Non-loss engraved circuit patterning method of semi-liquid metal for precision recyclable multi-substrate circuits

Domain: physics
Published: 2025-11-27
Editorial outcome: minor_revision

Abstract
Room-temperature liquid metal alloys have emerged as promising materials for flexible electronics due to their unique fluidity, conductivity, and biocompatibility. However, traditional patterning techniques for liquid metal circuits, including additive and subtractive manufacturing, face challenges such as high costs, complex processes, and environmental issues, limiting their large-scale application. This study presents a non-loss method for fabricating high-precision semi-liquid metal circuits by leveraging ethanol to modulate interfacial adhesion between liquid metal and substrates. By precisely controlling adhesion through a custom-designed displacement apparatus, the approach enables seamless patterning from 5 μm to centimeter scales across diverse substrates with features like stretchability (1000% strain), reusability, and recyclability. The technique overcomes limitations of conventional methods, offering advantages in cost-effectiveness, operational simplicity, and substrate compatibility. Demonstrations include multifunctional flexible circuits for wearable electronics, aerospace, and smart home applications, highlighting its potential to advance sustainable, scalable liquid metal electronics manufacturing.

Introduction
In recent years, room-temperature liquid metal alloys based on low-melting-point gallium have exhibited unique advantages in flexible electronics due to their excellent room-temperature fluidity, high electrical conductivity, solid-liquid phase transition properties, and biocompatibility1–3. These gallium-based alloys, integrating metallic and liquid properties, are widely employed in multifunctional flexible electronics and have garnered significant attention across disciplines including electronic skin4, soft robotics5, health monitoring6, information storage7,8, and energy systems9.

As a liquid, liquid metal exhibits infinite deformability10 and self-healing capacity11. The infinite deformability of liquid metal enables it to adapt to the mechanical properties of various flexible substrates, including high-molecular polymers, paper, fabrics and skin, and makes it applicable for the fabrication of wearable electronic devices on multiple substrates12,13. Stretchable interconnection wires made of liquid metal can be used to connect rigid devices attached to flexible substrates, forming an island-bridge structure, which can be applied to fabricate conformal circuits on complex curved surfaces, such as electrochemical sensors attached to the skin surface and conformal electrode arrays on the surface of internal organs14–16. However, the high fluidity and surface tension of liquid metal pose challenges for patterning via traditional circuit printing techniques17,18. To fabricate high-precision liquid metal circuits, processing techniques such as photolithography and ion-beam etching19–21, which are costly and time-consuming, are often required. This severely restricts the widespread use of liquid metal flexible circuits. In addition, the substrate materials used in various flexible electronic devices vary significantly in performance and surface morphology. Therefore, it is necessary to develop liquid metal circuit manufacturing methods that match the interfacial characteristics of the substrates.

To address the above issues, various liquid metal patterning techniques based on different principles have been developed in recent years, which mainly include two forms: additive manufacturing and subtractive manufacturing. Additive manufacturing refers to techniques based on material accumulation principles. These include: direct writing or 3D printing using surface-modified liquid metal22–24; screen printing or transfer printing utilizing customized templates25–30; direct fabricating the target circuit patterns leveraging laser engraving technology on specific substrates that need to be laser-activated31–33 and microchannel perfusion34–37, among others. Nevertheless, the application of additive manufacturing for fabricating liquid metal circuits typically incurs substantial costs and stringent processing demands. This is attributable to the requirement for customized nozzles, precision templates, specialized printing apparatus adept at fabricating intricate microchannels, and, in some cases, laser systems. Subtractive manufacturing represents a material-removal-based approach for circuit fabrication. For instance, it involves initially creating metal circuit patterns via laser sintering or chemical selective deposition, followed by methods such as contact wetting with liquid metal38,39. Despite its utility, subtractive manufacturing confronts notable challenges. This technique predominantly depends on costly photolithography apparatus. During the circuit fabrication process, it entails operations like pasting and peeling. These not only substantially elevate equipment expenses but also generate waste, giving rise to environmental contamination and further augmenting circuit manufacturing costs. Conventional liquid metal patterning techniques, encompassing both additive and subtractive manufacturing approaches, are encumbered by significant drawbacks, including elevated costs, intricate procedures, and environmental pollution. These limitations pose substantial barriers to the advancement and large-scale implementation of liquid metal-based flexible electronics technology. Consequently, the development of a liquid metal patterning methodology characterized by low cost, streamlined processing, high precision, compatibility with diverse substrates, zero waste production, and recyclability of raw materials has become an imperative research priority.

Building on our previous research on the selective adhesion mechanism of liquid metal40,41, we discovered that ethanol can precisely regulate the interfacial adhesion between semi-liquid metal and substrates. Leveraging this discovery, we demonstrate that by precisely applying ethanol to control the semi-liquid metal’s adhesion at designated locations on the substrate, it becomes feasible to achieve circuit patterning with high precision. Compared with previous studies where hydrogen bonds serve to enhance the adhesion between liquid metals and substrates, this study provides an approach that utilizes hydrogen bonds in ethanol to hinder the re-adhesion of semi-liquid metals to substrates. In response to the challenges of intricate operation, elevated costs, and resource inefficiency inherent in conventional high-precision flexible electronics manufacturing techniques, our study presents an innovative non-loss engraved circuit patterning (NECP) method that diverges significantly from traditional subtractive and additive methodologies. This process is characterized by zero material wastage, and it proficiently satisfies the stringent technical demands of high precision, compatibility with diverse substrates, stretchability, reusability, and recyclability. Notably, it offers a distinct advantage in enabling the cost-effective, large-scale production of flexible circuits. This study elucidates the mechanism through which ethanol modulates the adhesion of semi-liquid metal to substrates. We designed and fabricated a high-precision displacement apparatus, enabling precise manipulation of the interfacial adhesion between liquid metal and substrates at targeted locations. Leveraging this method, we successfully achieved patterning of semi-liquid metal across diverse substrates and demonstrated the fabrication of flexible circuits spanning multiple scales, from micrometers to centimeters. This non-destructive patterning technology is characterized by high efficiency, operational simplicity, and customizable precision, offering broad application prospects in wearable electronics, aerospace, and smart home systems.

Results
In this study, we obtained semi-liquid metal by doping solid metal particles into liquid metal (Supplementary Fig. 1), which exhibits lower fluidity compared to liquid metal. Numerous previous studies42,43 have confirmed that metallic silver exhibits better wettability with liquid metals than metallic copper, and relevant characterizations have revealed the presence of intermetallic compounds. Therefore, to facilitate the fabrication of semi-liquid metals and reduce material costs, we have selected metal particles with a silver coating on the surface of copper particles. Such metal particles are significantly cheaper than silver particles and still possess wettability similar to that of silver particles. This reduced fluidity overcomes the poor printability of liquid metal with various substrates due to its high surface tension, enabling the semi-liquid metal to be uniformly coated on the surfaces of multiple substrates. By preparing a series of samples with doping ratios of 0 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, and 25 wt%, we found that when the doping ratio of silver coated copper particles reaches 25 wt%, the physical form of semi-liquid metal becomes powdery, which cannot be used in printed circuits, and when the doping ratio above 25 wt%, the particles are difficult to enter the liquid metal, and the doping amount of silver-plated copper particles is negatively correlated with the fluidity of the semi-liquid metal (Supplementary Fig. 2). The results in Supplementary Fig. 3 demonstrate an increase in electrical conductivity as the doping ratio escalates from 0 wt% to 20 wt%. When the doping ratio was 15 wt%, the semi-liquid metal presented a slurry suitable for brushing and a higher electrical conductivity of 9 × 10^6 S/m, therefore subsequent studies were all based on this ratio. Figure 1a shows a functional schematic of fabricating semi-liquid metal circuits using the NECP method. This method achieves patterning through the synergistic regulation of the interfacial adhesion between semi-liquid metal and flexible substrates by a needle and ethanol. Silver coated copper particles exhibits excellent corrosion resistance, which ensures the long-term stability of semi-liquid metal. The Scanning Electron Microscope (SEM) photos in Supplementary Fig. 4 show the micro-morphology of the semi-liquid metal film prepared two months ago. This figure clearly indicates that only a slight change has occurred in the diameter of the solid particles. The X-ray Photoelectron Spectroscopy (XPS) curves in Supplementary Fig. 5 indicate that the surface of the semi-liquid metal is encapsulated by a metal oxide film predominantly composed of gallium oxide (Gallium oxide, Ga2O3). As a result, its physical state can remain relatively stable, and it exhibits long-term mechanical stability, maintaining good stretchability even after long-term storage. Prior investigations have established that the hydrogen bond interaction between this oxide film and the flexible substrate constitutes the primary mechanism driving adhesion. In this study, the needle served to exert mechanical force to disrupt the hydrogen bond network at the interface between the semi-liquid metal oxide layer and the flexible substrate, thereby inducing detachment of the semi-liquid metal from the substrate. Moreover, ethanol exhibited exceptional wettability toward both the semi-liquid metal oxide film and the flexible substrate, enabling rapid coverage of the substrate and detached semi-liquid metal. This phenomenon inherently prevented re-adhesion of the semi-liquid metal to the substrate. Liquid metals exhibit high surface tension (~500–700 mN/m at 25 °C), driving droplets to spontaneously form a spherical shape. In air, the oxide film on liquid metal droplets adheres to the glass substrate, flattening the droplets and reducing their contact angle. In contrast, in ethanol solution, the substrate is wetted and covered by ethanol, which prevents the droplet oxide film from contacting the substrate. Consequently, droplets are unaffected by substrate adhesion (no adhesive deformation), and their shape is dominated by surface tension, remaining spherical (Supplementary Fig. 6). Thus, semi-liquid metal immersed in ethanol showed a significantly larger substrate contact angle than that in air, indicating a non-adhesive state (Fig. 1b). Furthermore, the ethanol filled cross channel acted as a physical barrier, effectively preventing re-adhesion of the semi-liquid metal on either side to the original scratch location. Figure 1c shows the microscopic image of needle-tip non-loss-engraved semi-liquid metal wire arrays and the video is available in Supplementary Video 1. The arithmetic mean roughness (Ra = 5.22 μm) of the semi-liquid metal film was calculated based on the measured contour curve by the laser confocal microscope, as shown in Supplementary Fig. 7. As illustrated in Fig. 1d, when a substrate uniformly coated with semi-liquid metal is immersed in an ethanol environment and the needle tip traverses the substrate, ethanol reduces the adhesion between the liquid metal and the substrate, thereby preventing the needle tip from adhering to the liquid metal. Consequently, the mechanical force exerted by the needle tip propels the liquid metal to both sides of the channel, increasing the thickness of the liquid metal layers on either side. Simultaneously, the exposed substrate is rapidly wetted by ethanol, which served to inhibit backflow of the semi-liquid metal. A single wire is formed by two parallel channels, whereas multiple parallel channels yielded a liquid metal wire array with no discernible loss of semi-liquid metal throughout the process. Through precise control of the needle tip trajectory, the NECP method enables the fabrication of complex liquid metal circuit patterns, as demonstrated in the operational flowchart of Supplementary Fig. 8. Figure 1e graphically illustrates the multifaceted advantages of this method, encompassing low cost, simple and efficient process, high precision, large-area printing capability, multi-substrate compatibility, high stretchability, reusability, and recyclability. Notably, this method enables the fabrication of wire arrays with a resolution as low as 5 μm. Owing to its avoidance of harsh processing steps and expensive equipment, the approach exhibits low cost, accommodates circuit fabrication across multiple scales ranging from micrometers to decimeters, and demonstrates compatibility with diverse substrates, including VHB tape, polydimethylsiloxane (PDMS), polyethylene terephthalate (PET), polyimide (PI), polyurethane (PU), wood, glass, and paper. This versatility enables the technology highly adaptable for manufacturing a wider range of flexible electronic devices. Critically, given the scarcity of semi-liquid metal materials, the method achieves nearly complete recycling of semi-liquid metal. With no material loss incurred, this method facilitates circuit reusability, thereby significantly reducing technological application costs and mitigating both resource waste and environmental pollution. In Supplementary Fig. 9 illustrates the needle tip moving trajectories during the fabrication of large-area, stretchable, multi-substrate and recyclable circuits. To systematically characterize the technological breakthroughs relative to traditional methods, the study established a comparative framework across six key dimensions: manufacturing cost, recyclability, conductivity loss, material loss, resolution, and printability on diverse substrates, with detailed data presented in Supplementary Table S1.

Mechanisms for regulating interfacial adhesion between semi-liquid metal and substrates
The NECP method employed ethanol to suppress re-adhesion of liquid metal to the substrate, thereby enabling high-precision fabrication of circuit patterns. Thus, we systematically investigated the wetting behavior of ethanol on semi-liquid metal and flexible substrate surfaces during the engraving of flexible liquid metal circuits, along with the resultant regulatory mechanisms governing interfacial adhesion. The study began by assessing the wettability of two liquids (ethanol and water) on multiple substrates via contact angle measurement experiments, as depicted in Fig. 2a and Supplementary Video 2. In accordance with the theory of contact angle and wettability, a smaller contact angle signifies superior wettability. The results reveal that ethanol exhibited contact angles below 30° on diverse substrates, including liquid metal, PI, PDMS, PET, and Thermoplastic Polyurethane (TPU), thereby demonstrating high wettability. Conversely, water showed substantially larger contact angles (all exceeding 65°) on these substrates, indicative of reduced wettability. Notably, water droplets on PDMS and TPU substrates displayed contact angles exceeding 90°, classifying these interfaces as hydrophobic. Water molecules form strong hydrogen bonds, leading to high surface tension (~72 mN/m at 20 °C) and poor spreading on substrates. In contrast, ethanol molecules have fewer and weaker hydrogen bonds, resulting in much lower surface tension than water (~22.3 mN/m at 20 °C), that enables ethanol to spread more easily on substrates. Additionally, water only forms strong adhesion on polar substrates, while ethanol (with both polar and non-polar molecular characteristics) achieves strong adhesion on both polar and non-polar substrates, giving it broader applicability and more stable wetting performance. Thus, compared to water, ethanol exhibited superior wettability toward liquid metal and diverse flexible substrates, enabling efficient spreading and wetting on the surfaces of semi-liquid metal and flexible substrates during non-loss engraved patterning. Additionally, contact angles of liquid metal droplets on multiple substrates were measured in air and ethanol environments, respectively, as shown in Fig. 2b. The data discloses that liquid metal droplets exhibits smaller contact angles on all substrates in air than in ethanol. For instance, the contact angle of liquid metal droplets with the on PDMS substrate was approximately 50° in air, whereas it increased to approximately 130° in ethanol. The same trend was observed for PET, PI, Polyvinyl Chloride (PVC), VHB, PU, and glass. In air, the liquid metal droplet showed contact angles below 90° with all substrates, indicative of strong interfacial adhesion. In contrast, contact angles were significantly above 90° in ethanol, reflecting weak interfacial adhesion. Furthermore, liquid metal droplets in air and ethanol environments were positioned on inclined planes fabricated from the seven aforementioned substrates. As depicted in Fig. 2c, liquid metal droplets exhibited robust adhesion to these substrates, remaining stably attached even when the substrate was tilted to 90°. Conversely, ethanol-covered droplets failed to adhere stably. For instance, on a glass substrate inclined at just 7°, the droplets slipped. Results from contact angle and inclined-plane experiments indicate that ethanol spreading on semi-liquid metal and flexible substrate surfaces isolates the two materials, disrupting hydrogen bond interactions between the oxide film on the semi-liquid metal surface and the substrate. This disruption prevents re-adhesion of the semi-liquid metal to the flexible substrate, as schematically shown in Supplementary Fig. 10.

Second, this study employed a needle tip to exert mechanical pressure on semi-liquid metal, inducing its detachment from the substrate. Unlike the peeling of solid metal from the substrate, semi-liquid metal undergoes positional displacement due to its fluidity under mechanical loading. Although this process involves no metal loss, the extruded semi-liquid metal coalesces with the semi-liquid metal on both sides, potentially impacting the electrical characteristics of the circuit. Therefore, we investigated the flow dynamics of semi-liquid metal during needle tip extrusion. High-speed cameras were utilized to record the process of forming cross-shaped scratches by applying pressure with a metal needle tip to semi-liquid metal coatings in air and ethanol environments, respectively, as documented in Supplementary Fig. 11. In air, adjusting the moving speed of the needle tip cannot eliminate the semi-liquid metal adhesion at the cross, as shown in Supplementary Fig. 12. In air, when the metal needle tip engraves the semi-liquid metal coating, most of the semi-liquid metal is displaced from its original position. Notably, as the needle tip traverses the cross-intersection, semi-liquid metal from both sides is forced into the original scratch and reattaches to the substrate, obscuring the initial trace. In contrast, when in ethanol, the original scratch is infiltrated with ethanol, and even as the needle tip traverses the cross-intersection, semi-liquid metal from both sides remains unable to be forced into the original scratch, thereby precluding coverage of the initial trace. Additionally, gallium element distribution maps at cross-shaped scratches in air and ethanol environments (Fig. 2d) reveal that in air, the needle tip drives semi-liquid metal from both sides into the original scratch, causing circuit failure, whereas ethanol mitigates this issue. More critically, the persistence of minute semi-liquid metal residues in scratches during air-based engraving poses a risk of accidental circuit short-circuits, whereas engraving in ethanol fully displaces the metal from scratches, effectively precluding such short-circuits. This discrepancy is attributed to the adhesion of liquid metal to both the needle tip and the substrate in air, which leads to residual liquid metal along the needle tip’s path and incomplete material isolation. In ethanol, the needle tip and scratch are both wetted by ethanol, which acts as a physical barrier to liquid metal, thereby leaving no residue in the scratch. Furthermore, the high adhesive force between the semi-liquid metal and the substrate in air can overcome the cohesive force induced by the semi-liquid metal’s high surface tension, enabling the semi-liquid metal to adhere to the scratch. In contrast, in ethanol, the needle tip, the semi-liquid metal, and the substrate are isolated from one another. As a result, the semi-liquid metal cannot adhere to the substrate; its cohesive force prevents it from being pushed out by the needle tip and also keeps it from adhering to the scratch, as shown in Supplementary Fig. 13. Finally, we characterized the microstructural evolution of the semi-liquid metal flanking the scratch before and after engraving, as depicted in Fig. 2e, f. Through contour curve analysis across Fig. 2e, f, we observed a marked post-engraving increase in semi-liquid metal thickness on both scratch flanks, evidence of metal extrusion from the scratch into lateral regions. This process enhances the cross-sectional area of lateral wires, thereby boosting conductivity, while achieving material-loss-free operation.

