Shrinkage-transfer-assisted printing of microcircuits on fibers

Domain: chemistry
Published: 2026-02-17
Editorial outcome: minor_revision

Abstract
Fiber represents a transformative architecture for next-generation wearable electronics, owing to its intrinsic flexibility, spatial compactness, and manufacturing adaptability. However, the geometric incompatibility between curved fiber substrates and conventional planar photolithography/printing techniques has hindered the fabrication of high-density microcircuits on fibers. Here, we introduce a shrinkage-transfer-assisted printing (STAP) strategy that bridges 2D planar circuit fabrication and 1D fiber device construction by shrinking fluidic eutectic gallium-indium (EGaIn) circuits and transferring them onto curved fiber surfaces. This approach achieves a shrinkage ratio of up to 80% with a resolution of 60 μm via scalable screen printing, and employs a capillary-driven transfer process to realize 360° conformal coverage of circuits on fibers. The resulting fiber devices exhibit mechanical robustness over 16,000 bending cycles. As a proof of concept, we demonstrate an electroluminescent fiber display system with individually addressable pixels. This work provides a versatile strategy for manufacturing microcircuits on curved fiber surfaces, opening a route toward scalable and multifunctional fiber electronics.

Introduction
One-dimensional fiber-based architectures are emerging as promising platforms for next-generation flexible electronics, offering substantial potential for miniaturization, integration, and wearability1–5. The inherent structural features of fibers endow them with exceptional mechanical flexibility and processability, enabling versatile design possibilities6. Individual fiber devices can serve as self-sufficient electronic systems while also being directly assembled into advanced architectures, providing considerable design freedom for miniaturized wearable applications7. These unique attributes have driven notable progress in fiber-based technologies for health monitoring8–10, flexible displays11–13, and energy storage/conversion systems14–16.

The pursuit of unprecedented functionality in fiber devices necessitates compatibility between the geometric characteristics and those of functional materials and processing methods17,18. Current strategies to accommodate the high-aspect-ratio 1D geometry of fibers include axial deposition of functional coatings19,20 or incorporation of materials during spinning processes21. Taking advantage of the structural adaptability of fibers, established textile techniques such as twisting, stitching, and weaving further facilitate device integration18,22. Notably, 2D planar substrates support sophisticated electronic functionalities via complex circuitry and integrated components (e.g., printed circuit boards), inspiring a promising approach for fiber devices: direct circuit fabrication on curved fiber surfaces. Such an approach could enhance structural compactness, functional integration, and application versatility in fiber electronics.

However, conventional methods for fabricating electronic components, such as photolithography and direct ink writing, on 2D planes are not directly transferable to fibers, owing to geometric incompatibility with curved surfaces and challenges in achieving sufficient circuit resolution23–25. These limitations motivate an alternative strategy: first constructing electronic components on a 2D platform, then transforming them geometrically for integration onto 1D fibers. Such methodology could combine the advantages of planar fabrication technologies with the intrinsic benefits of fiber geometries, ultimately facilitating the development of high-performance fiber devices.

Results
The STAP process consists of two sequential steps: controlled shrinkage and conformal transfer. First, a silicone substrate (Ecoflex film) is omnidirectional pre-strained to a defined ratio and secured on an acrylic frame to maintain tension (Supplementary Fig. 1, Movie 1). EGaIn circuits are then screen-printed onto the stretched silicone substrate. Upon releasing the tension, the substrate contracts, resulting in a uniform reduction in the circuit size and forming microcircuits (Fig. 1a). Subsequently, the microcircuits are transferred conformally onto the target fiber using a water-soluble PVA carrier film. After dissolving the PVA layer, the EGaIn microcircuits remain intact and adherent to the fiber surface (Supplementary Movie 2). To demonstrate functional applicability, we spray-coated an EL layer consisting of ZnS:Cu particles dispersed in a styrene-ethylene-butylene-styrene (SEBS) matrix onto the fiber, achieving a light-emitting array with individually addressable pixels (Fig. 1b).

The shrinkage ratio of EGaIn microcircuits can be precisely controlled (Supplementary Fig. 2), enabling up to an 80% reduction in circuit area relative to the original printed design while preserving structural integrity and pattern fidelity (Fig. 1c). These microcircuits can be fabricated at arbitrary position along meter-length continuous fiber (Fig. 1d) and achieve 360° full circumferential coverage, thereby maximizing the available surface area for functional device integration (Fig. 1e). The transfer process preserves the microcircuit patterns without noticeable distortion. Owing to the ultrathin nature of the PVA carrier film (20 μm), residual PVA on the fiber surface is negligible and does not compromise the overall flexibility of the system.

The EL functionality of the pixels is driven by the high electric field generated within the microcircuits under pulsed voltage excitation. When an alternating electric field exceeding 2 kV/mm is applied across the luminescent layer coated on the circuits, electrons in ZnS:Cu absorb energy, being promoted to excited states, and emit photons upon returning to their ground states26. Controllable light emission is achieved by optimizing the interelectrode spacing within the microcircuits to maintain an electric field sufficient for luminescence while avoiding dielectric breakdown (Fig. 1f). The STAP strategy improves processing resolution through controlled size reduction, while the circuit fabrication itself remains a macroscale process. This approach readily produces electrode gaps as narrow as 35 μm (Supplementary Fig. 3), exceeding the typical resolution limit of conventional screen-printing methods (50 μm), which is constrained by the mesh size.

Screen-printable conductive ink is crucial for fabricating EGaIn microcircuits. We developed a water-based EGaIn/sericin ink composed of EGaIn with a melting point of 16 °C as the conductive component and silk sericin as the stabilizer (Fig. 2a). Bulk EGaIn was dispersed into EGaIn microparticles (EMPs) by blending it at 20,000 rpm. The resulting EMPs were slightly oxidized in water, forming a surface oxide layer that improves their affinity with sericin. Sericin contains amino acids such as serine, tyrosine, and aspartic acid, which have oxygen-rich functional side groups, as well as cysteine with sulfur-containing side groups27. Consequently, sericin can stably adhere to the surface of EMPs through hydrogen bonding and coordination interactions. This adsorption creates a physical barrier between individual EMPs. Furthermore, sericin is negatively charged in neutral aqueous solution (isoelectric point = 4)28, inducing electrostatic repulsion among sericin-coated EMPs due to Coulombic forces (Fig. 2b). The combined steric and electrostatic stabilization effects allow the EMPs to remain well-dispersed in water for more than one week without agglomeration (Fig. 2c, Supplementary Fig. 5).

Microscopic and spectroscopic characterizations confirm the interactions between EMPs and sericin. Scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) reveals a homogeneous distribution of O, N, and S elements across the EMP surfaces, confirming the presence of sericin adhesion (Fig. 2d). Transmission electron microscopy (TEM) images directly show a continuous shell layer of sericin coating the EMPs (Fig. 2e). Fourier-transform infrared spectroscopy (FT-IR) exhibits a red shift of 12.5 cm−1 in the characteristic sericin absorption peak at 3267.3 cm−1 after adsorption onto EMPs (Fig. 2f), suggesting hydrogen bonding formation between sericin and the surface oxide layer29,30. X-ray photoelectron spectroscopy (XPS) further reveals the interactions between sulfur atoms in cysteine residues and the EMP surface. The S 2p spectrum exhibit two characteristic peaks at 167.3 eV and 168.4 eV (Fig. 2g), corresponding to free thiol groups in cysteine31. Upon binding with EMPs, these peaks shift to lower binding energies (160.6 eV and 163.0 eV), consistent with the formation of metal-sulfur bonds or coordination32,33. The peak at 158.8 eV is attributed to the overlap of Ga 3s34. This distinct shift of S 2p peaks provides strong evidence of chemical interactions. Complementary N 1s spectra (Supplementary Fig. 4) reflect changes in nitrogen coordination environments, offering additional support for the sericin-mediated stabilization mechanism.

The affinity between EMPs and sericin endow the EGaIn/sericin ink with high colloidal stability and excellent printability. The size of EMPs can be tuned by varying the blending duration, yielding particles with an averaged diameter of approximately 3 μm that is suitable for unobstructed passage through screen meshes (Fig. 2h, Supplementary Fig. 6). Zeta potential measurements reveal a more negative surface charge for the EGaIn/sericin composite (−12.4 mV) compared to pure sericin solution (−7.4 mV) (Fig. 2i), suggesting that EMPs promote ionization of acidic functional groups in sericin, thereby enhancing electrostatic stabilization. Rheological analyses show that the incorporation of EMPs increases the viscosity of the sericin matrix, consistent with strong interfacial interactions. Notably, the EGaIn/sericin system exhibits a pronounced shear-thinning behavior (Fig. 2j), which is an essential requirement for high-resolution screen printing, as it facilitates flow during printing while ensuring shape retention thereafter35.

The printed circuit patterns are initially non-conductive due to the presence of surface oxides and surrounding polymer barriers, which typically require additional sintering steps, such as mechanical compression or chemical treatment, to form conductive pathways in conventional EGaIn circuits36. Remarkably, the STAP strategy integrates two in situ sintering mechanisms without requiring external interventions. The first mechanism, shrinkage-induced sintering, occurs autonomously during substrate contraction. Prior to screen printing, a pre-stretched silicone substrate is partially treated with air plasma (Fig. 3a, Supplementary Figs. 7, 8) to enhance ink adhesion. A plasma treatment duration of 3 min enables robust attachment of the printed circuit patterns (Fig. 3b, Supplementary Movie 3). Subsequent release of the pre-strain triggers spontaneous conductivity development (Fig. 3c). In samples with pre-stretch ratios of 450%, 300%, and 150%, the resistance evolution follows a characteristic three-stage profile: starting from infinity, dropping rapidly to a finite value, and finally stabilizing (Fig. 3e). All groups reached a resistance of 102 Ω after an initial 50% strain release, exhibiting diminishing returns with further release. Higher pre-strain ratios resulted in lower final resistances (Fig. 3f), indicating more efficient sintering of the EMPs. Mechanistic analysis suggests that the shrinkage of the substrate reduces the interparticle spacing until the friction force (Ff) between EMPs and the substrate exceeds the mechanical strength of the particle shells (Fig. 3d), resulting in shell rupture and EGaIn fusion. Larger pre-stretch amplifies this compressive force, thereby enhancing electrical conductivity. Notably, this sintering process preserves pattern integrity despite internal particle rearrangement.

The transfer-sintering mechanism is activated during the transfer of shrunken EGaIn microcircuits from the silicone substrates to PVA films. As the PVA is peeled from the silicone, continuous metallic patterns become visible on the PVA surface (Fig. 3g), confirming the formation of a conductive pathway. In situ SEM characterization reveals that EGaIn adheres to both surfaces without detectable EMP residues (Fig. 3h), indicating complete sintering. This transfer-induced sintering arises from competitive interfacial adhesion: the plasma-activated silicone and the PVA film both exhibit strong affinity to the EMPs, showing adhesion forces of 0.53 μN and 0.79 μN, respectively (Supplementary Figs. 11, 12). Consequently, the separation process ruptures the oxide shells, triggering instantaneous liquid metal coalescence. The stronger affinity between PVA and EMPs results in preferential transfer of the EGaIn circuits to the PVA surface. The affinity of PVA is primarily attributed to hydrogen bonds between the hydroxyl groups of PVA and the EMPs. To verify the role of hydroxyl groups, comparative adhesion tests were conducted using polyvinyl butyral (PVB), a polymer structurally analogous to PVA but with a portion of its hydroxyl groups blocked by acetal formation. Mechanical measurements reveal that the adhesion force of PVB films toward EMPs is 0.46 μN, significantly lower than that of PVA (0.79 μN) (Supplementary Fig. 12e, f). Laser confocal microscopy further reveals the morphological evolution and gap narrowing during dual-stage sintering, confirming that the STAP strategy synergistically combines circuit miniaturization and conductivity restoration without compromising structural integrity (Fig. 3i, Supplementary Fig. 13). Furthermore, the reduced feature sizes in EGaIn microcircuits directly enhance device integration density, an outcome governed by two principal parameters: the original screen mesh specifications and the applied shrinkage ratio.

The ultimate resolution achievable by STAP is governed by the initial screen-printing precision and the shrinkage behavior of the EMPs on the silicone platform. The intrinsic resolution (Ff) is defined by the screen-printing process determines the fineness of the microcircuit patterns. Screens with higher mesh counts provide finer patterning but reduce ink passage, lowering the amount of deposited EGaIn and creating a fundamental compromise between resolution and conductivity. In this work, 300-mesh represents a practical upper limit. Finer meshes fail to transfer sufficient ink to form continuous pathways even after shrinkage. As shown in Fig. 3j, the x-axis represents the pre-stretch ratio, which correlates with the magnitude of Ff that drives sintering. The y-axis denotes the EMP surface coverage, where lower values impede electrical percolation. The phase boundary identifies the combinations of pre-stretch and coverage that maintain conductivity above the percolation threshold. Moving along this boundary toward higher Ff enables smaller feature sizes while preserving electrical continuity (see Table S2 for electrical conductivity for each point). The resolution and lateral deviation of microcircuits fabricated with different screen meshes were systematically examined under an extreme area shrinkage of 80% (Table S1). This parametric framework study addresses the multi-parameter optimization challenge and facilitates the fabrication of high-resolution microcircuits (Fig. 3k). During shrinking, the compressive stress originating from the recovery of the silicone is transmitted upward through the microcircuit (Supplementary Fig. 14). Under extreme shrinkage, this stress can induce overflow of EMPs beyond the designed pattern boundaries. Since further improvement in the as-printed resolution is hindered by insufficient ink transfer through higher-mesh screens, these two factors together limit the final attainable result resolution (Supplementary Fig. 15).

The capillary-driven transfer process enables precise conformal wrapping of EGaIn microcircuit onto fiber substrates. Aramid fiber is chosen as the substrate due to its intrinsic hydrophilicity and relatively high dielectric constant. When a water droplet is introduced at the interface between the PVA film and the fiber, capillary forces induce radial liquid propagation along both the axial and circumferential directions of the fiber, simultaneously dissolving the PVA matrix and promoting interfacial adhesion (Fig. 4a). This process is governed by the thermodynamics of wetting, as described by the following equation (w = water, F = fiber, P = PVA):

ΔG T,p = γ w,P + γ w,F − γ Air,P − γ Air,F (1)

Spontaneous wrapping occurs when ΔG T,p < 0. Given the hydrophilic nature of both PVA and aramid fibers (contact angles < 90°), the following relationships hold:

cosθ w,P = (γ Air,P − γ w,P) / γ w,Air > 0 (2)

cosθ w,F = (γ Air,F − γ w,F) / γ w,Air > 0 (3)

Substituting (2) and (3) into Eq. (1) confirms ΔG T,p < 0, validating the self-driven nature of the transfer mechanism. This ensures conformal contact and reliable adhesion of the microcircuit to the fiber surface without external energy input.

Consequently, water droplets undergo spontaneous downward propagation through the capillary channels formed between the fiber and PVA film. Hydration-induced plasticization softens the PVA, reducing its modulus from 5 GPa to a compliant, rubbery state that enables conformal wrapping around the fiber circumference. Meanwhile, the decreased interfacial tension γ w,P further promotes wetting and adhesion (Fig. 4b). This transfer process demonstrates broad applicability across varying degrees of dimensional reduction (2D→1D). EGaIn microcircuits with shrinkage ratios ranging from 50% to 80% retain structural integrity and pattern fidelity after transfer (Fig. 4c), enabling on-demand fabrication of fiber devices with tunable feature sizes down to 60 μm (Fig. 4d).

Preserving pattern fidelity during fiber device integration is critical, where any circuit discontinuities or short circuits would lead to device failure. Radial gap analysis reveals a dimensional variation of ≤5% across the full 360° circumference (Fig. 4e), confirming the non-destructive nature of our transfer process. Notably, this transfer step can also be applied to fibers of different materials and diameters (Supplementary Fig. 19), and can be repeated on one fiber to construct a multilayer circuit (Supplementary Fig. 20).

