Strain-invariant omnidirectional stretchable MXetronics

Domain: chemistry
Published: 2026-01-31
Editorial outcome: minor_revision

Abstract
Titanium carbide MXene flakes hold great promise for system-level MXene-based electronics (MXetronics) due to their outstanding electrical conductivity and diverse functional properties. However, the weak MXene interlayer bonding often causes film fracturing under mechanical strain, ultimately leading to device failure, manifested as unstable operation, inaccurate data transmission, and potential electrical disconnection. Here, we present strain-invariant, omnidirectionally stretchable MXetronics (sos-MXetronics) through hierarchical stiffness microgrid engineering. This strategy synergistically integrates patterned elastiff regions and modulus-buffered interconnects, effectively preventing performance shifts in sos-MXetronics. This circular sos-MXetronics with a radius of 3.3 cm integrates a near-field communication (NFC) antenna, eight micro-supercapacitors (MSCs), three resistive sensors, and interconnected conductive networks, demonstrating exceptional strain invariance with 95–98% performance retention even under 40% strain. With the capability to minimize motion-induced artifacts, the system ensures accurate blood pressure (BP) monitoring without electrical disconnection, even during wrist deformations. This breakthrough not only marks a significant step toward the practical application of MXene in omnidirectional stretchable MXetronics, but also paves the way for reliable, high-performance electronics based on two-dimensional materials for next-generation healthcare monitoring systems that seamlessly integrate with the human body under real-world conditions.

Introduction
Skin-like electronics represent a transformative technology with immense potential for enabling continuous, large-scale, and high-fidelity monitoring of physiological conditions, as well as facilitating real-time health status analysis1–4. A comprehensive skin-like monitoring system typically comprises different functional modules, including power supply, sensing, signal acquisition, and transmission units2. However, given that human bodies frequently undergo movements that induce pronounced deformations in the skin, tissues, and organs, the resulting mechanical strain invariably degrades the electrical performance of these functional units, posing a significant challenge to their reliability5,6. To address this issue, it is crucial to design skin-like electronics with comparable stretchability. Such electronics must retain their functionality while conformably attached to surfaces under stretching deformation, ensuring stability in dynamic environments.

Considerable efforts have been devoted to developing stretchable and integrable electronics through material innovations7 and device engineering8. Despite these advancements in fabricating individual functional units with enhanced performance under strain, fundamental challenges remain in achieving seamless integration of diverse functional components without compromising reliability under dynamic operating conditions. As electronic systems grow increasingly complex, there is a pressing need to construct all functional components from a single material system, which could simplify integration and reduce manufacturing costs. However, such a strategy is often constrained by the intrinsic limitations of individual materials, which generally fail to satisfy the broad spectrum of performance criteria required by different functional devices (for example, although copper and liquid metals are commonly used in electrical wiring, they are unsuitable for energy storage applications due to inherent trade-offs among electrical conductivity, electrochemical activity, and processability)6. Addressing these challenges is essential for advancing the field of skin-like electronics and unlocking their full potential in wearable health monitoring and personalized healthcare applications.

MXene-based electronics, utilizing monolayer Ti3C2Tx MXene flakes with superior mechanical properties9, exhibit exceptional intra-layer conductivity enabled by the hybridization of transition metal and carbon atoms10–12. This unique electronic structure facilitates the efficient spread of electronic states, enabling the development of epidermal soft electronics, “MXetronics”13, and provides a versatile foundation for single-material integration. Significant attention has been given to its use in flexible electronics11, energy storage14, terahertz absorbing15, and many others10,16,17. An overlooked aspect of this research field is the stretchability of MXene-based electronics. MXene films are fairly stiff and prone to perpendicular fracture under tensile deformations due to weak interlayer interaction11,14,18, exhibiting limited intrinsic stretchability (<5%)10,14. Such fractures can severely affect in-plane charge carrier transport, compromising electrical performance19. This limitation is particularly problematic for sensors and radio frequency (RF) electronics, which are highly sensitive to changes in physical geometries7,8. To address these limitations, several strategies such as crack bridging, interlayer insertion, and bio-mimetic architecting have been developed to strengthen interlayer interactions and thereby improve the inherent deformability of MXene-based films20–22. Although these methods effectively suppress crack propagation and enable energy dissipation, the introduction of small molecules and polymers inevitably results in considerable conductivity degradation, creating a trade-off between stretchability and electrical performance that remains unresolved. Consequently, these methods are more suitable for strain sensors23, where resistance changes with strain, rather than for stretchable electronics that require stable electrical performance under deformation. Introducing various structural designs, such as wrinkled1, kirigami24, or island-bridge structures25, can effectively increase the stiffness and decrease the experienced strain of MXetronics. However, these approaches face limitations in achieving omnidirectional strain tolerance. In practical dynamic environments featuring anisotropic stress distribution and unpredictable multidirectional strains, off-axis stretching beyond designed deformation directions induce severe strain concentration at rigid-elastic interfaces, leading to interconnect failure. To achieve full mechanical stretchability of MXetronics, the adjacent electronics and their interconnections must exhibit strain-insensitive properties.

Here, we report a strain-invariant omnidirectional stretchable MXetronics (sos-MXetronics) that integrates energy storage, wireless communication, and sensing functionalities into a high-consistency material architecture (Fig. 1a, b). The strain-invariant behavior is realized through the synergistic design featuring patterned PDMS elastiff layers on an Ecoflex elastomeric base and stretchable modulus-buffered polyethylene terephthalate (PET) interconnects, thus enabling localized stiffening and strain redistribution to prevent MXene cracking (Fig. 1c–e). To ensure efficient signal exchange and energy delivery between the sos-MXetronics and the mobile terminal, we developed a high-conductivity (3500 S/cm) Li+ exchange MXene, which enables the fabricated system to wirelessly power and sense at distances up to 3.5 cm. Most importantly, the sos-MXetronics exhibits a strain insensitivity with less than 5% performance variation under 40% strain. Finally, the sos-MXetronics demonstrated motion interference-free monitoring of human pulse, temperature, and BP via near-field communication (NFC). The fully demonstrated strain-invariant all-MXene platform offers a powerful tool for large-scale integrated manufacturing of next-generation wearable and stretchable electronics.