Electrical characterization of semi-liquid metal wires via NECP method
The schematic illustration of the self-assembled 2-axis moving platform employed for the NECP method is depicted in Fig. 3a. A glass plate uniformly coated with semi-liquid metal was positioned on the 2-axis moving platform and immersed in ethanol. The 2-axis moving platform precisely manipulated the tip to etch the substrate surface, creating scratches with defined geometric configurations and achieving patterning (Supplementary Video 3). The NECP method of semi-liquid metal showcases a high level of precision and flexibility, enabling the fabrication of high-precision circuits with intricate patterns, as illustrated in Fig. 3b. Supplementary Fig. 14 reveals the movement path of the metal needle on the glass plate. Supplementary Fig. 15 presents more detailed information about the semi-liquid metal circuits on the glass plate, encompassing linear and circular arrays. Furthermore, the NECP method is suitable for fabricating circuit patterns with repeatability and high density, such as wireless charging coils (Supplementary Fig. 16). Herein, the width of the scratches can be adjusted by changing the width of the needle tip, thereby enabling the fabrication of coils with different spacing (Fig. 3c). Using a thinner needle tip can significantly reduce the coil spacing to minimize the coil size. Additionally, the needle tip squeezes the semi-liquid metal at the scratch into the wires on both sides, leading to an increase in the height of the wire edges, which can reduce the resistance of the wires, as shown in Supplementary Fig. 17. To verify the ability of this method to precisely control the width of the wires, wires with designed widths of 10 μm, 50 μm, 100 μm, and 200 μm were fabricated. The 3D contour diagrams and height information are presented in Fig. 3d. The results indicate that the cross-section of the semi-liquid metal wires is arched, and as the wire width increases, both the height and cross-sectional area of the wires increases substantially. This is due to the arc-shaped metal needle tip causing width variations in the scratch across different height levels. Additionally, the semi-liquid metal, exhibiting fluidity, tends to contract toward the scratch edges due to surface tension, resulting in an inverted trapezoidal cross-section (Supplementary Fig. 18). For closely spaced scratches, the arc tip displaces semi-liquid metal in higher regions, significantly reducing their height. Conversely, with larger spacing, the tip does not displace the metal in higher regions, allowing the wire’s middle section to retain the initial coating height. Owing to the uneven distribution of solid metal particles within the semi-liquid metal and the non-uniform substrate wettability induced by ethanol, the wire cross-sections exhibit significant irregularities. For instance, different segments of the same wire may appear flattened, elliptical, or locally bulged, as illustrated in the cross-sectional micrographs of Fig. 3d. This irregularity renders the cross-sectional area impossible to define in a stable and accurate manner. Consequently, calculating electrical conductivity via the conventional formula becomes unfeasible. To address this, we provided resistances for semi-liquid metal wires of different widths (Fig. 3e), and it is evident that the resistance decreases significantly as the wire width increases. From the microscopic images of semi-liquid metal wires with varying widths shown in Supplementary Fig. 19, it can be observed that there are slight defects at the edges of each wire. When the overall width of the wire is small, these defects can lead to significant changes in its resistance. Conversely, when the overall width of the wire is large, the impact of these defects gradually diminishes. For the wire with a width of 10 μm, its resistance value can reach 38.2 Ω/mm, and the resistance difference of the samples ranges from 28.5 Ω/mm to 47.9 Ω/mm, exhibiting a relatively large error. In contrast, when the wire width exceeds 100 μm, the resistance difference of the samples can be reduced to within 0.5 Ω/mm, and the consistency of the resistance value is excellent, which can meet most of the requirements of flexible electronics.

Subsequently, semi-liquid metal wires on VHB substrate and PI substrate (width: 1 mm, length: 2 cm) were respectively subjected to stretching and bending tests. Figure 3f demonstrates the relationship between the resistance variation and the stretching rate during the stretching process. Benefiting from the high stretchability of the VHB substrate and the fluidity of the semi-liquid metal, the semi-liquid metal can follow the stretching of the substrate up to 1000%, and the wire remains connected throughout the entire process. The bulk semi-liquid metal with initial resistance of 1.65 Ω shows significant resistance differences depending on the change of geometric shape, and its resistance variation at a stretching rate of 1000% can reach 12.2, indicating its potential application as a strain sensor. Semi-liquid metal wires exhibit reliable and stable responses under repeated application of strain (more than 10,000 cycles), and no electrical failures occur (Fig. 3g). The semi-liquid metal wires possess excellent overall stability during the cyclic stretching process, and the resistivity shows periodic fluctuations at different stages of the stretching process, with good repeatability of the resistivity change during each stretching-recovery process, suggesting a good mechanical-electrical response repeatability. After 10,000 stretching cycles, the increase in the resistance of the wire was attributed to the creep of the VHB substrate, which prevented it from returning to its initial length. Additionally, when the semi-liquid metal wire was bent by 90° along the PI substrate, its resistance variation can reach 1.015 (Fig. 3h). Figure 3i shows that when the wire was stretched at different states, the resistivity demonstrated good periodic repetition, indicating that the wire is sensitive to the stretching rate and can adapt to various mechanical environments. Figure 3j illustrates the resistance variation during 10,000 bending cycles. In the early cyclic bending of the substrate, part of the liquid metal in the semi-liquid metal flows to both sides under gravity and base vibration, reducing the cross-sectional area at the middle bending point and increasing resistance. However, as bending cycles increase, the liquid metal gradually stops flowing. Then, the slight rise in the resistance of semi-liquid metal is mainly due to surface oxidation. Although there is an overall slow upward trend, the resistance variation is only 1.04, and the resistance variation during the bending-recovery process has good repeatability, demonstrating the stability and repeatability of the mechanical-electrical response. Furthermore, the wire sample underwent 10,000 cyclic stretches at a higher strain (500%). As shown in Supplementary Fig. 20, the wire remained conductive after 10,000 stretches under high strain, while its resistance variation increased to 5.83. These results align with previous reports, attributed to gradual relaxation of the stretchable substrate (failing to recover initial length) after repeated stretches, combined with continuous oxide formation on the semi-liquid metal during cyclic stretching, which both leading to progressive resistance increase. Thus, this semi-liquid metal wire is suitable for stretchable conductors in flexible circuits but not for direct use as strain sensors, as resistance correction is required after multiple stretches. In addition, thinner (width: 0.5 mm) and thicker (width: 2 mm) semi-liquid metal wires were tested for stretching (Fig. 3f) and bending (Supplementary Fig. 21). Results showed the resistance variation of 2 mm-wide wire with initial resistance of 0.78 Ω reached 9.5 at maximum stretch, and it withstood 10,000 cycles of 200% stretching without fracture. Similarly, the resistance variation of 0.5 mm-wide wire with initial resistance of 4.25 Ω reached 13.2 at maximum stretch, and also endured 10,000 cycles of 200% stretching without breaking. For bending performance, the 2 mm-wide wire exhibited a resistance variation of only 1.004 at 90° bending and 1.04 after 10,000 bending cycles. Similarly, the 0.5 mm-wide wire showed 1.012 (90° bending) and 1.06 (10,000 cycles), respectively. Additionally, long-term property tests were performed on the semi-liquid metal. The resistance of 1 mm-wide, 2 cm-long semi-liquid metal wires and their resistance variation were measured over a two-month storage period (Supplementary Fig. 22). Results show the resistance variation of unencapsulated wires increased to 1.14, while that of encapsulated ones only reached 1.01. Moreover, after long-term storage, the wires still achieved large tensile deformation with the substrate while maintaining electrical continuity. The resistance variation at maximum stretch was 12.5, comparable to that of the original wires. These results confirm the long-term electrical and mechanical stability of semi-liquid metal. Finally, to confirm its integration capability with traditional electronic devices, we used HCl solution to deoxidize the pins of traditional electronic components44, such as LEDs, enabling them to be wetted and soldered with semi-liquid metal wires, forming stable electrical interconnections, as shown in Supplementary Fig. 23. Additionally, a rigid film (polyethylene) was embedded into the VHB tape to minimize deformation at the connection, as shown in Supplementary Fig. 24a. Supplementary Fig. 24b, c illustrate that during the 200% stretching process, the voltage and current across the LEDs gradually decreased, which is attributed to an increase of 0.8 Ω in the resistance of the semi-liquid metal wire. However, the increased wire resistance only caused a voltage drop of 4 mV and a current reduction of 4 μA across the LEDs. Therefore, the variation in wire resistance induced by deformation has a negligible impact on the circuit function. This stable wetting and soldering structure with rigid electronic components ensure the subsequent development of multifunctional flexible electronic devices.

Characterization of non-loss, recyclability, reusability, and multiple substrate-applicability to for NECP method
The NECP method enabled high-precision manufacturing of complex circuits using a 2-axis moving platform. Figure 4a demonstrated a semi-liquid metal wire array with linewidth of 50 μm. The array was attached to a PI film, which was conformally coated onto non-planar surface (fingernail tip), due to its thin thickness (50 μm). This feature makes it highly suitable for applications in skin-integrated bioelectronic devices. In addition, some electronic devices require transparency, such as optoelectronic devices fabricated on transparent substrates like PDMS. Therefore, in addition to engraving the semi-liquid metal circuit pattern, excess semi-liquid metal can be precisely directed to desired regions by modifying the trajectory of the metal needle, as exemplified by the LED array manufactured on a PDMS substrate in Fig. 4a. The needle’s movement path is provided in Supplementary Fig. 25. Additionally, mesh metal patterns with varied widths and pitches were fabricated (Supplementary Fig. 26). The mesh wires have widths of 1 mm and 0.5 mm, with corresponding spacings of 1 mm and 0.5 mm. All wires were produced via the second engraving method, where semi-liquid metal in the mesh holes is fully pressed into the wires. This engraving mode cannot only minimize the coverage area of the semi-liquid metal, but more importantly, the pushed semi-liquid metal can keep the resistance value of the wire stable and improve the uniformity of the wire. As shown in Fig. 4b, a copper sheet and a semi-liquid metal wire with an initial width of 1 cm were successively cut to 1 mm, with a reduction of 1 mm each time. Since the semi-liquid metal is pushed into the adjacent wire by the needle tip, the overall volume of the wire remains almost unchanged. According to the conductor resistance calculation formula:

R = ρL / A = ρL^2 / V

where L is the wire length, R is the resistance, ρ is the resistivity, V is the volume, and A is the cross-sectional area. The resistance should theoretically remain unchanged. Furthermore, after each engraving step, the noticeable increase in wire edge thickness also confirms the constant volume of wire (Supplementary Fig. 27). Experimental results highlight the distinct electrical behavior of copper strips and semi-liquid metal wires during dimensional reduction. When reduced from an initial width of 1 cm to 1 mm, copper resistance increased by tenfold, consistent with expected resistivity variations based on width changes. In contrast, semi-liquid metal wires exhibited stable or even slightly decreased resistance when reduced from 10 mm to 5 mm, and a gradual increase to 115% of the initial value as the width decreases further to 1 mm. Observations from pictures in Fig. 4b and Supplementary Video 4 revealed semi-liquid metal thickness increased during the narrowing process, which leading to more uniform distribution and lower resistance. However, as a drawback of the second engraving approach, prolonged reduction caused irregularities at the wire edges due to ethanol effects, resulting in a slight increase in resistance. Therefore, the second engraving approach is not suitable for manufacturing high-precision wires.

Moreover, the NECP method enabled highly reconfigurable circuit fabrication without material loss, as demonstrated by its ability to erase and reuse patterns. As illustrated in Fig. 4c, four distinct circuits were successfully created on the same glass substrate. After each circuit was fabricated, it could be erased using a simple scraping technique, enabling the creation of subsequent circuits on the same base. The fractures caused by the metal needle can be completely filled with semi-liquid metal using a scraper, restoring the resistance to the state before the pattern was engraved. even when the width of the fracture reaches 5 mm, as shown in Supplementary Fig. 28. The needle’s movement path for these circuits is provided in Supplementary Fig. 29. Remarkably, the mass of semi-liquid metal remained consistent at 8.42 g after each sequential fabrication process. In addition, a large number of repeated engraving operations were carried out to evaluate the material loss caused by multiple repeated usages. The results shown in Supplementary Fig. 30 indicate that during the engraving process repeated 50 times, the mass of the semi-liquid metal remains at 8.42 grams throughout. These results underscore the exceptional reusability and resource efficiency of this method, eliminating material waste in electronic manufacturing. The arbitrary disposal or improper handling of liquid metal may lead to environmental contamination, as it can enter soil and water systems. Consequently, achieving effective recycling of liquid metal is crucial for reducing its impact on the environment and preventing resource waste while cutting down costs. Here, as a proof-of-concept, we demonstrated the recovery process of semi-liquid metal from LED arrays in NaOH solution (1 mol/L) and HCl solution (1 mol/L), as shown in Fig. 4d. When NaOH solution was applied to the PI substrate with semi-liquid metal circuits, the semi-liquid metal layer separated from the PI substrate instantly and eventually formed a single droplet (Supplementary Video 5). This occurs because Ga2O3 is an amphoteric oxide, which reacts with NaOH according to the following chemical equation:

Ga2O3 + 2NaOH = 2NaGaO2 + H2O

In this reaction, Ga2O3 reacts with NaOH to form sodium metagalate (NaGaO2) and water. Therefore, the semi-liquid metal loses its adhesion to the substrate and aggregates into droplets under high surface tension. Furthermore, we fabricated a semi-liquid metal-based LED array on a PVA substrate. When immersed in HCl solution, the PVA film dissolved, causing the LED to extinguish instantly and the semi-liquid metal to separate from the PVA membrane, ultimately yielding a single semi-liquid metal droplet and LED components (Supplementary Video 5). Unlike the NaOH solution, when Ga2O3 reacts with HCl, it forms gallium chloride (GaCl3) and water:

Ga2O3 + 6HCl = 2GaCl3 + 3H2O

Thus, the semi-liquid metal separated from the PVA membrane in HCl and eventually aggregates into droplets. The dissolution process completed within approximately 300 s at 60 °C with a constant rate, allowing the dissolution time to be controlled by varying the thickness of the PVA film and the heating temperature. Finally, we compared the mass of recovered semi-liquid metal (Supplementary Fig. 31) before and after recycling in NaOH and HCl solutions. The results indicated that only 3.35% and 2.67% of material loss occurred in each recycling process, significantly reducing the resource waste and the raw material costs.

Prior studies have demonstrated that semi-liquid metal exhibits high adhesion to various smooth substrates due to hydrogen bonding interactions at the oxide-substrate interface, enabling uniform coating on these surfaces45. Besides, the solid metal particles within semi-liquid metal experience increased friction with rough substrates, allowing external pressure to force the material onto such surfaces46. Leveraging these properties, semi-liquid metal can be patterned across diverse substrates, opening possibilities for versatile circuit manufacturing. Therefore, NECP method was used to fabricate semi-liquid metal patterns on various substrates with different surface chemistries and roughness. As illustrated in Fig. 4e, the method was tested on eight types of substrates: four smooth substrates (PDMS, Glass, PET, PU) and four rough substrates (paper, pig skin, leaf, wood board). The needle’s movement path for these substrates is provided in Supplementary Fig. 32. These substrates span a wide range from polymers to everyday items and biological tissues, encompassing both rigid and flexible materials. This universality of this method exhibit potential applications in wearable devices, medical health, and Internet of Things (IoT), facilitating flexible integration and functional expansion across diverse fields.

Improved NECP method for 3D curved electronics
In addition to the fabrication of planar circuits, the NECP method is also applicable to the fabrication of 3D curved electronics. However, when the planar circuit fabrication method described previously is used to fabricate 3D curved electronics, the entire 3D object must be immersed in ethanol, and the 2-axis moving platform is unable to control the movement of the metal needle on the 3D curved surface. Moreover, the semi-liquid metal possesses a certain level of flowability, and the structural stability of the semi-liquid metal on the 3D curved surface still need to be further optimized. To address these three issues, we have carried out a series of modifications to the planar circuit fabrication equipment and developed a NECP method for 3D curved electronics, as shown in Fig. 5a. First, an ethanol-dipped marker pen was employed instead of metal needles, as shown in Supplementary Fig. 33. The marker pen’s tip was wetted with ethanol and isolated the semi-liquid metal during movement on 3D curved surfaces by depositing ethanol into the grooves. Second, a 5-axis moving platform (Supplementary Fig. 34) was assembled to fix 3D objects and precisely control the marker pen across their surfaces. Finally, the doping ratio of solid metal particles in the semi-liquid metal was adjusted to 20%, resulting in the semi-liquid metal with lower fluidity. This semi-liquid metal was able to maintain its initial shape for up to 10 days when coated on the curved surface. In contrast, the pure liquid metal gathered at the bottom under the influence of gravity right after it was coated on the curved surface, as shown in Supplementary Fig. 35. This semi-liquid metal with lower fluidity was evenly applied to the 3D curved surface, and the NECP method of the semi-liquid metal on the 3D curved surface was accomplished using the ethanol pen and the 5-axis moving platform, as demonstrated in Supplementary Video 6. To demonstrate the method’s versatility, some LED arrays were conformally applied to various 3D-printed models with complex shapes like spherical, wavy, and arc-shaped surfaces, as shown in Fig. 5b. This method also worked across diverse materials, including objects like pepper, egg, and mouse (Fig. 5c). Supplementary Fig. 36 illustrates the ethanol pen’s movement paths on these surfaces.

The NECP method demonstrated remarkable operational simplicity and broad universality. The conformal 3D electronic devices fabricated by this method can perfectly conform to the surfaces of 3D curved objects, and they possess extensive application prospects in various fields such as aerospace and smart home. For instance, aircraft icing in cold weather poses risks by increasing weight and energy consumption. Traditional de-icing methods, such as spraying chemical de-icing fluids on the wings or installing hot air de-icing systems, are inefficient and costly. In contrast, this method enabled conformal anti-icing systems on aircraft surfaces, as shown in Fig. 5d. This de-icing system was composed of an electrically heated wire and an LED array. Supplementary Fig. 37 show the movement path of the ethanol pen on the curved surface of the fuselage. As shown in Fig. 5e, the electrically heated wires can effectively heat the wing under a current of 3A, increasing the surface temperature of the wing from 23.5 °C to 60.7 °C within 80 s. The pattern of the LED array was customizable and could provide guidance for night flights. The part of the LED array also can be replaced by other functional circuits to meet different requirements. In addition, conformal electronics demonstrate significant application value in the field of smart home. They can closely adhere to the complex shapes of household items to achieve the integration of electronic circuits. While maintaining the aesthetic harmony of the equipment, they endow households with functions of intelligent monitoring and control, greatly enhancing the intelligence and convenience of the home. Figure 5f show the LED array circuits implemented on a house model using the NECP method, covering substrates such as the glass roof windows, wooden tables, and plastic floors. Supplementary Fig. 38 shows the movement paths of the ethanol pen on the surfaces of three parts of the house model. The above results indicated that the NECP method enables precise fabrication of flexible circuits on diverse material surfaces without requiring complex pretreatment, offering operational simplicity and high compatibility.

Demonstration of customizable and zero-waste skin-interfaced electrodes
The NECP method exhibits exceptional customizability, which significantly facilitates the fabrication of wearable devices. By tailoring designs to specific body areas or individual needs with unique dimensions and configurations, comfort and signal detection accuracy can be notably enhanced. Here, utilizing non-loss engraved semi-liquid metal circuits for the fabrication of skin-interfaced electrodes, we demonstrated the effectiveness of this method in monitoring electrophysiological signals such as electrocardiogram (ECG) and electromyogram (EMG). As illustrated in Fig. 6a, the ECG monitoring system comprises semi-liquid metal electrodes printed on a PU film using the NECP method, along with a compact circuit board housed in a 3D-printed casing. The system was affixed to the chest area of a male volunteer via an adhesive film at the base of the PU film. Initially, semi-liquid metal was uniformly coated onto the PU film, electrodes were patterned using the NECP method subsequently (Fig. 6b). The collected signals were processed and transmitted via a microprocessor and Bluetooth module on the circuit board, enabling heart rate calculation at the computer end (Supplementary Fig. 39). In the experiment of human ECG signal acquisition, the ECG waveform was successfully obtained, and the P wave, QRS complex, and T wave could be clearly distinguished. The baseline drift and external interference were low. Enlarged waveforms revealed that the semi-liquid metal electrodes captured QRS complexes with comparable precision to traditional Ag/AgCl electrodes, with peak amplitudes and intervals within acceptable error ranges (Fig. 6c). This demonstrates the potential of semi-liquid metal electrodes to match conventional medical electrodes in ECG signal quality. Over a 60-min monitoring period, the system remained stable, reflecting dynamic heart rate variations corresponding to physiological states, ranging from approximately 58 to 110 beats per min (Fig. 6d). Even during dynamic posture change such as lying, sitting, and standing, the collected ECGs exhibited intact characteristic waveforms with minimal baseline displacement (Supplementary Fig. 40), indicating the electrodes’ ability to maintain conformal contact with skin during movement. The RR interval scatter plot displays spindle-shaped distribution, with data points clustering around the 45° line, suggesting sinusoidal rhythm regularity and normal cardiac function in the subject (Fig. 6e). These results underscore the capability of semi-liquid metal electrodes to precisely capture ECG features, offering an innovative solution for wearable ECG monitoring devices. Furthermore, Fig. 6f demonstrates the NECP method for the construction of the desired deformable EMG electrodes. These semi-liquid metal electrodes were attached to the male volunteer’s forearm to construct a dual-channel EMG acquisition system (Supplementary Fig. 41). Benefiting from the fluidity and deformability of the semi-liquid metal, the electrodes can conformally adhere to the skin. Even when the skin is rubbed and stretched, the electrodes can stably adhere to the skin surface (Supplementary Fig. 42). Figure 6g show the EMG signals of six typical hand gestures measured on the forearm using the semi-liquid metal electrodes, verifying its ability to sense high-fidelity EMG signals. Supplementary Fig. 43 presents the EMG signal-to-noise ratio (SNR, Channel 1) for the semi-liquid metal electrodes and traditional Ag/AgCl electrodes across 6 gestures. The semi-liquid metal electrodes exhibit higher SNR than Ag/AgCl electrodes under most gestures, and only in gesture 2 is their SNR slightly lower. Since higher SNR indicates less noise interference and better signal quality, the semi-liquid metal electrodes perform better in EMG signal acquisition for these 6 gestures. Finally, we measured the impedance between the semi-liquid metal electrodes, traditional Ag/AgCl electrodes and the skin, and compared it with the impedance of the semi-liquid metal electrodes on moist skin, as shown in Supplementary Fig. 44. These semi-liquid metal electrodes have lower interfacial impedance than the traditional Ag/AgCl electrodes due to their excellent fluid deformability, which can adaptively fit the micro-topography of the skin surface, and higher electrical conductivity. When the skin sweats, the interfacial impedance between the semi-liquid metal electrode and the skin decreases. This is because sweat forms a continuous ionic conductive film on the skin surface. It not only fills the tiny gaps between the electrode and the skin, but also penetrates the stratum corneum to increase its water content, and enhance internal ion migration to reduce resistance. Additionally, sweat acts as a lubricant and filling medium, promoting the semi-liquid metal to fully wet the skin, lowering contact resistance and thus the overall interfacial impedance. After the semi-liquid metal electrode is removed, slight benign residues may occasionally appear (similar to some commercial electrocardiogram gels). However, such residues can be easily and completely removed by simple wiping with an alcohol swab, which is a standard item in medical and personal care settings, as shown in Supplementary Fig. 45. Benefiting from the advantages of non-loss and recyclability of the NECP method, there was no loss of semi-liquid metal during the electrode manufacturing process, and NaOH solution was used to achieve nearly complete recycling of semi-liquid metal. Figure 6h displays that the ECG and EMG electrodes were detached from the substrate in the NaOH solution and merge into reusable bulk liquid metal droplets. The mass of the recovered semi-liquid metal droplets was almost consistent with that of the semi-liquid metal used for electrode fabrication. These demonstrations collectively indicate that the non-loss engraved semi-liquid metal circuits can conveniently and quickly provide customized and highly stable signal acquisition solutions for wearable physiological electrical signal monitoring devices. Such semi-liquid metal electrodes are expected to be applied to zero-waste medical electronic devices, addressing the environmental pollution and resource waste caused by disposable medical devices.