The resulting fiber devices exhibit exceptional mechanical compliance, enduring 16,000 bending cycles at a curvature radius of 1.6 cm with only a 1.4% increase in resistance. The fiber microcircuit can be bent to a critical radius (rc, defined as the bending radius at which ΔR/R₀ begins to exceed 200%) of 2.3 mm (Fig. 4f), demonstrating good robustness for wearable applications. This performance originates from the intrinsic fluidity and strain-insensitive conductivity of EGaIn, as confirmed by microscopy observations of continuous EGaIn pathways during bending (Supplementary Fig. 21). The bending limit of the fiber microcircuit is governed by the PVA adhesive layer, whose flexibility increases with temperature and humidity, leading to different critical radii across different environmental conditions (Supplementary Fig. 22). The shrinkage ratio of EGaIn microcircuits, modulated via the STAP process, directly governs the performance of fiber devices. Capacitance measurements of interdigitated electrodes reveal a 103 enhancement (10 Hz) as the shrinkage ratio increases from 50% to 80% (Fig. 4g), attributed to a reduced interelectrode spacing and increased effective electrode area.

The EL performance of the pixels is determined by electric field intensity (E), which we optimized through precise control of the shrinkage ratio. Finite element simulations of the electric field distribution (Fig. 4h) identified 2 kV/mm as the minimum field required to activate ZnS:Cu particles. Excessively large gaps (>50 μm) result in a reduced number of activated phosphor particles due to field decay, whereas undersized gaps (<25 μm) lead to highly concentrated fields that induce dielectric breakdown. Although the aramid fiber substrate has high tolerance to strong electric fields37, the breakdown of the emissive functional layer remains affecting luminescence efficiency. Thus, an intermediate gap width is required to achieve optimal luminescence. Experimentally, peak luminance is achieved at gap distances of 50–60 μm, where the simulated electric field maximizes the excitation area within the phosphor layer while avoiding dielectric failure (Fig. 4i).

Guided by these design principles, we successfully fabricated an EL pixel array on a fiber. The intrinsic flexibility of the fiber, the EGaIn circuitry, and the SEBS matrix works synergistically to sustain device functionality under mechanical deformation, as demonstrated by a fully operational curved array (Fig. 4j). The pixel array is designed with (2n-3) contact points to individually address n EL pixels, maximizing the number of controllable elements within a limited area (5 contacts controlling 7 pixels in Fig. 4k). Functionalization was carried out by spray-coating a ZnS:Cu/SEBS dispersion, followed by ambient drying to form the electroluminescence layer. Selective pixel activation can be achieved by electrical addressing through designated contacts (Fig. 4l, Supplementary Movie 4), enabling the multiplexed display on a single fiber. Luminance stability remains 94% when bent to a radius of 15 mm, but then decreases rapidly as the curvature increases further (Supplementary Fig. 23). Single-fiber displays, featuring pixel-level addressability, can be seamlessly woven into protective garments for dynamic visual communication. In critical scenarios such as firefighting, rescue operations, and outdoor exploration, they can provide real-time navigation, hazard alerts, or team status. They also enable monitoring of vital signs for medical assistance and facilitate communication by displaying information for individuals with speech or language barriers. It is noted that the STAP process is also compatible with other typical commercially available inks besides the EGaIn/sericin ink (Supplementary Fig. 24). This STAP strategy overcomes the long-standing challenge of integrating high-precision microcircuits onto curved fiber substrates, paving the way for multifunctional and high-density wearable electronics. Further efforts on developing automated stretching and continuous transfer systems could improve the scalability of STAP and facilitate its adoption in practical manufacturing settings.

Methods
Materials
All materials were used as received. EGaIn (75%Ga, 25%In, melting point 16 °C) was purchased from Alibaba. Silk sericin and PVA (MW: 100,000) were purchased from Macklin. ZnS:Cu phosphor powder was purchased from Shanghai Keyan Phosphor Technology Co., Ltd. Ecoflex 0030 was purchased from Smooth-On. Aramid fiber was purchased from DuPont. SEBS and chloroform were purchased from Sigma. Ag/AgCl ink and PEDOT:PSS ink were purchased from Prtronic, and the carbon ink was obtained from Loctite. All inks were used as received, without further purification or modification.

Fabrication of EGaIn/sericin ink
First, prepare 100 ml of 2 wt% sericin aqueous solution. Using a syringe, inject 4 ml of EGaIn into the solution, and disperse it using an IKA mill at a speed of 20,000 rpm for 1 min. Subsequently, cool the mixture to 20 °C using an ice-water bath, and repeat the process three times.

Fabrication of Shrunk microcircuits
The fabrication of shrunk microcircuits was carried out in two main steps: screen printing and pattern shrinkage. First, a 200 μm-thick Ecoflex film was omnidirectionally stretched and mounted onto a clean acrylic frame under tension. Next, a patterned screen was placed on the surface of the Ecoflex film as a mask, and the sample was exposed to air plasma for 3 min. Then, EGaIn/sericin ink was screen-printed onto the film. After drying, the EGaIn circuit was formed on the silicone substrate. Pattern shrinkage was achieved by releasing the pre-strained Ecoflex film from the acrylic frame, resulting in the contraction of the substrate and the formation of the final shrunk microcircuits. All the processes, including the fabrication of shrunk microcircuits and their transfer, were performed at 20 °C and 50% relative humidity, unless otherwise specified.

Process of transferring microcircuits
The transfer of the microcircuit was accomplished using a PVA carrier film. A 20 μm thick PVA film was prepared by casting, then handled with tweezers, and its bottom surface was briefly contacted with a water surface for 0.5 s to achieve partial hydration. The moistened film was then carefully laminated onto the Ecoflex substrate bearing the microcircuit. After allowing the PVA film to partially dissolve, the assembly was dried under 60 °C for 30 min to enhance adhesion and facilitate the formation of a continuous bilayer. Finally, the PVA film was peeled off, transferring the highly conductive, intact EGaIn microcircuit to the PVA surface.

Fabrication of single-point controllable EL fiber device
The fabricated PVA film carrying the microcircuit was placed onto the target fiber surface. Using a syringe, water was carefully applied along the edges of the PVA film to allow capillary action to penetrate the interface, enabling the circuit to adhere to the fiber surface and forming the fiber circuit. Special care should be taken to ensure that the water is applied to the gaps between the PVA film and the fiber, rather than directly on the surface of the PVA film. Upon complete dissolution of the PVA, the circuit remained attached to the fiber, forming a continuous fiber-integrated microcircuit. The assembly was then dried at 60 °C for 30 min to enhance stability. Subsequently, an electroluminescent layer was applied by spray-coating a formulated ink suspension consisting of ZnS:Cu fluorescent powder, SEBS elastomer, and chloroform (mass ratio: 1 g: 0.5 g: 5 g). The coated fiber was dried again to evaporate the solvent, forming a solid emissive composite layer. Finally, the device was completed by connecting the fiber circuit to an external power supply for activation and operation.

Morphology characterization
Transmission electron microscopy (JEOL, JEM-2100F) and scanning electron microscopy (Thermo Fisher, Phenom XL G2 Desktop SEM) were used to characterize the morphology of EGaIn microparticles and microcircuits. The in situ observation of PVA/Ecoflex delamination and the shrinkage-sintering of microcircuits was carried out using an SEM equipped with an in situ tensile holder. Image processing and EGaIn microparticle diameter analysis were conducted using ImageJ software. Laser confocal microscopy (Zeiss, LSM900) was used to observe surface morphology changes during the shrinking and transfer processes of the microcircuits.

Spectroscopic and rheological characterization
Fourier-transform infrared spectroscopy (FTIR, BRUKER, VERTEX) was used to evaluate hydrogen bonding interactions between EGaIn and sericin. X-ray photoelectron spectroscopy (XPS, Thermo Fisher, ESCALAB Xi+) was used to analyze the coordination interactions between EGaIn and sericin. Viscosity measurements were conducted using a rotational rheometer (Anton Paar, MCR302).