Results
Design conception and workflow of the sos-MXetronics
The idea of integrated omnidirectional stretchable MXetronics is illustrated in Fig. 1a, where eight micro-supercapacitors (MSCs), three resistive sensors, one NFC antenna, and interconnected conductive networks are ingeniously arranged within a 3.3 cm radius, endowing the entire stretchable system with unparalleled integrity. The circuits, sensors, energy harvesting, and storage components are fabricated on a PET substrate using a spray-coating process and subsequently transferred to a stretchable patterned Ecoflex/PDMS substrate (Supplementary Fig. 1), enabling exceptional flexibility and comfortable attachment to human skin. The MXene antenna achieves an open-circuit potential (OCP) > 3 V, generating over 5 mW average power output to drive the system at maximum power point, which enables fast charging of the MXene MSCs at 50 mA/cm2. In series/parallel configuration, the MSCs output 2.4 V with 4.17 mW/cm2 power density, which is sufficient to sustain the microcontroller unit (MCU) operation. Power sourcing automatically switches between the NFC antenna (near-field mode, ≤ 3.5 cm) and MSCs (far-field mode) based on proximity. Resistive sensors continuously monitor vital signs (temperature, pulse, and blood pressure), while the MCU digitizes analog signals via an ADC and relays data wirelessly via NFC for cloud analysis. Figure 1b compares the proposed strain-invariant stretchable system with conventional stretchable electronics. Conventional systems exhibit significant performance degradation under strain, including shifted antenna resonance frequencies, drifted sensor calibration values, and reduced energy storage capacity, which collectively lead to measurement inaccuracies and potential wireless signal dropout. In contrast, our sos-MXetronics demonstrates strain-invariant performance, synergistically achieved by patterning PDMS elastiff layers on an Ecoflex elastomer layer with modulus-buffered PET interconnects (Fig. 1c). This design strategically localizes strain to the lower-modulus interspaces between active components, effectively minimizing functional degradation. The serpentine interconnects provide stretchability, while elastiff layers protect the straight-line-based devices to maintain performance stability (Fig. 1d), ultimately forming the stretchable sos-MXetronics. Figure 1e exhibits the unique crack modulation behavior of sos-MXetronics, where applied strain induces localized MXene flake sliding rather than catastrophic through-cracks and large conductive islands, preserving conductive pathways. Comparative analysis (Supplementary Table 1) reveal that the sos-MXetronics system exhibits superior strain-invariant performance (<5% variation under 40% strain), outperforming previously reported integrated electronics based on MXenes and other materials across all key functional metrics (Fig. 1f). The standalone stretchable sos-MXetronics features thin layout (~300 µm thickness) and low-modulus substrate interface, exhibits robust electromechanical performance upon various mechanical deformations (e.g., stretching, bending, and twisting) as verified by both finite element analysis (FEA) and experimental tests (Fig. 1g, h, Supplementary Fig. 2, and Supplementary Note 1).

Fabrication and characterization of sos-MXetronics
The fabrication of the sos-MXetronics begins with a low-temperature molten salt (LTMS) etching strategy, a rapid and scalable approach that can produce over 100 g of Ti3C2Tx MXene within 5 min (Supplementary Fig. 3 and Supplementary Note 2)26,27. This etching duration is two orders of magnitude shorter than the most commonly used etching methods (Supplementary Table 2). The disappearance of the Al (104) peak in the X-ray diffraction (XRD) pattern28, along with the accordion-like morphology observed in the scanning electron microscopy (SEM) image and the multilayer structure revealed in the transmission electron microscopy (TEM) image, collectively confirm the successful exfoliation and synthesis of the Ti3C2Tx (Supplementary Fig. 4). To obtain few-layer MXene nanosheets, NH4HF2-synthesized Ti3C2Tx is commonly delaminated using large organic molecules such as tetramethylammonium hydroxide (TMAH)29. However, the complete removal of TMA+ ions is difficult, often resulting in MXene films with larger interlayer spacing, poorer stability, and lower electrical conductivities (<500 S/cm)30, which limit their effectiveness in electronic devices. To address this dilemma, we demonstrated an ion-exchange and flocculation method to remove residual organic intercalants (Supplementary Fig. 5, A similar method for V2CTx was reported by Yury’s group)31. Figure 2a illustrates the ion-exchange process, where the surface-adsorbed TMA+ ions on MXene are removed and replaced with Li+ ions. This process is driven by the electrostatic attraction between the negatively charged 2D MXene and alkali metal cations, as well as the concentration gradient created by the high concentration of Li+ ions (Supplementary Note 3). XRD results show a clear and distinct shift of (002) peak of MXene toward higher Bragg angles (smaller spacing: from 14.6 Å to 12.5 Å) after ion-exchange (Fig. 2b). Thermogravimetric analysis (TGA) also confirmed the removal of residual TMA+ by the absence of weight loss around 400 °C in the Li-exchanged samples (Supplementary Fig. 6). Note that the Li-exchanged MXene, with an average lateral size of 1.3 µm in its aqueous dispersion, remains stable in its flocculated state for at least two months without degradation. After removing the salt, the flocculated MXene can be redispersed in water (Supplementary Fig. 7). The Li-exchanged films without annealing demonstrate higher conductivity (3505 ± 41 S/cm) than that of TMA-retained MXene films (216 ± 14 S/cm) due to the reduced interlayer spacing and the removal of organic molecules, which facilitates electron transport between flakes (Fig. 2c). The conductivity is comparable to that of product obtained by the common conventional HCl/LiF etching method (1000–6000 S/cm)26,32–38, while the total synthesized time is reduced to less than one-third of the conventional method (Fig. 2d and “Methods”).

The resulting MXene solution exhibited rheological shear-thinning behavior (Supplementary Fig. 8), enabling continuous extrusion for spraying and quick solidification upon heating to remove most of the intercalation moisture (Fig. 2e). The MXene filaments can be readily sprayed onto various substrates, as evidenced by the identical MXene fingerprints in Raman spectra (Fig. 2f). We used PET as the substrate to support the MXene layers. The PET (modulus of 1.78 GPa, Supplementary Fig. 9) was selected for its close mechanical match to our MXene films (measured modulus of 6.39 GPa). The PET substrate was plasma-treated and APTES-modified to enable electrostatic assembly of stable MXene layers (Supplementary Fig. 10)39. Subsequently, diverse patterned circuits can be efficiently fabricated on various substrates through transferring and programmable laser cutting (Fig. 2g left and Supplementary Fig. 11). We ultimately used Ecoflex with a low modulus (68 kPa) as a stretchable substrate, capable of withstanding up to 660% strain. The Ecoflex-PET adhesion energy was tuned to 87 J/m2 by UV-ozone treatment, providing sufficient shear resistance while allowing controlled delamination after laser cutting (Supplementary Fig. 12 and Supplementary movie 1). The smooth and continuous cross-sectional interface further confirms the strong bonding and successful layer integration (Fig. 2g). The serpentine interconnections maintain a relative resistance change below 5% within the functional strain range (up to 75%) in both X and Y directions, while the structure itself can withstand nearly 160% strain before mechanical failure (Fig. 2h, Supplementary Figs. 13 and 14). The rigid serpentine island effectively shields the MXene film from large global strain, enabling the electrode to deform through localized MXene flake sliding rather than catastrophic crack propagation. This mechanism prevents the formation of long cut-through cracks and large conductive islands, thereby maintaining electrical integrity even under repeated high tensile strain (Supplementary Figs. 15–18).