Methods
Materials
Gallium (Ga, 99.9%) and indium (In, 99.9%) were purchased from Anhui Minor New Materials Co., Ltd. Silver-plated copper microparticles (mean diameter: 15 μm, Ag content: 3 wt%) were purchased from Hebei Jingrui Alloy Products Co., Ltd. Anhydrous ethanol (99%) was purchased from Xintai Yixinkang Medical Supplies Co., Ltd. Stainless-steel needles (NO.0517) were purchased from Dandong Shuangyan Needle-making Co., Ltd. Sodium hydroxide were purchased from Xilong Scientific Co., Ltd.

Fabrication of semi-liquid metal
Gallium with a mass fraction of 75.5% and indium with a mass fraction of 24.5% were mixed in a beaker, and the mixture was heated at 200 °C for 2 h to prepare liquid metal (EGaIn). Then, silver-plated copper microparticles with a mass fraction of 15% and 20% were added to the prepared EGaIn. Some sodium hydroxide aqueous solution (1 mol/L) was poured into the beaker. After stirring for 3 min, the silver-plated copper microparticles entered the liquid metal and semi-liquid metal was obtained.

Fabrication of multiple substrates
PDMS (Sylgard 184, Dow Corning, Inc.) and Ecoflex (Beijing Tiantong Huayi Landscape Technology Co., Ltd.) were prepared using conventional methods. The VHB tape is a transparent universal acrylic adhesive tape (VHB™ 4905), was purchased from Minnesota Mining and Manufacturing Co., Ltd. Wood was purchased from Shuyang Shengteng Trade Co., Ltd. PI film (C81854-25MG) and PVA film was purchased from Sigma-Aldrich Corp. PU film was purchased from Zibo Tangjian Medical Devices Co., Ltd. Paper was purchased from Deli Group Co., Ltd. Glass was purchased from Nantong Bestest Experimental Equipment Co., Ltd.

Pattern devices. An assembled 2-dimensional moving platform was used to fabricate high-precision non-loss engraved semi-liquid metal circuits. A plotter (42HD00, Jinhua Jinqian Intelligent Technology Co., Ltd.) was utilized for creating complex and large non-loss engraved semi-liquid metal circuits. An assembled 5-axis moving platform was used to fabricate the non-loss engraved patterned semi-liquid metal circuits on the 3D curved surface. The ethanol pen was made by filling ethanol into an empty marker pen.

Electrical characterization
The electrical conductivity of semi-liquid metal with varying doping ratios was determined via the standard four-point probe method. Prior to testing, the samples were placed and secured within a trapezoidal groove; this groove measured 50 mm in length and had a cross-sectional area of 15 mm^2. The resistances of semi-liquid metal wire samples with different widths were measured by a digital multimeter (Keithley 2002, Tektronix, Inc.). A four-terminal method was employed to avoid the influence of contact resistance. The semi-liquid metal wires (with a width of 1 mm and a length of 2 cm) on the VHB substrate and the PI substrate were fixed onto a dynamic mechanical test system (HC-01, Dongtai Suheng Transmission Technology Co., Ltd.), and a multimeter (U1251B, Agilent Technologies, Inc.) was used to measure the resistance changes of the two types of wires during the stretching process (on the VHB substrate) and the bending process (on the PI substrate). In the stretching test, the VHB substrate was stretched to a 1000% stretching rate at a speed of 1 mm/s; in the bending test, the PI substrate was bent to 90° with a bending radius of 5 mm, and one bending cycle takes 5 s. An infrared camera (FOTRIC 220s, Fotric Smart Technology Co., Ltd.) was used to measure the temperature distribution of the heating circuit on wings. All our replicates are biological replicates, meaning that different samples were prepared for measurement.

Morphology characterization
A contact angle measuring instrument (SDC-200, Shengding Precision Instrument Co., Ltd) was used to measure the contact angles of liquid metal droplets on various substrates. To characterize the adhesion between semi-liquid metal and substrate, the critical slip angles were were tested on a platform with an adjustable incline angle, and recorded using a camera (EOS 200D II, Canon Inc.). High-resolution optical images and element distribution of the patterned semi-liquid metal circuits were obtained using environmental scanning electron microscope (Apreo, Thermo Fisher Technology Co., Ltd). The complex patterned semi-liquid metal circuits were observed using an optical microscope (FHD Camera V2, Shenzhen Shunhuali Electronics Co., Ltd.). 3D images and cross-sections were obtained using a laser confocal microscope (Olympus, LEXT OLS 4000). The valence states of elements were characterized by XPS (ESCALAB 250Xi, Thermo Fisher Scientific, Oxford, UK).

Circuits
LEDs (1206) and a microcontroller (MSP430G2553) were pressed onto PDMS substrate to fabricate a running light circuit. LEDs (1206) and touch switch chip (TTP223-BA6) were pressed onto a wooden table in the house model. An analog front-end amplifier (BMD101, NeuroSky Electronic Technology Co., Ltd) was used to collect ECG signals. An analog front-end amplifier (ADS1298, Texas Instruments, Inc., Dallas, TX, USA) was used to collect EMG signals. All procedures involving the attachment of electrodes to human skin comply with ethical guidelines, which have been approved by Tianjin University (approval number: TJUE2025-H-S-063). All subjects voluntarily involved in experiments after informed consent.