Electrical and mechanical characterization
Electrical characterization was performed using an electrochemical workstation (Shanghai Chenhua, CHI760E). Mechanical tests were conducted using a SHIMADZU AGS-X universal testing machine. For simultaneous electromechanical characterization, the fiber device was mounted onto the tensile tester while electrically connected to the workstation via wires. Data acquisition from both instruments was synchronized through time alignment to correlate mechanical strain with electrical response. Repeated bending deformation was performed at a maximum curvature radius of 16 mm, at 20 °C and relative humidity of 50%, with a frequency of 1 Hz. The samples were stored in a temperature- and humidity-controlled chamber for 3 h before the test.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "This is a highly innovative manuscript, with advances in both the printing of microcircuits and the fabrication of fiber devices. The authors utilize a two-dimensional stretchable silicone platform as the substrate for screen printing, thereby overcoming the resolution limit of conventional screen printing techniques and achieving flexible EGaIn microcircuits. The proposed method also provides valuable guidance for other planar circuit fabrication techniques beyond screen printing. As an application demonstration, the authors transfer the miniaturized circuits onto fiber surfaces. This surface-based circuit construction approach makes the fabrication of fiber devices versatile, and the transfer strategy appears to be extendable to other small and complex curved surfaces. In addition, the manuscript is logically organized and clearly written. I would recommend acceptance after minor revision, provided that the authors address the following points:\n1) In page 3, the authors chose silk sericin as the stabilizer. It is suggested that the authors include comparative SEM images to show the influence of adding silk sericin on the morphology of EGaIn microparticles, in order to further demonstrate the necessity of using the stabilizer.\n2) The authors are encouraged to include a discussion on the choice of fiber substrate material. Specifically, why was aramid fiber selected as the transfer base for EGaIn microcircuits?\n3) According to Fig. 3b and Supplementary Video 2, patterned plasma treatment on the silicone substrate enhances the wettability and adhesion of the water-based EGaIn/sericin ink, ensuring accurate pattern deposition. Why is patterned plasma treatment necessary instead of treating the entire surface uniformly? The authors should elaborate on the processing steps and rationale for using patterned plasma treatment.\n4) Page 6, line 174: “This transfer-induced sintering arises from competitive interfacial adhesion…”. While this mechanism is clearly illustrated in Supplementary Fig. 9, the authors are advised to provide supporting data to further substantiate this claim of competitive interfacial adhesion.\n5) Page 2, line 62: The authors employ a polyvinyl alcohol (PVA) film as the transfer medium for EGaIn microcircuits, primarily due to its water solubility and affinity toward EGaIn microparticles. It is suggested that the authors further justify the advantages of choosing PVA, for instance by explaining its chemical structure or interfacial interactions in more detail.\n6) Page 7: It is suggested that the authors add a brief discussion on the potential applications of the fiber device described in Fig. 4. For example, what practical scenarios this fiber device could be applied to.", "reviewer_2": "This manuscript presents a highly original approach to addressing the persistent challenge of integrating microscale circuits onto curved fiber surfaces. The proposed shrinkage-transfer-assisted printing (STAP) method elegantly bridges the gap between 2D circuit fabrication and 1D fiber device realization, achieving impressive miniaturization (up to 80% shrinkage) and 360° conformal coverage. The concept is novel, technically sound, and well supported by systematic experiments. The combination of stress-engineered silicone substrates, EGaIn/sericin ink chemistry, and capillary-driven transfer represents a meaningful advance in fiber-based electronics.\nThe manuscript is generally well written, visually clear, and methodologically detailed. It convincingly demonstrates functionality through the electroluminescent fiber device. The work is clearly distinct from previously published studies—including our earlier Nature Communications paper on integrated microfibre electronics—by offering a different dimensional transformation and processing strategy.\nThat said, a few aspects need clarification and strengthening before acceptance. These concern (1) the universality and scalability of the claimed “universal fabrication strategy,” (2) quantitative treatment of the scaling-down limit for metallic patterns, and (3) mechanical durability and interfacial reliability under extended cyclic deformation.\nOverall, this is an excellent and innovative contribution that will attract broad attention in the field of fiber electronics and soft-matter circuit integration. The concept of geometric transformation from 2D to 1D is elegant, and the results are compelling.\nAddressing the issues above, particularly regarding the scaling limit and mechanical reliability, will further strengthen the manuscript’s impact and technical completeness.\nMajor Comments\n- The Introduction concludes that STAP is a “universal fabrication strategy,” yet experimental demonstrations are limited to EGaIn and PVA-based transfer. To substantiate this claim, the authors should briefly discuss whether the STAP process is compatible with other inks (e.g., silver nanoparticle, conductive polymer) or elastomeric substrates.\n- A comparative comment on scalability with respect to textile-level or roll-to-roll fabrication methods would provide valuable context for its practical universality.\n- What is possible resolution and Scaling-Down Limitations?\n- While the manuscript demonstrates a 60 μm feature size and 35 μm electrode gaps, it remains unclear what factors fundamentally limit further miniaturization, whether by the screen mesh resolution, ink rheology, or mechanical shrinkage threshold of the substrate. Please provide indetail.\n- Providing a scaling analysis or discussing the potential challenges in pushing esolution below 50 μm would be insightful. For instance, could oxide shell rupture or uneven compressive stress during shrinkage impose a lower limit?\n- The manuscript claims retention of 98.6 % conductivity after 16,000 bending cycles, which is impressive. However, the detailed stress conditions (bending radius, strain amplitude, test frequency) should be more explicitly stated in Methods or figure captions to allow fair comparison with prior works.\n- Since the circuit–fiber interface is critical, it would be helpful to discuss or test failure modes such as delamination or crack initiation, particularly under humidity or temperature variation. Supplementary Fig. 14 shows morphological stability but does not provide long-term cycling data.\n- If available, resistance evolution over more extreme bending radii (≤ 4 mm) or torsional deformation would enhance confidence in durability claims.\n- The Methods should specify environmental parameters (temperature, humidity) during shrinkage and transfer, as these can influence EGaIn’s viscosity, oxidation, and adhesion.\n- Clarify how uniform stretching was maintained—manual stretching may lead to edge effects. Was a biaxial stretcher or measured tension used? Including a schematic or photo of the setup (possibly in Supplementary Fig. 1) would improve reproducibility.\nMinor Comments and Editorial Suggestions\n1. Figure 1c: Add explicit “before” and “after shrinkage” labels and indicate quantitative shrinkage ratios on the figure or in the caption.\nSupplementary Figures:\n1. Fig. 1: Add direct annotations (e.g., “Ecoflex cast film,” “peeled film,” “stretched film on frame”) instead of relying solely on the caption.\n2. Fig. 2–3: Clarify whether EGaIn–PVA interfaces exhibit cracking or delamination during shrinkage.\n3. Fig. 3c: Mark the region of the high-magnification image within the main panel.\n4. Terminology: Replace “universal fabrication strategy” with “versatile fabrication strategy” unless broader material compatibility can be experimentally verified.\n5. Supplementary Video 3: A brief quantitative comparison of luminance stability under bending would add scientific value beyond qualitative demonstration.", "reviewer_3": "The manuscript is generally well written and clearly presented. However, there are several issues that limit the overall scope and relevence of the work.\nMaterial specificity:\nThe materials used in the study are very specialized and are not easily replaced or adapted to other functional materials (substrate, ink, GaIn ....)\nScalability and reproducibility:\nKey steps in the process—such as pre-stretching, tension release, transferring onto a PVA sheet, water-assisted transfer, and the shrinkage of the printed circuits—introduce a lot of variability and are not easily scalable. As a result, achieving consistent reproducibility is challenging. In addition, the conductivity variations that come from shrinkage sintering and transfer sintering need to be supported with more detailed statistical data.\nMultilayer printing limitations:\nThe approach does not seem capable of true multilayer printing. In the demonstrated device, the conductive layer is printed and transferred onto the thread, while the luminescent layer is applied by coating rather than printing. This highlights an inherent limitation of the technique.\nLimited use on small-diameter substrates:\nThe method is demonstrated only on threads a few millimeters in diameter. Its potential for use on finer fibers or true one-dimensional substrates is not addressed, which restricts the broader relevance of the work."}, "author_response": "We thank the reviewers for the constructive comments and suggestions on our manuscript. Accordingly, we have carried out additional experiments and revised the manuscript carefully. The changes are marked in BLUE in the revised manuscript and are marked in RED here. The following is a point-to-point response to each of the comments.\nReviewer #1:\nSummary Comment:\nThis is a highly innovative manuscript, with advances in both the printing of microcircuits and the fabrication of fiber devices. The authors utilize a two-dimensional stretchable silicone platform as the substrate for screen printing, thereby overcoming the resolution limit of conventional screen printing techniques and achieving flexible EGaIn microcircuits. The proposed method also provides valuable guidance for other planar circuit fabrication techniques beyond screen printing. As an application demonstration, the authors transfer the miniaturized circuits onto fiber surfaces. This surface-based circuit construction approach makes the fabrication of fiber devices versatile, and the transfer strategy appears to be extendable to other small and complex curved surfaces. In addition, the manuscript is logically organized and clearly written.\nReply:\nThank you very much for your careful review and high evaluation of this work. Your constructive comments and suggestions have helped us to further improve our manuscript. Our point-by-point responses to your comments are listed below.\nComment #1:\nIn page 3, the authors chose silk sericin as the stabilizer. It is suggested that the authors include comparative SEM images to show the influence of adding silk sericin on the morphology of EGaIn microparticles, in order to further demonstrate the necessity of using the stabilizer.\nReply:\nThank you for your constructive suggestion. Sericin in the ink serves to isolate the EGaIn microparticles (EMPs), preventing their aggregation through physical separation and Coulombic repulsion. In addition, the attachment of sericin onto the EMP surface helps slow down overall oxidation. In order to provide experimental evidence, we carried out further experiments. Inks with and without sericin were exposed to a harsh atmospheric environment at 60 °C for 30 min, followed by SEM characterization of the resulting EMP morphologies. The results showed that the sericin-free inks exhibited agglomeration, whereas the sericin-containing inks did not.\nAccordingly, we added discussion in the main text and Supplementary Fig. 6 in the supplementary information. The related contents are copied in the following for your convenience:\nIn the main text:\n(Page 3, Line 99) Furthermore, sericin is negative charged in neutral aqueous solution (isoelectric point = 4) 28, inducing electrostatic repulsion among sericin-coated EMPs due to Coulombic forces (Fig. 2b). The combined steric and electrostatic stabilization effects allow the EMPs to remain well-dispersed in water for more than one week without agglomeration (Fig. 2c, Supplementary Fig. 5).\nIn the supplementary information:\nSupplementary Fig. 5. SEM images comparing morphologies of EMPs in inks with and without sericin, after being placed in an atmospheric environment at 60 °C for 30 min.\nComment #2:\nThe authors are encouraged to include a discussion on the choice of fiber substrate material. Specifically, why was aramid fiber selected as the transfer base for EGaIn microcircuits?\nReply:\nThank you for raising this point. We selected aramid fiber as the circuit substrate due to its hydrophilic nature and relatively high dielectric constant, which facilitate water-assisted transfer and support the high electric field required for electroluminescence.\nAccordingly, we added related information in the main text. The related contents are copied in the following for your convenience:\nIn the main text:\n(Page 7, Line 221) The capillary-driven transfer process enables precise conformal wrapping of EGaIn microcircuit onto fiber substrates. Aramid fiber is chosen as the substrate due to its intrinsic hydrophilicity and relatively high dielectric constant.\n(Page 8, Line 265) Although the aramid fiber substrate has high tolerance to strong electric fields 36, the breakdown of emissive functional layer remains affecting luminescence efficiency. Thus, an intermediate gap width is required to achieve optimal luminescence…\nComment #3:\nAccording to Fig. 3b and Supplementary Video 2, patterned plasma treatment on the silicone substrate enhances the wettability and adhesion of the water-based EGaIn/sericin ink, ensuring accurate pattern deposition. Why is patterned plasma treatment necessary instead of treating the entire surface uniformly? The authors should elaborate on the processing steps and rationale for using patterned plasma treatment.\nReply:\nThank you for raising this insightful point. Yes, plasma treatment of the silicone substrate (Ecoflex film) is crucial, because silicone is inherently hydrophobic, exhibiting a water contact angle as high as 104.5° (Fig. 3a). As a result, the water-based EGaIn/sericin ink cannot properly wet or adhere to its surface. The use of patterned plasma treatment serves two purposes. First, it enables the ink to remain confined within the patterned regions without spreading. Second, it facilitates the subsequent peeling of the PVA layer. If the entire silicone surface were plasma-treated uniformly, the wet PVA would also contact the activated silicone, and after drying, strong hydrogen-bond interactions would form, making the PVA layer impossible to peel off.\nAccordingly, we added related discussion in the main text and Supplementary Fig. 8 in the supplementary information. The related contents are copied in the following for your convenience:\nIn the main text:\n(Page 6, Line 157) Prior to screen printing, pre-stretched silicone substrate is partially treated with air plasma (Fig. 3a, Supplementary Fig. 7-8) to enhance ink adhesion.\n(Page 10, Line 334) Fabrication of Shrunk microcircuits\nFirst, a 200 μm-thick Ecoflex film was omnidirectionally stretched and mounted onto a clean acrylic frame under tension. Next, a patterned screen was placed on the surface of the Ecoflex film as a mask and the sample was exposed to air plasma for 3 minutes. Then, EGaIn/sericin ink was screen-printed onto the film.\nIn the supplementary information:\nSupplementary Fig. 8. Photograph showing the mask placed on the pre-stretched Ecoflex substrate for plasma treatment and the screen printing.\nComment #4:\nPage 6, line 174: “This transfer-induced sintering arises from competitive interfacial adhesion…”. While this mechanism is clearly illustrated in Supplementary Fig. 9, the authors are advised to provide supporting data to further substantiate this claim of competitive interfacial adhesion.\nReply:\nThank you for your constructive suggestion. To addressed this point, we carried out further experiments to provide more evidence for the mechanism. We investigated the interactions between EMP and different substrates using atomic force microscopy (AFM). The results indicate the EMP exhibit strong affinity toward the substrates, which facilitates the rupture of their oxide shells during separation and thereby enables sintering. PVA with stronger adhesion to the EMPs tend to retain more EGaIn on its surfaces, which explains the observed transfer behavior.\nAccordingly, we added related discussion in the main text, and Supplementary Fig. 12 in the supplementary information. The related contents are copied in the following for your convenience:\nIn the main text:\n(Page 6, Line 174) This transfer-induced sintering arises from competitive interfacial adhesion: the plasma-activated silicone and the PVA film both exhibit strong affinity to the EMPs, showing adhesion forces of 0.53 μN and 0.79 μN, respectively (Supplementary Fig. 11-12). Consequently, the separation process ruptures the oxide shells, triggering instantaneous liquid metal coalescence.\nIn the supplementary information:\nSupplementary Fig. 12. Force measurements between the EMP and different substrates. (a) SEM image of an EMP attached to an AFM probe. (b) Magnified view of the probe shown in (a). (c-f) Approach-retract force curves acquired between the EMP and a pristine Ecoflex film (c), an Ecoflex film treatment with 3 min plasma (d), a PVA film (e), and a polyvinyl butyral (PVB) film (f).\nComment #5:\nPage 2, line 62: The authors employ a polyvinyl alcohol (PVA) film as the transfer medium for EGaIn microcircuits, primarily due to its water solubility and affinity toward EGaIn microparticles. It is suggested that the authors further justify the advantages of choosing PVA, for instance by explaining its chemical structure or interfacial interactions in more detail.\nReply:\nThank you for the insightful suggestion. In this work, the hydroxyl groups on the PVA chains form hydrogen bonds with the oxide shell of the EMPs, contributing to the strong interfacial affinity. To validate the role of hydroxyl groups, we carried out further experiments to compare PVA with polyvinyl butyral (PVB), a structurally similar polymer in which a portion of the hydroxyl groups is blocked through acetal formation. Mechanical measurements on PVB films show an adhesion force of 0.46 μN toward the EMPs, substantially lower than that of PVA (0.79 μN), confirming the critical contribution of hydroxyl groups to the affinity.