Characterization of MXene NFC system of sos-MXetronics
Wireless technologies, particularly RF-based techniques, enable the development of battery-free skin electronics by eliminating the need for extensive external connections7,40. MXene-based NFC antennas are designed to provide emergency power for MXene MSCs and facilitate efficient transmission of sensing signals (Fig. 2i). Notably, geometric deformations can alter the electromagnetic properties of NFC antennas, leading to unstable inductive coupling efficiency. This instability poses a challenge in delivering a consistent power supply for supercapacitors and sensors. To address this issue, we redesign the conventional spiral coil by incorporating a sine-wave modulation, which can ensure uniform stretching of the coil in all directions during elongation (Fig. 2j). To achieve better resonance matching, the geometry of the omnidirectional MXene coils was pre-simulated, showing that the outer radius and the number of turns have the greatest impact on inductance (Supplementary Fig. 19). At a frequency of 13.56 MHz, the inductors displayed similar inductance (L) and resistance (R) values with the corresponding simulation results (Fig. 2k). To ensure compatibility with the external circuit and space for additional MXene components, the designed sine-wave MXene coil antenna features an inductance of ~2.7 µH, 5 turns, and dimensions of ~6.6 cm in both length and width. Figure 2l shows that the fabricated omnidirectional sine-wave MXene coil exhibits only a 6% change in inductance under extreme elongation of 50%. The stable magnetic coupling area of the coil under 40% strain also reflects this behavior, with a change of only 3.3% (Supplementary Fig. 20 and Supplementary Note 4). In contrast, traditional MXene circular coils, despite good adhesion between PET and Ecoflex, tend to delaminate and suffer nearly 20% inductance variation, leading to electrical disconnection (Supplementary Fig. 21). To match the MXene coils with the NFC chip (NTAG), the resonant frequency of the sine-wave MXene coil can be adjusted by modulating its own capacitance and inductance without an additional matching capacitor to achieve the 13.56 MHz resonance frequency required for NFC operation (Fig. 2m). From Fig. 2n, the as-fabricated MXene NFC antenna exhibits a resonance frequency of 13.57 MHz, with an S11 value of around −9 dB. Although the measured resonance frequency is slightly higher than 13.56 MHz, this hardly affects the energy transmission since more than 70% of the power is transmitted within a 5 dB bandwidth from 11.5 MHz to 16.2 MHz. The MXene antenna can effectively harvest wireless energy from a smartphone to power and light up an LED under stretching conditions (Fig. 2o and Supplementary Movie 2), demonstrating its excellent energy transmission capabilities. The electromagnetic stability of the MXene antenna was validated through over 1500 cycles of 40% uniaxial stretching (Fig. 2p). In addition, the MXene antenna enables bidirectional data exchange under extreme bending conditions (Fig. 2q, Supplementary Fig. 22 and Supplementary Movie 3). The MXene NFC module, with its excellent energy transmission capabilities and data exchange properties under omnidirectional strain, lays a solid foundation for the sensing and energy storage modules in sos-MXetronics.

Characterization of MXene sensing system of sos-MXetronics
To expand the functionality of our sos-MXetronics, we seamlessly integrated omnidirectional strain-invariant MXene-based pressure and temperature sensors (P-sensor and T-sensor) into the system. This integration achieves additional sensing capabilities without enlarging the device footprint, while the aforementioned MXene antenna ensures a stable power supply. The P-sensor consists of an interdigital MXene electrode and a microstructured PDMS/MXene film (Fig. 3a). Here, a microstructured film with an intermittent architecture was fabricated using large-area programmed laser etching and replica molding, followed by spin-coating MXene nanosheets onto the surface (Supplementary Figs. 23 and 24). Compared with planar and uniform structured films, the intermittent architecture significantly reduces the compressive stress required during deformation (Fig. 3b), with a compressive strength below 50 kPa across the 0–28% strain range. By effectively transmitting pressure from the film surface to the micro-pillars, this design maintains a low equivalent modulus even under largest rain and facilitates greater changes in contact area (Supplementary Figs. 25 and 26). Extensive experimental data (Fig. 3c) show that the incorporation of intermittent structure also enhances the electrical performance of the sensing film, with the sensitivity of 56.1 kPa−1 in the low-pressure region, which is about 120 times greater than planar film-based P-sensor (Supplementary Fig. 27). Notably, the effect of interdigitated electrode density and MXene loading on sensor performance is detailed in Supplementary Figs. 28 and 29. Additionally, the sensor demonstrates fast and accurate responses to subtle pressures below 10 kPa (Fig. 3d), and maintains highly stable performance over 25,000 cyclic compressions (Supplementary Fig. 30).

To achieve omnidirectional strain-invariant MXene P-sensors, PDMS was selected as the elastiff layer to enhance the stiffness of the entire P-sensor region. It is worth noting that even the conventional PDMS with 10:1 mixing ratio exhibits a 16-fold higher modulus than that of Ecoflex (Supplementary Fig. 9), minimizing deformation in the active regions of the devices. Moreover, both PDMS and Ecoflex were cured via the hydrosilylation of vinyl and Si-H bonds (Supplementary Fig. 31)41, forming a robust adhesive interface capable of enduring large shearing stresses generated by the substantial in-plane strain differences across the interface (Supplementary Fig. 32). The isolated PDMS domains ensure dominant strain accommodation occurs through compliant Ecoflex matrix and serpentine interconnects during stretching, thereby decoupling mechanical deformation from pressure sensing functionality (Fig. 3e). This strain-partitioning mechanism maintains constant interdigitated electrode spacing (ΔD/D0 < 5%) across 0–40% strain (Fig. 3f). Without the elastiff layer, the stretching significantly alters the pressure sensing performance over the entire pressure sensing range. For instance, current change readings under the same pressure can vary by up to 80% between no stretching and 40% strain conditions (Supplementary Fig. 33). In contrast, the partially reinforced sensor exhibits negligible performance variation when stretched from 0% to 40% strain (Supplementary Fig. 34). Quantitative analysis reveals a strain insensitivity of approximately 96% (Fig. 3g). Moreover, this strain-invariant pressure sensing performance is well maintained over repeated stretching cycles to 40% strain (Fig. 3h).

In addition to the P-sensor, MXene was also utilized as an active material for wearable temperature sensing. In sos-MXetronics, the MXene-based temperature sensor adopted an omnidirectional strain-invariant serpentine meandering structure (Fig. 3i). By shifting toward the axis of deformation, this design releases stress energy across the pattern, ensuring stable performance during daily use. The MXene T-sensor exhibits a negative temperature coefficient behavior (NTC)42, where elevated temperatures enhance charge hopping between MXene flakes, thereby increasing conductivity. The developed MXene T-sensors with different linewidths demonstrated a sensitivity of 0.95% °C−1 across a temperature range of 25 °C to 60 °C (Fig. 3j and Supplementary Fig. 35). Under strain (40%), the initial resistance offset was limited to 5%, remaining within an acceptable range (Fig. 3k). Furthermore, the temperature sensor exhibited fast response capability and strain-invariant performance when applied to human skin (Fig. 3l and Supplementary Fig. 36).