Statistics and reproducibility
All experiments were repeated independently with similar results at least three times.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "Semi-LM has been already reported by the same group, so there is no novelty in material itself. However, NECP patterning method is newly reported in this manuscript. Although authors mentioned that this method can save material waste, there is no clear explanation about how to make patterns from blank-coated semi-LN including how to remove the material in the areas except for the patterns. In order to meet the high standard for Nat. Comm., authors must report long-term material reliability and electrical/mechanical properties, and feasibility of the patterning method in mass production. In addition, the following issues must be solved. The current manuscript is not acceptable in Nat. Comm.\n1. Experimental conditions of Initial resistance of electrodes, stretching condition, bending radius, etc. must be presented in Fig. 3F-3J. More experiment with electrodes with various widths (not just 1 mm width) must be performed.\n2. In Fig. 3D, pattern thickness decreases and resistance increases according to reduction of pattern width. It must be clearly explained. Why?\n3. When pattern width reduces via NECP for blank-coated semi-LM, the pattern thickness increases. (Fig. 4B) However, from movie 4, pattern edge gets irregular as the thickness increases, leading to failure for application to fine feature patterning. Which is disadvantage of the method.\n4. Authors must describe in detail about how to remove semi-LM from the area except for the defined electrodes after patterning electrodes via NECP method. (Fig. 3B & Movie 3) They need to show us NECP method can produce mesh metal patterns with various ling widths and pitches.\n5. Consistency of resistance change unit. % in line 191-198, but resistance in Fig. 3f~3j. Description about the figures is wrong.\n6. Authors claims that advantage of NECP method is less waste of material but it is difficult to agree. They also need to remove semi-LM in the non-patterned area of blank-coated LM. In comparison with other subtractive methods, what % of the removed material can be reused?\n7. Conductivity for various widths of electrodes must be provided. The maximum conductivity of 9x10^6 s/m was obtained for which electrodes?\n8. Why do they use the maximum % (15~20%) of Ag coated Cu particle? What is the reason? Conductivity with the content of Ag coated Cu particles?\n9. Author must clarify that there is intermetallic compound formation between EGaIn and AgCu. Resistance changes with time? Stretchability changes with time? Data is required.\n10. Uniformity of the thickness of the EGaIn film coated on the substrate must be provided.", "reviewer_2": "The manuscript presents a non-loss method for fabricating semi-liquid metal circuits by using alcohol to modulate interfacial adhesion between liquid metal and substrates. Furthermore, by controlling adhesion through a custom-designed displacement apparatus, facilitate patterning from 5 μm to centimeter scales across diverse substrates. This is interesting and I enjoyed reading it. However, the underlying principle has been established in prior works. Thus, the authors may need to clarify the novelty of the work and specify the details in order to publish this work.\n1. The underlying mechanism of interaction between alcohol group (-OH) and liquid metal oxide resulting in selective interfacial adhesion has already been well established in previous literatures (please refer C. Park et al Adv. Mater. 2020, 32, 2002178, DOI: 10.1002/adma.202002178; K. K. Zadeh et al, Adv. Funct. Mater. 2021, 31, 2007336, DOI: 10.1002/adfm.202007336). The authors should clearly and carefully highlight the innovative aspects of their findings in comparison to the previous works.\n2. The authors repeatedly mention \"alcohol\" without specifying the type. Please clarify which alcohol was used to ensure reproducibility and clarity. In method section, correct “Athanol”.\n3. The typical electrical conductivity of EGaIn is around ~3.4x106 S/m (please refer G. M. Whitesides et al, Angew. Chem. Int. Ed. 2008, 47, 142–144; DOI: 10.1002/anie.200703642; C. Majid et al, Adv. Mater. Interfaces 2018, 5, 1701596; DOI: 10.1002/admi.201701596). Is it really possible to achieve electrical conductivity more than typical values? Please verify and correct. If it is possible, explain the underlying mechanism.\n4. How only metallic electrode would be effective to collect ECG and EMG signals? Authors will need to provide more evidence; the reviewer recommend to perform comparative skin-electrode interface impedance analysis using both the semi-liquid metal electrode and traditional Ag/AgCl electrode (Frequency range 1000kHz to 0.1 Hz).\n5. In EMG monitoring, please provide signal to noise ratio for both the electrodes.\n6. The recent advances in circuit patterning technology using Liquid metals for wearable electronics have been introduced. The authors may consider to cite some relevant references to strengthen the research background.\ndoi.org/10.1007/s40820-024-01457-7 / DOI: 10.1126/science.adp3299 / doi.org/10.1016/j.cej.2022.139832.\n7. Lines 110-113, explain the necessity of silver coated copper particles instead of pure copper particles to modulate the fluidity of LMs. Because plenty of previous studies (eg. 10.1002/inf2.12466, 10.3390/polym13152407, 10.1002/adma.201904309, 10.1002/admt.201700351) had modulated LM fluidity through particle inclusion. Is it to promote better wettability between LM and particles and to protect the reactive Cu ?\n8. In Fig.1B, how is the contact angle measured? Was the substrate immersed in alcohol followed by semi LM placement? Also, please explain the reason behind the significant difference in contact angle values in air and in alcohol? Is it because the presence of more hydrogen bonding sites in alcohol lowers the surface energy of the placed semi LM ?\n9. The supplementary table S1 is missing\n10. In Fig 2A, it is advised to provide more details as to why the wettability of alcohol on various substrates is better than water? The surface tensions of most alcohols are in the range 20-25 mN/m which is less than one-third of water, so they can spread on surfaces more easily.\n11. Lines 210-221, rather than reporting the phenomenon, it is advised to justify the findings with more scientific reason. During the second stroke air, why are there bridges which are clearly not forming in alcohol (Supplementary Figure 8)? The inferior adhesion between semi LM and substrate in alcohol compared to the highly cohesive nature of the semi LM drives the semi LM to reduce its area? Did the authors monitor whether there is a critical speed of scratching upto which it can prevent short circuiting? Or is the phenomenon speed invariant?\n12. Figures 2E and F and 3D are not enough. One of the biggest advantages of subtractive manufacturing using LM is not only to obtain very fine resolution patterns but to also reduce gaps between patterns in order to downsize circuits, eg. inductors for proximity sensing or wireless powering. The authors should provide detailed study by varying pitch (i.e. gap) and pattern width and monitor the increase in height (or change in shape of the pattern).\n13. In Figure 3C how was the conductivity measured? Is it the conductivity of the bulk material or conductivity measured from some defined patterns? If it is the former then please mention it, if it is the latter, its value can vary (given that the experimental resistance values are showing deviations from mean value , Figue 3E)\n14. What is the resolution of the wire stretched in Figure 3F? And why is the gauge factor changing drastically after 800%?. In previous reports related to LM patterns (10.1016/j.cej.2022.139832, 10.1038/s41528-021-00123-x etc.) the gauge factor does not seem to vary drastically. Whereas in case of carbon fiber based conductors, non percolation at definite strain can alter gauge factor (10.1038/s41467-018-08016-w), LM patterns are in continuous phase and their geometries at strain will be defined by the substrate. In case of hyperelastic substrates, due to non uniform poisson effects the width of the substrate will decrease quickly in the beginning and as strain proceeds this decrement rate will be gradually minimal, this also affects the geometry of the printed wire. Therefore the author should do resistance vs strain of different width patterns and compare the behaviors with previous literatures; and also explain the behaviors rather than reporting a single curve.\n15. In Figure 3G what's the strain and what's the test speed? In Figure 3J, what is the bending angle? And why can a very steep increase in resistance be observed within the first 1000 cycles of bending? In Figure 4B, please correct the legends' color, it is difficult to distinguish. Also, the explanation behind the low resistance change should be done carefully. Supporting Video 4 clearly reveals very inhomogeneous distribution of particles in the LM matrix and does not reveal much about the thickness. Can it be possible that the highly conductive particles are aggregated together during narrowing down of the lines which also aids to reduce large resistance change?\n16. In Figure 6, is there any special advantage of using semi LM as ECG electrodes? Because previous works have directly deposited LM on skin (10.1021/acs.chemrev.3c00317) or in the form of composites coupled with elastomers (doi/10.1002/inf2.12302) in order to achieve superior conformability. Here the semi LM seems to be in non-encapsulated state and direct contact with the skin? Will any residue be left after its use or will the cohesive nature of semi LM prevent it? Also the metallic electrode is itself not protected from sweat and during sweat generation the skin-electrode contact impedance will change and can significantly impact signal to noise ratio.\n17. In supplementary figure 12, the wettability of the terminals is crucial for full functionality of the LED. Please refer to relevant literature(10.1016/j.snb.2015.07.062) and it is recommended to calculate current voltage across the LED after various modes of deformation to ascertain that no parasitic resistance is generated in the LM-LED interfaces.\n18. In Figure 5e, what is the current value applied for heating?", "reviewer_3": "The authors present here an approach for using mechanical engraving in alcohol for high resolution patterning of liquid metal circuits. I thought overall the concept appears novel, testing appears thorough and the paper is largely well written with compelling figures; stretchable electronics and liquid metal circuits are also of substantial broader interest making the article well suited for your readership. There were however a number of minor errors and misstatements that should be corrected before acceptance; a full list of my concerns is below.\nFig. 3 C is more than a little confusing, appearing to conflate material property (the authors have a novel liquid metal loaded with copper particles, and get a higher conductivity) and fabrication approach. In practice, the two parameters are largely independent (the authors could for instance have injected their material into microchannels and gotten a different position on their plot) and it is misleading to imply that microchannel injection, or screen printing, or laser ablation, have specific conductivity numbers.\nIn Fig. 2 (a), water and common alcohols are well known materials and presumably contact angles on many common substrates are available in the literature, particularly substrates like PDMS that are very widely used in microfluidics. How did their results compare to the literature? Is this test truly necessary to include, given the common nature of the two liquids involved?\nIn a scientific context, alcohol is a material class, not a specific liquid; in looking at the materials section the authors identify the material as ‘athonol’, which I am not familiar with and does not appear to be a common alcohol. Do the authors mean ‘ethanol’? If so, the authors should consistently and correctly identify this throughout the manuscript, rather than using ‘alcohol’\nIn the two cyclic tests (Figures 3 G and J), it is very important to clarify the bend and stretch conditions during the cycling; how much is the sample being bent or stretched in each case? It is somewhat concerning that the value never looks stable in either case (and for the stretching in particular the change is more than ten percent, which is not insubstantial).\nBased on the cycling test, it appears that even for a modest strain a permanent resistance change is occurring. The authors argue that there is value in their printed traces as a strain sensor up to nearly 1000% strain; is the resistance stable at higher strains under repeated strains? A more aggressive cycling strain test is necessary to defend this claim, based on what is being presented here.\nRecovering and recycling liquid metal electronics has been demonstrated previously elsewhere (for example, in L. Teng et al., Liquid metal-based transient circuits for flexible and recyclable electronics, Adv. Funct. Mater., 2019), and needs to be properly credited and compared with here\nSimilarly, copper-liquid gallium amalgams do not appear to be new to this work, and have been previously investigated by these researchers (for instance in J. Tang et al., ACS Appl. Mater. Interfaces 2017). It is important to clarify this in the text to help the reader understand the specific contribution here."}, "author_response": "RESPONSE TO REVIEW COMMENTS\nREVIEWER #1\nComment: Semi-LM has been already reported by the same group, so there is no novelty in material\nitself. However, NECP patterning method is newly reported in this manuscript. Although authors\nmentioned that this method can save material waste, there is no clear explanation about how to make\npatterns from blank-coated semi-LN including how to remove the material in the areas except for the\npatterns. In order to meet the high standard for Nat. Comm., authors must report long-term material\nreliability and electrical/mechanical properties, and feasibility of the patterning method in mass\nproduction. In addition, the following issues must be solved. The current manuscript is not acceptable\nin Nat. Comm.\nRe: We greatly appreciate the reviewer for such helpful comments. We have carefully considered each\nof your comments and suggestions. We have made extensive revisions to the manuscript, and we\nbelieve these changes have significantly improved the quality of our work. To help you quickly identify\nthe modifications, we have highlighted the revised sections in red font throughout the document.\nAlthough semi-liquid metals have been reported in previous studies, the main innovation of this paper\nlies in providing a non-destructive circuit fabrication method. The use of semi-liquid metals only\nserves to achieve more uniform coating of liquid metals on a variety of substrates, especially 3D curved\nsubstrates. Therefore, the semi-liquid metal material itself is not the main innovation of this paper. The\ncharacterization of the electrical and mechanical properties of semi-liquid metal has been conducted\nmultiple times in our previous studies (Science Bulletin, 2024, 69, (17), 2723-2734; Applied Energy,\n2024, 367, 123397; Adv. Fiber Mater. 2024, 6, 354-366). Thus, this paper does not perform duplicate\nexperiments to verify the material properties already demonstrated in previous studies. However, to\nensure the rigor and authenticity of this research, we re-tested the long-term performance of the semi-\nliquid metal material and supplemented this part in the new manuscript (Refer to Comment 9 for further\ndetails). In addition, we took SEM images of the semi-liquid metal immediately after preparation and\nafter two months of storage, as shown in Fig. R1. It can be seen from the figures that the volume of\nsolid metal particles inside the semi-liquid metal slightly increases after long-term storage.\nNevertheless, the oxide film covering the surface of the semi-liquid metal prevents further oxidation\nof the semi-liquid metal. As a result, its physical state can remain relatively stable, and it exhibits long-\nterm mechanical stability, maintaining good stretchability even after long-term storage.\nFig. R1 SEM images of the freshly prepared semi-liquid metal and that has been stored for two months.\nAt present, the needle tip movement speed controlled by our independently designed and manufactured\n2-axis motion platform and 5-axis motion platform is relatively low. Therefore, a longer time is\nrequired when manufacturing complex circuits, and it is thus difficult to achieve mass production with\nthe current technical level. For this reason, in the original manuscript, we focused on highlighting the\nadvantages of our technology, such as high precision, large area, multi-substrate compatibility,\nstretchability, reusability, and recyclability. Therefore, we believe that with the current technical level,\nthis circuit fabrication method is more suitable for the customization of personalized circuits. In future\nresearch, we plan to optimize printing parameters (e.g., pressure, temperature, speed) in real time\nthrough machine learning algorithms and build fully automatic unmanned manufacturing equipment.\nIn addition, we can develop multi-scale needles ranging from micro-nano to macro scales, enabling\nthe entire manufacturing process from micron-level wires to centimeter-level wires to be completed\non the same equipment. This will help improve manufacturing speed and realize mass production.\nThe following changes have been introduced to address the comment:\nMain text (line #129): Silver coated copper particles exhibits excellent corrosion resistance, which\nensures the long-term stability of semi-liquid metal. The Scanning Electron Microscope (SEM) photos\nin Supplementary Fig. 4 show the micro-morphology of the semi-liquid metal film prepared two\nmonths ago. This figure clearly indicates that only a slight change has occurred in the diameter of the\nsolid particles. The X-ray Photoelectron Spectroscopy (XPS) curves in Supplementary Fig. 5 indicate\nthat the surface of the semi-liquid metal is encapsulated by a metal oxide film predominantly composed\nof gallium oxide and indium oxide. As a result, its physical state can remain relatively stable, and it\nexhibits long-term mechanical stability, maintaining good stretchability even after long-term storage.\nMain text (line #632): However, the current technical level makes mass production difficult to achieve,\nso this technology is only suitable for the rapid fabrication of personalized custom circuits. In our next\nstep, we will optimize printing parameters in real time through machine learning algorithms, build fully\nautomatic unmanned manufacturing equipment, and develop multi-scale needles ranging from micro-\nnano to macro scales. This will enable the entire manufacturing process from micron-level wires to\ncentimeter-level wires to be completed on the same equipment, thereby improving manufacturing\nspeed and realizing mass production.\nSupporting information (Pages #2): Fig. R1 has been included as Supplementary Fig. 4 in the revised\nSupporting Information.\nComment 1: Experimental conditions of Initial resistance of electrodes, stretching condition, bending\nradius, etc. must be presented in Fig. 3F-3J. More experiment with electrodes with various widths (not\njust 1 mm width) must be performed.\nRe: We highly appreciate the reviewers' critical reminders. In the revised manuscript, we have\nsupplemented the missing experimental conditions, including the initial resistance, stretching\nconditions, and bending radius of the semi-liquid metal wires. Furthermore, in accordance with your\nsuggestions, we re-conducted the stretching and bending experiments using thinner (width: 0.5 mm)\nand thicker (width: 2 mm) semi-liquid metal wires. We obtained the resistance variation of the two\ntypes of wires under different stretching states (Fig. R2), as well as the changes in their resistance\nduring 10,000 cycles of stretching and bending (Fig. R3). The experimental results are similar to those\nof the original semi-liquid metal wires (width: 1 mm): both can maintain stable connection of the wires\nwithout breakage. However, the resistance variation of the semi-liquid metal wires after cyclic\nstretching is relatively significant. Considering the substantial variation in the resistance of the wires\nafter cyclic stretching, we have removed the relevant description stating that the semi-liquid metal\nwires have the potential to be used as strain sensors from the revised manuscript. In addition, we\nperformed 10,000 cycles of stretching on the wire samples under a higher strain (500%), as shown in\nFig. R4. The results show that the wires can maintain stable connectivity, but the change in resistance\nis relatively obvious. Therefore, we suggest that this semi-liquid metal wire is suitable for use as a\nstretchable wire in flexible circuits, rather than directly as a strain sensor-this is because it requires\nresistance correction after multiple stretches.\nFig. R2 Resistance variation of the three types of wires under different stretching states.\nFig. R3 a Resistance variation of semi-liquid metal wire (width of 2 mm) during 10,000 stretching\ncycles. b Relationship between resistance variation and bending angle during semi-liquid metal wire\n(width of 2 mm) bending. c Resistance variation of semi-liquid metal wire (width of 2 mm) during\n10,000 bending cycles. d Resistance variation of semi-liquid metal wire (width of 0.5 mm) during\n10,000 stretching cycles. e Relationship between resistance variation and bending angle during semi-\nliquid metal wire (width of 0.5 mm) bending. f Resistance variation of semi-liquid metal wire (width\nof 0.5 mm) during 10,000 bending cycles.\nFig. R4 Resistance variation of semi-liquid metal wire under 500% strain during 10,000 stretching\ncycles.\nThe following changes have been introduced to address the comment:\nMain text (line #347): Furthermore, the wire sample underwent 10,000 cyclic stretches at a higher\nstrain (500%). As shown in Supplementary Fig. 20, the wire remained conductive after 10,000\nstretches under high strain, while its resistance variation increased to 5.83. These results align with\nprevious reports, attributed to gradual relaxation of the stretchable substrate (failing to recover initial\nlength) after repeated stretches, combined with continuous oxide formation on the semi-liquid metal\nduring cyclic stretching, which both leading to progressive resistance increase. Thus, this semi-liquid\nmetal wire is suitable for stretchable conductors in flexible circuits but not for direct use as strain\nsensors, as resistance correction is required after multiple stretches. In addition, thinner (width: 0.5 mm)\nand thicker (width: 2 mm) semi-liquid metal wires were tested for stretching (Fig. 3f) and bending\n(Supplementary Fig. 21). Results showed the resistance variation of 2 mm-wide wire with initial\nresistance of 0.78 Ω reached 9.5 at maximum stretch, and it withstood 10,000 cycles of 200% stretching\nwithout fracture. Similarly, the resistance variation of 0.5 mm-wide wire with initial resistance of 4.25\nΩ reached 13.2 at maximum stretch, and also endured 10,000 cycles of 200% stretching without\nbreaking. For bending performance, the 2 mm-wide wire exhibited a resistance variation of only 1.004\nat 90° bending and 1.04 after 10,000 bending cycles. Similarly, the 0.5 mm-wide wire showed 1.012\n(90° bending) and 1.06 (10,000 cycles), respectively.\nMain text (line #326): The bulk semi-liquid metal with initial resistance of 1.65 Ω shows significant\nresistance differences depending on the change of geometric shape, and its resistance variation at a\nstretching rate of 1000% can reach 12.2. The semi-liquid metal wires exhibit reliable and stable\nresponses under repeated 200% strain (more than 10,000 cycles), and no electrical failures occur (Fig.\n3g).\nMain text (line #678): In the stretching test, the VHB substrate was stretched to a 1000% stretching\nrate at a speed of 1mm/s; in the bending test, the PI substrate was bent to 90° with a bending radius of\n5 mm, and one bending cycle takes 5 s.\nMain text (line #382): Fig. R2 have been included as Fig. 3f in the revised manuscript.\nSupporting information (Pages #6): Fig. R3, R4 have been included as Supplementary Fig. 20 and\nFig. 21 in the revised Supporting Information.\nComment 2: In Fig. 3D, pattern thickness decreases and resistance increases according to reduction\nof pattern width. It must be clearly explained. Why?\nRe: We greatly appreciate the reviewer for such helpful comments. We have provided an explanation\nfor this phenomenon in the new manuscript. During the experiment, we observed that the arc-shaped\nprofile of the metal needle tip gives rise to differences in the width of the scratches at various height\nlevels. Additionally, the semi-liquid metal exhibits a certain degree of fluidity, and the surface tension\nof the liquid metal imparts a tendency for it to contract toward the two sides of the scratches.