\nAccordingly, we added related discussion in the main text and Supplementary Fig. 12e-f in the supplementary information. The related contents are copied in the following for your convenience:\nIn the main text:\n(Page 6, Line 177) The stronger affinity between PVA and EMPs results in preferential transfer of the EGaIn circuits to the PVA surface. The affinity of PVA is primarily attributed to hydrogen bonds between the hydroxyl groups of PVA and the EMPs. To verify the role of hydroxyl groups, comparative adhesion tests were conducted using polyvinyl butyral (PVB), a polymer structurally analogous to PVA but with a portion of its hydroxyl groups blocked by acetal formation. Mechanical measurements reveal that the adhesion force of PVB films toward EMPs is 0.46 μN, significantly lower than that of PVA (0.79 μN) (Supplementary Fig. 12e-f).\nIn the supplementary information:\nSupplementary Fig. 12 Approach-retract force curves acquired between the EMP and a PVA film (e), and a polyvinyl butyral (PVB) film (f).\nComment #6:\nPage 7: It is suggested that the authors add a brief discussion on the potential applications of the fiber device described in Fig. 4. For example, what practical scenarios this fiber device could be applied to.\nReply:\nThank you for the valuable suggestion. Accordingly, we have added a brief discussion on the potential applications of the single-fiber displays in the main text. The related contents are copied in the following for your convenience:\nIn the main text:\n(Page 9, Line 280) Single-fiber displays, featuring pixel-level addressability, can be seamlessly woven into protective garments for dynamic visual communication. In critical scenarios such as firefighting, rescue operations, and outdoor exploration, they can provide real-time navigation, hazard alerts, or team status. They also enable monitoring of vital signs for medical assistance and facilitate communication by displaying information for individuals with speech or language barriers.\nReviewer #2:\nSummary Comment:\nThis manuscript presents a highly original approach to addressing the persistent challenge of integrating microscale circuits onto curved fiber surfaces. The proposed shrinkage-transfer-assisted printing (STAP) method elegantly bridges the gap between 2D circuit fabrication and 1D fiber device realization, achieving impressive miniaturization (up to 80% shrinkage) and 360° conformal coverage. The concept is novel, technically sound, and well supported by systematic experiments. The combination of stress-engineered silicone substrates, EGaIn/sericin ink chemistry, and capillary-driven transfer represents a meaningful advance in fiber-based electronics.\nThe manuscript is generally well written, visually clear, and methodologically detailed. It convincingly demonstrates functionality through the electroluminescent fiber device. The work is clearly distinct from previously published studies—including our earlier Nature Communications paper on integrated microfibre electronics—by offering a different dimensional transformation and processing strategy.\nThat said, a few aspects need clarification and strengthening before acceptance. These concern (1) the universality and scalability of the claimed “universal fabrication strategy,” (2) quantitative treatment of the scaling-down limit for metallic patterns, and (3) mechanical durability and interfacial reliability under extended cyclic deformation.\nOverall, this is an excellent and innovative contribution that will attract broad attention in the field of fiber electronics and soft-matter circuit integration. The concept of geometric transformation from 2D to 1D is elegant, and the results are compelling.\nAddressing the issues above, particularly regarding the scaling limit and mechanical reliability, will further strengthen the manuscript’s impact and technical completeness.\nReply:\nWe sincerely thank you for your careful review of our manuscript and greatly appreciate your constructive suggestions. Accordingly, we have carried out further experiment and carefully revised the manuscript. Below are point-by-point responses to each of your comments.\nComment #1:\nThe Introduction concludes that STAP is a “universal fabrication strategy,” yet experimental demonstrations are limited to EGaIn and PVA-based transfer. To substantiate this claim, the authors should briefly discuss whether the STAP process is compatible with other inks (e.g., silver nanoparticle, conductive polymer) or elastomeric substrates.\nReply:\nThank you very much for raising this point. In order to address this point, we carried out further experiments. Beside the EGaIn/sericin ink, three commercially available and widely used inks, including Ag/AgCl ink and carbon ink, which are commonly employed in printed electrochemical sensors, and PEDOT:PSS ink, which is one of the most broadly used conductive polymers, were studied. We found that all the three inks can be successfully applied in our process, demonstrating the versatility of the STAP process. We propose the following are the requirements for the inks used in this process: (i) The ink should remain flowable during the interval between printing and substrate shrinkage, which allows the shrinkage-induced stress to propagate upward from the bottom of the pattern and to drive spatial reorganization of the ink material. (ii) The ink should possess adequate viscosity, since low-viscosity inks would easily overflow the intended pattern boundaries during substrate motion and cause feature distortion. (iii) The ink should have affinity toward the targeted film, which in this work is PVA. For example, EMPs with hydrophilic surfaces exhibit strong affinity to PVA, which is essential for successful transfer.\nAs for the selection of elastomeric substrates, the STAP process requires substates with high stretchability, recoverability and hydrophobicity. The silicone elastomer we used fits these requirements perfectly. Other common elastomers such as styrene-ethylene-butylene-styrene copolymer (SEBS) and thermoplastic polyurethane (TPU) could in principle work with STAP, but their stretchability is usually lower than that of silicone unless molecular modification is applied. Therefore, in this work, we selected commercial Ecoflex and did not study other elastomeric substrates.\nAccordingly, we have added related discussion in the main text, and Supplementary Fig. 24 in the supplementary information. Besides, we have replaced the term “universality” with “versatility” in the main text to be more rigor. The related contents are copied in the following for your convenience:\nIn the main text:\n(Page 9, Line 285) It is noted that the STAP process is also compatible with other typical commercially available inks besides the EGaIn/sericin ink (Supplementary Fig. 24).\n(Page 9, Line 310) Looking forward, several key challenges must be addressed to advance the practical deployment of STAP… Finally, standardizing process parameters and characterization protocols across different material systems will be essential for ensuring reproducibility and facilitating broader adoption in flexible and textile electronics. By addressing these challenges, STAP can evolve from a laboratory-scale technique into a practical manufacturing process for producing high-performance, seamlessly integrated fiber-based devices.\nIn the supplementary information:\nSupplementary Fig. 24. Applying STAP process using three typical commercial electronic inks. The inks include Ag/AgCl ink (purchased from Prtronic), carbon ink (purchased from Loctite), and PEDOT:PSS ink (purchased from Prtronic), showing consistent printing, ~80% shrinkage, and successful transfer, confirming the compatibility of the STAP process with other inks.\nComment #2:\nA comparative comment on scalability with respect to textile-level or roll-to-roll fabrication methods would provide valuable context for its practical universality.\nReply:\nThank you for this valuable suggestion. Frankly, we think that the textile-level and roll-to-roll fabrication methods currently offer advantages in scalability over our present laboratory-scale preparation. Nonetheless, we believe STAP possesses potential for large-scale implementation, though several challenges remain at this stage. The stress-engineered 2D silicone platform could be scaled up by using larger substrates. However, continuous large-scale manufacturing would require an automated stretching system capable of applying uniform tension along the entire film. On the other hand, the transfer step is in principle compatible with roll-to-roll processing. After shrinkage, the silicone film carrying the microcircuits could be brought into contact with a continuous PVA roll, following by wetting, drying, transfer and collection along a production line. This approach appears feasible and would mainly require engineering design to automate wetting and rapid drying.\nOverall, your comment provides a forward-looking perspective on the practical deployment of STAP. Accordingly, we have added related discussion in the main text. The related contents are copied in the following for your convenience:\nIn the main text:\n(Page 9, Line 288) Further efforts on developing automated stretching and continuous transfer systems could improve the scalability of STAP and facilitate its adoption in practical manufacturing settings.\n(Page 9, Line 310) Looking forward, several key challenges must be addressed to advance the practical deployment of STAP …Second, scaling the technology for industrial production will require the development of automated stretching systems capable of applying uniform omnidirectional strain to large-area elastic substrates, thereby improving reproducibility.\nComment #3-5:\n(Comment 3) What is possible resolution and Scaling-Down Limitations?\n(Comment 4) While the manuscript demonstrates a 60 μm feature size and 35 μm electrode gaps, it remains unclear what factors fundamentally limit further miniaturization, whether by the screen mesh resolution, ink rheology, or mechanical shrinkage threshold of the substrate. Please provide in detail.\n(Comment 5) Providing a scaling analysis or discussing the potential challenges in pushing resolution below 50 μm would be insightful. For instance, could oxide shell rupture or uneven compressive stress during shrinkage impose a lower limit?\nReply:\nWe appreciate the insightful questions regarding resolution and scaling-down limitations. Since Comments #3-5 are closely related, we address them collectively below. We have supplemented the discussion with schematic illustrations, SEM characterizations and additional data. The fundamental limits on resolution and miniaturization arise from two main aspects:\n(i) Printing resolution on the pre-stretched silicone substrate. The initial patterning fidelity is governed by the screen-printing process. The resolution here refers to the clarity and continuity of the printed EGaIn/sericin pattern after the ink passes through the screen mesh. This printed pattern must be optically distinguishable and electrically continuous after shrinkage. Screen mesh resolution and ink rheology are key factors. Screens with larger mesh openings reduce pattern resolution but allow more ink to pass through, which benefits conductivity, but at the cost of feature definition. Conversely, finer meshes improve printed resolution but reduce ink deposition, lowering conductivity, a trade-off illustrated in Fig. 3j. Ink viscosity also plays a critical role. higher viscosity helps suppress post-printing spreading and improves pattern fidelity (Hong et al., J. Mater. Sci. Technol., 67, 145-155 (2021)), yet it also limits ink passage and conductivity. Optimizing print resolution thus requires balancing these competing parameters.\n(ii) Ink overflow under extreme shrinkage. When the silicone substrate is shrunk severely, the resulting compressive stress can cause EMP ink to overflow beyond the intended pattern boundaries, distorting the printed features. In this study, the Ecoflex film can sustain large uniaxial strains up to 700%, as shown in Supplementary Fig. 10. Under omnidirectional stretching, a 200-μm-thick film can reach approximately 300% strain, corresponding to an area expansion of ~16×, as demonstrated in the newly added Supplementary Video 1. Theoretically, this allows up to ~94% areal shrinkage, but in practice we observe reliable shrinking only up to ~80%. Beyond this point, EMPs overflow becomes pronounced, leading to line broadening, loss of resolution, and in capacitor structures (e.g., interdigitated electrodes), catastrophic short-circuiting. This overflow persists even with a finer 300-mesh screen. However, when using a finer 420-mesh screen, the ink can no longer pass through to form continuous conductive pathways, presenting a key barrier to achieving features below 50 μm.\nAccordingly, we have included the data from our initial orthogonal experiments in Table S1 to show how different screen parameters affect the printing resolution before and after shrinkage. A schematic illustration is provided in Supplementary Fig. 14, and SEM images of EMP overflow under shrinkage are presented in Supplementary Fig. 15, in the supplementary information. The related contents are copied in the following for your convenience:\nIn the main text:\n(Page 6, Line 190) The ultimate resolution achievable by STAP is governed by the initial screen-printing precision and the shrinkage behavior of the EMPs on the silicone platform. The intrinsic resolution defined by the screen-printing process determines the fineness of the microcircuit patterns. Screens with higher mesh counts provide finer patterning but reduce ink passage, lowering the amount of deposited EGaIn and creating a fundamental compromise between resolution and conductivity. In this work, 300-mesh represents a practical upper limit. Finer meshes fail to transfer sufficient ink to form continuous pathways even after shrinkage…\n(Page 6, Line 201) …The resolution and lateral deviation of microcircuits fabricated with different screen meshes were systematically examined under an extreme area shrinkage of 80% (Table S1).\n(Page 6, Line 204) …During shrinking, the compressive stress originating from the recovery of the silicone (F) is transmitted upward through the microcircuit f (Supplementary Fig. 14). Under extreme shrinkage, this stress can induce overflow of EMPs beyond the designed pattern boundaries. Since further improvement in the as-printed resolution is hindered by insufficient ink transfer through higher-mesh screens, these two factors together limit the final attainable result resolution (Supplementary Fig. 15).\nIn the supplementary information:\nSupplementary Fig. 14. Schematic illustration showing the shrinkage-induced resolution limit in the shrinkage process. Excessive shrinkage causes overflow of EMP ink beyond the pattern boundaries, thereby limiting the minimum achievable resolution.\nSupplementary Fig. 15. Side-view SEM images of microcircuits shrunk by 94% in area. (a) The actual line width becomes larger than the designed width due to EMP overflow. (b) Short-circuit behavior observed in the capacitor.\n(Page S19) Table S1. Parameters of screens with different mesh counts, the resolution of as-printed EGaIn/sericin ink, and the resolution after shrinkage (shrunk by 80% in area).\nMesh Resolution-after-EMPs coverage Resolution\ncount extreme shrink ratio (%) (μm)\n(/inch) (μm)\n420 12 Discontinuous Discontinuous\n300 16 136 63\n250 21 160 74\n200 26 202 95\n180 29 245 122\n150 34 272 128\n120 41 285 138\n100 47 300 148\n80 54 325 180\n60 63 420 221\nComment #6:\nThe manuscript claims retention of 98.6 % conductivity after 16,000 bending cycles, which is impressive. However, the detailed stress conditions (bending radius, strain amplitude, test frequency) should be more explicitly stated in Methods or figure captions to allow fair comparison with prior works.\nReply:\nAccording, we have added the related information into Figure caption. Besides, the key information is also presented in the main text. The related contents are copied in the following for your convenience:\nIn the main text:\n(Page 7, Line 210) Fig. 4. Construction and performance of electroluminescent fiber devices. …f, Relative change in resistance of the fiber under cyclic bending deformation with bending radius of 16 mm at 1 Hz (upper) and different bending radii (lower). Temperature, 20 °C; Relative humidity, 50%.\n(Page 8, Line 249) The resulting fiber devices exhibit exceptional mechanical compliance, enduring 16,000 bending cycles at a curvature radius of 1.6 cm with only a 1.4% increase in resistance… (Fig. 4f)\nComment #7:\nSince the circuit–fiber interface is critical, it would be helpful to discuss or test failure modes such as delamination or crack initiation, particularly under humidity or temperature variation. Supplementary Fig. 14 shows morphological stability but does not provide long-term cycling data.\nReply:\nThank you for your constructive suggestion. According, we carried out further experiments to investigate the failure modes and the performance of the fiber circuits under different temperature and humidity.\nWe found that the failure modes at the circuit-fiber interface are primarily governed by the fracture of the PVA adhesive layer. When examining the SEM image of the fiber-circuit tip bent at a curvature radius of 1.8 mm under 20 °C and 50% relative humidity (RH), we observed speckled EGaIn residues on the PVA surface as well as exposed fiber substrate underneath. This indicates that plastic deformation of the PVA layer exceeded the flow limit of EGaIn, leading to electrical failure.\nTo study the influence of temperature, we investigated interfacial failure at -20 °C, which is below the melting point of EGaIn. In this condition, the critical curvature radius (defined as the bending radius at which ΔR/R₀ begins to exceed 200%) increased from 2.3 mm at 20 °C to 20 mm at -20 °C. SEM examination revealed microfibrils generated by the fracture of PVA. The results indicate failure still originates from the PVA layer, whose increased brittleness at low temperature leads to a larger critical curvature radius. In contrast, elevated temperatures (30-60 °C) do not significantly affect the critical curvature radius. Besides, while oxidation of EGaIn at high temperature could be a concern, we did experimental study and the results show that the resistance increased by only 2.6% after continuous heating at 100 °C for 12 h, indicating that thermal oxidation is negligible under these conditions.\nThe influence of RH on the PVA adhesive layer mainly through its effect on flexibility. Higher humidity induces solvent-mediated plasticization, which increases the elongation at break of PVA. Correspondingly, the critical curvature radius of the EGaIn microcircuit decreases progressively with increasing RH, consistent with expectations.\nAccordingly, we have added related discussion in the main text and Supplementary Fig. 21 and Supplementary Fig. 22 in the supplementary information. The related contents are copied in the following for your convenience:\nIn the main text:\n(Page 8, Line 252) This performance originates from the intrinsic fluidity and strain-insensitive conductivity of EGaIn, as confirmed by microscopy observations of continuous EGaIn pathways during bending (Supplementary Fig. 21). The bending limit of the fiber microcircuit is governed by the PVA adhesive layer, whose flexibility increases with temperature and humidity, leading to different critical radii across different environmental conditions (Supplementary Fig. 22).