Characterization of wireless harvesting and MXene MSCs charging
To validate the energy harvesting and storage management system, we performed a series of wireless charging and discharging evaluations to assess the robustness and efficiency of the fully MXene-based device. The developed wireless charging system comprises a transmitting unit and a receiving unit, as schematically displayed in Fig. 4a. It operates on the principle of inductive coupling, where the rectifier circuit converts alternating current into direct current to efficiently charge the MXene MSCs featuring interdigitated MXene electrodes and a PVA/H2SO4 semi-solid electrolyte (Fig. 4b). The interdigitated structure of MSCs plays a crucial role in ion diffusion and transport (Supplementary Fig. 37). By optimizing the fingers spacing (d), width (w), aspect ratio (l/w), and number of fingers (N), the device achieves an areal capacitance of up to 35.4 mF/cm2, with energy and power densities reaching 2.1 µWh/cm2 and 4.17 mW/cm2, respectively (Supplementary Figs. 38–42). Additionally, the MXene MSC units can be configured in series or parallel to meet specific power/voltage demands (Supplementary Fig. 43 and Supplementary Note 5). The device also exhibited excellent cycling stability, maintaining 93% capacitance retention after 10,000 cycles (Supplementary Fig. 44). To enhance mechanical deformability, an elastiff layer consistent with the MXene P-sensor region in sos-MXetronics was adopted. Compared with omnidirectional strain-unconstrained MXene MSCs (Supplementary Fig. 45), our device exhibits negligible capacitance change across the 0–40% strain range (Fig. 4c and Supplementary Fig. 46), demonstrating a high capacitance retention rate of 98% (Fig. 4d). Similarly, under bending conditions (Fig. 4e), the capacitance of the MXene MSC increased instead, which can be attributed to the enhanced ion transport properties caused by the contraction of the inner surface during bending (Fig. 4f). When excited by a smartphone, the MXene antenna delivers a stable power output of approximately 5.5 mW (Fig. 4g and Supplementary Fig. 47), which is sufficient to power most microgrids and systems5,43,44. The wireless charging distance can be tuned from 1.9 cm to 3.5 cm depending on the load power (Supplementary Note 6). Furthermore, under 40% strain, the designed MXene antenna maintains an almost constant open-circuit voltage (~3.2 V), showing robust immunity to interference from integrated components while also preventing the strain-induced power interruption typical of traditional circular coils (Fig. 4h and Supplementary Figs. 48 and 49). Following the separate performance characterization of the MXene MSCs and the MXene antenna, the extended energy harvesting and storage function was examined. Based on the self-regulating design principle, the series-parallel MXene MSCs array achieved a voltage window of 3 V, which could be charged to 2 V at a rate of approximately 50 mA/cm2 within 2 s (Fig. 4i). The wirelessly charged MXene MSCs array was able to discharge at a constant current of 0.2 mA/cm2 for over 460 s. In addition, the charging distance does not affect the charging efficiency (Supplementary Fig. 50). The mechanical stability and transmission efficiency of the synergistic system were evaluated under 0–40% uniaxial stretching and repeated wireless charging-discharging cycles (50 cycles). The capacitance change of the MSCs under these conditions was negligible (Fig. 4j). Further LED illumination tests demonstrated the functions of the MXene-based closed-loop system for energy harvesting, storage, and power supply (Fig. 4k and Supplementary Movie 4).

Integrated wearable strain-invariant MXene microgrid system
Figure 5a shows a photograph of the fully MXene-based omnidirectional strain-invariant wireless healthcare monitoring system. Detailed fabrication procedures and circuit diagrams are provided in “Methods” and Supplementary Figs. 1 and 51. An ultra-low-power MCU (~400 µW), operating below 1.8 V and fully compatible with NFC, enables data acquisition, storage, and wireless transmission to a smartphone (Fig. 5b). The entire sos-MXetronics could withstand 40% tensile strain deformation without any physical damage (Fig. 5c), enabling conformal and biocompatible contact with the wrist for stable, long-term pulse-rate and temperature monitoring (Supplementary Fig. 52). Under full-load operation, the MXene MSC array functions as a backup power source, maintaining system activity for ~10 s after external power removal (Supplementary Movie 5). Furthermore, the pressure and temperature sensors show minimal variation under repeated 40% strain (Fig. 5d and Supplementary Movie 6). Device-level fatigue testing up to 15,000 stretching cycles reveals no detectable degradation in the electrical or sensing performance of the integrated system (Supplementary Fig. 53), confirming its long-term mechanical robustness. In addition, temperature-humidity aging tests demonstrate that the Ecoflex encapsulation effectively suppresses MXene oxidation, enabling stable device operation even after 30 days of environmental exposure (Supplementary Fig. 54). Subsequently, the pulse was measured in a fully wireless and battery-free manner. Natural wrist movements may induce up to 20% strain at the interface between sos-MXetronics and human skin (Fig. 5e), which often leads to wireless disconnection in traditional MXene-based integrated systems due to changes in RF properties, thereby disrupting accurate sensing data transmission. In contrast, the sos-MXetronics continuously delivers accurate sensing data even under stretching conditions (Fig. 5f). Notably, the elastiff layer-based MXene P-sensor in sos-MXetronics exhibits minimal interference in pulse detection under strain, with the distinct response frequency of the arterial pulse and its higher harmonics validating the stability of our device (Supplementary Fig. 55). Similarly, continuous wavelet transforms (CWT) further confirm that wrist bending has negligible impact on the frequency band (Fig. 5g), with no transient enhancement or attenuation of instantaneous frequencies observed.

Building on these advantages, the sos-MXetronics not only demonstrates precise pulse monitoring capabilities but also holds promise for BP estimation. To ensure reliable coverage of the radial artery, two P-sensors with a working distance of ~2 cm were employed (Fig. 5h), thereby guaranteeing that at least one sensor consistently provides a stable response even in the absence of external preloading pressure (Supplementary Figs. 56 and 57). To effectively capture cardiac cycle characteristics from a single waveform, we identified key points in the segments, as shown in Fig. 5i and Supplementary Table 345,46. Slight variations in waveform morphology among participants were observed due to differences in radial artery depth (Supplementary Fig. 58). Figure 5j shows key features (such as systolic peak time, diastolic peak height and relative augmentation index) extracted from the pulse waves using our algorithm, inspired by photoplethysmography (PPG)47. These features reflect subtle changes in cardiac status. Notably, the minimal fluctuations in these features before and after wrist bending demonstrate the sos-MXetronics’s ability to consistently capture high-quality pulse waves even during body movements (Supplementary Fig. 59). Then, the multiple morphological characteristics in the pulse waveform were used as the input for a deep learning training model (Supplementary Fig. 60). The systolic blood pressure (SBP) and diastolic blood pressure (DBP) obtained from a commercial sphygmomanometer (YUYUE) served as reference labels for model training (Supplementary Note 7). The rapid decrease in the loss function during training indicates effective learning and convergence of the model (Supplementary Fig. 61). To further evaluate the agreement between the predicted BP from sos-MXetronics and the measurements from the commercial sphygmomanometer, a Bland-Altman analysis was conducted. These results show mean differences of 1.51 ± 6.27 mmHg for SBP and 0.87 ± 4.29 mmHg for DBP (Supplementary Fig. 62), respectively, reaching the highest Grade A level according to the IEEE standard. In addition, the integrated system maintains stable pulse waveforms and consistent SBP/DBP estimation during walking, jumping, and sweating, indicating that daily motion and perspiration do not compromise the sensing performance of the sos-MXetronics (Supplementary Figs. 63 and 64). To validate the capability of the sos-MXetronics for long-term and repeated wireless healthcare monitoring, a participant wore the device on the wrist to track physiological parameters including BP and temperature hourly during routine activities such as deskwork, meals and exercising (Fig. 5k). The physiological data were translated in real time and displayed on a custom-designed mobile application, with each reading stored in the cloud for access at any time (Supplementary Fig. 65). Clearly, BP showed a significant increase after eating or exercising, while temperature and blood pressure remained stable during wrist bending, demonstrating the device’s reliability (Supplementary Movie 7). These results collectively demonstrate the potential of the sos-MXetronics as a completely wireless system capable of delivering clinically relevant data, even under large strain conditions (up to 40% strain).