\nConsequently, the cross-section of the scratches assumes an inverted trapezoidal shape, as illustrated\nin the schematic diagram of Fig. R5. When the spacing between two scratches is very small, the semi-\nliquid metal at the higher regions is pushed away by the arc-shaped needle tip. Moreover, the residual\nsemi-liquid metal re-fuses under the influence of surface tension, leading to a significant reduction in\nits height and, accordingly, a marked increase in its resistance value. In contrast, when the spacing\nbetween the two scratches is relatively large, the semi-liquid metal at the higher regions is not pushed\naway by the arc-shaped needle tip. As a result, only the height of the semi-liquid metal on both sides\nof the wire decreases, while the middle part of the wire maintains the same height as the initial semi-\nliquid metal coating.\nFig. R5 Schematic diagram of semi-liquid metal wire height decreasing with reducing wire width\ncaused by arc-shaped needle tip.\nThe following changes have been introduced to address the comment:\nMain text (line #297): This is due to the arc-shaped metal needle tip causing width variations in the\nscratch across different height levels. Additionally, the semi-liquid metal, exhibiting fluidity, tends to\ncontract toward the scratch edges due to surface tension, resulting in an inverted trapezoidal cross-\nsection (Supplementary Fig. 18). For closely spaced scratches, the arc tip displaces semi-liquid metal\nin higher regions, significantly reducing their height. Conversely, with larger spacing, the tip does not\ndisplace the metal in higher regions, allowing the wire's middle section to retain the initial coating\nheight.\nSupporting information (Pages #5): Fig. R5 has been included as Supplementary Fig. 18 in the revised\nSupporting Information.\nComment 3: When pattern width reduces via NECP for blank-coated semi-LM, the pattern thickness\nincreases. (Fig. 4B) However, from movie 4, pattern edge gets irregular as the thickness increases,\nleading to failure for application to fine feature patterning. Which is disadvantage of the method.\nRe: We are thankful for your constructive criticism. In fact, the engraving method demonstrated in Fig.\n4b corresponds to the second engraving approach we proposed. This engraving method pushes the\nsemi-liquid metal in the unwanted areas completely into the pattern area; as a result, the thickness of\nthe semi-liquid metal at the pattern region increases significantly. Moreover, the thicker semi-liquid\nmetal exhibits more prominent surface tension, which leads to uneven boundaries. Thinner wires\ncaused irregularities at the wire edges due to alcohol effects, resulting in a slight increase in resistance.\nTherefore, this hollowed-out engraving method is not suitable for fabricating high-precision semi-\nliquid metal wires. Consequently, the minimum width of the semi-liquid metal wire shown in Fig. 4b\nis 1 mm, and it is not used to produce thinner wires. In the new manuscript, we have supplemented the\nlimitations of the second engraving method regarding the fabrication of high-precision wires.\nThe following changes have been introduced to address the comment:\nMain text (line #424): However, as a drawback of the second engraving approach, prolonged reduction\nled to irregularities at the wire edges due to the effects of alcohol, resulting in a slight increase in\nresistance. Therefore, the second engraving approach is not suitable for manufacturing high-precision\nwires.\nComment 4: Authors must describe in detail about how to remove semi-LM from the area except\nfor the defined electrodes after patterning electrodes via NECP method. (Fig. 3B & Movie 3) They\nneed to show us NECP method can produce mesh metal patterns with various ling widths and pitches.\nRe: Your expertise has significantly contributed to the quality of our research. In fact, the original\nmanuscript has elaborated on how to realize circuit patterning and the reasons why this manufacturing\nmethod saves materials. The specific preparation process is as follows: first, uniformly coat the semi-\nliquid metal on the substrate, then soak it in an alcohol solution, and then manipulate the needle tip to\nextrude the semi-liquid metal. The semi-liquid metal at the scratched area is actually squeezed to both\nsides of the scratch, so there is no material loss. The specific operation process is shown in the Fig.1d.\nBesides, we have produced mesh metal patterns with various widths and pitches, as shown in Fig. R6.\nThe widths of the newly fabricated mesh wires are 1 mm and 0.5 mm, with spacings of 1 mm and 0.5\nmm respectively. All these wires are manufactured using the second engraving approach, where the\nsemi-liquid metal in the hollowed-out areas is completely pushed into the wires.\nFig. R6 Mesh circuits with two mesh sizes.\nThe following changes have been introduced to address the comment:\nMain text (line #402): Additionally, mesh metal patterns with varied widths and pitches were fabricated\n(Supplementary Fig. 26). The newly prepared mesh wires have widths of 1 mm and 0.5 mm, with\ncorresponding spacings of 1 mm and 0.5 mm. All wires were produced via the second engraving\nmethod, where semi-liquid metal in the mesh holes is fully pressed into the wires.\nSupporting information (Pages #7): Fig. R6 has been included as Supplementary Fig. 26 in the revised\nSupporting Information.\nComment 5: Consistency of resistance change unit. % in line 191-198, but resistance in Fig. 3f~3j.\nDescription about the figures is wrong.\nRe: We are grateful for your insightful comments. In the new manuscript, we have standardized the\nunits of resistance variation used in the figures and the main text.\nThe following changes have been introduced to address the comment:\nMain text (line #336): Additionally, when the semi-liquid metal wire was bent by 90° along the PI\nsubstrate, its resistance variation can reach 1.015 (Fig. 3h). Fig. 3i shows that when the wire was\nstretched at different states, the resistivity demonstrated good periodic repetition, indicating that the\nwire is sensitive to the stretching rate and can adapt to various mechanical environments. Fig. 3j\nillustrates the resistance variation during 10,000 bending cycles.\nMain text (line #344): Although there is an overall slow upward trend, the resistance variation is only\n1.04.\nComment 6: Authors claims that advantage of NECP method is less waste of material but it is\ndifficult to agree. They also need to remove semi-LM in the non-patterned area of blank-coated LM.\nIn comparison with other subtractive methods, what % of the removed material can be reused?\nRe: We appreciate the reviewers' valuable suggestions, which have helped us to refine our analysis.\nThe recovery of semi-liquid metal refers to the complete recovery of all semi-liquid metal on the\nsubstrate, rather than only recovering the semi-liquid metal at the non-circuit pattern positions.\nTherefore, the semi-liquid metal at the non-circuit pattern positions remains in place. Considering this\nlimitation, we believe that this non-destructive engraving method is suitable for fabricating circuit\npatterns with repeatability and high density, such as wireless charging coils. In the new manuscript, we\nfabricated coils for wireless charging to demonstrate the unique advantage of the NECP method in\nreducing wire spacing, as shown in Fig.R7. In addition, the second engraving mode proposed by us in\nFig. 4 can push the semi-liquid metal at the non-circuit pattern positions to the surrounding circuit\npattern positions, thereby reducing the waste of semi-liquid metal and lowering the resistance of the\nwires. The second engraving mode can be used to fabricate mesh circuits, as shown in Fig. R8, where\nthe semi-liquid metal at the mesh positions is pushed to the wire positions around the meshes. The\nrecovery method mentioned in Fig. 4 involves pouring an alkaline solution over the entire circuit to\nrecover all the semi-liquid metal.\nFig. R7 The wireless charging coil.\nFig. R8 Mesh circuits with two mesh sizes.\nThe following changes have been introduced to address the comment:\nMain text (line #287): Furthermore, the NECP method is suitable for fabricating circuit patterns with\nrepeatability and high density, such as wireless charging coils (Supplementary Fig. 16).\nMain text (line #402): Additionally, mesh metal patterns with varied widths and pitches were fabricated\n(Supplementary Fig. 26). The newly prepared mesh wires have widths of 1 mm and 0.5 mm, with\ncorresponding spacings of 1 mm and 0.5 mm. All wires were produced via the second engraving\nmethod, where semi-liquid metal in the mesh holes is fully pressed into the wires.\nSupporting information (Pages #5, 8): Fig. R7 and R8 have been included as Supplementary Fig. 16\nand Fig. 26 in the revised Supporting Information.\nComment 7: Conductivity for various widths of electrodes must be provided. The maximum\nconductivity of 9x10^6 s/m was obtained for which electrodes?\nRe: Thank you for your careful consideration of our manuscript and for your helpful comments. The\n\"electrical conductivity of wires with different widths\" you focused on is indeed a crucial indicator for\nevaluating circuit performance, and we fully understand its necessity. Regarding this issue, we hereby\nelaborate on the reasons for being unable to provide the electrical conductivity as well as the solution\nideas, and sincerely request your understanding.\nL\nThe calculation of electrical conductivity is based on the formula σ = , where L is the wire length,\nR𝐴\nR is the resistance, and A is the cross-sectional area. However, in the preparation of the semi-liquid\nmetal wires in this study, due to the uneven distribution of solid metal particles inside the semi-liquid\nmetal material and the uneven substrate wettability caused by alcohol, the cross-sectional shape of the\nwires exhibits significant irregularities (for example, different positions of the same wire may show\nflat, elliptical, or locally convex morphologies, as shown in the cross-sectional microscopic images in\nFig. 3d). This makes it impossible to define the cross-sectional area A stably and accurately. Although\nwe attempted to measure the cross-sectional dimensions at different positions using a laser confocal\nmicroscope, the data dispersion was extremely large, and a reliable average cross-sectional area could\nnot be obtained. Therefore, it is difficult to calculate the electrical conductivity using the traditional\nformula.\nTo reflect the electrical properties of the wires as accurately as possible, we provided the resistance\nvalues of wires with different widths in the original manuscript, as shown in Fig. 3E. Although the\nresistance value is not directly equivalent to electrical conductivity, when combined with the nominal\nwidth of the wire (the process design value), it can reflect the relative differences in its conductive\nperformance to a certain extent (e.g., the variation trend of resistance as the width increases). In\naddition, we also provided the electrical conductivity of the bulk semi-liquid metal material itself—\ni.e., the semi-liquid metal bulk from the same batch—with σ = 9×10⁶ S/m, which serves as a reference\nfor the intrinsic properties of the material. The detailed measurement method for electrical conductivity\nis described in the \" Methods\" section. Furthermore, to avoid misleading readers into regarding the\nelectrical conductivity of the bulk material as that of the wires, we have removed Fig. 3c. In fact, the\nresolution of the wires is independent of the materials own electrical conductivity, and the innovation\nof this study lies in the preparation method rather than the material itself. Therefore, the description\nabout the innovation of the materials high electrical conductivity has also been removed from the new\nmanuscript.\nWe have recognized the importance of cross-sectional uniformity for the characterization of electrical\nproperties. In future research, it will be necessary to develop new types of organic solvents to replace\nthe alcohol solution, so as to control the shape of the wire edges more precisely and improve the\nregularity of the wire cross-sections. In addition, the diameter of the solid metal particles doped in the\nliquid metal is still relatively large, and a large number of particle agglomerations occur, as shown in\nFig. R9. Consequently, during the manufacturing of high-precision wires, the uneven distribution of\nsolid metal particles in the wires is caused, which affects the consistency of electrical conductivity.\nTherefore, in future research, we will develop new types of semi-liquid metal pastes to avoid particle\nagglomeration in the semi-liquid metal.\nFig. R9 SEM images of the freshly prepared semi-liquid metal and that has been stored for two months.\nThe following changes have been introduced to address the comment:\nMain text (line #303): Owing to the uneven distribution of solid metal particles within the semi-liquid\nmetal and the non-uniform substrate wettability induced by ethanol, the wire cross-sections exhibit\nsignificant irregularities. For instance, different segments of the same wire may appear flattened,\nelliptical, or locally bulged, as illustrated in the cross-sectional micrographs of Fig. 3d. This irregularity\nrenders the cross-sectional area impossible to define in a stable and accurate manner. Consequently,\ncalculating electrical conductivity via the conventional formula becomes unfeasible. To address this,\nwe provided resistances for semi-liquid metal wires of different widths (Fig. 3e), and it is evident that\nthe resistance decreases significantly as the wire width increases.\nMain text (line #668): The electrical conductivity of semi-liquid metal with varying doping ratios was\ndetermined via the standard four-point probe method. Prior to testing, the samples were placed and\nsecured within a trapezoidal groove; this groove measured 50 mm in length and had a cross-sectional\narea of 15 mm2.\nSupporting information (Pages #2): Fig. R9 has been included as Supplementary Fig. 4 in the revised\nSupporting Information.\nComment 8: Why do they use the maximum % (15~20%) of Ag coated Cu particle? What is the\nreason? Conductivity with the content of Ag coated Cu particles?\nRe: We appreciate the reviewer’s valuable suggestions. We selected the doping ratio of the semi-liquid\nmetal mainly based on considerations of its fluidity and coating uniformity. In fact, we did not use the\nsemi-liquid metal with the maximum doping ratio. In this study, we prepared semi-liquid metal with a\nmaximum doping ratio of 25 wt%. In the process of preparing semi-liquid metal, we found that when\nthe doping ratio of silver coated copper particles reaches 25 wt%, the physical form of semi-liquid\nmetal becomes powdery, which cannot be used in printed circuits, and when the doping ratio above 25\nwt%, the particles are difficult to enter the liquid metal, and as shown in the Supplementary Fig. 2.\nWhen the doping ratio was 15 wt%, the semi-liquid metal presented a slurry suitable for brushing,\ntherefore subsequent studies were all based on this ratio. Furthermore, in order to maintain the stability\nof the semi-liquid metal on 3D curved surfaces, we used the semi-liquid metal with a doping ratio of\n20 wt% to fabricate conformal circuits.\nThe electrical conductivities of semi-liquid metals with different doping ratios have been characterized\nmultiple times in our previous study (Adv. Fiber Mater.2024, 6, 354-366), so this paper does not\nconduct repeated experiments to verify the material properties already demonstrated in the earlier\nresearch. However, to ensure the rigor and authenticity of this study, we remeasured the conductivity\nof the semi-liquid metal with different contents of Ag-coated Cu particles and supplemented this part\nof the data in the new manuscript (Fig.R10).\n)m\n0\n/ 18\n( 1\ny\n15\nvit 12\nu\ncti\n9\nd\no n 6\nc\nal 3\nc\ne\nctri\n0\n0 5 10 15 20\nEl Silver-plated copper particles (wt%)\nFig.R10 The electrical conductivities of semi-liquid metal with varying doping ratios of silver coated\ncopper particles.\nThe following changes have been introduced to address the comment:\nMain text (line #117): By preparing a series of samples with doping ratios of 0 wt%, 5 wt%, 10 wt%,\n15 wt%, 20 wt%, and 25 wt%, we found that when the doping ratio of silver coated copper particles\nreaches 25 wt%, the physical form of semi-liquid metal becomes powdery, which cannot be used in\nprinted circuits, and when the doping ratio above 25 wt%, the particles are difficult to enter the liquid\nmetal, and the doping amount of silver-plated copper particles is negatively correlated with the fluidity\nof the semi-liquid metal (Supplementary Fig. 2).\nMain text (line #123): The results in Supplementary Fig. 3 demonstrate an increase in electrical\nconductivity as the doping ratio escalates from 0 wt% to 20 wt%. When the doping ratio was 15 wt%,\nthe semi-liquid metal presented a slurry suitable for brushing and a higher electrical conductivity of\n9×10⁶ S/m, therefore subsequent studies were all based on this ratio.\nSupporting information (Pages #1): Fig. R10 has been included as Supplementary Fig. 3 in the\nrevised Supporting Information.\nComment 9: Author must clarify that there is intermetallic compound formation between EGaIn and\nAgCu. Resistance changes with time? Stretchability changes with time? Data is required.\nRe: We greatly appreciate the reviewer for such supportive comments. The reasons for using silver-\nplated copper microparticles in this study mainly include the following aspects: First, during the\npreparation of semi-liquid metals, we found that the wettability of copper particles with liquid metals\nis significantly lower than that of silver particles with liquid metals. Second, the price of silver particles\nis significantly higher than that of copper particles. Therefore, to facilitate the fabrication of semi-\nliquid metals and reduce material costs, we selected metal particles with a silver coating on the surface\nof copper particles. The price of such metal particles is significantly lower than that of silver particles,\nand they still exhibit wettability similar to that of silver particles.\nNumerous previous studies have confirmed that metallic silver has better wettability with liquid metals\nthan metallic copper, and relevant characterizations have revealed the existence of intermetallic\ncompounds. For example, the literature (J. Tang et al., ACS Appl. Mater. Interfaces 2017) points out\nthat the infiltration of copper particles into liquid metals is due to the formation of intermetallic\ncompounds between copper and gallium metal, which exhibit long-term stability, as shown in Fig.\nR11A. The literature (Surfaces and Interfaces 72 (2025) 107098) clarifies that due to the higher\nchemical inertness of silver, the wetting rate of liquid metals on silver substrates is faster than that on\ncopper substrates in sodium hydroxide solution, as shown in Fig. R11B. Therefore, in the new\nmanuscript, we cite the conclusions from the above-mentioned literatures to illustrate the formation of\nintermetallic compounds between liquid metals and metallic silver.\nIn addition, long-term material property tests were conducted on the semi-liquid metal. Specifically,\nthe resistance of semi-liquid metal wires (1 mm in width, 2 cm in length) and the curves of their\nresistance varying with elongation rate were measured over a two-month storage period, as shown in\nFig. R12. The experimental results indicate that the resistance variation of the unencapsulated semi-\nliquid metal wires increased to 1.14, while that of the encapsulated ones only increased to 1.01.\nFurthermore, the semi-liquid metal wires after long-term storage could still undergo large tensile\ndeformation with the substrate while maintaining electrical continuity; their resistance variation\nreached 12.5 under maximum stretching, which is comparable to that of the original semi-liquid metal\nwires. These results demonstrate that the semi-liquid metal exhibits long-term electrical and\nmechanical stability.\nFig. R11 A SEM images of the intermetallic compound formed by copper and gallium metal. B In\nsodium hydroxide solution, the wetting rate of liquid metal on silver substrates is faster than that on\ncopper substrates.\nFig. R12 Long-term resistance stability of semi-liquid metal wires. a Resistance-time variation curves\nof encapsulated and unencapsulated semi-liquid metal wires. b Resistance-elongation variation curve\nof the unencapsulated semi-liquid metal wire after two months of storage.\nThe following changes have been introduced to address the comment:\nMain text (line #110): Numerous previous studies [42, 43] have confirmed that metallic silver exhibits\nbetter wettability with liquid metals than metallic copper, and relevant characterizations have revealed\nthe presence of intermetallic compounds. Therefore, to facilitate the fabrication of semi-liquid metals\nand reduce material costs, we have selected metal particles with a silver coating on the surface of\ncopper particles. Such metal particles are significantly cheaper than silver particles and still possess\nwettability similar to that of silver particles.\nMain text (line #363): Additionally, long-term property tests were performed on the semi-liquid metal.\nThe resistance of 1 mm-wide, 2 cm-long semi-liquid metal wires and their resistance variation were\nmeasured over a two-month storage period (Supplementary Fig. 22). Results show the resistance\nvariation of unencapsulated wires increased to 1.14, while that of encapsulated ones only reached 1.01.\nMoreover, after long-term storage, the wires still achieved large tensile deformation with the substrate\nwhile maintaining electrical continuity. The resistance variation at maximum stretch was 12.5,\ncomparable to that of the original wires. These results confirm the long-term electrical and mechanical\nstability of semi-liquid metal.\nMain text (line #797):\n[42] Tang, J. et al. Gallium-Based Liquid Metal Amalgams: Transitional-State Metallic Mixtures\n(TransM2ixes) with Enhanced and Tunable Electrical, Thermal, and Mechanical Properties. ACS Appl.\nMater. Interfaces. 9, 35977-35987 (2017).\n[43] Xing, Z. et al. Reactive Wetting Induced Instantaneous Nanoparticles Internalization in Gallium-\nbased Liquid Metal. Surf. Interfaces. 72, 107098 (2025).\nSupporting information (Pages #6): Fig. R12 has been included as Supplementary Fig. 22 in the\nrevised Supporting Information.\nComment 10: Uniformity of the thickness of the EGaIn film coated on the substrate must be\nprovided.\nRe: We greatly appreciate the reviewer for such supportive comments. In the new manuscript, we\nmeasured the roughness of the semi-liquid metal film coated on the glass substrate using the laser\nconfocal microscope, as shown in Fig. R13. The arithmetic mean roughness (Ra=5.22 μm) of the semi-\nliquid metal film was calculated based on the measured contour curve.\nFig. R13 The contour curve of the semi-liquid metal film.\nThe following changes have been introduced to address the comment:\nMain text (line #156): The arithmetic mean roughness (Ra=5.22 μm) of the semi-liquid metal film was\ncalculated based on the measured contour curve by the laser confocal microscope, as shown in\nSupplementary Fig. 7.\nSupporting information (Pages #2): Fig. R13 has been included as Supplementary Fig.7 in the\nrevised Supporting Information.\nREVIEWER #2\nComment: The manuscript presents a non-loss method for fabricating semi-liquid metal circuits by\nusing alcohol to modulate interfacial adhesion between liquid metal and substrates. Furthermore, by\ncontrolling adhesion through a custom-designed displacement apparatus, facilitate patterning from 5\nμm to centimeter scales across diverse substrates. This is interesting and I enjoyed reading it. However,\nthe underlying principle has been established in prior works. Thus, the authors may need to clarify the\nnovelty of the work and specify the details in order to publish this work.\nRe: We greatly appreciate the reviewer for such supportive comments. We have carefully considered\neach of your comments and suggestions. We have made extensive revisions to the manuscript, and we\nbelieve these changes have significantly improved the quality of our work. To help you quickly identify\nthe modifications, we have highlighted the revised sections in red font throughout the document.\nComment 1. The underlying mechanism of interaction between alcohol group (-OH) and liquid metal\noxide resulting in selective interfacial adhesion has already been well established in previous literatures\n(please refer C. Park et al Adv. Mater. 2020, 32, 2002178, DOI: 10.1002/adma.202002178; K. K.\nZadeh et al, Adv. Funct. Mater. 2021, 31, 2007336, DOI: 10.1002/adfm.202007336). The authors\nshould clearly and carefully highlight the innovative aspects of their findings in comparison to the\nprevious works.