\nIn the supplementary information:\nSupplementary Fig. 21. SEM images of the circuit-fiber interface at different temperature and humidity. (a) Interfacial morphology at 20 °C and 50% relative humidity (RH). Bending radius: 2.3 mm. (b) Morphology of the interface after bending-induced failure under the same environment conditions as in (a). Bending radius:1.8 mm. (c) Image of the fracture at -20 °C and 50% RH, showing PVA microfibrils at the failure cross-section, indicating PVA-dominated interfacial failure. (d) Magnified view of (b), revealing abundant EGaIn speckles at the fractured region, indicating plastic deformation of the PVA. (e) Intact interface at bending radius of 1.8 mm under 20 °C and 100% RH, in contrast to the fractured interface in (d).\nSupplementary Fig. 22. Influence of humidity and temperature on the mechanical stability of EGaIn microcircuits on fibers. (a) Influence of RH on the critical radius at 20 °C. Critical radius is defined as the bending radius at which ΔR/R₀ begins to exceed 200%. (b) Influence of temperature on the critical radius at 50% RH. (c) Resistance variation of the microcircuit during prolonged thermal exposure at 100 °C and RH of 50%. All samples were stored under the corresponding environmental conditions for 3 h to ensure equilibrium.\nComment #8:\nIf available, resistance evolution over more extreme bending radii (≤ 4 mm) or torsional deformation would enhance confidence in durability claims.\nReply:\nFollowing your suggestion, we studied the resistance evolution under more extreme bending radii (≤ 4 mm) and characterized the failure morphology using SEM (as shown in Reply to your Comment #7). To facilitate discussion, we defined critical radius as the bending radius at which ΔR/R₀ begins to exceed 200%. We confirmed that the critical radius is 2.3 mm at temperature of 20 °C and RH of 50%.\nAccordingly, we have added the resistance evolution at smaller bending radii (≤ 4 mm) in Fig. 4f. The related contents are copied in the following for your convenience:\nIn the main text:\n(Page 8, Line 249) The resulting fiber devices exhibit exceptional mechanical compliance, enduring 16,000 bending cycles at a curvature radius of 1.6 cm with only a 1.4% increase in resistance. The fiber microcircuit can be bent to a critical radius (r , defined as the bending radius at which ΔR/R₀ begins to exceed 200%) of 2.3 mm (Fig. 4f), demonstrating good robustness for wearable applications.\nFig. 4f. Relative change in resistance of the fiber under cyclic bending deformation with bending radius of 16 mm at 1 Hz (upper) and different bending radii (lower). Temperature, 20 °C; Relative humidity, 50%.\nComment #9:\nThe Methods should specify environmental parameters (temperature, humidity) during shrinkage and transfer, as these can influence EGaIn’s viscosity, oxidation, and adhesion.\nReply:\nAccordingly, we added these information into the Methods in the main text：\nIn the main text:\n(Page 10, Line 334) Fabrication of Shrunk microcircuits\n… All the processes, including the fabrication of shrunk microcircuits and its transfer, were performed at 20 °C and 50% relative humidity, unless otherwise specified.\nComment #10:\nClarify how uniform stretching was maintained—manual stretching may lead to edge effects. Was a biaxial stretcher or measured tension used? Including a schematic or photo of the setup (possibly in Supplementary Fig. 1) would improve reproducibility.\nReply:\nThank you for raising this question regarding the uniformity of stretching. The stress-engineered 2D silicone platform requires precise strain regulation, where the strain along each point of the perimeter should be carefully adjusted to ensure that every element remains distortion-free after stretching. Conventional biaxial stretching fixtures often fail to maintain uniform strain near the four corner regions. To overcome this limitation, we employed a frame-based stretching approach that allows manual adjustment of the silicone film’s deformation, enabling the elimination of localized strain non-uniformity during the process. While the current manual adjustment method has certain limitations, it effectively ensures uniform omnidirectional stretching under controlled conditions. We acknowledge that further automation and standardization of the stretching process would be beneficial for improving reproducibility and scalability.\nAccordingly, we have revised Supplementary Fig. 1 and added a new video S1 in the supplementary information to more clearly illustrate the stretching process. The related contents are copied in the following for your convenience:\nIn the main text:\n(Page 2, Line 57) …First, a silicone substrate (Ecoflex film) is omnidirectional pre-strained to a defined ratio and secured on an acrylic frame to maintain tension (Supplementary Fig. 1, Video 1).…\nIn the supplementary information:\n(Page S2) Supplementary Video 1. (Separate file) | Fabrication of stress-engineered 2D silicone platform\nSupplementary Fig. 1. Ecoflex film platform used for shrinking EGaIn circuits. (a) Ecoflex was cast onto an acrylic plate to prepare a stretchable platform (the 1 cm × 1 cm grid here is to help to illustrate the uniformity of the stretchable platform, which will not present during actual shrink process). (b) Ecoflex film peeled off from the acrylic plate. (c) Uniformly stretched Ecoflex film fixed onto an acrylic frame, ready for circuit construction on its surface.\nComment #11:\nMinor Comments and Editorial Suggestions\nFigure 1c: Add explicit “before” and “after shrinkage” labels and indicate quantitative shrinkage ratios on the figure or in the caption.\nReply:\nAccordingly, we revised the Figure 1c and updated the corresponding caption. The updated ones are provided below:\nIn the main text:\nFig. 1c, Optical images of EGaIn circuits on an Ecoflex film before and after shrinkage (shrunk by 80% in area) …\nComment #12:\nSupplementary Figures:\nFig. 1: Add direct annotations (e.g., “Ecoflex cast film,” “peeled film,” “stretched film on frame”) instead of relying solely on the caption.\nReply:\nThank you very much for your careful review and kindly suggestions. Accordingly, we added direct annotations in Supplementary Fig. 1 and checked the manuscript for similar issues.\nComment #13-14:\nFig. 2–3: Clarify whether EGaIn–PVA interfaces exhibit cracking or delamination during shrinkage.\nFig. 3c: Mark the region of the high-magnification image within the main panel.\nReply:\nThank you for raising this point. We agree that the interfacial interactions between different components are very important for the successful STAP process. Supplementary Fig. 2 and 3 respectively show the Ecoflex-EMP interface after shrinkage and the EGaIn-PVA interface after transfer. The PVA film is attached to the EGaIn microcircuits only after the shrinkage process. Thus, during the shrinkage process, no EGaIn-PVA interface is present. We guess the misunderstanding may have arisen from the original caption for Supplementary Fig. 2 and 3. As for the Ecoflex-EMP interface, during the shrinkage process, it remains stable and does not show cracking or delamination. The interfacial area simply decreases uniformly as the Ecoflex shrinks. However, new interfaces will generate when EMP overflow occurs under extreme shrinkage, as discussed in Reply to your Comments #3-5.\nAccordingly, we revised the corresponding caption of Supplementary Fig. 2-3 to avoid such confusion and updated the Supplementary Figure 3. The related contents are copied below for your convenience:\nIn the supplementary information:\nSupplementary Fig. 2. Images of EGaIn microcircuits on Ecoflex films with different shrinkage ratios. From left to right, shrunk by 0%, 60%, 70%, 80% in area.\nSupplementary Fig. 3. Transferred EGaIn microcircuits on PVA. (a) A single line. (b) Sharp corner of the circuit. (c) Enlarged view of the circuit surface. (d) Multiple lines. (e) Small gaps (35 μm).\nComment #15:\nTerminology: Replace “universal fabrication strategy” with “versatile fabrication strategy” unless broader material compatibility can be experimentally verified.\nReply:\nThank you for your insightful comment. As discussed in details in Reply to your Comment #1, we have experimentally verified the compatibility of this strategy with other inks, supplied new data and discussion in the revised films. Besides, we have also replaced “universal fabrication strategy” with “versatile fabrication strategy” to be more rigor.\nComment #16:\nSupplementary Video 3: A brief quantitative comparison of luminance stability under bending would add scientific value beyond qualitative demonstration.\nReply:\nThank you for your professional suggestion. We have carried out experiments to quantitatively compare the luminance stability of the EL pixel under different bending radii. We collected digital photographs of the same sample under the same environmental conditions at different bending radii, then used software (ImageJ) to measure the average grayscale intensity of the emitting pixel after subtracting the corresponding background brightness. The results show that the luminance stability remains 94% when bent to a radius of 15 mm, but then decreases sharply as the curvature increases.\nAccordingly, we have added related discussion in the main text and corresponding luminance stability data (Supplementary Fig. 23) in the supplementary information. The related contents are copied below for your convenience：\nIn the main text:\n(Page 9, Line 277) Selective pixel activation can be achieved by electrical addressing through designated contacts (Fig. 4l, Supplementary Video 4), enabling the multiplexed display on a single fiber. Luminance stability remains 94% when bent to a radius of 15 mm, but then decreases rapidly as the curvature increases further (Supplementary Fig. 23).\nIn the supplementary information:\nSupplementary Fig. 23. Evolution of brightness of luminance pixel with decease of bending radius. (a-e) Optical images of a single EL pixel on the fiber device bent to different curvature radius ((a) flat, (b) 20 mm, (c) 15 mm, (d) 10 mm, (e) 5 mm). (f) Corrected grayscale intensity extracted from a fixed region of interest (ROI) for each pixel. Pixel brightness was quantified using ImageJ by measuring the mean grayscale value and subtracting a nearby background region to remove illumination variations.\nReviewer #3:\nSummary Comment:\nThe manuscript is generally well written and clearly presented. However, there are several issues that limit the overall scope and relevance of the work.\nReply:\nThank you very much for your careful review and insightful comments/suggestions on our manuscript. Accordingly, we carried out further experiments and revised the manuscript to address each of the points you raised. These revisions should be helpful for refining the boundaries of this work and strengthening its scientific relevance. We sincerely appreciate your constructive guidance. The following is a point-by-point response.\nComment #1:\nMaterial specificity:\nThe materials used in the study are very specialized and are not easily replaced or adapted to other functional materials (substrate, ink, GaIn ....)\nReply:\nThank you very much for raising this point. In order to address this point, we carried out further experiments.\nBeside the EGaIn/sericin ink, three typical commercial conductive inks, including Ag/AgCl ink and carbon ink, which are commonly employed in printed electrochemical sensors, and PEDOT:PSS ink, which is one of the most broadly used conductive polymers, were studied with the STAP process. All the three inks can be successfully applied in the STAP process, demonstrating the versatility of the process. We propose the following are the requirements for the inks used in this process: (i) The ink should remain flowable during the interval between printing and substrate shrinkage, which allows the shrinkage-induced stress to propagate upward from the bottom of the pattern and to drive spatial reorganization of the ink material. (ii) The ink should possess adequate viscosity, since low-viscosity inks would easily overflow the intended pattern boundaries during substrate motion and cause feature distortion. (iii) The ink should have affinity toward the targeted film, which in this work is PVA. For example, EMPs with hydrophilic surfaces exhibit strong affinity to PVA, which is essential for successful transfer.\nAs for the selection of elastomeric substrates, the STAP process requires substates with high stretchability, recoverability and hydrophobicity. The silicone elastomer we used fits these requirements perfectly. Other common elastomers such as styrene-ethylene-butylene-styrene copolymer (SEBS) and thermoplastic polyurethane (TPU) could in principle work with STAP, but their stretchability is usually lower than that of silicone unless molecular modification is applied. Therefore, in this work, we selected commercial Ecoflex and did not study other elastomeric substrates.\nAccordingly, we have added related discussion in the main text, and Supplementary Fig. 24 in the supplementary information. Besides, we have replaced the term “universality” with “versatility” in the main text to be more rigor. The related contents are copied in the following for your convenience:\nIn the main text:\n(Page 9, Line 285) It is noted that the STAP process is also compatible with other typical commercially available inks besides the EGaIn/sericin ink (Supplementary Fig. 24).\n(Page 9, Line 317) Finally, standardizing process parameters and characterization protocols across different material systems will be essential for ensuring reproducibility and facilitating broader adoption in flexible and textile electronics.\nIn the supplementary information:\nSupplementary Fig. 24. Applying STAP process using three typical commercial electronic inks. The inks include Ag/AgCl ink (purchased from Prtronic), carbon ink (purchased from Loctite), and PEDOT:PSS ink (purchased from Prtronic), showing consistent printing, ~80% shrinkage, and successful transfer, confirming the compatibility of the STAP process with other inks.\nComment #2:\nScalability and reproducibility:\nKey steps in the process—such as pre-stretching, tension release, transferring onto a PVA sheet, water-assisted transfer, and the shrinkage of the printed circuits—introduce a lot of variability and are not easily scalable. As a result, achieving consistent reproducibility is challenging. In addition, the conductivity variations that come from shrinkage sintering and transfer sintering need to be supported with more detailed statistical data.\nReply:\nThank you for your insightful comment. We agree that the STAP workflow involves multiple steps, imposing challenges for scalability and reproducibility.\nRegarding reproducibility, all the key steps, including pre-stretching, tension regulation, circuit shrinkage, hydration of the PVA film, and the final transfer, can be governed by controllable experimental parameters. The pre-stretching process is performed on a stress-engineered silicone platform with adjustable pre-strain, and the deformation state can be monitored using an orthogonal finite-element grid (Supplementary Video 1). We also investigated the effects of shrinkage and transfer parameters on the restoration of EMP conductivity. The PVA-assisted transfer reliably recovers the conductivity of EMP networks to the same order of magnitude as bulk EGaIn, and experimental results show that the transfer and reconstruction process proceeds with a very high success rate (nearly 100% for across 20 times trials). Besides, the screen printing in the STAP process is an industrial-scale patterning method widely used in textile manufacturing.\nRegarding scalability, we acknowledge that our current laboratory-scale preparation has limitations. Despite of this, we think it has potential for large-scale applications as the mechanism itself does not impose fundamental barriers to scaling. The stress-engineered 2D silicone platform could be scaled up by using larger substrates. However, continuous large-scale manufacturing would require an automated stretching system capable of applying uniform tension along the entire film. After shrinkage, the silicone film carrying the microcircuits could be brought into contact with a continuous PVA roll, following by wetting, drying, transfer and collection along a production line. This approach appears feasible and would mainly require engineering design for automate wetting and rapid drying. Your comment provides a forward-looking perspective on the practical deployment of STAP.\nAccordingly, we have added a discussion in the main text. And the detailed conductivity data associated with shrinkage sintering and transfer sintering have been included in the supplementary Table S2. The related contents are copied below for your convenience:\nIn the main text:\n(Page 6, Line 199) …Moving along this boundary toward higher F enables smaller feature sizes while preserving electrical continuity (see Table S2 for electrical conductivity for each point)\n(Page 9, Line 286) …This STAP strategy overcomes the long-standing challenge of integrating high-precision microcircuits onto curved fiber substrates, paving the way for multifunctional and high-density wearable electronics. Further efforts on developing automated stretching and continuous transfer systems could improve the scalability of STAP and facilitate its adoption in practical manufacturing settings.\n(Page 9, Line 312) Second, scaling the technology for industrial production will require the development of automated stretching systems capable of applying uniform omnidirectional strain to large-area elastic substrates, thereby improving reproducibility.\nIn the supplementary information:\n(Page S19) Table S2. Conductivity of EGaIn microcircuits prepared with different pre-stretch ratio and EMPs coverage ratio.\nEMPs coverage Pre-stretch ratio\nratio (%) 0% 75% 150% 225% 300% 375% 450% 525%\n63.2 0 0.25 0.36 0.39 0.42 0.46 0.47 0.48\n53.7 0 0.13 0.18 0.20 0.24 0.29 0.32 0.33\n47.4 0 0.06 0.10 0.13 0.18 0.21 0.21 0.24\n41.1 0 0/28.8 0.05 0.09 0.15 0.20 0.21 0.21\n33.8 0 0/28.3 0/28.5 0.02 0.08 0.17 0.19 0.21\n29.2 0 0/27.6 0/28.5 0.01 0.05 0.11 0.16 0.17\n26.3 0 0/27.2 0/28.2 0/28.4 0.02 0.02 0.03 0.04\n20.6 0 0 0/27.9 0/28.2 0/28.2 0/28.4 0/28.4 0/28.5\n16.4 0 0 0 0/27.3 0/27.3 0/27.5 0/27.5 0/27.5\n12.4 0 0 0 0 0 0 0 0\nNote: Corresponding to the measured electrical conductivity (×105 S m-1) after shrinkage. A single non-zero value indicates conductivity obtained by shrinkage alone. Entries in the form “0/x” denote circuits that remained non-conductive after shrinkage but became conductive (x ×105 S m-1) after transfer.\nComment #3:\nMultilayer printing limitations:\nThe approach does not seem capable of true multilayer printing. In the demonstrated device, the conductive layer is printed and transferred onto the thread, while the luminescent layer is applied by coating rather than printing. This highlights an inherent limitation of the technique.\nReply:\nThank you for your insightful comment. Accordingly, we carried out further experiment to explore the possibility for construction multilayer circuits with the STAP strategy. We found that multilayer circuits can be constructed on separate PVA films using different screen-printing masks. These films can then be sequentially transferred to the aligned position of the fiber surface. We also considered that possibility for the printing of the luminescent layer. However, as for the STAP process involves the wetting and drying of the PVA film, constructing a non-permeable luminescent layer on the film would influence the wetting behavior, and thus introduce non-uniform stress.