according to claim 17, wherein one or more of the one or more electronic components is a sensor.

21. The electronic device according to claim 17, wherein the one or more electronic components form a sensor network comprising multiple sensors.

22. The electronic device according to claim 21, wherein each sensor of the multiple sensors is selected from the group consisting of a thermocouple, a strain gauge, an accelerometer, a radio-frequency identification (RFID) sensor, a surface acoustic wave sensor, and combinations thereof.

23. The electronic device according to any one of claims 17-22, wherein the electronic device is manufactured using the method of claim 1.1833060352.1

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