\nRe: Thank you for your careful consideration of our manuscript and for your helpful comments. In\nfact, we have already cited the two articles you provided (see References 12 and 27) in the original\nmanuscript. These two articles, along with other references we consulted (see References 22-24), all\ninvolve the interaction between alcohol groups (-OH) and liquid metal oxides. However, the role of -\nOH in these articles is to disperse liquid metal droplets or to achieve selective printing by utilizing the\nhigh adhesion between -OH in hydrogels and liquid metal oxide films, respectively. The -OH involved\nin these studies is either pre-coated on the substrate or dispersed in liquid metal droplets, and it serves\nto enhance the adhesion between liquid metals and substrates, which falls under the category of an\nadditive manufacturing method.\nNevertheless, in this study, an alcohol solution is used to disrupt the adhesion between semi-liquid\nmetals and the substrate, thereby enabling the semi-liquid metals at specific locations to move toward\nthe wires on both sides. The entire manufacturing process involves no metal loss, making it an\ninnovative manufacturing method that is completely different from traditional additive and subtractive\nmanufacturing techniques.\nIn summary, we believe that this study provides a novel approach to regulating the adhesion between\nsemi-liquid metals and substrates using -OH in alcohol, which is entirely different from previous\nstudies and has no similar reports in the existing literature. Furthermore, this manufacturing method\nexhibits distinct advantages in achieving high precision, compatibility with diverse substrates,\nstretchability, reusability, and recyclability of circuits. In the revised manuscript, we have added a\ncomparison between this method and the previous circuit manufacturing methods that utilize the\ninteraction between alcohol groups (-OH) and liquid metal oxides.\nThe following changes have been introduced to address the comment:\nMain text (line #88): Compared with previous studies where hydrogen bonds serve to enhance the\nadhesion between liquid metals and substrates, this study provides a novel approach that utilizes\nhydrogen bonds in ethanol to hinder the re-adhesion of semi-liquid metals to substrates.\nComment 2. The authors repeatedly mention \"alcohol\" without specifying the type. Please clarify\nwhich alcohol was used to ensure reproducibility and clarity. In method section, correct “Athanol”.\nRe: We really appreciate the helpful comments from the reviewer. The \"alcohol\" mentioned throughout\nthis study refers specifically to anhydrous ethanol (99%, purchased from Xintai Yixinkang Medical\nSupplies Co., Ltd.). In the new manuscript, we corrected \"alcohol\" to \"ethanol\" to ensure\nreproducibility and clarity and corrected \"Athanol\" into \"Anhydrous ethanol\" in method section.\nComment 3. The typical electrical conductivity of EGaIn is around ~3.4x106 S/m (please refer G. M.\nWhitesides et al, Angew. Chem. Int. Ed. 2008, 47, 142-144; DOI: 10.1002/anie.200703642; C. Majid\net al, Adv. Mater. Interfaces 2018, 5, 1701596; DOI: 10.1002/admi.201701596). Is it really possible to\nachieve electrical conductivity more than typical values? Please verify and correct. If it is possible,\nexplain the underlying mechanism.\nRe: Thank you for your careful consideration of our manuscript. The semi-liquid metal used in this\nstudy indeed has a higher electrical conductivity compared to EGaIn. The electrical conductivity of\nthe bulk semi-liquid metal with varying doping ratios was determined via the standard four-point probe\nmethod. Prior to testing, the samples were placed and secured within a trapezoidal groove; this groove\nmeasured 50 mm in length and had a cross-sectional area of 15 mm2. The characterization of the\nelectrical conductivity of semi-liquid metal has been conducted multiple times in our previous studies\n(Science Bulletin, 2024, 69, (17), 2723-2734; Applied Energy, 2024, 367, 123397; Adv. Fiber Mater.\n2024, 6, 354-366). The literature (J. Tang et al., ACS Appl. Mater. Interfaces 2017) points out that the\ninfiltration of copper particles into liquid metals is due to the formation of intermetallic compounds\nbetween copper and gallium metal, as shown in Fig. R14. Similar to copper, silver can also form\nintermetallic compounds with liquid metals (Surfaces and Interfaces 72 (2025) 107098). Therefore,\nliquid metals exhibit good wettability on silver-coated copper particles (meaning liquid metals can\nspread on the surface of silver-coated copper particles), and the contact resistance at the interface\nbetween the two is extremely low. Considering that the room-temperature electrical conductivity of\npure copper is approximately 5.96×10⁷ S/m (Ag content: 3 wt%; The electrical conductivity of silver\nis 1.59×10⁸ S/m), which is much higher than that of EGaIn (3.4×10⁶ S/m), and that silver-coated\ncopper particles are uniformly dispersed in the liquid metal, the silver-coated copper particles reduce\nthe overall resistance of the semi-liquid metal, resulting in higher electrical conductivity. Furthermore,\nas the mass fraction of copper particles increases, the overall electrical conductivity increases gradually.\nIn the new manuscript, we have cited relevant literatures to explain the existence of intermetallic\ncompounds.\nFig. R14 SEM images of the intermetallic compound formed by copper and gallium metal.\nThe following changes have been introduced to address the comment:\nMain text (line #110): Numerous previous studies [42, 43] have confirmed that metallic silver exhibits\nbetter wettability with liquid metals than metallic copper, and relevant characterizations have revealed\nthe presence of intermetallic compounds. Therefore, to facilitate the fabrication of semi-liquid metals\nand reduce material costs, we have selected metal particles with a silver coating on the surface of\ncopper particles. Such metal particles are significantly cheaper than silver particles and still possess\nwettability similar to that of silver particles.\nMain text (line #797):\n[42] Tang, J. et al. Gallium-Based Liquid Metal Amalgams: Transitional-State Metallic Mixtures\n(TransM2ixes) with Enhanced and Tunable Electrical, Thermal, and Mechanical Properties. ACS Appl.\nMater. Interfaces. 9, 35977-35987 (2017).\n[43] Xing, Z. et al. Reactive Wetting Induced Instantaneous Nanoparticles Internalization in Gallium-\nbased Liquid Metal. Surf. Interfaces. 72, 107098 (2025).\nComment 4. How only metallic electrode would be effective to collect ECG and EMG signals?\nAuthors will need to provide more evidence; the reviewer recommend to perform comparative skin-\nelectrode interface impedance analysis using both the semi-liquid metal electrode and traditional\nAg/AgCl electrode (Frequency range 1000kHz to 0.1 Hz).\nRe: Thank you for your careful consideration of our manuscript. When in contact with the body surface,\nmetal sheets can efficiently receive the weak potential difference on the body surface and convert it\ninto transmittable electrical signals. However, gaps exist between traditional rigid metals and skin folds,\nreducing the skin contact area; additionally, during skin deformation, rigid metal sheets tend to detach\nfrom the skin, leading to signal loss. In contrast, semi-liquid metals can fill into the micro-folds of the\nskin, increasing the skin contact area, and can conform to skin deformation without easy detachment.\nThus, semi-liquid metal electrodes can acquire superior signals, as shown in Fig. R15 (Liu et al. Soft\nSci. 2025, 5, 34).\nFinally, we measured the impedance between the semi-liquid metal electrodes, traditional Ag/AgCl\nelectrodes and the skin, and compared it with the impedance of the semi-liquid metal electrodes on\nmoist skin, as shown in Fig. R16. It can be seen from the figure that the semi-liquid metal electrodes\nhave lower interfacial impedance than the traditional Ag/AgCl electrodes. This is because the liquid\nmetal has excellent fluid deformability, which can adaptively fit the microtopography of the skin\nsurface, and also has higher electrical conductivity.\nFig. R15 Comparison of contact area between semi-liquid metal electrodes and rigid metal\nelectrodes on the skin.\nFig. R16 Skin-electrode interface impedance of the semi-liquid metal electrodes and traditional\nAg/AgCl electrodes.\nThe following changes have been introduced to address the comment:\nMain text (line #584): Finally, we measured the impedance between the semi-liquid metal electrodes,\ntraditional Ag/AgCl electrodes and the skin, and compared it with the impedance of the semi-liquid\nmetal electrodes on moist skin, as shown in Supplementary Fig. 44. The semi-liquid metal electrodes\nhave lower interfacial impedance than the traditional Ag/AgCl electrodes due to their excellent fluid\ndeformability, which can adaptively fit the microtopography of the skin surface, and higher electrical\nconductivity. When the skin sweats, the interfacial impedance between the semi-liquid metal electrode\nand the skin decreases. This is because sweat forms a continuous ionic conductive film on the skin\nsurface. It not only fills the tiny gaps between the electrode and the skin, but also penetrates the stratum\ncorneum to increase its water content, and enhance internal ion migration to reduce resistance.\nAdditionally, sweat acts as a lubricant and filling medium, promoting the semi-liquid metal to fully\nwet the skin, lowering contact resistance and thus the overall interfacial impedance.\nSupporting information (Pages #12): Fig. R16 has been included as Supplementary Fig. 44 in the\nrevised Supporting Information.\nComment 5. In EMG monitoring, please provide signal to noise ratio for both the electrodes.\nRe: Thank you for your valuable feedback regarding the lack of signal to noise ratio (SNR) parameters\nin our submitted paper on EMG signals. We appreciate this suggestion as it significantly enhances the\ncomprehensiveness and reliability of our research. Below, we present the principle, calculation steps,\nand the SNR results for the EMG monitoring.\nFirst, the signal to noise ratio is a measure that quantifies the level of a desired signal relative to the\nlevel of background noise. In the context of EMG signals, it helps us understand the quality of the\nacquired muscle activity signals by comparing the variance of the actual EMG signal (when muscle is\nactive) to the variance of the noise signal (when the muscle is at rest). Next, we will illustrate the\ncalculation steps in detail. For data acquisition, we have two sets of data for each of the six gestures.\nOne set is the EMG signal data collected when the muscle is actively contracting, while the other set\nis the noise data collected when the muscle is at rest. Each file contains 500 data points representing\nthe power of the respective signal or noise. Then we use the pandas library in Python to read the Excel\nfiles. For each group, we load the signal and noise data into separate data frames. After reading the\ndata, we use the numpy library to calculate the variance of the signal and noise data.\nIn the new manuscript, we supplemented the signal to noise ratio of EMG signals (Channel 1)\ncorresponding to 6 gestures for the semi-liquid metal electrodes and traditional Ag/AgCl electrodes,\nas shown in Fig. R17. It can be seen from the figure that the signal to noise ratio of the semi- liquid\nmetal electrode is higher than that of the Ag/AgCl electrode under multiple gestures. The signal to\nnoise ratio of the semi-liquid metal electrode is only slightly lower than that of the Ag/AgCl electrode\nin the EMG signal of gesture 2. The higher the signal to noise ratio, the less the EMG signal is\ninterfered by noise, and the better the signal quality. Therefore, when collecting EMG signals of these\n6 gestures, the semi-liquid metal electrode has better performance.\nFig. R17 Signal to noise ratio for the semi-liquid metal electrodes and traditional Ag/AgCl electrodes.\nThe following changes have been introduced to address the comment:\nMain text (line #579): Supplementary Fig. 43 presents the EMG signal-to-noise ratio (SNR, Channel\n1) for the semi-liquid metal electrodes and traditional Ag/AgCl electrodes across 6 gestures. The semi-\nliquid metal electrodes exhibit higher SNR than Ag/AgCl electrodes under most gestures, and only in\ngesture 2 is their SNR slightly lower. Since higher SNR indicates less noise interference and better\nsignal quality, the semi-liquid metal electrodes perform better in EMG signal acquisition for these 6\ngestures.\nSupporting information (Pages #12): Fig. R17 has been included as Supplementary Fig. 43 in the\nrevised Supporting Information.\nComment 6. The recent advances in circuit patterning technology using Liquid metals for wearable\nelectronics have been introduced. The authors may consider to cite some relevant references to\nstrengthen the research background. doi.org/10.1007/s40820-024-01457-7 / DOI:\n10.1126/science.adp3299 / doi.org/10.1016/j.cej.2022.139832.\nRe: We greatly appreciate the reviewer for such supportive comments. These literatures have greatly\nhelped improve the quality of our article. In the new manuscript, we have already cited these papers.\nThe following changes have been introduced to address the comment:\nMain text (line #763):\n[28] Wei, Y. et al. Liquid Metal Grid Patterned Thin Film Devices Toward Absorption-Dominant and\nStrain-Tunable Electromagnetic Interference Shielding. Nano-Micro Lett. 16, 248 (2024).\n[29] Minsik K. et al. Ambient printing of native oxides for ultrathin transparent flexible circuit boards.\nScience. 385, 731-737(2024).\n[30] Bhuyan, P. et al. Multifunctional ultrastretchable and ultrasoft electronics enabled by\nuncrosslinked polysiloxane elastomers patterned with rheologically modified liquid metal electrodes:\nbeyond current soft and stretchable electronics. Chem. Eng. J. 453 ,1385-8947 (2022).\nComment 7. Lines 110-113, explain the necessity of silver coated copper particles instead of pure\ncopper particles to modulate the fluidity of LMs. Because plenty of previous studies (eg.\n10.1002/inf2.12466, 10.3390/polym13152407, 10.1002/adma.201904309, 10.1002/admt.201700351)\nhad modulated LM fluidity through particle inclusion. Is it to promote better wettability between LM\nand particles and to protect the reactive Cu ?\nRe: Thank you for your careful consideration of our manuscript. The reasons for using silver-plated\ncopper microparticles in this study mainly include the following aspects: First, during the preparation\nof semi-liquid metals, we found that the wettability of copper particles with liquid metals is\nsignificantly lower than that of silver particles with liquid metals. Second, the price of silver particles\nis significantly higher than that of copper particles. Therefore, to facilitate the fabrication of semi-\nliquid metals and reduce material costs, we selected metal particles with a silver coating on the surface\nof copper particles. The price of such metal particles is significantly lower than that of silver particles,\nand they still exhibit wettability similar to that of silver particles.\nNumerous previous studies have confirmed that metallic silver has better wettability with liquid metals\nthan metallic copper, and relevant characterizations have revealed the existence of intermetallic\ncompounds. For example, the literature (J. Tang et al., ACS Appl. Mater. Interfaces 2017) points out\nthat the infiltration of copper particles into liquid metals is due to the formation of intermetallic\ncompounds between copper and gallium metal, which exhibit long-term stability, as shown in Fig.\nR18A. The literature (Surfaces and Interfaces 72 (2025) 107098) clarifies that due to the higher\nchemical inertness of silver, the wetting rate of liquid metals on silver substrates is faster than that on\ncopper substrates in sodium hydroxide solution, as shown in Fig. R18B. Therefore, in the new\nmanuscript, we cite the conclusions from the above-mentioned literatures to illustrate the formation of\nintermetallic compounds between liquid metals and metallic silver. Because silver has lower chemical\nactivity, it can make the semi - liquid metal have more stable performance. Thus, we took SEM images\nof the semi-liquid metal immediately after preparation and after two months of storage, as shown in\nFig. R19. It can be seen from the figures that the volume of solid metal particles inside the semi-liquid\nmetal slightly increases after long-term storage.\nFig. R18 A SEM images of the intermetallic compound formed by copper and gallium metal. B In\nsodium hydroxide solution, the wetting rate of liquid metal on silver substrates is faster than that on\ncopper substrates.\nFig. R19 SEM images of the freshly prepared semi-liquid metal and that has been stored for two\nmonths.\nThe following changes have been introduced to address the comment:\nMain text (line #110): Numerous previous studies [42, 43] have confirmed that metallic silver exhibits\nbetter wettability with liquid metals than metallic copper, and relevant characterizations have revealed\nthe presence of intermetallic compounds. Therefore, to facilitate the fabrication of semi-liquid metals\nand reduce material costs, we have selected metal particles with a silver coating on the surface of\ncopper particles. Such metal particles are significantly cheaper than silver particles and still possess\nwettability similar to that of silver particles.\nMain text (line #129): Silver coated copper particles exhibits excellent corrosion resistance, which\nensures the long-term stability of semi-liquid metal. The Scanning Electron Microscope (SEM) photos\nin Supplementary Fig. 4 show the micro-morphology of the semi-liquid metal film prepared two\nmonths ago. This figure clearly indicates that only a slight change has occurred in the diameter of the\nsolid particles. The X-ray Photoelectron Spectroscopy (XPS) curves in Supplementary Fig. 5 indicate\nthat the surface of the semi-liquid metal is encapsulated by a metal oxide film predominantly composed\nof gallium oxide and indium oxide. As a result, its physical state can remain relatively stable, and it\nexhibits long-term mechanical stability, maintaining good stretchability even after long-term storage.\nMain text (line #797):\n[42] Tang, J. et al. Gallium-Based Liquid Metal Amalgams: Transitional-State Metallic Mixtures\n(TransM2ixes) with Enhanced and Tunable Electrical, Thermal, and Mechanical Properties. ACS Appl.\nMater. Interfaces. 9, 35977-35987 (2017).\n[43] Xing, Z. et al. Reactive Wetting Induced Instantaneous Nanoparticles Internalization in Gallium-\nbased Liquid Metal. Surf. Interfaces. 72, 107098 (2025).\nSupporting information (Pages #2): Fig. R19 has been included as Supplementary Fig. 4 in the\nrevised Supporting Information.\nComment 8. In Fig.1B, how is the contact angle measured? Was the substrate immersed in alcohol\nfollowed by semi LM placement? Also, please explain the reason behind the significant difference in\ncontact angle values in air and in alcohol? Is it because the presence of more hydrogen bonding sites\nin alcohol lowers the surface energy of the placed semi LM ?\nRe: Thank you for your careful consideration of our manuscript. In this study, the contact angles were\nmeasured through the following process: liquid metal droplets were extruded from a syringe and\ndeposited onto a horizontal substrate in air. The side profiles of the droplets were then captured using\nan optical system, and the contact angles were calculated via profile fitting. The contact angle in\nethanol was measured by the following method: first, a small amount of ethanol was dropped onto a\nhorizontal substrate; subsequently, a liquid metal droplet was immediately deposited onto the ethanol-\ncovered surface, followed by contact angle measurement.\nThe differences in the contact angle of liquid metal droplets between air and ethanol mainly stem from\nthe following reasons, as shown in Fig. R20. Liquid metals themselves possess extremely high surface\ntension; for instance, the surface tension of gallium-indium alloy is approximately 500-700 mN/m at\n25°C, causing the droplets to spontaneously tend to form a spherical shape. When liquid metal droplets\nare extruded from a syringe, an oxide film is formed on their surface due to oxidation. In air, this oxide\nfilm on the surface of the liquid metal droplets adheres when in contact with the glass substrate, leading\nthe droplets to be flattened and thus reducing the contact angle. In contrast, in an ethanol solution, the\nsubstrate is wetted and covered by ethanol, which prevents the oxide film on the liquid metal droplets\nfrom coming into contact with the substrate. As a result, the droplets are not affected by the adhesive\nforce of the substrate and do not undergo adhesive deformation. The surface tension dominates the\nshape of the droplets, causing them to appear spherical.\nFig. R20 Schematic diagram of the formation mechanism for the difference in contact angle of liquid\nmetal droplets between air and ethanol.\nThe following changes have been introduced to address the comment:\nMain text (line #145): Liquid metals exhibit extremely high surface tension (~500–700 mN/m at 25°\nC), driving droplets to spontaneously form a spherical shape. In air, the oxide film on liquid metal\ndroplets adheres to the glass substrate, flattening the droplets and reducing their contact angle. In\ncontrast, in ethanol solution, the substrate is wetted and covered by ethanol, which prevents the droplet\noxide film from contacting the substrate. Consequently, droplets are unaffected by substrate adhesion\n(no adhesive deformation), and their shape is dominated by surface tension, remaining spherical\n(Supplementary Fig. 6). Thus, semi-liquid metal immersed in ethanol showed a significantly larger\nsubstrate contact angle than that in air, indicating a non-adhesive state (Fig. 1b).\nSupporting information (Pages #2): Fig. R20 has been included as Supplementary Fig. 6 in the revised\nSupporting Information.\nComment 9. The supplementary table S1 is missing\nRe: Thank you for your reminder. We have included the missing table in the new manuscript.\nTable R1 Comparative framework across six key dimensions: manufacturing cost, recyclability, conductivity loss,\nmaterial loss, resolution, and printability on diverse substrates.\nManufactu Conductivity Material Printability on various\nRecyclable Resolution(μm)\nre cost (S/m) loss substrates\nThis work Low √ 9×106 × High (5) √\nRef.12 Low × 2.9×105-1.2×106 × Low (500) √\nRef.19 High × 3.4×106 √ High (20) ×\nRef.20 High × 3×106 √ High(20) ×\nRef.21 High √ 3.4×106 √ High(0.18） ×\nRef.22 High √ 3.4×106 × High(5) √\nRef.23 Low × 1.5×106 × High(50) √\nRef.26 High √ 2.06×106 × High (25) ×\nRef.27 Low √ 3.4×106 √ Low (100) ×\nRef.28 High × 3.4×106 √ 350 ×\nRef.29 High × 5.65×105 √ High(4.5) ×\nRef.30 High × 3.4×106 √ Low (150) ×\nRef.33 High × 3.4×106 × Low (200) ×\nRef.34 High √ 3.4×106 × Low(200) ×\nRef.35 High × 3.4-6.73×106 √ Low (1.3) ×\nRef.36 Low × 4.15×104 √ Low (100) ×\nRef.S1 High √ 3.4×106 × High (1.9) √\nRef.S2 High × ~106 √ Low (138) ×\nRef.S3 High √ 7.7×105 √ High(37) ×\nRef.S4 High × 3.4×106 √ Low ×\nRef.S5 Low √ - × Low (250) ×\n[S1] Park, Y-G., An, H.S., Kim, J-Y., Park, J-U. High-resolution, reconfigurable printing of liquid metals with three-\ndimensional structures. Sci. Adv.5, eaaw2844(2019).\n[S2] Li, S., Zhao, H., Xu, H., Lu, H., Luo, P., Zhou, T. Ultra-flexible stretchable liquid metal circuits with\nantimicrobial properties through selective laser activation for health monitoring. Chem. Eng. J.482 , 149173 (2024).\n[S3]Liu, S., Kim, S.Y., Henry, K.E., Shah, D.S., Kramer-Bottiglio, R. Printed and Laser-Activated Liquid Metal-\nElastomer Conductors Enabled by Ethanol/PDMS/Liquid Metal Double Emulsions. ACS Appl. Mater. Interfaces.\n13, 28729-28736 (2021).\n[S4] Li ,Y., Feng, S., Cao, S., Zhang, J., Kong, D. Printable Liquid Metal Microparticle Ink for Ultrastretchable\nElectronics. ACS Appl. Mater. Interfaces. 12, 50852-50859 (2020).\n[S5] L. Teng, S. C. Ye, S. Handschuh-Wang, X. H. Zhou, T. S. Gan, X. C. Zhou. Liquid Metal-Based Transient\nCircuits for Flexible and Recyclable Electronics.Adv. Funct. Mater. 29, 1808739(2019).\nThe following changes have been introduced to address the comment:\nSupporting information (Pages #13): Supplementary Table R1 has been included as Supplementary\nTable S1 in the revised Supporting Information.\nComment 10. In Fig 2A, it is advised to provide more details as to why the wettability of alcohol on\nvarious substrates is better than water? The surface tensions of most alcohols are in the range 20-25\nmN/m which is less than one-third of water, so they can spread on surfaces more easily.\nRe: Thank you for your valuable help of our manuscript. The key reason why ethanol outperforms\nwater in wettability lies in that ethanol has a much lower surface tension than water. There exist\nextremely strong hydrogen bonds between water molecules, which result in high surface tension\n(approximately 72 mN/m at 20°C) and make it difficult for water to spread on the substrate surface. In\ncontrast, the number of hydrogen bonds between ethanol molecules is smaller and their strength is\nweaker, leading to a surface tension far lower than that of water (about 22.3 mN/m at 20°C) - a property\nthat enables ethanol to spread more easily on the substrate surface. Additionally, water can only form\nstrong adhesion on polar substrates; however, due to its molecular structure that \"combines both polar\nand non-polar characteristics\", ethanol can form strong adhesion on both polar and non-polar substrates.