\nAccordingly, we have added related discussion in the main text and an image of a fiber with multilayer-circuits (Supplementary Fig. 20). The related contents are copied below for your convenience:\nIn the main text:\n(Page 8, Line 247) Notably, this transfer step can also be applied to fibers of different materials and diameters (Supplementary Fig. 19), and can be repeated on one fiber to construct multilayer circuit (Supplementary Fig. 20).\nIn the supplementary information:\nSupplementary Fig. 20. Optical image of a fiber (diameter, 1.5 mm) with two layers of EGaIn microcircuits.\nComment #4:\nLimited use on small-diameter substrates:\nThe method is demonstrated only on threads a few millimeters in diameter. Its potential for use on finer fibers or true one-dimensional substrates is not addressed, which restricts the broader relevance of the work\nReply:\nThank you for your raising this critical comment the use of smaller-diameter fibers. We agree that extending the method to finer one-dimensional substrates is an important direction for broader applicability.\nIn the present work, the fiber devices were designed primarily to demonstrate single-pixel electroluminescence. As fiber diameter decreases, pixel crosstalk between densely packed microcircuits becomes significantly more pronounced. To ensure clear functionality and avoid signal interference, we therefore used relatively thicker fibers in the main demonstrations.\nIn this work, the minimum diameter of fibers we used is 1.5 mm. We think the minimum usable fiber diameter in our approach is constrained mainly by two factors: (1) the achievable printing resolution, and (2) the shrinkage limit of the substrate. Together, these define the smallest reliable circuit feature size, which in then determines how thin a fiber can be reliably patterned. Moving to significantly thinner fibers will require further downscaling of the circuit dimensions, which is one of the goals of our future work.\nAccordingly, we have added discussion on the key challenges in the main text, and images of fiber devices fabricated on 2.0 mm and 1.5 mm fibers made of different materials (Supplementary Fig. 19) and multilayer circuits fabricated on 1.5 mm fibers (Supplementary Fig. 20) in the supplementary information. The related contents are copied below for your convenience:\nIn the main text:\n(Page 8, Line 247) Notably, this transfer step can also be applied to fibers of different materials and diameters (Supplementary Fig. 19) …\n(Page 9, Line 310) Looking forward, several key challenges must be addressed to advance the practical deployment of STAP. First, extending the method to finer fiber diameters will necessitate advances in ink formulation and substrate engineering to prevent pixel crosstalk and ensure reliable patterning at the microscale. Second… Third… Finally, standardizing process parameters and characterization protocols across different material systems will be essential for ensuring reproducibility and facilitating broader adoption in flexible and textile electronics. By addressing these challenges, STAP can evolve from a laboratory-scale technique into a practical manufacturing process for producing high-performance, seamlessly integrated fiber-based devices.\nIn the supplementary information:\nSupplementary Fig. 19. Optical images of EGaIn microcircuits on fibers with different materials and diameters. (a) Thermoplastic polyurethane (TPU), smooth surface, diameter 1.5 mm. (b) High-density polyethylene (HDPE), rough surface, diameter 2 mm. (c) Kevlar, rough surface, diameter 2 mm.\nSupplementary Fig. 20. Optical image of a fiber (diameter, 1.5 mm) with two layers of EGaIn microcircuits.\nFinally, we would like thank all the three reviewers for the insightful comments and constructive suggestions, which have helped us in further improving this work."}, {"round": 2, "reviewer_comments": {"reviewer_1": "The authors have addressed all of the issues with this manuscript, which is suitable for publication in Nature Communications. I believe this work will have a significant impact on the future preparation of functional fibers/fabrics.", "reviewer_2": "The authors have addressed all of my questions carefully. The revised manuscript is now acceptable without further revision.", "reviewer_3": "Response to Reviewers’ comments\nWe thank the reviewers for the constructive comments and suggestions on our\nmanuscript. Accordingly, we have carried out additional experiments and revised the\nmanuscript carefully. The changes are marked in BLUE in the revised manuscript and\nare marked in RED here. The following is a point-to-point response to each of the\ncomments.\nReviewer #1:\nSummary Comment:\nThis is a highly innovative manuscript, with advances in both the printing of\nmicrocircuits and the fabrication of fiber devices. The authors utilize a two-dimensional\nstretchable silicone platform as the substrate for screen printing, thereby overcoming\nthe resolution limit of conventional screen printing techniques and achieving flexible\nEGaIn microcircuits. The proposed method also provides valuable guidance for other\nplanar circuit fabrication techniques beyond screen printing. As an application\ndemonstration, the authors transfer the miniaturized circuits onto fiber surfaces. This\nsurface-based circuit construction approach makes the fabrication of fiber devices\nversatile, and the transfer strategy appears to be extendable to other small and complex\ncurved surfaces. In addition, the manuscript is logically organized and clearly written.\nReply:\nThank you very much for your careful review and high evaluation of this work. Your\nconstructive comments and suggestions have helped us to further improve our\nmanuscript. Our point-by-point responses to your comments are listed below.\nComment #1:\nIn page 3, the authors chose silk sericin as the stabilizer. It is suggested that the authors\ninclude comparative SEM images to show the influence of adding silk sericin on the\nmorphology of EGaIn microparticles, in order to further demonstrate the necessity of\nusing the stabilizer.\nReply:\nThank you for your constructive suggestion. Sericin in the ink serves to isolate the\nEGaIn microparticles (EMPs), preventing their aggregation through physical separation\nand Coulombic repulsion. In addition, the attachment of sericin onto the EMP surface\nhelps slow down overall oxidation. In order to provide experimental evidence, we\ncarried out further experiments. Inks with and without sericin were exposed to a harsh\natmospheric environment at 60 °C for 30 min, followed by SEM characterization of the\nresulting EMP morphologies. The results showed that the sericin-free inks exhibited\nagglomeration, whereas the sericin-containing inks did not.\n1 / 31\nAccordingly, we added discussion in the main text and Supplementary Fig. 6 in the\nsupplementary information. The related contents are copied in the following for your\nconvenience:\nIn the main text:\n(Page 3, Line 99) Furthermore, sericin is negative charged in neutral aqueous\nsolution (isoelectric point = 4) 28, inducing electrostatic repulsion among sericin-\ncoated EMPs due to Coulombic forces (Fig. 2b). The combined steric and\nelectrostatic stabilization effects allow the EMPs to remain well-dispersed in water\nfor more than one week without agglomeration (Fig. 2c, Supplementary Fig. 5).\nIn the supplementary information:\nSupplementary Fig. 5. SEM images comparing morphologies of EMPs in inks\nwith and without sericin, after being placed in an atmospheric environment at\n60 °C for 30 min.\nComment #2:\nThe authors are encouraged to include a discussion on the choice of fiber substrate\nmaterial. Specifically, why was aramid fiber selected as the transfer base for EGaIn\nmicrocircuits?\nReply:\nThank you for raising this point. We selected aramid fiber as the circuit substrate due\nto its hydrophilic nature and relatively high dielectric constant, which facilitate water-\nassisted transfer and support the high electric field required for electroluminescence.\nAccordingly, we added related information in the main text. The related contents are\ncopied in the following for your convenience:\nIn the main text:\n(Page 7, Line 221) The capillary-driven transfer process enables precise conformal\nwrapping of EGaIn microcircuit onto fiber substrates. Aramid fiber is chosen as the\nsubstrate due to its intrinsic hydrophilicity and relatively high dielectric constant.\n2 / 31\n(Page 8, Line 265) Although the aramid fiber substrate has high tolerance to strong\nelectric fields 36, the breakdown of emissive functional layer remains affecting\nluminescence efficiency. Thus, an intermediate gap width is required to achieve\noptimal luminescence…\nComment #3:\nAccording to Fig. 3b and Supplementary Video 2, patterned plasma treatment on the\nsilicone substrate enhances the wettability and adhesion of the water-based\nEGaIn/sericin ink, ensuring accurate pattern deposition. Why is patterned plasma\ntreatment necessary instead of treating the entire surface uniformly? The authors should\nelaborate on the processing steps and rationale for using patterned plasma treatment.\nReply:\nThank you for raising this insightful point. Yes, plasma treatment of the silicone\nsubstrate (Ecoflex film) is crucial, because silicone is inherently hydrophobic,\nexhibiting a water contact angle as high as 104.5° (Fig. 3a). As a result, the water-based\nEGaIn/sericin ink cannot properly wet or adhere to its surface. The use of patterned\nplasma treatment serves two purposes. First, it enables the ink to remain confined within\nthe patterned regions without spreading. Second, it facilitates the subsequent peeling of\nthe PVA layer. If the entire silicone surface were plasma-treated uniformly, the wet PVA\nwould also contact the activated silicone, and after drying, strong hydrogen-bond\ninteractions would form, making the PVA layer impossible to peel off.\nAccordingly, we added related discussion in the main text and Supplementary Fig. 8 in\nthe supplementary information. The related contents are copied in the following for\nyour convenience:\nIn the main text:\n(Page 6, Line 157) Prior to screen printing, pre-stretched silicone substrate is\npartially treated with air plasma (Fig. 3a, Supplementary Fig. 7-8) to enhance ink\nadhesion.\n(Page 10, Line 334) Fabrication of Shrunk microcircuits\nFirst, a 200 μm-thick Ecoflex film was omnidirectionally stretched and mounted\nonto a clean acrylic frame under tension. Next, a patterned screen was placed on\nthe surface of the Ecoflex film as a mask and the sample was exposed to air plasma\nfor 3 minutes. Then, EGaIn/sericin ink was screen-printed onto the film.\nIn the supplementary information:\n3 / 31\nSupplementary Fig. 8. Photograph showing the mask placed on the pre-\nstretched Ecoflex substrate for plasma treatment and the screen printing.\nComment #4:\nPage 6, line 174: “This transfer-induced sintering arises from competitive interfacial\nadhesion…”. While this mechanism is clearly illustrated in Supplementary Fig. 9, the\nauthors are advised to provide supporting data to further substantiate this claim of\ncompetitive interfacial adhesion.\nReply:\nThank you for your constructive suggestion. To addressed this point, we carried out\nfurther experiments to provide more evidence for the mechanism. We investigated the\ninteractions between EMP and different substrates using atomic force microscopy\n(AFM). The results indicate the EMP exhibit strong affinity toward the substrates,\nwhich facilitates the rupture of their oxide shells during separation and thereby enables\nsintering. PVA with stronger adhesion to the EMPs tend to retain more EGaIn on its\nsurfaces, which explains the observed transfer behavior.\nAccordingly, we added related discussion in the main text, and Supplementary Fig. 12\nin the supplementary information. The related contents are copied in the following for\nyour convenience:\nIn the main text:\n(Page 6, Line 174) This transfer-induced sintering arises from competitive\ninterfacial adhesion: the plasma-activated silicone and the PVA film both exhibit\nstrong affinity to the EMPs, showing adhesion forces of 0.53 μN and 0.79 μN,\nrespectively (Supplementary Fig. 11-12). Consequently, the separation process\nruptures the oxide shells, triggering instantaneous liquid metal coalescence.\nIn the supplementary information:\n4 / 31\nSupplementary Fig. 12. Force measurements between the EMP and different\nsubstrates. (a) SEM image of an EMP attached to an AFM probe. (b) Magnified\nview of the probe shown in (a). (c-f) Approach-retract force curves acquired\nbetween the EMP and a pristine Ecoflex film (c), an Ecoflex film treatment with 3\nmin plasma (d), a PVA film (e), and a polyvinyl butyral (PVB) film (f).\nComment #5:\nPage 2, line 62: The authors employ a polyvinyl alcohol (PVA) film as the transfer\nmedium for EGaIn microcircuits, primarily due to its water solubility and affinity\ntoward EGaIn microparticles. It is suggested that the authors further justify the\nadvantages of choosing PVA, for instance by explaining its chemical structure or\ninterfacial interactions in more detail.\nReply:\nThank you for the insightful suggestion. In this work, the hydroxyl groups on the PVA\nchains form hydrogen bonds with the oxide shell of the EMPs, contributing to the strong\n5 / 31\ninterfacial affinity. To validate the role of hydroxyl groups, we carried out further\nexperiments to compare PVA with polyvinyl butyral (PVB), a structurally similar\npolymer in which a portion of the hydroxyl groups is blocked through acetal formation.\nMechanical measurements on PVB films show an adhesion force of 0.46 μN toward\nthe EMPs, substantially lower than that of PVA (0.79 μN), confirming the critical\ncontribution of hydroxyl groups to the affinity.\nAccordingly, we added related discussion in the main text and Supplementary Fig. 12e-\nf in the supplementary information. The related contents are copied in the following for\nyour convenience:\nIn the main text:\n(Page 6, Line 177) The stronger affinity between PVA and EMPs results in\npreferential transfer of the EGaIn circuits to the PVA surface. The affinity of PVA\nis primarily attributed to hydrogen bonds between the hydroxyl groups of PVA and\nthe EMPs. To verify the role of hydroxyl groups, comparative adhesion tests were\nconducted using polyvinyl butyral (PVB), a polymer structurally analogous to PVA\nbut with a portion of its hydroxyl groups blocked by acetal formation. Mechanical\nmeasurements reveal that the adhesion force of PVB films toward EMPs is 0.46\nμN, significantly lower than that of PVA (0.79 μN) (Supplementary Fig. 12e-f).\nIn the supplementary information:\nSupplementary Fig. 12 Approach-retract force curves acquired between the EMP\nand a PVA film (e), and a polyvinyl butyral (PVB) film (f).\nComment #6:\nPage 7: It is suggested that the authors add a brief discussion on the potential\napplications of the fiber device described in Fig. 4. For example, what practical\nscenarios this fiber device could be applied to.\nReply:\n6 / 31\nThank you for the valuable suggestion. Accordingly, we have added a brief discussion\non the potential applications of the single-fiber displays in the main text. The related\ncontents are copied in the following for your convenience:\nIn the main text:\n(Page 9, Line 280) Single-fiber displays, featuring pixel-level addressability, can\nbe seamlessly woven into protective garments for dynamic visual communication.\nIn critical scenarios such as firefighting, rescue operations, and outdoor exploration,\nthey can provide real-time navigation, hazard alerts, or team status. They also\nenable monitoring of vital signs for medical assistance and facilitate\ncommunication by displaying information for individuals with speech or language\nbarriers.\n7 / 31\nReviewer #2:\nSummary Comment:\nThis manuscript presents a highly original approach to addressing the persistent\nchallenge of integrating microscale circuits onto curved fiber surfaces. The proposed\nshrinkage-transfer-assisted printing (STAP) method elegantly bridges the gap between\n2D circuit fabrication and 1D fiber device realization, achieving impressive\nminiaturization (up to 80% shrinkage) and 360° conformal coverage. The concept is\nnovel, technically sound, and well supported by systematic experiments. The\ncombination of stress-engineered silicone substrates, EGaIn/sericin ink chemistry, and\ncapillary-driven transfer represents a meaningful advance in fiber-based electronics.\nThe manuscript is generally well written, visually clear, and methodologically detailed.\nIt convincingly demonstrates functionality through the electroluminescent fiber device.\nThe work is clearly distinct from previously published studies—including our earlier\nNature Communications paper on integrated microfibre electronics—by offering a\ndifferent dimensional transformation and processing strategy.\nThat said, a few aspects need clarification and strengthening before acceptance. These\nconcern (1) the universality and scalability of the claimed “universal fabrication\nstrategy,” (2) quantitative treatment of the scaling-down limit for metallic patterns,\nand (3) mechanical durability and interfacial reliability under extended cyclic deformation.\nOverall, this is an excellent and innovative contribution that will attract broad attention\nin the field of fiber electronics and soft-matter circuit integration. The concept of\ngeometric transformation from 2D to 1D is elegant, and the results are compelling.\nAddressing the issues above, particularly regarding the scaling limit and mechanical\nreliability, will further strengthen the manuscript’s impact and technical completeness.\nReply:\nWe sincerely thank you for your careful review of our manuscript and greatly appreciate\nyour constructive suggestions. Accordingly, we have carried out further experiment and\ncarefully revised the manuscript. Below are point-by-point responses to each of your\ncomments.\nComment #1:\nThe Introduction concludes that STAP is a “universal fabrication strategy,” yet\nexperimental demonstrations are limited to EGaIn and PVA-based transfer. To\nsubstantiate this claim, the authors should briefly discuss whether the STAP process is\ncompatible with other inks (e.g., silver nanoparticle, conductive polymer) or\nelastomeric substrates.\nReply:\nThank you very much for raising this point. In order to address this point, we carried\nout further experiments. Beside the EGaIn/sericin ink, three commercially available and\n8 / 31\nwidely used inks, including Ag/AgCl ink and carbon ink, which are commonly\nemployed in printed electrochemical sensors, and PEDOT:PSS ink, which is one of the\nmost broadly used conductive polymers, were studied. We found that all the three inks\ncan be successfully applied in our process, demonstrating the versatility of the STAP\nprocess. We propose the following are the requirements for the inks used in this process:\n(i) The ink should remain flowable during the interval between printing and substrate\nshrinkage, which allows the shrinkage-induced stress to propagate upward from the\nbottom of the pattern and to drive spatial reorganization of the ink material. (ii) The ink\nshould possess adequate viscosity, since low-viscosity inks would easily overflow the\nintended pattern boundaries during substrate motion and cause feature distortion. (iii)\nThe ink should have affinity toward the targeted film, which in this work is PVA. For\nexample, EMPs with hydrophilic surfaces exhibit strong affinity to PVA, which is\nessential for successful transfer.