Methods
Materials
The MAX precursor was sourced from Jilin 11 Technology (Ti3AlC2, 400 mesh). Tetramethylammonium hydroxide (TMAOH, 25%), lithium chloride (LiCl, 98%), polyvinyl alcohol (PVA, 1799 type), and aminopropyltriethoxysilane (APTES, 99%) were purchased from Aladdin Reagent. Ammonium hydrogen fluoride (NH4HF2, 98%) was sourced from Shanghai Macklin Biochemical Co. Ltd. Sulfuric acid (H2SO4) and ethanol were obtained from Chengdu Chron Chemicals. Polydimethylsiloxane (PDMS) was purchased from Dow Corning sylgard 184. Ecoflex 00-30 was supplied by Smooth-On, and polyethylene terephthalate (PET) adhesive printing paper was obtained from JiaHan Company. The conductive silver paste was provided by WeiXiuLao Company.

Synthesis of LTMS-Ti3C2Tx
(1) Small-batch synthesis of MXene. The LTMS-Ti3C2Tx MXene was synthesized by rapidly reacting Ti3AlC2 and NH4HF2 molten salt in a two-necked flask. A mixture of 2 g of Ti3AlC2 and 12 g of NH4HF2 (98.5%, Shanghai Macklin Biochemical Co., Ltd.) was introduced into the flask within an argon-filled glove box. The flask was then placed in a 130 °C-oil bath, where it was stirred under an argon flow for 5 min. After the reaction, the product was washed multiple times with deionized water to remove impurities. The purified LTMS-Ti3C2Tx was dried under vacuum at 40 °C for 24 h. (2) Large-scale synthesis of MXene. For the large-scale production of Ti3C2Tx MXene, 660 g of NH4HF2 was placed into a 5 L three-neck flask under an argon atmosphere, while 115 g of Ti3AlC2 powder was introduced into the continuous feeder. The entire system was continuously flushed with argon to maintain an inert atmosphere. The flask was then placed in a 130 °C-oil bath and magnetically stirred. As NH4HF2 melted, Ti3AlC2 was steadily fed into the flask from the feeder. After adding Ti3AlC2 completely, the reaction proceeded for several minutes before removing the flask from the oil bath. The subsequent steps are the same as before.

Delamination and ion-exchange for Li-Ti3C2Tx aqueous inks
Initially, 2 g of Ti3C2Tx was added to 40 mL of 1 M TMAH solution and stirred for 2 h at 50 °C to ensure complete intercalation. After intercalation, the multilayered powder was transferred to a centrifuge tube filled with deionized water (DI water). The solution was centrifuged at 1200 × g to remove most of the residual TMAH, and the supernatant was discarded. Subsequently, the dispersion was subjected to ultrasound treatment for 1 h under an ice bath and an argon atmosphere. Next, the solution was centrifuged at 1200 × g for 1 h to obtain a colloidal dispersion of few-layer TMA-Ti3C2Tx nanosheets. To further remove TMAH, a 10 M LiCl solution was prepared and mixed with the TMA-Ti3C2Tx dispersion in a 1:5 volume ratio. It is important to carry out this step immediately after preparing the fresh MXene nanosheet dispersion to prevent degradation. After the flocculation of the sample, it was allowed to settle naturally, and after 3 h of ion exchange, the supernatant becomes clear. Subsequently, the flocculated MXene can be washed with deionized water to remove excess lithium ions and redispersed (similar to the washing after intercalation). Specifically, the mixture is centrifuged several times at 1200 × g to remove the supernatant until the liquid becomes green, and then ultrasonic treatment is applied for 30 min to obtain a uniform Li-Ti3C2Tx dispersion.

Material characterization
The flake sizes of MXene were measured using dynamic light scattering (DLS, Nano ZS). Film morphology and thickness were measured by FESEM (JEOL, JSM-7800F) with an accelerating voltage of 5 kV. The crystalline structure of MAX, LTMS-MXene, TMA-MXene, and Li-MXene was characterized by X-ray diffraction (XRD, Empyrean, PANalytical). The electroconductivity results were obtained using a digital four-probe tester (ST-2258C, JGR). Thermogravimetric analysis was measured using a Mettler Toledo TGA. X-ray photoelectron spectroscopy (XPS) was conducted on Thermo Scientific ESCALAB 250Xi. TEM images of multilayer and few-layer MXene were obtained using a JEM-2100F at an accelerating voltage of 200 kV.

Fabrication of PVA-H2SO4 gel electrolyte
First, 8 g of H2SO4 was slowly added to 80 mL of deionized water. After the solution had cooled to room temperature, 8 g of PVA was gradually introduced into the H2SO4 aqueous solution. The resulting mixture was stirred for 1 h in an 80 °C water bath, allowing it to stand for an additional hour until it returned to room temperature.

Fabrication of the silicon template and structured MXene/PDMS sensing film
A silicon wafer was patterned using a UV laser marker (UV-3S, Hans Laser). By adjusting the number of laser etching cycles (1–2 times), a template with intermittent structures was created48,49. The spacing between the structures was set to 100 µm. The patterned silicon template was treated by chemical vapor deposition of trimethylchlorosilane (TMCS) to enhance mold release properties. A mixture of PDMS base and curing agent (10:1 ratio) was spin-coated onto the silicon template. The coated template was cured at 80 °C for 1 h to produce a PDMS film with microstructures. The PDMS film was carefully peeled from the silicon template and plasma-treated for 5 min to achieve hydrophilicity. The plasma-treated PDMS film was spin-coated with an MXene solution (1 mg/mL). The spin-coating speed was controlled to achieve a tunable MXene coating, producing pressure-sensitive materials.

Preparation of the sos-MXetronics
(1) Preparation of stretchable substrate. A 200 µm thick Ecoflex film (a mixed liquid of components A and B in a 1:1 ratio, cured at 50 °C for 0.5 h) was used as the stretchable substrate. The Ecoflex film was perforated using a laser cutter (Mingchuang 6090) to create perforated area. PDMS was mixed at a 10:1 ratio and spread to fill the perforated regions of the Ecoflex. The PDMS was then cured at 80 °C for 1 h to form an elastic, hardened region. (2) Surface treatment and coating of PET. The PET film was treated with air plasma (BEK, BMS-150) for 5 min at 100 W. After plasma treatment, the PET was aminated by immersing it in a solution of 10% APTES, 45% ethanol, and 45% water at 50 °C for 30 min. The aminated PET was used as a spray coating substrate. Using a nitrogen gas flow of 0.15 MPa, 100 mL of MXene suspension (10 mg/mL) was evenly sprayed onto the PET substrate with an area of 20 cm × 15 cm. (3) Attachment of MXene-coated PET to Ecoflex/PDMS substrate. The Ecoflex/PDMS stretchable substrate from step (1) was treated with UV-ozone for 2 min. After that, one side of the PET pattern from step (2) was peeled off and attached to the Ecoflex/PDMS substrate. Air bubbles were removed, and the assembly was left for 1 h to ensure stable bonding. (4) Laser cutting of functional patterns. Using a UV laser marker, the desired patterns, including coils, sensors, supercapacitors, and wires, were cut at a low power setting (20 W). The non-functional regions of the MXene/PET film were carefully peeled off. The MXene coils, MXene temperature sensors, and wires can be used directly. (5) Fabrication of MXene MSCs. A PVA/H2SO4 gel electrolyte was drop-coated onto the interdigital electrode patterns of the supercapacitor portion. The device was allowed to dry at room temperature for 3 h, forming the MXene supercapacitor. (6) Fabrication of MXene pressure sensor. The MXene/PDMS intermittent structured film was laminated onto the interdigital electrode pattern of the sensor portion. The assembly was then sealed with small medical PU tape (50 µm) to ensure stable integration, resulting in the MXene pressure sensor.