\nThis gives ethanol a wider range of applications and more stable wettability performance.\nThe following changes have been introduced to address the comment:\nMain text (line #206): Water molecules form extremely strong hydrogen bonds, leading to high surface\ntension (~72 mN/m at 20°C) and poor spreading on substrates. In contrast, ethanol molecules have\nfewer and weaker hydrogen bonds, resulting in much lower surface tension than water (~22.3 mN/m\nat 20°C), that enables ethanol to spread more easily on substrates. Additionally, water only forms strong\nadhesion on polar substrates, while ethanol (with both polar and non-polar molecular characteristics)\nachieves strong adhesion on both polar and non-polar substrates, giving it broader applicability and\nmore stable wetting performance.\nComment 11. Lines 210-221, rather than reporting the phenomenon, it is advised to justify the findings\nwith more scientific reason. During the second stroke air, why are there bridges which are clearly not\nforming in alcohol (Supplementary Figure 8)? The inferior adhesion between semi LM and substrate\nin alcohol compared to the highly cohesive nature of the semi LM drives the semi LM to reduce its\narea? Did the authors monitor whether there is a critical speed of scratching upto which it can prevent\nshort circuiting? Or is the phenomenon speed invariant?\nRe: Thank you for your careful consideration of our manuscript. This discrepancy is attributed to the\nadhesion of liquid metal to both the needle tip and the substrate in air, which leads to residual liquid\nmetal along the needle tip’s path and incomplete material isolation. In ethanol, the needle tip and\nscratch are both wetted by ethanol, which acts as a physical barrier to liquid metal, thereby leaving no\nresidue in the scratch. Furthermore, the high adhesive force between the semi-liquid metal and the\nsubstrate in air can overcome the cohesive force induced by the semi-liquid metal's high surface tension,\nenabling the semi-liquid metal to adhere to the scratch. In contrast, in ethanol, the needle tip, the semi-\nliquid metal, and the substrate are isolated from one another. As a result, the semi-liquid metal cannot\nadhere to the substrate; its cohesive force prevents it from being pushed out by the needle tip and also\nkeeps it from adhering to the scratch, as shown in Fig. R21. In the new manuscript, we evaluated the\nadhesion effect of the semi-liquid metal caused by the needle tip on the cross-scratch area under\ndifferent moving speeds, as shown in Fig. R22. It can be seen from the figure that in air, adjusting the\nmoving speed of the needle tip cannot eliminate the semi-liquid metal adhesion at the cross. This is\nbecause the semi-liquid metal adheres to the needle tip, thereby being pushed out by the needle tip and\nadhering to the substrate.\nFig. R21 Schematic diagram of the mechanism by which ethanol prevents semi-liquid metal adhesion\nat secondary scratch.\nFig. R22 The adhesion effect of the semi-liquid metal caused by the needle tip on the cross-scratch\narea under different moving speeds.\nThe following changes have been introduced to address the comment:\nMain text (line #241): In air, adjusting the moving speed of the needle tip cannot eliminate the semi-\nliquid metal adhesion at the cross, as shown in Supplementary Fig. 12.\nMain text (line #258): Furthermore, the high adhesive force between the semi-liquid metal and the\nsubstrate in air can overcome the cohesive force induced by the semi-liquid metal's high surface tension,\nenabling the semi-liquid metal to adhere to the scratch. In contrast, in ethanol, the needle tip, the semi-\nliquid metal, and the substrate are isolated from one another. As a result, the semi-liquid metal cannot\nadhere to the substrate; its cohesive force prevents it from being pushed out by the needle tip and also\nkeeps it from adhering to the scratch, as shown in Supplementary Fig. 13.\nSupporting information (Pages #4): Fig. R21and R22 have been included as Supplementary Fig. 13\nand Fig.12 in the revised Supporting Information.\nComment 12. Figures 2E and F and 3D are not enough. One of the biggest advantages of subtractive\nmanufacturing using LM is not only to obtain very fine resolution patterns but to also reduce gaps\nbetween patterns in order to downsize circuits, eg. inductors for proximity sensing or wireless powering.\nThe authors should provide detailed study by varying pitch (i.e. gap) and pattern width and monitor\nthe increase in height (or change in shape of the pattern).\nRe: Thank you for your careful consideration of our manuscript. In the new manuscript, we fabricated\ncoils for wireless charging to demonstrate the unique advantage of the NECP method in reducing wire\nspacing, as shown in Fig.R23. The spacing between the wires is controlled by the scratches produced\nby the tip moving once, so the width of the spacing depends on the width of the tip. In the new\nmanuscript, we made two different spaced coils using two different diameters of the tip, as shown in\nFig. R24. As can be seen from the cross-sectional curve of the wire in Fig. R25, the tip squeezes the\nsemi-liquid metal at the scratch into the wires on both sides, and causes an increase in the height of the\nwire edge, thereby reducing the resistance of the wire. In addition, we also consider using the same\ndiameter tip to move multiple times to adjust the width of the scratch, that is, the engraving method\ndemonstrated in Fig. 4b corresponds to the second engraving approach we proposed. However, this\nengraving method pushes the semi-liquid metal in the unwanted areas completely into the pattern area;\nas a result, the thickness of the semi-liquid metal at the pattern region increases significantly. Moreover,\nthe thicker semi-liquid metal exhibits more prominent surface tension, which leads to uneven\nboundaries. Thinner wires caused irregularities at the wire edges due to alcohol effects, resulting in a\nslight increase in resistance. Therefore, this hollowed-out engraving method is not suitable for\nfabricating high-precision semi-liquid metal wires. Consequently, the minimum width of the semi-\nliquid metal wire shown in Fig. 4b is 1 mm, and it is not used to produce thinner wires. In the new\nmanuscript, we have supplemented the limitations of the second engraving method regarding the\nfabrication of high-precision wires.\nFig. R23 The wireless charging coil.\nFig. R24 Two different spaced coils made by two different diameters of the tips.\nFig. R25 The cross-sectional curve of the two different spaced coils wires.\nThe following changes have been introduced to address the comment:\nMain text (line #287): Furthermore, the NECP method is suitable for fabricating circuit patterns with\nrepeatability and high density, such as wireless charging coils (Supplementary Fig. 16). Herein, the\nwidth of the scratches can be adjusted by changing the width of the needle tip, thereby enabling the\nfabrication of coils with different spacing (Fig. 3c). Using a thinner needle tip can significantly reduce\nthe coil spacing to minimize the coil size. Additionally, the needle tip squeezes the semi-liquid metal\nat the scratch into the wires on both sides, leading to an increase in the height of the wire edges, which\ncan reduce the resistance of the wires, as shown in Supplementary Fig. 17.\nMain text (line #382): Fig. R23 has been included as Fig. 3c in the revised manuscript.\nSupporting information (Pages #5): Fig. R23 and R25 have been included as Supplementary Fig. 16,\nand Fig. 17 in the revised Supporting Information.\nComment 13. In Figure 3C how was the conductivity measured? Is it the conductivity of the bulk\nmaterial or conductivity measured from some defined patterns? If it is the former then please mention\nit, if it is the latter, its value can vary (given that the experimental resistance values are showing\ndeviations from mean value , Figue 3E)\nRe: Thank you for your careful consideration of our manuscript. The electrical conductivity in Fig. 3c\nrefers to that of the bulk semi-liquid metal. The detailed measurement method for electrical\nconductivity is described in the \" Methods\" section. Furthermore, to avoid misleading readers into\nregarding the electrical conductivity of the bulk material as that of the wires, we have removed Fig. 3c.\nIn fact, the resolution of the wires is independent of the materials own electrical conductivity, and the\ninnovation of this study lies in the preparation method rather than the material itself. Therefore, the\ndescription about the innovation of the materials high electrical conductivity has also been removed\nfrom the new manuscript.\nThe following changes have been introduced to address the comment:\nMain text (line #668): The electrical conductivity of semi-liquid metal with varying doping ratios was\ndetermined via the standard four-point probe method. Prior to testing, the samples were placed and\nsecured within a trapezoidal groove; this groove measured 50 mm in length and had a cross-sectional\narea of 15 mm2.\nComment 14. What is the resolution of the wire stretched in Figure 3F? And why is the gauge factor\nchanging drastically after 800%?. In previous reports related to LM patterns\n(10.1016/j.cej.2022.139832, 10.1038/s41528-021-00123-x etc.) the gauge factor does not seem to vary\ndrastically. Whereas in case of carbon fiber based conductors, non percolation at definite strain can\nalter gauge factor (10.1038/s41467-018-08016-w), LM patterns are in continuous phase and their\ngeometries at strain will be defined by the substrate. In case of hyperelastic substrates, due to non\nuniform poisson effects the width of the substrate will decrease quickly in the beginning and as strain\nproceeds this decrement rate will be gradually minimal, this also affects the geometry of the printed\nwire. Therefore the author should do resistance vs strain of different width patterns and compare the\nbehaviors with previous literatures; and also explain the behaviors rather than reporting a single curve.\nRe: Your thorough review and valuable insights have been instrumental in refining our study, and we\nwould like to express our sincere thanks. We re-examined the semi-liquid metal wire samples used for\ntensile testing and found that the local agglomeration of solid metal particles caused a significant\nincrease in resistance of the samples under high tensile conditions. Under high tensile stress, the\nnarrowing of the semi-liquid metal wire width leads to the extrusion of agglomerated solid metal\nparticles from the wire, resulting in a significant reduction in the cross-sectional area of the wire and\nthus a sharp increase in resistance. Therefore, in the new manuscript, we remanufactured the semi-\nliquid metal wires for tensile testing (Fig. R26) and added wire samples with widths of 0.5 mm and 2\nmm to evaluate the effect of wire width on the electrical properties under tensile conditions (Fig. R27).\nThe new samples were inspected using a microscope to ensure that there was no agglomeration of solid\nmetal particles. We obtained the resistance variation of the three types of wires under the maximum\nstretching state, as well as the changes in their resistance during 10,000 cycles of stretching and bending.\nThe experimental results are similar to those of the original semi-liquid metal wires (width: 1 mm):\nboth can maintain stable connection of the wires without breakage. However, the resistance variation\nof the semi-liquid metal wires after cyclic stretching is relatively significant. The above results are\nsimilar to previous reports, both attributed to the fact that the stretchable substrate gradually relaxes\nafter multiple stretches and fails to return to its initial length, coupled with the continuous formation\nof new oxides on the semi-liquid metal during repeated stretching, thus leading to a gradual increase\nin resistance. Considering the substantial variation in the resistance of the wires after cyclic stretching,\nwe have removed the relevant description stating that the semi-liquid metal wires have the potential to\nbe used as strain sensors from the revised manuscript. In addition, we performed 10,000 cycles of\nstretching on the wire samples under a higher strain (500%), as shown in Fig. R28. The results show\nthat the wires can maintain stable connectivity, but the change in resistance is relatively obvious.\nTherefore, we suggest that this semi-liquid metal wire is suitable for use as a stretchable wire in flexible\ncircuits, rather than directly as a strain sensor-this is because it requires resistance correction after\nmultiple stretches.\nFig. R26 f Resistance variation of the three types of wires under different stretching states. g Resistance\nvariation during 10,000 cyclic stretching cycles.\nFig. R27 a Resistance variation of semi-liquid metal wire (width of 2 mm) during 10,000 stretching\ncycles. b Relationship between resistance variation and bending angle during semi-liquid metal wire\n(width of 2 mm) bending. c Resistance variation of semi-liquid metal wire (width of 2 mm) during\n10,000 bending cycles. d Resistance variation of semi-liquid metal wire (width of 0.5 mm) during\n10,000 stretching cycles. e Relationship between resistance variation and bending angle during semi-\nliquid metal wire (width of 0.5 mm) bending. f Resistance variation of semi-liquid metal wire (width\nof 0.5 mm) during 10,000 bending cycles.\nFig. R28 Resistance variation of semi-liquid metal wire under 500% strain during 10,000 stretching\ncycles.\nThe following changes have been introduced to address the comment:\nMain text (line #347): Furthermore, the wire sample underwent 10,000 cyclic stretches at a higher\nstrain (500%). As shown in Supplementary Fig. 20, the wire remained conductive after 10,000\nstretches under high strain, while its resistance variation increased to 5.83. These results align with\nprevious reports, attributed to gradual relaxation of the stretchable substrate (failing to recover initial\nlength) after repeated stretches, combined with continuous oxide formation on the semi-liquid metal\nduring cyclic stretching, which both leading to progressive resistance increase. Thus, this semi-liquid\nmetal wire is suitable for stretchable conductors in flexible circuits but not for direct use as strain\nsensors, as resistance correction is required after multiple stretches.\nIn addition, thinner (width: 0.5 mm) and thicker (width: 2 mm) semi-liquid metal wires were tested for\nstretching (Fig. 3f) and bending (Supplementary Fig. 21). Results showed the resistance variation of\n2 mm-wide wire with initial resistance of 0.78 Ω reached 9.5 at maximum stretch, and it withstood\n10,000 cycles of 200% stretching without fracture. Similarly, the resistance variation of 0.5 mm-wide\nwire with initial resistance of 4.25 Ω reached 13.2 at maximum stretch, and also endured 10,000 cycles\nof 200% stretching without breaking. For bending performance, the 2 mm-wide wire exhibited a\nresistance variation of only 1.004 at 90° bending and 1.04 after 10,000 bending cycles. Similarly, the\n0.5 mm-wide wire showed 1.012 (90° bending) and 1.06 (10,000 cycles), respectively.\nMain text (line #326): The bulk semi-liquid metal with initial resistance of 1.65 Ω shows significant\nresistance differences depending on the change of geometric shape, and its resistance variation at a\nstretching rate of 1000% can reach 12.2. The semi-liquid metal wires exhibit reliable and stable\nresponses under repeated 200% strain (more than 10,000 cycles), and no electrical failures occur (Fig.\n3g).\nMain text (line #382): Fig. R26 have been included as Fig. 3f, g in the revised manuscript.\nSupporting information (Pages #6): Fig. R27, R28 have been included as Supplementary Fig. 21 and\nFig. 20 in the revised Supporting Information.\nComment 15. In Figure 3G what's the strain and what's the test speed? In Figure 3J, what is the bending\nangle? And why can a very steep increase in resistance be observed within the first 1000 cycles of\nbending? In Figure 4B, please correct the legends' color, it is difficult to distinguish. Also, the\nexplanation behind the low resistance change should be done carefully. Supporting Video 4 clearly\nreveals very inhomogeneous distribution of particles in the LM matrix and does not reveal much about\nthe thickness. Can it be possible that the highly conductive particles are aggregated together during\nnarrowing down of the lines which also aids to reduce large resistance change?\nRe: Thank you for your careful consideration of our manuscript. In the revised manuscript, we have\nsupplemented the missing experimental conditions, including the initial resistance, stretching\nconditions, and bending radius of the semi-liquid metal wires. The increase in resistance of the semi-\nliquid metal wire during the initial stage of cyclic bending is attributed to the flow of liquid metal\ninside it. When the substrate is bent, part of the liquid metal in the semi-liquid metal flows to both\nsides under the action of gravity and base vibration, resulting in a reduction in the cross-sectional area\nat the middle bending point and thus an increase in resistance. However, as the number of bending\ncycles increases, the liquid metal in the semi-liquid metal gradually stabilizes and stops flowing, and\nthe surface oxidation of the semi-liquid metal during the bending process also leads to a slight increase\nin resistance.\nIn the revised manuscript, we have modified the color scheme of Fig. 4b, as shown in Fig. R29.\nSince the semi-liquid metal is pushed into the adjacent wire by the needle tip, no semi-liquid metal is\nremoved when the width of the semi-liquid metal wire in Fig. 4b decreases from 1 cm to 1 mm, and\nthe overall volume of the wire remains almost unchanged. With the volume kept constant, the cross-\nsectional area increases as the wire width decreases. Additionally, in the revised manuscript, we\nmeasured the change in the edge shape of the semi-liquid metal wire during the gradual reduction of\nits width, as illustrated in Fig. R30. It can be observed from the figure that the edge thickness of the\nwire increases significantly after each engraving step. According to the conductor resistance\nρL ρL ρ𝐿2\ncalculation formula: 𝑅 = = = , where L is the wire length, R is the resistance, ρ is the\n𝐴 𝑉/𝐿 𝑉\nresistivity, V is the volume, and A is the cross-sectional area. The resistance should theoretically remain\nunchanged. Nevertheless, due to ethanol wetting and the high surface tension of the liquid metal, the\nwire edges become irregular, resulting in uneven cross-sectional areas at different positions, which\ncauses slight changes in resistance as shown in the curve of Fig. 4b. We believe that this resistance\nstability is unrelated to the distribution of solid metal particles.\nFig. R29 Resistance variation of a copper wire and semi-liquid metal as the line width was reduced\nfrom 1 cm to 1 mm.\nFig. R30 The contour curve of the semi-liquid metal as the line width was reduced from 1 cm to 1 mm.\nThe following changes have been introduced to address the comment:\nMain text (line #340): In the early cyclic bending of the substrate, part of the liquid metal in the semi-\nliquid metal flows to both sides under gravity and base vibration, reducing the cross-sectional area at\nthe middle bending point and increasing resistance. However, as bending cycles increase, the liquid\nmetal gradually stops flowing. Then, the slight rise in the s resistance of semi-liquid metal is mainly\ndue to surface oxidation.\nMain text (line #410): Since the semi-liquid metal is pushed into the adjacent wire by the needle tip,\nthe overall volume of the wire remains almost unchanged. According to the conductor resistance\nρL ρ𝐿 ρ𝐿2\ncalculation formula: 𝑅 = = = , where L is the wire length, R is the resistance, ρ is the\n𝐴 𝑉/𝐿 𝑉\nresistivity, V is the volume, and A is the cross-sectional area. The resistance should theoretically remain\nunchanged. Furthermore, after each engraving step, the noticeable increase in wire edge thickness also\nconfirms the constant volume of wire (Supplementary Fig. 27).\nMain text (line #678): In the stretching test, the VHB substrate was stretched to a 1000% stretching\nrate at a speed of 1mm/s; in the bending test, the PI substrate was bent to 90° with a bending radius of\n5 mm, and one bending cycle takes 5 s.\nMain text (line #481): Fig. R29 has been included as Fig. 4b in the revised manuscript.\nSupporting information (Pages #8): Fig. R30 have been included as Supplementary Fig. 27 in the\nrevised Supporting Information.\nComment 16. In Figure 6, is there any special advantage of using semi LM as ECG electrodes?\nBecause previous works have directly deposited LM on skin (10.1021/acs.chemrev.3c00317) or in the\nform of composites coupled with elastomers (doi/10.1002/inf2.12302) in order to achieve superior\nconformability. Here the semi LM seems to be in non-encapsulated state and direct contact with the\nskin? Will any residue be left after its use or will the cohesive nature of semi LM prevent it? Also the\nmetallic electrode is itself not protected from sweat and during sweat generation the skin-electrode\ncontact impedance will change and can significantly impact signal to noise ratio.\nRe: We sincerely thank the reviewer for this insightful comment and for raising these critical points\nregarding the advantages and practical considerations of our semi-liquid metal electrodes. We agree\nthat conformality and stability are key metrics for skin-interfaced electrodes. Our approach offers a\nunique set of advantages that complement and advance the existing strategies mentioned by the\nreviewer.\nFirst, the cited excellent works represent two dominant paradigms. The direct deposition of pure\nLM onto skin (10.1021/acs.chemrev.3c00317), which can suffer from migration and residue. The\nencapsulation of LM within elastomeric microchannels (doi/10.1002/inf2.12302), which adds\nmanufacturing complexity and can introduce a mechanical mismatch with the skin. Our non-\nencapsulated, semi-liquid metal electrode establishes a third pathway that balances superior\nperformance, user-friendly handling, and straightforward fabrication. Compared to the directly\ndeposited LM, the semi-liquid metal in this work has significantly higher viscosity and cohesion due\nto the doped solid metal particles. This prevents the uncontrolled migration, leakage, and bead-up\nphenomena common with pure LM, especially on curved surfaces or under motion. It is a structurally\nrobust, freestanding conductive film that is easily handled and patterned using our novel NECP method.\nCompared to the elastomer-encapsulated LM, our electrode is a single-material system, eliminating\nthe need for complex microchannel fabrication, bonding, or liquid metal injection. This results in an\nextremely thin and lightweight interface (just the PU film and the SLM layer) with minimal mechanical\nimpedance, conforming to skin textures without the constraining feel of a thicker elastomeric patch.\nFurthermore, the reviewer correctly identifies a potential concern with direct skin contact, and we have\nspecifically investigated it through its controlled cohesion and easy cleanability. On the one hand, the\nsemi-solid nature of our material provides sufficient internal cohesion to remain as a continuous,\nadherent film during normal use. It does not behave like a low-viscosity fluid that readily smears. On\nthe other hand, an experiment was conducted to present its cleanability and the results are as follows:\nWe acknowledge that upon removal, minor, benign residue can sometimes occur (similar to some\ncommercial ECG gels). However, as raised in the comment and verified in our tests, this residue is\neffortlessly and completely removed by a simple wipe with an alcohol swab, a standard item in medical\nand personal care, as shown in Fig.R31. The residue consists of gallium oxide particles, which are\nhighly biocompatible and non-toxic. We have added a discussion on the cleanability to the revised\nmanuscript to ensure these points are clear to all readers.\nFinally, we measured the impedance between the semi-liquid metal electrodes, traditional Ag/AgCl\nelectrodes and the skin, and compared it with the impedance of the semi-liquid metal electrodes on\nmoist skin, as shown in Fig. R32. It can be seen from the figure that the semi-liquid metal electrodes\nhave lower interfacial impedance than the traditional Ag/AgCl electrodes. This is because the liquid\nmetal has excellent fluid deformability, which can adaptively fit the microtopography of the skin\nsurface, and also has higher electrical conductivity. When the skin surface sweats, the interfacial\nimpedance between the semi-liquid metal electrode and the skin decreases. This is because sweat is\nessentially an ionic solution with a certain degree of conductivity, which forms a continuous ionic\nconductive film on the skin surface. This film not only directly fills the tiny gaps between the semi-\nliquid metal electrode and the skin surface, but also penetrates into the stratum corneum and increases\nits water content, softening the stratum corneum, enhancing the internal ion migration ability, and\nsignificantly reducing the resistance. In addition, after sweating, sweat acts as a lubricating and filling\nmedium, which can promote the semi-liquid metal to more fully wet the skin surface, significantly\nreduce the contact resistance, and thus lower the overall interfacial impedance.