\nAs for the selection of elastomeric substrates, the STAP process requires substates with\nhigh stretchability, recoverability and hydrophobicity. The silicone elastomer we used\nfits these requirements perfectly. Other common elastomers such as styrene-ethylene-\nbutylene-styrene copolymer (SEBS) and thermoplastic polyurethane (TPU) could in\nprinciple work with STAP, but their stretchability is usually lower than that of silicone\nunless molecular modification is applied. Therefore, in this work, we selected\ncommercial Ecoflex and did not study other elastomeric substrates.\nAccordingly, we have added related discussion in the main text, and Supplementary Fig.\n24 in the supplementary information. Besides, we have replaced the term “universality”\nwith “versatility” in the main text to be more rigor. The related contents are copied in\nthe following for your convenience:\nIn the main text:\n(Page 9, Line 285) It is noted that the STAP process is also compatible with other\ntypical commercially available inks besides the EGaIn/sericin ink (Supplementary\nFig. 24).\n(Page 9, Line 310) Looking forward, several key challenges must be addressed to\nadvance the practical deployment of STAP… Finally, standardizing process\nparameters and characterization protocols across different material systems will be\nessential for ensuring reproducibility and facilitating broader adoption in flexible\nand textile electronics. By addressing these challenges, STAP can evolve from a\nlaboratory-scale technique into a practical manufacturing process for producing\nhigh-performance, seamlessly integrated fiber-based devices.\nIn the supplementary information:\n9 / 31\nSupplementary Fig. 24. Applying STAP process using three typical\ncommercial electronic inks. The inks include Ag/AgCl ink (purchased from\nPrtronic), carbon ink (purchased from Loctite), and PEDOT:PSS ink (purchased\nfrom Prtronic), showing consistent printing, ~80% shrinkage, and successful\ntransfer, confirming the compatibility of the STAP process with other inks.\nComment #2:\nA comparative comment on scalability with respect to textile-level or roll-to-roll\nfabrication methods would provide valuable context for its practical universality.\nReply:\nThank you for this valuable suggestion. Frankly, we think that the textile-level and roll-\nto-roll fabrication methods currently offer advantages in scalability over our present\nlaboratory-scale preparation. Nonetheless, we believe STAP possesses potential for\n10 / 31\nlarge-scale implementation, though several challenges remain at this stage. The stress-\nengineered 2D silicone platform could be scaled up by using larger substrates. However,\ncontinuous large-scale manufacturing would require an automated stretching system\ncapable of applying uniform tension along the entire film. On the other hand, the\ntransfer step is in principle compatible with roll-to-roll processing. After shrinkage,\nthe silicone film carrying the microcircuits could be brought into contact with a continuous\nPVA roll, following by wetting, drying, transfer and collection along a production line.\nThis approach appears feasible and would mainly require engineering design to\nautomate wetting and rapid drying.\nOverall, your comment provides a forward-looking perspective on the practical\ndeployment of STAP. Accordingly, we have added related discussion in the main text.\nThe related contents are copied in the following for your convenience:\nIn the main text:\n(Page 9, Line 288) Further efforts on developing automated stretching and\ncontinuous transfer systems could improve the scalability of STAP and facilitate\nits adoption in practical manufacturing settings.\n(Page 9, Line 310) Looking forward, several key challenges must be addressed to\nadvance the practical deployment of STAP …Second, scaling the technology for\nindustrial production will require the development of automated stretching systems\ncapable of applying uniform omnidirectional strain to large-area elastic substrates,\nthereby improving reproducibility.\nComment #3-5:\n(Comment 3) What is possible resolution and Scaling-Down Limitations?\n(Comment 4) While the manuscript demonstrates a 60 μm feature size and 35 μm\nelectrode gaps, it remains unclear what factors fundamentally limit further\nminiaturization, whether by the screen mesh resolution, ink rheology, or mechanical\nshrinkage threshold of the substrate. Please provide in detail.\n(Comment 5) Providing a scaling analysis or discussing the potential challenges in\npushing resolution below 50 μm would be insightful. For instance, could oxide shell\nrupture or uneven compressive stress during shrinkage impose a lower limit?\nReply:\nWe appreciate the insightful questions regarding resolution and scaling-down\nlimitations. Since Comments #3-5 are closely related, we address them collectively\nbelow. We have supplemented the discussion with schematic illustrations, SEM\ncharacterizations and additional data. The fundamental limits on resolution and\nminiaturization arise from two main aspects:\n11 / 31\n(i) Printing resolution on the pre-stretched silicone substrate. The initial patterning\nfidelity is governed by the screen-printing process. The resolution here refers to the\nclarity and continuity of the printed EGaIn/sericin pattern after the ink passes through\nthe screen mesh. This printed pattern must be optically distinguishable and electrically\ncontinuous after shrinkage. Screen mesh resolution and ink rheology are key factors.\nScreens with larger mesh openings reduce pattern resolution but allow more ink to pass\nthrough, which benefits conductivity, but at the cost of feature definition. Conversely,\nfiner meshes improve printed resolution but reduce ink deposition, lowering\nconductivity, a trade-off illustrated in Fig. 3j. Ink viscosity also plays a critical role.\nhigher viscosity helps suppress post-printing spreading and improves pattern fidelity\n(Hong et al., J. Mater. Sci. Technol., 67, 145-155 (2021)), yet it also limits ink passage\nand conductivity. Optimizing print resolution thus requires balancing these competing\nparameters.\n(ii) Ink overflow under extreme shrinkage. When the silicone substrate is shrunk\nseverely, the resulting compressive stress can cause EMP ink to overflow beyond the\nintended pattern boundaries, distorting the printed features. In this study, the Ecoflex\nfilm can sustain large uniaxial strains up to 700%, as shown in Supplementary Fig. 10.\nUnder omnidirectional stretching, a 200-μm-thick film can reach approximately 300%\nstrain, corresponding to an area expansion of ~16×, as demonstrated in the newly added\nSupplementary Video 1. Theoretically, this allows up to ~94% areal shrinkage, but in\npractice we observe reliable shrinking only up to ~80%. Beyond this point, EMPs\noverflow becomes pronounced, leading to line broadening, loss of resolution, and in\ncapacitor structures (e.g., interdigitated electrodes), catastrophic short-circuiting. This\noverflow persists even with a finer 300-mesh screen. However, when using a finer 420-\nmesh screen, the ink can no longer pass through to form continuous conductive\npathways, presenting a key barrier to achieving features below 50 μm.\nAccordingly, we have included the data from our initial orthogonal experiments in\nTable S1 to show how different screen parameters affect the printing resolution before\nand after shrinkage. A schematic illustration is provided in Supplementary Fig. 14, and\nSEM images of EMP overflow under shrinkage are presented in Supplementary Fig. 15,\nin the supplementary information. The related contents are copied in the following for\nyour convenience:\nIn the main text:\n(Page 6, Line 190) The ultimate resolution achievable by STAP is governed by the\ninitial screen-printing precision and the shrinkage behavior of the EMPs on the\nsilicone platform. The intrinsic resolution defined by the screen-printing process\ndetermines the fineness of the microcircuit patterns. Screens with higher mesh\ncounts provide finer patterning but reduce ink passage, lowering the amount of\ndeposited EGaIn and creating a fundamental compromise between resolution and\nconductivity. In this work, 300-mesh represents a practical upper limit. Finer\nmeshes fail to transfer sufficient ink to form continuous pathways even after\nshrinkage…\n12 / 31\n(Page 6, Line 201) …The resolution and lateral deviation of microcircuits\nfabricated with different screen meshes were systematically examined under an\nextreme area shrinkage of 80% (Table S1).\n(Page 6, Line 204) …During shrinking, the compressive stress originating from the\nrecovery of the silicone (F) is transmitted upward through the microcircuit\nf\n(Supplementary Fig. 14). Under extreme shrinkage, this stress can induce overflow\nof EMPs beyond the designed pattern boundaries. Since further improvement in\nthe as-printed resolution is hindered by insufficient ink transfer through higher-\nmesh screens, these two factors together limit the final attainable result resolution\n(Supplementary Fig. 15).\nIn the supplementary information:\nSupplementary Fig. 14. Schematic illustration showing the shrinkage-induced\nresolution limit in the shrinkage process. Excessive shrinkage causes overflow\nof EMP ink beyond the pattern boundaries, thereby limiting the minimum\nachievable resolution.\n13 / 31\nSupplementary Fig. 15. Side-view SEM images of microcircuits shrunk by 94%\nin area. (a) The actual line width becomes larger than the designed width due to\nEMP overflow. (b) Short-circuit behavior observed in the capacitor.\n(Page S19) Table S1. Parameters of screens with different mesh counts, the\nresolution of as-printed EGaIn/sericin ink, and the resolution after shrinkage\n(shrunk by 80% in area).\nMesh Resolution-after-\nEMPs coverage Resolution\ncount extreme shrink\nratio (%) (μm)\n(/inch) (μm)\n420 12 Discontinuous Discontinuous\n300 16 136 63\n250 21 160 74\n200 26 202 95\n180 29 245 122\n150 34 272 128\n120 41 285 138\n100 47 300 148\n80 54 325 180\n60 63 420 221\nComment #6:\nThe manuscript claims retention of 98.6 % conductivity after 16,000 bending cycles,\nwhich is impressive. However, the detailed stress conditions (bending radius, strain\namplitude, test frequency) should be more explicitly stated in Methods or figure\ncaptions to allow fair comparison with prior works.\nReply:\nAccording, we have added the related information into Figure caption. Besides, the key\ninformation is also presented in the main text. The related contents are copied in the\nfollowing for your convenience:\nIn the main text:\n14 / 31\n(Page 7, Line 210) Fig. 4. Construction and performance of electroluminescent\nfiber devices. …f, Relative change in resistance of the fiber under cyclic bending\ndeformation with bending radius of 16 mm at 1 Hz (upper) and different bending\nradii (lower). Temperature, 20 °C; Relative humidity, 50%.\n(Page 8, Line 249) The resulting fiber devices exhibit exceptional mechanical\ncompliance, enduring 16,000 bending cycles at a curvature radius of 1.6 cm with\nonly a 1.4% increase in resistance… (Fig. 4f)\nComment #7:\nSince the circuit–fiber interface is critical, it would be helpful to discuss or test failure\nmodes such as delamination or crack initiation, particularly under humidity or\ntemperature variation. Supplementary Fig. 14 shows morphological stability but does\nnot provide long-term cycling data.\nReply:\nThank you for your constructive suggestion. According, we carried out further\nexperiments to investigate the failure modes and the performance of the fiber circuits\nunder different temperature and humidity.\nWe found that the failure modes at the circuit-fiber interface are primarily governed by\nthe fracture of the PVA adhesive layer. When examining the SEM image of the fiber-\ncircuit tip bent at a curvature radius of 1.8 mm under 20 °C and 50% relative humidity\n(RH), we observed speckled EGaIn residues on the PVA surface as well as exposed\nfiber substrate underneath. This indicates that plastic deformation of the PVA layer\nexceeded the flow limit of EGaIn, leading to electrical failure.\nTo study the influence of temperature, we investigated interfacial failure at -20 °C,\nwhich is below the melting point of EGaIn. In this condition, the critical curvature\nradius (defined as the bending radius at which ΔR/R₀ begins to exceed 200%) increased\nfrom 2.3 mm at 20 °C to 20 mm at -20 °C. SEM examination revealed microfibrils\ngenerated by the fracture of PVA. The results indicate failure still originates from the\nPVA layer, whose increased brittleness at low temperature leads to a larger critical\ncurvature radius. In contrast, elevated temperatures (30-60 °C) do not significantly\naffect the critical curvature radius. Besides, while oxidation of EGaIn at high\ntemperature could be a concern, we did experimental study and the results show that\nthe resistance increased by only 2.6% after continuous heating at 100 °C for 12 h,\nindicating that thermal oxidation is negligible under these conditions.\nThe influence of RH on the PVA adhesive layer mainly through its effect on flexibility.\nHigher humidity induces solvent-mediated plasticization, which increases the\nelongation at break of PVA. Correspondingly, the critical curvature radius of the EGaIn\nmicrocircuit decreases progressively with increasing RH, consistent with expectations.\n15 / 31\nAccordingly, we have added related discussion in the main text and Supplementary Fig.\n21 and Supplementary Fig. 22 in the supplementary information. The related contents\nare copied in the following for your convenience:\nIn the main text:\n(Page 8, Line 252) This performance originates from the intrinsic fluidity and\nstrain-insensitive conductivity of EGaIn, as confirmed by microscopy observations\nof continuous EGaIn pathways during bending (Supplementary Fig. 21). The\nbending limit of the fiber microcircuit is governed by the PVA adhesive layer,\nwhose flexibility increases with temperature and humidity, leading to different\ncritical radii across different environmental conditions (Supplementary Fig. 22).\nIn the supplementary information:\nSupplementary Fig. 21. SEM images of the circuit-fiber interface at different\ntemperature and humidity. (a) Interfacial morphology at 20 °C and 50% relative\nhumidity (RH). Bending radius: 2.3 mm. (b) Morphology of the interface after\nbending-induced failure under the same environment conditions as in (a). Bending\n16 / 31\nradius:1.8 mm. (c) Image of the fracture at -20 °C and 50% RH, showing PVA\nmicrofibrils at the failure cross-section, indicating PVA-dominated interfacial\nfailure. (d) Magnified view of (b), revealing abundant EGaIn speckles at the\nfractured region, indicating plastic deformation of the PVA. (e) Intact interface at\nbending radius of 1.8 mm under 20 °C and 100% RH, in contrast to the fractured\ninterface in (d).\nSupplementary Fig. 22. Influence of humidity and temperature on the\nmechanical stability of EGaIn microcircuits on fibers. (a) Influence of RH on\nthe critical radius at 20 °C. Critical radius is defined as the bending radius at which\nΔR/R₀ begins to exceed 200%. (b) Influence of temperature on the critical radius at\n50% RH. (c) Resistance variation of the microcircuit during prolonged thermal\nexposure at 100 °C and RH of 50%. All samples were stored under the\ncorresponding environmental conditions for 3 h to ensure equilibrium.\nComment #8:\nIf available, resistance evolution over more extreme bending radii (≤ 4 mm) or torsional\ndeformation would enhance confidence in durability claims.\nReply:\n17 / 31\nFollowing your suggestion, we studied the resistance evolution under more extreme\nbending radii (≤ 4 mm) and characterized the failure morphology using SEM (as shown\nin Reply to your Comment #7). To facilitate discussion, we defined critical radius as\nthe bending radius at which ΔR/R₀ begins to exceed 200%. We confirmed that the\ncritical radius is 2.3 mm at temperature of 20 °C and RH of 50%.\nAccordingly, we have added the resistance evolution at smaller bending radii (≤ 4 mm)\nin Fig. 4f. The related contents are copied in the following for your convenience:\nIn the main text:\n(Page 8, Line 249) The resulting fiber devices exhibit exceptional mechanical\ncompliance, enduring 16,000 bending cycles at a curvature radius of 1.6 cm with\nonly a 1.4% increase in resistance. The fiber microcircuit can be bent to a critical\nradius (r , defined as the bending radius at which ΔR/R₀ begins to exceed 200%) of\nc\n2.3 mm (Fig. 4f), demonstrating good robustness for wearable applications.\nFig. 4f. Relative change in resistance of the fiber under cyclic bending deformation\nwith bending radius of 16 mm at 1 Hz (upper) and different bending radii (lower).\nTemperature, 20 °C; Relative humidity, 50%.\nComment #9:\nThe Methods should specify environmental parameters (temperature, humidity)\nduring\nshrinkage and transfer, as these can influence EGaIn’s viscosity, oxidation, and\nadhesion.\nReply:\nAccordingly, we added these information into the Methods in the main text：\nIn the main text:\n(Page 10, Line 334) Fabrication of Shrunk microcircuits\n18 / 31\n… All the processes, including the fabrication of shrunk microcircuits and its\ntransfer, were performed at 20 °C and 50% relative humidity, unless otherwise\nspecified.\nComment #10:\nClarify how uniform stretching was maintained—manual stretching may lead to edge\neffects. Was a biaxial stretcher or measured tension used? Including a schematic or\nphoto of the setup (possibly in Supplementary Fig. 1) would improve reproducibility.\nReply:\nThank you for raising this question regarding the uniformity of stretching. The stress-\nengineered 2D silicone platform requires precise strain regulation, where the strain\nalong each point of the perimeter should be carefully adjusted to ensure that every\nelement remains distortion-free after stretching. Conventional biaxial stretching\nfixtures often fail to maintain uniform strain near the four corner regions. To overcome\nthis limitation, we employed a frame-based stretching approach that allows manual\nadjustment of the silicone film’s deformation, enabling the elimination of localized\nstrain non-uniformity during the process. While the current manual adjustment method\nhas certain limitations, it effectively ensures uniform omnidirectional stretching under\ncontrolled conditions. We acknowledge that further automation and standardization of\nthe stretching process would be beneficial for improving reproducibility and scalability.\nAccordingly, we have revised Supplementary Fig. 1 and added a new video S1 in the\nsupplementary information to more clearly illustrate the stretching process. The related\ncontents are copied in the following for your convenience:\nIn the main text:\n(Page 2, Line 57) …First, a silicone substrate (Ecoflex film) is omnidirectional pre-\nstrained to a defined ratio and secured on an acrylic frame to maintain tension\n(Supplementary Fig. 1, Video 1).