Fabrication of skin-interfaced MXene wireless system
The printed flexible circuit board (FPCB) was designed and manufactured by Jialichuang. Copper wires were then used to establish connections between the MXene devices and the FPCB. Specifically, on the MXene device side, a high-concentration MXene precipitate was first used to establish a connection with the copper wire and the MXene conductor. After curing for 30 min at 60 °C, conductive silver paste was added to reinforce the connection in the bonding area (80 °C for 10 min). Subsequently, an Ecoflex solution with a mass ratio of 1:1 was prepared, then poured and scraped onto the MXene-functionalized areas (such as coils, supercapacitors, etc.) and electrode connections to slow down the oxidation of MXene. The mixture was allowed to cure for 4 h at room temperature.

Characterization of mechanical properties
PDMS and Ecoflex were cast into dumbbell-shaped molds for tensile testing, while PET was laser-cut into dumbbell-shaped specimens from available rectangular sheets. Serpentine PET and serpentine PET/Ecoflex were directly stretched according to the original pattern. A strain rate of 50 mm min−1 was applied during stretching, with force and displacement values recorded by the tensile testing machine (LDW-1). For MXene films, these films were laser-cut into rectangular strips (15 mm × 5 mm) for tensile testing under the same conditions. For the peeling test, a silicone rubber adhesive (Sil-poxy, Smooth-On) was used to bond a rigid polyester layer (50 µm thick) to the peeling surface as the backing layer. The sample width varied between 2 and 3 cm, and the peeling speed was kept constant at 50 mm min−1. For the compression test, thin films (250 µm) were tested using a precision motor (FET-60).

Measurements of electromagnetic properties
The electromagnetic properties (S11, Q factor, impedance, and operating frequency) of the coils within a frequency range of 1–20 MHz were measured by a network analyzer (miniVNA Pro). While testing the coil’s resonant characteristic under stretching, a binder clip was used to stretch the coil at different displacements. The changes in electromagnetic properties were recorded by a network analyzer, and a digital camera was used to capture the coil’s deformation. The average change in the coil’s area was then extracted using ImageJ.

Characterization of electrical properties of the sensors and electrode
The mechanical data and current changes of the pressure sensor during compression were tested using a mechanical testing system (FET-60) with a computer-controlled platform and a source meter (Keithley 2450, USA). The temperature sensor was characterized on a hot plate, and the resistance response was recorded using a Keithley-6517B. The resistance of the serpentine MXene/PET/Ecoflex electrode under bending and stretching was measured by the force gauge and source meter mentioned above.

Cytotoxicity and live/dead assays
Cytocompatibility of Ecoflex and PDMS was evaluated using bone-marrow-derived mesenchymal stem cells (BMSCs). Samples (10 mm diameter) were sterilized and incubated with cells (2 × 104 cells per well) in 48-well plates. Cell viability was quantified by a CCK-8 assay (OD450, Day 1 and Day 3) and further visualized by live/dead fluorescence staining.

Electrochemical characterization
Cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS) were all performed using a CHI660E electrochemical workstation (Chenhua, China). The cycling stability test was conducted using an Arbin MSTAT4 multi-channel potentiostat (Arbin, USA), with a current density of 1 mA cm−2. The voltage window for all device tests was 0–0.6 V. EIS testing was carried out at open-circuit voltage, with a frequency range of 100 kHz to 0.1 Hz. The area used in the test was based on the effective working area of the miniaturized supercapacitors. Detailed calculation formulas for specific capacitance (Cs), energy density (E), and power density (P) are also provided in Supplementary Note 5.

Characterization of energy harvesting, storage, and sensing integration
The wireless charging and discharging capability was validated through the source-meter setup. A mobile phone with NFC functionality (Xiaomi 14) was used to power the system. After charging, the system was discharged in GCD mode. After integrating the sensing unit, the MSCs supplied power to the MSP430. The analog signal was then converted into a digital signal by the analog-to-digital converter (ADC) in the MCU. The digital signal was stored in the static random-access memory (SRAM) of the NFC chip. Finally, the data was wirelessly transmitted to a smartphone via the MXene NFC antenna. The data was read and stored using software developed in Android Studio. After the phone was removed, the entire system could be powered continuously by the MXene MSCs.

Ethical approval
All procedures involving human participants were approved by the Ethics Committee of Southwest Jiaotong University (SWJTU-23012-NSFC(133)). Written informed consent was obtained from all participants. In this study, ten volunteers of different genders (aged 20–30 years) participated in the experiment. The MXene-integrated devices were mounted on their wrists to monitor temperature and pulse. Meanwhile, measurements from a commercial blood pressure monitor (YE600C, Yuyue) were used as a comparative reference. Sufficient blood pressure and pulse data were collected during intense physical activity, and measurements were taken at different intervals. Further processing of the pulse signals and the deep learning model used for blood pressure prediction are detailed in Supplementary Note 7.