\nFig. R31 Removal of semi-liquid metal residues after removing the semi-liquid metal electrodes.\nFig. R32 Skin-electrode interface impedance of the semi-liquid metal electrodes and traditional\nAg/AgCl electrodes.\nThe following changes have been introduced to address the comment:\nMain text (line #595): After the semi-liquid metal electrode is removed, slight benign residues may\noccasionally appear (similar to some commercial electrocardiogram gels). However, such residues can\nbe easily and completely removed by simple wiping with an alcohol swab, which is a standard item in\nmedical and personal care settings, as shown in Supplementary Fig. 45.\nMain text (line #584): Finally, we measured the impedance between the semi-liquid metal electrodes,\ntraditional Ag/AgCl electrodes and the skin, and compared it with the impedance of the semi-liquid\nmetal electrodes on moist skin, as shown in Supplementary Fig. 44. The semi-liquid metal electrodes\nhave lower interfacial impedance than the traditional Ag/AgCl electrodes due to their excellent fluid\ndeformability, which can adaptively fit the microtopography of the skin surface, and higher electrical\nconductivity. When the skin sweats, the interfacial impedance between the semi-liquid metal electrode\nand the skin decreases. This is because sweat forms a continuous ionic conductive film on the skin\nsurface. It not only fills the tiny gaps between the electrode and the skin, but also penetrates the stratum\ncorneum to increase its water content, and enhance internal ion migration to reduce resistance.\nAdditionally, sweat acts as a lubricant and filling medium, promoting the semi-liquid metal to fully\nwet the skin, lowering contact resistance and thus the overall interfacial impedance.\nSupporting information (Pages #12): Fig. R31 and R32 have been included as Supplementary Fig.\n45 and Fig. 44 in the revised Supporting Information.\nComment 17. In supplementary figure 12, the wettability of the terminals is crucial for full\nfunctionality of the LED. Please refer to relevant literature(10.1016/j.snb.2015.07.062) and it is\nrecommended to calculate current voltage across the LED after various modes of deformation to\nascertain that no parasitic resistance is generated in the LM-LED interfaces.\nRe: Thank you for your careful consideration of our manuscript. In the new manuscript, to reduce\nparasitic resistance, we pre-soaked the LEDs in a HCl solution to remove oxides from the pads and\nenable intermetallic wetting when the pads come into contact with the semi-liquid metal, thereby\nforming stable solder joints. Additionally, to reduce the parasitic resistance caused by deformation at\nthe junction between the semi-liquid metal wire and the LED during stretching, we embedded rigid\nfilm into the VHB substrate to minimize the deformation at the junction, as shown in Fig.R33a. After\nthese improvements, we measured the voltage and current across the LEDs during 200% stretching\nprocess, as presented in Fig.R33b,c. It can be observed from the figure that the voltage across the LED\ndecreases under 200% stretching; this is because the resistance of the semi-liquid metal wire increases\nby 0.8 Ω. However, the increased wire resistance only causes a voltage drop of 4 mV and a current\ndrop of 4 μA across the LED, so the parasitic resistance at the junction between the LED pad and the\nsemi-liquid metal wire is negligible.\nFig. R33 a LED on the VHB tape of composite rigid film under different stretching states. b The\nvoltage across the LEDs during 200% stretching process. c The current across the LEDs during 200%\nstretching process.\nThe following changes have been introduced to address the comment:\nMain text (line #370): Finally, to confirm its integration capability with traditional electronic devices,\nwe used HCl solution to deoxidize the pins of traditional electronic components [46], such as LEDs,\nenabling them to be wetted and soldered with semi-liquid metal wires, forming stable electrical\ninterconnections, as shown in Supplementary Fig. 23. Additionally, a rigid film (polyethylene) was\nembedded into the VHB tape to minimize deformation at the connection, as shown in Supplementary\nFig. 24a. Supplementary Fig. 24b, c illustrate that during the 200% stretching process, the voltage\nand current across the LEDs gradually decreased, which is attributed to an increase of 0.8 Ω in the\nresistance of the semi-liquid metal wire. However, the increased wire resistance only caused a voltage\ndrop of 4 mV and a current reduction of 4 μA across the LEDs. Therefore, the variation in wire\nresistance induced by deformation has a negligible impact on the circuit function.\nMain text (line #807):\n[46] Li, G., Wu, X., Lee, D-W. Selectively Plated Stretchable Liquid Metal Wires for Transparent\nElectronics. Sensors and Actuators B. 221, 1114-1119 (2015).\nSupporting information (Pages #7): Fig. R33 has been included as Supplementary Fig. 24 in the\nrevised Supporting Information.\nComment 18. In Figure 5e, what is the current value applied for heating?\nRe: Thank you for your reminder. The current value applied for heating used in the experiment was 3A.\nIn the new manuscript, we have supplemented the missing information.\nMain text (line #522): As shown in Fig. 5E, the electrically heated wires can effectively heat the wing\nunder a current of 3 A, increasing the surface temperature of the wing from 23.5°C to 60.7°C within\n80 s.\nREVIEWER #3\nComment: The authors present here an approach for using mechanical engraving in alcohol for high\nresolution patterning of liquid metal circuits. I thought overall the concept appears novel, testing\nappears thorough and the paper is largely well written with compelling figures; stretchable electronics\nand liquid metal circuits are also of substantial broader interest making the article well suited for your\nreadership. There were however a number of minor errors and misstatements that should be corrected\nbefore acceptance; a full list of my concerns is below.\nRe: We greatly appreciate the reviewer for such supportive comments. We have carefully considered\neach of your comments and suggestions. We have made extensive revisions to the manuscript, and we\nbelieve these changes have significantly improved the quality of our work. To help you quickly identify\nthe modifications, we have highlighted the revised sections in red font throughout the document.\nComment 1. Fig. 3 C is more than a little confusing, appearing to conflate material property (the\nauthors have a novel liquid metal loaded with copper particles, and get a higher conductivity) and\nfabrication approach. In practice, the two parameters are largely independent (the authors could for\ninstance have injected their material into microchannels and gotten a different position on their plot)\nand it is misleading to imply that microchannel injection, or screen printing, or laser ablation, have\nspecific conductivity numbers.\nRe: Thank you for your careful consideration of our manuscript. We agree with your suggestions and\nhave made the revisions. To avoid misleading readers into regarding the electrical conductivity of the\nbulk material as that of the wires, we have removed Fig. 3c. In fact, the resolution of the wires is\nindependent of the materials own electrical conductivity, and the innovation of this study lies in the\npreparation method rather than the material itself. Therefore, the description about the innovation of\nthe materials high electrical conductivity has also been removed from the new manuscript.\nComment 2. In Fig. 2 (a), water and common alcohols are well known materials and presumably\ncontact angles on many common substrates are available in the literature, particularly substrates like\nPDMS that are very widely used in microfluidics. How did their results compare to the literature?\nIs this test truly necessary to include, given the common nature of the two liquids involved?\nRe: Thank you for your careful consideration of our manuscript. We agree that contact angles of water\nand common alcohols on substrates such as PDMS have been reported in the literature. We have also\nconducted a search for relevant supporting literature: the water contact angle on PDMS measured in\nthis study is ~103°, and the anhydrous ethanol contact angle is ~30°, which are highly consistent\nwith previously reported values (e.g., [L. Shuai et al., Enhanced condensation heat transfer by\nwater/ethanol binary liquids on polydimethylsiloxane brushes. Droplet. ,2022]: water: 100°~105°;\nethanol: 23°~31°). Given that the core objective of this study is not to investigate the contact angle\ncharacteristics of these two liquids on PDMS, the relevant data only serve as auxiliary information to\ndescribe the basic state of the substrate surface. By intuitively comparing the wettability differences\nbetween water and ethanol on a variety of common substrates, readers can clearly understand that\nethanol enables the engraving method described in this paper more effectively than water.\nComment 3. In a scientific context, alcohol is a material class, not a specific liquid; in looking at the\nmaterials section the authors identify the material as athonol, which I am not familiar with and does\nnot appear to be a common alcohol. Do the authors mean ethanol? If so, the authors should consistently\nand correctly identify this throughout the manuscript, rather than using alcohol\nRe: We really appreciate the helpful comments from the reviewer. The \"alcohol\" mentioned throughout\nthis study refers specifically to anhydrous ethanol (99%, purchased from Xintai Yixinkang Medical\nSupplies Co., Ltd.). In the new manuscript, we corrected \"alcohol\" to \"ethanol\" to ensure\nreproducibility and clarity and corrected \"Athanol\" into \"Anhydrous ethanol\" in method section.\nComment 4. In the two cyclic tests (Figures 3 G and J), it is very important to clarify the bend and\nstretch conditions during the cycling; how much is the sample being bent or stretched in each case? It\nis somewhat concerning that the value never looks stable in either case (and for the stretching in\nparticular the change is more than ten percent, which is not insubstantial).\nRe: We highly appreciate the reviewers' critical reminders. In the revised manuscript, we have\nsupplemented the missing experimental conditions, including the initial resistance, stretching\nconditions, and bending radius of the semi-liquid metal wires. We re-examined the semi-liquid metal\nwire samples used for tensile testing and found that the local agglomeration of solid metal particles\ncaused a significant increase in resistance of the samples under high tensile conditions. Under high\ntensile stress, the narrowing of the semi-liquid metal wire width leads to the extrusion of agglomerated\nsolid metal particles from the wire, resulting in a significant reduction in the cross-sectional area of the\nwire and thus a sharp increase in resistance. Therefore, in the new manuscript, we remanufactured the\nsemi-liquid metal wires for tensile testing (Fig. R34) and added wire samples with widths of 0.5 mm\nand 2 mm to evaluate the effect of wire width on the electrical properties under tensile conditions (Fig.\nR35). The new samples were inspected using a microscope to ensure that there was no agglomeration\nof solid metal particles. We obtained the resistance variation of the three types of wires under the\nmaximum stretching state, as well as the changes in their resistance during 10,000 cycles of stretching\nand bending. The experimental results are similar to those of the original semi-liquid metal wires (width:\n1 mm): both can maintain stable connection of the wires without breakage. However, the resistance\nvariation of the semi-liquid metal wires after cyclic stretching is relatively significant. The above\nresults are similar to previous reports, both attributed to the fact that the stretchable substrate gradually\nrelaxes after multiple stretches and fails to return to its initial length, coupled with the continuous\nformation of new oxides on the semi-liquid metal during repeated stretching, thus leading to a gradual\nincrease in resistance. Although the resistance of the wire gradually increases with the increase in the\nnumber of stretching and bending cycles, this increase in resistance is relatively slight compared to that\nof commonly used electronic components. For example, the initial resistance of the semi-liquid metal\nwire is 1.65 Ω; after 10,000 stretching cycles, its resistance increases by 20%, which is only an increase\nof 0.33 Ω-far lower than the internal resistance of commonly used electronic components. To verify\nthis, we measured the voltage and current across the LEDs during 200% stretching process, as\npresented in Fig.R36. It can be observed from the figure that the voltage across the LED decreases\nunder 200% stretching; this is because the resistance of the semi-liquid metal wire increases by 0.8 Ω.\nHowever, the increased wire resistance only causes a voltage drop of 4 mV and a current drop of 4 μA\nacross the LED, so the parasitic resistance at the junction between the LED pad and the semi-liquid\nmetal wire is negligible.\nFig. R34 f Resistance variation of the three types of wires under different stretching states. g Resistance\nvariation during 10,000 cyclic stretching cycles.\nFig. R35 a Resistance variation of semi-liquid metal wire (width of 2 mm) during 10,000 stretching\ncycles. b Relationship between resistance variation and bending angle during semi-liquid metal wire\n(width of 2 mm) bending. c Resistance variation of semi-liquid metal wire (width of 2 mm) during\n10,000 bending cycles. d Resistance variation of semi-liquid metal wire (width of 0.5 mm) during\n10,000 stretching cycles. e Relationship between resistance variation and bending angle during semi-\nliquid metal wire (width of 0.5 mm) bending. f Resistance variation of semi-liquid metal wire (width\nof 0.5 mm) during 10,000 bending cycles.\nFig. R36 B The voltage across the LEDs during 200% stretching process. C The current across the\nLEDs during 200% stretching process.\nThe following changes have been introduced to address the comment:\nMain text (line #354): In addition, thinner (width: 0.5 mm) and thicker (width: 2 mm) semi-liquid metal\nwires were tested for stretching (Fig. 3f) and bending (Supplementary Fig. 21). Results showed the\nresistance variation of 2 mm-wide wire with initial resistance of 0.78 Ω reached 9.5 at maximum stretch,\nand it withstood 10,000 cycles of 200% stretching without fracture. Similarly, the resistance variation\nof 0.5 mm-wide wire with initial resistance of 4.25 Ω reached 13.2 at maximum stretch, and also\nendured 10,000 cycles of 200% stretching without breaking. For bending performance, the 2 mm-wide\nwire exhibited a resistance variation of only 1.004 at 90° bending and 1.04 after 10,000 bending cycles.\nSimilarly, the 0.5 mm-wide wire showed 1.012 (90° bending) and 1.06 (10,000 cycles), respectively.\nMain text (line #326): The bulk semi-liquid metal with initial resistance of 1.65 Ω shows significant\nresistance differences depending on the change of geometric shape, and its resistance variation at a\nstretching rate of 1000% can reach 12.2. The semi-liquid metal wires exhibit reliable and stable\nresponses under repeated 200% strain (more than 10,000 cycles), and no electrical failures occur (Fig.\n3g).\nMain text (line #370): Finally, to confirm its integration capability with traditional electronic devices,\nwe used HCl solution to deoxidize the pins of traditional electronic components [46], such as LEDs,\nenabling them to be wetted and soldered with semi-liquid metal wires, forming stable electrical\ninterconnections, as shown in Supplementary Fig. 23. Additionally, a rigid film (polyethylene) was\nembedded into the VHB tape to minimize deformation at the connection, as shown in Supplementary\nFig. 24a. Supplementary Fig. 24b, c illustrate that during the 200% stretching process, the voltage\nand current across the LEDs gradually decreased, which is attributed to an increase of 0.8 Ω in the\nresistance of the semi-liquid metal wire. However, the increased wire resistance only caused a voltage\ndrop of 4 mV and a current reduction of 4 μA across the LEDs. Therefore, the variation in wire\nresistance induced by deformation has a negligible impact on the circuit function.\nMain text (line #678): In the stretching test, the VHB substrate was stretched to a 1000% stretching\nrate at a speed of 1mm/s; in the bending test, the PI substrate was bent to 90° with a bending radius of\n5 mm, and one bending cycle takes 5 s.\nMain text (line #807):\n[46] Li, G., Wu, X., Lee, D-W. Selectively Plated Stretchable Liquid Metal Wires for Transparent\nElectronics. Sensors and Actuators B. 221, 1114-1119 (2015).\nMain text (line #382): Fig. R34 has been included as Fig. 3f, g in the revised manuscript.\nSupporting information (Pages #6-7): Fig. R35, R36 have been included as Supplementary Fig. 21\nand Fig. 24b, c in the revised Supporting Information.\nComment 5. Based on the cycling test, it appears that even for a modest strain a permanent resistance\nchange is occurring. The authors argue that there is value in their printed traces as a strain sensor up to\nnearly 1000% strain; is the resistance stable at higher strains under repeated strains? A more aggressive\ncycling strain test is necessary to defend this claim, based on what is being presented here.\nRe: Your thorough review and valuable insights have been instrumental in refining our study, and we\nwould like to express our sincere thanks. Considering the substantial variation in the resistance of the\nwires after cyclic stretching, we have removed the relevant description stating that the semi-liquid\nmetal wires have the potential to be used as strain sensors from the revised manuscript. In addition, we\nperformed 10,000 cycles of stretching on the wire samples under a higher strain (500%), as shown in\nFig. R37. The results show that the wires can maintain stable connectivity, but the change in resistance\nis relatively obvious. Therefore, we suggest that this semi-liquid metal wire is suitable for use as a\nstretchable wire in flexible circuits, rather than directly as a strain sensor-this is because it requires\nresistance correction after multiple stretches.\nFig. R37 Resistance variation of semi-liquid metal wire under 500% strain during 10,000 stretching\ncycles.\nThe following changes have been introduced to address the comment:\nMain text (line #347): Furthermore, the wire sample underwent 10,000 cyclic stretches at a higher\nstrain (500%). As shown in Supplementary Fig. 20, the wire remained conductive after 10,000\nstretches under high strain, while its resistance variation increased to 5.83. These results align with\nprevious reports, attributed to gradual relaxation of the stretchable substrate (failing to recover initial\nlength) after repeated stretches, combined with continuous oxide formation on the semi-liquid metal\nduring cyclic stretching, which both leading to progressive resistance increase. Thus, this semi-liquid\nmetal wire is suitable for stretchable conductors in flexible circuits but not for direct use as strain\nsensors, as resistance correction is required after multiple stretches.\nSupporting information (Pages #6): Fig. R37 have been included as Supplementary Fig. 20 in the\nrevised Supporting Information.\nComment 6. Recovering and recycling liquid metal electronics has been demonstrated previously\nelsewhere (for example, in L. Teng et al., Liquid metal-based transient circuits for flexible and\nrecyclable electronics, Adv. Funct. Mater., 2019), and needs to be properly credited and compared with\nhere.\nRe: Thank you for your reminder. We have added the literature (Ref.S5) you suggested to Table S1.\nTable R1 Comparative framework across six key dimensions: manufacturing cost, recyclability, conductivity loss,\nmaterial loss, resolution, and printability on diverse substrates.\nManufactu Conductivity Material Printability on various\nRecyclable Resolution(μm)\nre cost (S/m) loss substrates\nThis work Low √ 9×106 × High (5) √\nRef.12 Low × 2.9×105-1.2×106 × Low (500) √\nRef.19 High × 3.4×106 √ High (20) ×\nRef.20 High × 3×106 √ High(20) ×\nRef.21 High √ 3.4×106 √ High(0.18） ×\nRef.22 High √ 3.4×106 × High(5) √\nRef.23 Low × 1.5×106 × High(50) √\nRef.26 High √ 2.06×106 × High (25) ×\nRef.27 Low √ 3.4×106 √ Low (100) ×\nRef.28 High × 3.4×106 √ 350 ×\nRef.29 High × 5.65×105 √ High(4.5) ×\nRef.30 High × 3.4×106 √ Low (150) ×\nRef.33 High × 3.4×106 × Low (200) ×\nRef.34 High √ 3.4×106 × Low(200) ×\nRef.35 High × 3.4-6.73×106 √ Low (1.3) ×\nRef.36 Low × 4.15×104 √ Low (100) ×\nRef.S1 High √ 3.4×106 × High (1.9) √\nRef.S2 High × ~106 √ Low (138) ×\nRef.S3 High √ 7.7×105 √ High(37) ×\nRef.S4 High × 3.4×106 √ Low ×\nRef.S5 Low √ - × Low (250) ×\n[S1] Park, Y-G., An, H.S., Kim, J-Y., Park, J-U. High-resolution, reconfigurable printing of liquid metals with three-\ndimensional structures. Sci. Adv.5, eaaw2844(2019).\n[S2] Li, S., Zhao, H., Xu, H., Lu, H., Luo, P., Zhou, T. Ultra-flexible stretchable liquid metal circuits with\nantimicrobial properties through selective laser activation for health monitoring. Chem. Eng. J.482 , 149173 (2024).\n[S3]Liu, S., Kim, S.Y., Henry, K.E., Shah, D.S., Kramer-Bottiglio, R. Printed and Laser-Activated Liquid Metal-\nElastomer Conductors Enabled by Ethanol/PDMS/Liquid Metal Double Emulsions. ACS Appl. Mater. Interfaces.\n13, 28729-28736 (2021).\n[S4] Li ,Y., Feng, S., Cao, S., Zhang, J., Kong, D. Printable Liquid Metal Microparticle Ink for Ultrastretchable\nElectronics. ACS Appl. Mater. Interfaces. 12, 50852-50859 (2020).\n[S5] L. Teng, S. C. Ye, S. Handschuh-Wang, X. H. Zhou, T. S. Gan, X. C. Zhou. Liquid Metal-Based Transient\nCircuits for Flexible and Recyclable Electronics.Adv. Funct. Mater. 29, 1808739(2019).\nThe following changes have been introduced to address the comment:\nSupporting information (Pages #12): Table R1 have been included as Table S1 in the revised\nSupporting Information.\nComment 7. Similarly, copper-liquid gallium amalgams do not appear to be new to this work, and\nhave been previously investigated by these researchers (for instance in J. Tang et al., ACS Appl.\nMater. Interfaces 2017). It is important to clarify this in the text to help the reader understand the\nspecific contribution here.\nRe: We greatly appreciate the reviewer for such supportive comments. These literatures have greatly\nhelped improve the quality of our article. In the new manuscript, we have already cited these papers.\nThe following changes have been introduced to address the comment:\nMain text (line #797):\n[42] Tang, J. et al. Gallium-Based Liquid Metal Amalgams: Transitional-State Metallic Mixtures\n(TransM2ixes) with Enhanced and Tunable Electrical, Thermal, and Mechanical Properties. ACS Appl.\nMater. Interfaces. 9, 35977-35987 (2017).\nREVIEWERS' COMMENTS\nReviewer #1 (Remarks to the Author):\nAuthors well modified the manuscript. The reviewer think that the paper is good for publication in\nNat. Comm.\nRe: We would like to express our sincere gratitude to the reviewer for your positive feedback and\nrecognition of our revised manuscript. We greatly appreciate your acknowledgment that the\nmanuscript, after revisions, meets the standards and is suitable for publication in Nature\nCommunications.\nReviewer #2 (Remarks to the Author):\nThe authors have well addressed the prior concerns. I recommend publication of the revised\nmanuscript.\nRe: We would like to express our sincere gratitude to the reviewer for your positive feedback and\nrecognition of our revised manuscript. We greatly appreciate your acknowledgment that the\nmanuscript, after revisions, meets the standards and is suitable for publication in Nature\nCommunications.\nReviewer #3 (Remarks to the Author):\nThe authors have addressed my concerns, and I believe the paper is ready for publication.\nRe: We would like to express our sincere gratitude to the reviewer for your positive feedback and\nrecognition of our revised manuscript. We greatly appreciate your acknowledgment that the\nmanuscript, after revisions, meets the standards and is suitable for publication in Nature\nCommunications."}, {"round": 2, "reviewer_comments": {"reviewer_1": "Authors well modified the manuscript. The reviewer think that the paper is good for publication in Nat. Comm.", "reviewer_2": "The authors have well addressed the prior concerns. I recommend publication of the revised manuscript.", "reviewer_3": "The authors have addressed my concerns, and I believe the paper is ready for publication."}, "author_response": ""}]

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