…\nIn the supplementary information:\n(Page S2) Supplementary Video 1. (Separate file) | Fabrication of stress-engineered\n2D silicone platform\n19 / 31\nSupplementary Fig. 1. Ecoflex film platform used for shrinking EGaIn\ncircuits. (a) Ecoflex was cast onto an acrylic plate to prepare a stretchable platform\n(the 1 cm × 1 cm grid here is to help to illustrate the uniformity of the stretchable\nplatform, which will not present during actual shrink process). (b) Ecoflex film\npeeled off from the acrylic plate. (c) Uniformly stretched Ecoflex film fixed onto\nan acrylic frame, ready for circuit construction on its surface.\nComment #11:\nMinor Comments and Editorial Suggestions\nFigure 1c: Add explicit “before” and “after shrinkage” labels and indicate quantitative\nshrinkage ratios on the figure or in the caption.\nReply:\nAccordingly, we revised the Figure 1c and updated the corresponding caption. The\nupdated ones are provided below:\nIn the main text:\nFig. 1c, Optical images of EGaIn circuits on an Ecoflex film before and after\nshrinkage (shrunk by 80% in area) …\n20 / 31\nComment #12:\nSupplementary Figures:\nFig. 1: Add direct annotations (e.g., “Ecoflex cast film,” “peeled film,” “stretched film\non frame”) instead of relying solely on the caption.\nReply:\nThank you very much for your careful review and kindly suggestions. Accordingly, we\nadded direct annotations in Supplementary Fig. 1 and checked the manuscript for\nsimilar issues.\nComment #13-14:\nFig. 2–3: Clarify whether EGaIn–PVA interfaces exhibit cracking or delamination\nduring shrinkage.\nFig. 3c: Mark the region of the high-magnification image within the main panel.\nReply:\nThank you for raising this point. We agree that the interfacial interactions between\ndifferent components are very important for the successful STAP process.\nSupplementary Fig. 2 and 3 respectively show the Ecoflex-EMP interface after\nshrinkage and the EGaIn-PVA interface after transfer. The PVA film is attached to the\nEGaIn microcircuits only after the shrinkage process. Thus, during the shrinkage\nprocess, no EGaIn-PVA interface is present. We guess the misunderstanding may have\narisen from the original caption for Supplementary Fig. 2 and 3. As for the Ecoflex-\nEMP interface, during the shrinkage process, it remains stable and does not show\ncracking or delamination. The interfacial area simply decreases uniformly as the\nEcoflex shrinks. However, new interfaces will generate when EMP overflow occurs\nunder extreme shrinkage, as discussed in Reply to your Comments #3-5.\nAccordingly, we revised the corresponding caption of Supplementary Fig. 2-3 to avoid\nsuch confusion and updated the Supplementary Figure 3. The related contents are\ncopied below for your convenience:\nIn the supplementary information:\n21 / 31\nSupplementary Fig. 2. Images of EGaIn microcircuits on Ecoflex films with\ndifferent shrinkage ratios. From left to right, shrunk by 0%, 60%, 70%, 80%\nin area.\nSupplementary Fig. 3. Transferred EGaIn microcircuits on PVA. (a) A single\nline. (b) Sharp corner of the circuit. (c) Enlarged view of the circuit surface. (d)\nMultiple lines. (e) Small gaps (35 μm).\nComment #15:\nTerminology: Replace “universal fabrication strategy” with “versatile fabrication\nstrategy” unless broader material compatibility can be experimentally verified.\nReply:\nThank you for your insightful comment. As discussed in details in Reply to your\nComment #1, we have experimentally verified the compatibility of this strategy with\nother inks, supplied new data and discussion in the revised films. Besides, we have also\nreplaced “universal fabrication strategy” with “versatile fabrication strategy” to be\nmore rigor.\n22 / 31\nComment #16:\nSupplementary Video 3: A brief quantitative comparison of luminance stability under\nbending would add scientific value beyond qualitative demonstration.\nReply:\nThank you for your professional suggestion. We have carried out experiments to\nquantitatively compare the luminance stability of the EL pixel under different bending\nradii. We collected digital photographs of the same sample under the same\nenvironmental conditions at different bending radii, then used software (ImageJ) to\nmeasure the average grayscale intensity of the emitting pixel after subtracting the\ncorresponding background brightness. The results show that the luminance stability\nremains 94% when bent to a radius of 15 mm, but then decreases sharply as the\ncurvature increases.\nAccordingly, we have added related discussion in the main text and corresponding\nluminance stability data (Supplementary Fig. 23) in the supplementary information.\nThe related contents are copied below for your convenience：\nIn the main text:\n(Page 9, Line 277) Selective pixel activation can be achieved by electrical\naddressing through designated contacts (Fig. 4l, Supplementary Video 4),\nenabling the multiplexed display on a single fiber. Luminance stability remains\n94% when bent to a radius of 15 mm, but then decreases rapidly as the curvature\nincreases further (Supplementary Fig. 23).\nIn the supplementary information:\n23 / 31\nSupplementary Fig. 23. Evolution of brightness of luminance pixel with\ndecease of bending radius. (a-e) Optical images of a single EL pixel on the fiber\ndevice bent to different curvature radius ((a) flat, (b) 20 mm, (c) 15 mm, (d) 10 mm,\n(e) 5 mm). (f) Corrected grayscale intensity extracted from a fixed region of interest\n(ROI) for each pixel. Pixel brightness was quantified using ImageJ by measuring\nthe mean grayscale value and subtracting a nearby background region to remove\nillumination variations.\n24 / 31\nReviewer #3:\nSummary Comment:\nThe manuscript is generally well written and clearly presented. However, there are\nseveral issues that limit the overall scope and relevance of the work.\nReply:\nThank you very much for your careful review and insightful comments/suggestions on\nour manuscript. Accordingly, we carried out further experiments and revised the\nmanuscript to address each of the points you raised. These revisions should be helpful\nfor refining the boundaries of this work and strengthening its scientific relevance. We\nsincerely appreciate your constructive guidance. The following is a point-by-point\nresponse.\nComment #1:\nMaterial specificity:\nThe materials used in the study are very specialized and are not easily replaced or\nadapted to other functional materials (substrate, ink, GaIn ....)\nReply:\nThank you very much for raising this point. In order to address this point, we carried\nout further experiments.\nBeside the EGaIn/sericin ink, three typical commercial conductive inks, including\nAg/AgCl ink and carbon ink, which are commonly employed in printed electrochemical\nsensors, and PEDOT:PSS ink, which is one of the most broadly used conductive\npolymers, were studied with the STAP process. All the three inks can be successfully\napplied in the STAP process, demonstrating the versatility of the process. We propose\nthe following are the requirements for the inks used in this process: (i) The ink should\nremain flowable during the interval between printing and substrate shrinkage, which\nallows the shrinkage-induced stress to propagate upward from the bottom of the pattern\nand to drive spatial reorganization of the ink material. (ii) The ink should possess\nadequate viscosity, since low-viscosity inks would easily overflow the intended pattern\nboundaries during substrate motion and cause feature distortion. (iii) The ink should\nhave affinity toward the targeted film, which in this work is PVA. For example,\nEMPs with hydrophilic surfaces exhibit strong affinity to PVA, which is essential for\nsuccessful transfer.\nAs for the selection of elastomeric substrates, the STAP process requires substates with\nhigh stretchability, recoverability and hydrophobicity. The silicone elastomer we used\nfits these requirements perfectly. Other common elastomers such as styrene-ethylene-\nbutylene-styrene copolymer (SEBS) and thermoplastic polyurethane (TPU) could in\nprinciple work with STAP, but their stretchability is usually lower than that of silicone\n25 / 31\nunless molecular modification is applied. Therefore, in this work, we selected\ncommercial Ecoflex and did not study other elastomeric substrates.\nAccordingly, we have added related discussion in the main text, and Supplementary Fig.\n24 in the supplementary information. Besides, we have replaced the term “universality”\nwith “versatility” in the main text to be more rigor. The related contents are copied in\nthe following for your convenience:\nIn the main text:\n(Page 9, Line 285) It is noted that the STAP process is also compatible with other\ntypical commercially available inks besides the EGaIn/sericin ink (Supplementary\nFig. 24).\n(Page 9, Line 317) Finally, standardizing process parameters and characterization\nprotocols across different material systems will be essential for ensuring\nreproducibility and facilitating broader adoption in flexible and textile electronics.\nIn the supplementary information:\n26 / 31\nSupplementary Fig. 24. Applying STAP process using three typical\ncommercial electronic inks. The inks include Ag/AgCl ink (purchased from\nPrtronic), carbon ink (purchased from Loctite), and PEDOT:PSS ink (purchased\nfrom Prtronic), showing consistent printing, ~80% shrinkage, and successful\ntransfer, confirming the compatibility of the STAP process with other inks.\nComment #2:\nScalability and reproducibility:\nKey steps in the process—such as pre-stretching, tension release, transferring onto a\nPVA sheet, water-assisted transfer, and the shrinkage of the printed circuits—introduce\na lot of variability and are not easily scalable. As a result, achieving consistent\nreproducibility is challenging. In addition, the conductivity variations that come from\nshrinkage sintering and transfer sintering need to be supported with more detailed\nstatistical data.\nReply:\nThank you for your insightful comment. We agree that the STAP workflow involves\nmultiple steps, imposing challenges for scalability and reproducibility.\nRegarding reproducibility, all the key steps, including pre-stretching, tension regulation,\ncircuit shrinkage, hydration of the PVA film, and the final transfer, can be governed by\ncontrollable experimental parameters. The pre-stretching process is performed on a\nstress-engineered silicone platform with adjustable pre-strain, and the deformation state\ncan be monitored using an orthogonal finite-element grid (Supplementary Video 1).\nWe also investigated the effects of shrinkage and transfer parameters on the restoration of\nEMP conductivity. The PVA-assisted transfer reliably recovers the conductivity of EMP\nnetworks to the same order of magnitude as bulk EGaIn, and experimental results show\nthat the transfer and reconstruction process proceeds with a very high success rate\n(nearly 100% for across 20 times trials). Besides, the screen printing in the STAP\nprocess is an industrial-scale patterning method widely used in textile manufacturing.\nRegarding scalability, we acknowledge that our current laboratory-scale preparation has\nlimitations. Despite of this, we think it has potential for large-scale applications as the\nmechanism itself does not impose fundamental barriers to scaling. The stress-\nengineered 2D silicone platform could be scaled up by using larger substrates. However,\ncontinuous large-scale manufacturing would require an automated stretching system\ncapable of applying uniform tension along the entire film. After shrinkage, the silicone\nfilm carrying the microcircuits could be brought into contact with a continuous PVA\nroll, following by wetting, drying, transfer and collection along a production line.\nThis approach appears feasible and would mainly require engineering design for automate\nwetting and rapid drying. Your comment provides a forward-looking perspective on the\npractical deployment of STAP.\n27 / 31\nAccordingly, we have added a discussion in the main text. And the detailed conductivity\ndata associated with shrinkage sintering and transfer sintering have been included in\nthe supplementary Table S2. The related contents are copied below for your\nconvenience:\nIn the main text:\n(Page 6, Line 199) …Moving along this boundary toward higher F enables smaller\nf\nfeature sizes while preserving electrical continuity (see Table S2 for electrical\nconductivity for each point)\n(Page 9, Line 286) …This STAP strategy overcomes the long-standing challenge\nof integrating high-precision microcircuits onto curved fiber substrates, paving the\nway for multifunctional and high-density wearable electronics. Further efforts on\ndeveloping automated stretching and continuous transfer systems could improve\nthe scalability of STAP and facilitate its adoption in practical manufacturing\nsettings.\n(Page 9, Line 312) Second, scaling the technology for industrial production will\nrequire the development of automated stretching systems capable of applying\nuniform omnidirectional strain to large-area elastic substrates, thereby improving\nreproducibility.\nIn the supplementary information:\n(Page S19) Table S2. Conductivity of EGaIn microcircuits prepared with different\npre-stretch ratio and EMPs coverage ratio.\nEMPs coverage Pre-stretch ratio\nratio (%) 0% 75% 150% 225% 300% 375% 450% 525%\n63.2 0 0.25 0.36 0.39 0.42 0.46 0.47 0.48\n53.7 0 0.13 0.18 0.20 0.24 0.29 0.32 0.33\n47.4 0 0.06 0.10 0.13 0.18 0.21 0.21 0.24\n41.1 0 0/28.8 0.05 0.09 0.15 0.20 0.21 0.21\n33.8 0 0/28.3 0/28.5 0.02 0.08 0.17 0.19 0.21\n29.2 0 0/27.6 0/28.5 0.01 0.05 0.11 0.16 0.17\n26.3 0 0/27.2 0/28.2 0/28.4 0.02 0.02 0.03 0.04\n20.6 0 0 0/27.9 0/28.2 0/28.2 0/28.4 0/28.4 0/28.5\n16.4 0 0 0 0/27.3 0/27.3 0/27.5 0/27.5 0/27.5\n12.4 0 0 0 0 0 0 0 0\nNote: Corresponding to the measured electrical conductivity (×105 S m-1) after\nshrinkage. A single non-zero value indicates conductivity obtained by shrinkage alone.\nEntries in the form “0/x” denote circuits that remained non-conductive after shrinkage\nbut became conductive (x ×105 S m-1) after transfer.\n28 / 31\nComment #3:\nMultilayer printing limitations:\nThe approach does not seem capable of true multilayer printing. In the demonstrated\ndevice, the conductive layer is printed and transferred onto the thread, while the\nluminescent layer is applied by coating rather than printing. This highlights an inherent\nlimitation of the technique.\nReply:\nThank you for your insightful comment. Accordingly, we carried out further experiment\nto explore the possibility for construction multilayer circuits with the STAP strategy.\nWe found that multilayer circuits can be constructed on separate PVA films using\ndifferent screen-printing masks. These films can then be sequentially transferred to the\naligned position of the fiber surface. We also considered that possibility for the printing\nof the luminescent layer. However, as for the STAP process involves the wetting and\ndrying of the PVA film, constructing a non-permeable luminescent layer on the film\nwould influence the wetting behavior, and thus introduce non-uniform stress.\nAccordingly, we have added related discussion in the main text and an image of a fiber\nwith multilayer-circuits (Supplementary Fig. 20). The related contents are copied below\nfor your convenience:\nIn the main text:\n(Page 8, Line 247) Notably, this transfer step can also be applied to fibers of\ndifferent materials and diameters (Supplementary Fig. 19), and can be repeated on\none fiber to construct multilayer circuit (Supplementary Fig. 20).\nIn the supplementary information:\nSupplementary Fig. 20. Optical image of a fiber (diameter, 1.5 mm) with two\nlayers of EGaIn microcircuits.\nComment #4:\nLimited use on small-diameter substrates:\nThe method is demonstrated only on threads a few millimeters in diameter. Its potential\nfor use on finer fibers or true one-dimensional substrates is not addressed, which\nrestricts the broader relevance of the work\nReply:\n29 / 31\nThank you for your raising this critical comment the use of smaller-diameter fibers. We\nagree that extending the method to finer one-dimensional substrates is an important\ndirection for broader applicability.\nIn the present work, the fiber devices were designed primarily to demonstrate single-\npixel electroluminescence. As fiber diameter decreases, pixel crosstalk between densely\npacked microcircuits becomes significantly more pronounced. To ensure clear\nfunctionality and avoid signal interference, we therefore used relatively thicker fibers\nin the main demonstrations.\nIn this work, the minimum diameter of fibers we used is 1.5 mm. We think the minimum\nusable fiber diameter in our approach is constrained mainly by two factors: (1) the\nachievable printing resolution, and (2) the shrinkage limit of the substrate. Together,\nthese define the smallest reliable circuit feature size, which in then determines how thin\na fiber can be reliably patterned. Moving to significantly thinner fibers will require\nfurther downscaling of the circuit dimensions, which is one of the goals of our future\nwork.\nAccordingly, we have added discussion on the key challenges in the main text, and\nimages of fiber devices fabricated on 2.0 mm and 1.5 mm fibers made of different\nmaterials (Supplementary Fig. 19) and multilayer circuits fabricated on 1.5 mm fibers\n(Supplementary Fig. 20) in the supplementary information. The related contents are\ncopied below for your convenience:\nIn the main text:\n(Page 8, Line 247) Notably, this transfer step can also be applied to fibers of\ndifferent materials and diameters (Supplementary Fig. 19) …\n(Page 9, Line 310) Looking forward, several key challenges must be addressed to\nadvance the practical deployment of STAP. First, extending the method to finer\nfiber diameters will necessitate advances in ink formulation and substrate\nengineering to prevent pixel crosstalk and ensure reliable patterning at the\nmicroscale. Second… Third… Finally, standardizing process parameters and\ncharacterization protocols across different material systems will be essential for\nensuring reproducibility and facilitating broader adoption in flexible and textile\nelectronics. By addressing these challenges, STAP can evolve from a laboratory-\nscale technique into a practical manufacturing process for producing high-\nperformance, seamlessly integrated fiber-based devices.\nIn the supplementary information:\n30 / 31\nSupplementary Fig. 19. Optical images of EGaIn microcircuits on fibers with\ndifferent materials and diameters. (a) Thermoplastic polyurethane (TPU),\nsmooth surface, diameter 1.5 mm. (b) High-density polyethylene (HDPE), rough\nsurface, diameter 2 mm. (c) Kevlar, rough surface, diameter 2 mm.\nSupplementary Fig. 20. Optical image of a fiber (diameter, 1.5 mm) with two\nlayers of EGaIn microcircuits.\nFinally, we would like thank all the three reviewers for the insightful comments and\nconstructive suggestions, which have helped us in further improving this work.\n31 / 31\nResponse to Reviewers’ comments\nWe thank the reviewers for their careful evaluation of our manuscript. In this round of\nreview, both Reviewer #1 and Reviewer #2 indicated that all of their previous\ncomments had been fully addressed and that the revised manuscript is acceptable for\npublication without further revision.\n1 / 1"}, "author_response": "Response to Reviewers’ comments\nWe thank the reviewers for their careful evaluation of our manuscript. In this round of review, both Reviewer #1 and Reviewer #2 indicated that all of their previous comments had been fully addressed and that the revised manuscript is acceptable for publication without further revision."}]

Decision letter