FEA simulation
For the electromagnetic simulation of the coil, a parameterized curve was used to define its shape. The properties of the materials were set as follows: the conductivity of the MXene material was set to 3500 S/cm, and the relative permeability was set to 1. The coil was enclosed in a spherical air domain, with the conductivity of the air sphere set to 0 S/cm. A characteristic impedance of 50 ohms was set at the lumped port. The electromagnetic characteristics of the coil at 13.56 MHz were extracted in the frequency domain. For the mechanical simulation of the MXene-integrated device, a steady-state solution was used. Specific settings for the simulation can be referenced in Supplementary Note 1.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "The present version of this work cannot reach the level of Nature Communications.\nFirst, the innovation in this work appears limited. Structural design and interfacial interactions have already been extensively\nexplored in previously reported studies achieving similar functions. The structures or materials employed here appear to lack\nfundamental differences.\nDuring the tensile process, which specific interaction forces between MXene nanosheets resist slippage to maintain\nconstant resistivity? In situ TEM/SEM during tensile testing could visually confirm the stretching mechanism.\nCan the long-cycle performance of the sos-MXetronics, which is prepared solely through structural design optimization,\nremain stable under a strain of 40%? Data on environmental stability (e.g., humidity, temperature) and prolonged mechanical\nfatigue are needed.\nDo multilayer substrates design ensure adequate breathability in wearable devices? Please provide breathability test data\nfor the wearable devices.\nHow reliable are the sos-MXetronics during physical activity? Can sos-MXetronics maintain good adhesion to the skin\nduring sweating? Would physical activity and profuse sweating impact the accuracy of the sos-MXetronics readings?\nDoes the wearable device exhibit sufficient biocompatibility for prolonged skin contact? This research needs to provide the\nresults of cytotoxicity tests, as well as some data on the corrosion rate in simulated body fluids.\nProvide some discussion on Scalability Limitations due to solvent toxicity and cost.", "reviewer_2": "This manuscript reports an omnidirectional strain-invariant, fully MXene-based microgrid system (sos-MXetronics) that\nseamlessly integrates energy harvesting, storage, sensing, and wireless communication within a single architecture. This\nwork represents a substantial advance beyond all previously reported MXene-based integrated devices, both in terms of\nfunctional complexity and mechanical robustness, highlighting the critical role of multifunctional unit integration in advancing\nnext-generation wearable electronics. The research is comprehensive, the integration strategy is highly innovative, and the\noverall presentation is clear and compelling. Therefore, the manuscript could be published in Nature Communications after\nminor revision. My specific comments are as follows:\n1.MXene is prone to oxidation in humid or oxygen-rich environments. To more comprehensively understand its performance,\nit is necessary to determine whether the fully integrated device can operate reliably over the long term, especially given that\nwearable devices often function in sweat-rich environments.\n2.For MXene obtained via molten salt etching, is it possible to directly produce MXene nanosheets through ultrasonication to\navoid organic intercalation, or to use alkali metal salts for direct intercalation?\n3.The authors mention that the modulus of MXene is close to the GPa range and cite previous literature for support. Given\nthat different preparation methods can greatly influence the modulus of MXene, it is recommended that the authors measure\nand present the tensile stress–strain curves of their MXene to substantiate this claim.\n4.The authors propose unifying all components with MXene and have demonstrated its feasibility. Could this approach also\nbe applicable to other materials?\n5.The authors discuss the sensitivity range of the MXene pressure sensor; however, there is a lack of discussion on the\nsensor’s consistency and long-term cyclic stability, which are crucial for stable pulse measurement.\n6.In Figures 4i and 4j, the MXene coil charges wirelessly to 2.8 V. Why is this specific voltage chosen? Could it be higher or\nlower? In this regard, what considerations are involved in the matching design between the coil and the capacitor?\n7.The current system radius is 3.3 cm. For broader adoption, especially in wearable health monitoring, integration into\nsmaller form factors may be desired. A brief discussion on possible scaling strategies or design modifications for\nminiaturization would strengthen the impact.\n8.It is recommended to compare this work with all previously reported MXene fully integrated devices and highlight an in-\ndepth comparative analysis with other integrated systems, which would help enhance the depth of the paper and its\nrelevance from a forward-looking perspective.", "reviewer_3": "In this manuscript, the authors fabricate strain-invariant omnidirectional stretchable MXetronics (sos-MXetronics) through\nhierarchical stiffness engineering by introducing patterned elastiff regions and achieving strong bonding with an elastomeric\nsubstrate. The authors demonstrate the potential of sos-MXetronics for human physiological signal monitoring using fully\nMXene-based near-field communication (NFC) antennas, micro-supercapacitors (MSCs), and resistive-type pressure and\ntemperature sensors. Specifically, the sos-MXetronics successfully acquire pulse and body-temperature signals while\nminimizing the influence of wrist deformation, thereby improving data reliability. Overall, I think that the authors have\neffectively demonstrated the potential of sos-MXetronics for human physiological signal monitoring with convincing\nexperimental results. However, the manuscript lacks sufficient explanation regarding the operating mechanism of the\npressure sensor (P-sensor) and leaves some questions about the omnidirectional stability of fabricated electrode. Therefore, I\nrecommend that the authors address the following issues, as detailed below.\n1. More detailed specifications of the pressure sensor’s stability and properties should be analyzed.\n1.1. As mentioned in Figure 1, conventional stretchable devices without a hierarchical structure composed of elastiff and\nrigid layers often lose their electrical properties upon deformation. From this conclusion, the MXene spin-coated PDMS (PDMS–MXene) can be inferred to be unstable under compressive deformation. Therefore, the stability of the PDMS–\nMXene should be verified through cyclic loading tests.\n1.2. The observation that the intermittent pattern exhibits high pressure sensitivity but low strain sensitivity is an interesting\nand unique characteristic. However, the underlying mechanism for the enhanced sensitivity of the intermittent pattern\ncompared to the homogeneous pattern should be clarified for better reader understanding, which is likely related to changes\nin contact area under applied pressure. In addition, presenting the sensor’s performance under strain would help elucidate its strain-insensitive behavior. Moreover, in Supplementary Figure 24, the authors state that the intermittent pattern exhibits good hysteresis behavior as reported in previous studies; however, the relevant reference is not provided and should be cited.\n2. Additional analysis of line-pattern stability and deformation behavior is required.\n2.1. The interdigitated MXene patterns used in the pressure sensor and MSCs consist of line electrodes that are likely to be\nsignificantly influenced by the direction of applied strain. However, the manuscript only analyzes unidirectional deformation.\nTo validate the omni-directional stability of sos-MXetronics, additional tests under multi-directional deformation should be\nconducted.\n2.2. In Figure 2h, the relative resistance change of the straight-line structure with rigid isolation should also be evaluated to\nfurther support the stability of the line-patterned electrodes. Moreover, resistance variation under different strain directions\nshould be examined to confirm the claimed omni-directional mechanical stability.\n3. The effect of the serpentine electrode pattern is not clearly demonstrated in Figure 2h. Presenting a larger-scale graph\nwould help clarify its role in mechanical stability, and the inset image should be described in greater detail for better reader\nunderstanding.\n4. The authors successfully demonstrate the advantage of a fully MXene-based platform by employing MXene electrodes as\nNFC antennas, micro-supercapacitors (MSCs), and multifunctional sensors. However, it raises concerns about the long-term\nstability of the device, since MXene materials are prone to oxidation, which can significantly reduce their electrical\nconductivity over time. Therefore, a discussion or experimental verification of the device’s durability under ambient or\noperational conditions would be beneficial."}, "author_response": "List of Responses to the Reviewers’ Comments\nWe would like to thank the reviewers for their valuable comments and suggestions on this\nmanuscript (marked in blue color), which greatly improved the quality of our manuscript.\nFollowing these comments and suggestions, we have made careful revisions to our previous\nmanuscript and supplementary information (marked in red color), and provided responses to\nthe comments point-by-point as follows:\nReviewer #1 (Remarks to the Author):\nThe present version of this work cannot reach the level of Nature Communications.\nResponse:\nWe sincerely thank you for your thoughtful and candid assessment. We fully respect the high\nstandards of Nature Communications and appreciate your feedback, which has been very\nvaluable for strengthening the overall clarity and rigor of the manuscript. We believe the core\nconcept and findings of this work demonstrate substantial novelty and scientific significance-\nparticularly the introduction of hierarchical stiffness engineering, which enables\nomnidirectional strain-invariant all-MXene electronics.\nIn response to your comments, we have substantially expanded the experimental evidence,\nclarified the mechanistic insights, and improved the presentation of the key concepts. We hope\nthat the extensive new data and the strengthened discussions in the revised manuscript more\nclearly convey the originality, robustness, and broader impact of the proposed sos-MXetronics\nplatform.\nComment 1: First, the innovation in this work appears limited. Structural design and interfacial\ninteractions have already been extensively explored in previously reported studies achieving\nsimilar functions. The structures or materials employed here appear to lack fundamental\ndifferences.\nResponse:\nWe sincerely appreciate your insightful comment and fully agree that extensive efforts have\n1\nbeen devoted to structural design and interfacial engineering within the field of stretchable\nelectronics. However, the primary novelty of our work lies in realizing a fully integrated,\nsystem-level MXene-based microgrid platform rather than isolated structural optimization. We\nrespectfully clarify that the innovation of this study does not lie solely in structural design or\ninterfacial modification, but rather in achieving a system-level breakthrough that has not been\nrealized in previous MXene-based electronics.\nIt is important to note that the single island-bridge structure is effective for certain materials,\nsuch as liquid metals, which are inherently stretchable. These materials can endure large strains\nwithout compromising performance, making the single island-bridge design suitable for them.\nHowever, this approach is not applicable to MXene, which is inherently non-stretchable and\nbrittle under high strain. When MXene is directly patterned onto a soft elastomeric substrate, it\nexperiences localized strain concentration, leading to cracking and failure. Therefore, a single\nisland-bridge structure alone would be insufficient to maintain both the mechanical integrity\nand electrical conductivity of the system.\nTo address this limitation, we introduced a hierarchical stiffness microgrid architecture. In this\ndesign, MXene is initially deposited on PET islands, which have a modulus significantly higher\nthan the elastomeric layers (Ecoflex/PDMS). This configuration forms the first island-bridge\nlayer, where MXene is supported and stabilized by the rigid PET islands. Next, based on the\npatterned geometry of the PET islands, MXene is placed onto PDMS/Ecoflex islands, with the\nEcoflex /PDMS layers acting as soft, flexible bridges. This second layer forms another island-\nbridge structure, where the MXene is supported by the stiffer PDMS under regions requiring\nless flexibility (e.g., straight-line interdigital electrodes), while the softer Ecoflex supports more\nflexible regions (e.g., serpentine patterns). As a result, the system achieves omnidirectional\nstrain-invariant performance rather than mere unidirectional stretchability. In addition, the\nstrong interfacial coupling among the gradient elastomer layers (PDMS/Ecoflex) and the PET\ninterconnects ensures mechanical integrity and stable electrical coupling at high strain, which\ndistinguishes our sos-MXetronics from prior MXene-based devices that often suffer from\ndelamination or mismatch at heterogeneous interfaces.\nadded a new comparative schematic (Figure R1) that summarizes the evolution of MXene\nelectronics1-11, acknowledging the important contributions from previous researchers:\n Early MXene electronics demonstrated the integration of energy storage and consumption\nmodules on rigid silicon wafers, representing the initial proof of concept for MXene-based\nmicro supercapacitors. (ACS Nano 2022, 16, 3, 3776–3784)\n Subsequent studies combined rigid polysilicon photovoltaic collectors with MXene\nstorage units, achieving hybrid energy harvesting-storage integration. (Adv. Energy Mater.\n2021, 11, 2100746)\n The field then evolved toward multifunctionality and flexibility, exemplified by studies\nthat integrated MXene-based sensing and storage functions, as well as hybrid systems\ncombining energy harvesting and storage capabilities. (Adv. Mater. 2021, 33, 2005449,\nAdv. Mater. 2021, 33, 2007890, Nano Energy. 2018, 45, 266-272, Energy Storage Mater.\n2022, 50: 444-453)\n Further progress led to flexible system-level integrations, such as Yury’s MXene textile\nelectronics, Bai’s MXene implementations, and Ping’s high-concentration printed MXene\ndevices fabricated on flexible substrates. (Sci. Adv. 2024, 10(40): eadp8866, Nat Commun\n2022,13, 3223, Materials Today, 2024, 81: 59-69)\nomnidirectional strain-invariant sos-MXetronics.\nWhile these studies laid an essential foundation for MXene-based integration, none of the\nexisting systems can conform to continuously deforming, skin-like surfaces, nor have they\naddressed how mechanical strain affects the overall functionality of an integrated MXene\nsystem, which can lead to signal discontinuity, device failure, and inaccurate physiological\nreadings during real-world body motion. Moreover, although many previously reported systems\nappear to be “integrated,” in practice their individual functional units (e.g., sensors, storage,\nantennas) often operate independently and lack true synergistic coordination, resulting in\nsystems that are assembled rather than genuinely unified. This absence of system-level\n4\nintegration prevents consistent performance coupling among modules and limits real-world\napplicability. To overcome these limitations, we developed the first fully MXene-based\nomnidirectional strain-invariant wearable microgrid system, termed sos-MXetronics. All\nfunctional modules, such as energy harvesting, micro-supercapacitor storage, sensing, and NFC\ncommunication, are seamlessly interconnected through a common MXene network and\ncoordinated within a hierarchical stiffness microgrid framework, achieving minimal\nperformance variation (<5%) under 40% multidirectional strain. To clearly illustrate these\ndistinctions, we have added a comparative summary (Supplementary Table 1) that contrasts\nour sos-MXetronics with representative MXene-based electronic systems, highlighting the\nsuperior integration, mechanical robustness, and functional completeness of our approach.\nSupplementary Table 1 | Comparison of representative MXene-based multifunctional electronic\nsystems (Strain-invariant performance is expressed as the relative change in electrical signal\nunder the indicated tensile strain).\nFunctional Wireless Strain-\nMaterial Method Solvent Substrate function Ref\nCoupling Capability invariant\nFully coupled\nEcofelx/ Antenna, MSC, 40%\n(self-powered This\nTi3C2TX Spraying Water PDMS T/P sensors and Yes (change:\nand wirelessly work\n/PET wires < 5%)\ncommunicative)\nMSC, P Independent No Non-\nScreen\nTi3C2TX water A4 paper Sensor and (external signal (external stretchabl 1\nprinting\nwires readout required) source) e\nAntenna, Non-\nExtrusion\nTi3C2TX water PDMS MSC, and Sequential Yes stretchabl 2\nprinting\nsensors e\nNominally\nSensors, coupled (no Non-\nDrop-\nTi3C2TX water Parylene heater and demonstrated No stretchabl 3\ncasting\nstimulator wireless or e\nenergy linkage)\nPartial coupling\nNon-\nExtrusion T/P sensors (heterogeneous\nTi3C2TX water SBS Yes stretchabl 4\nprinting and MSC materials, limited\ne\nintegration)\n5\n100%\nTransfer- Independent\nTi3C2TX water PDMS Sensor No (change: 5\nprinting (only sensor)\n~ 60%)\nNon-\nDIW Coil，sEMG\nTi3C2TX water Textile Sequential No stretchabl 6\nprinting electrodes\ne\nAcetone Non-\nDrop- MScs and\nTi3C2TX -water Si Independent No stretchabl 7\ncasting wires\nmixture e\nPartial coupling\n600%\nExtrusion Coil and (heterogeneous\nEGaIn DMF IBA No (change: 8\nprinting wires materials, limited\n~ 100%)\nintegration)\nPartial coupling 400%\nStencil Electrode and\nEGaIn / SBS (heterogeneous yes (change: 9\nprinting wires\nmaterials) ~ 40%)\nPartial coupling Non-\nExtrusion TENG and\nGO water paper (heterogeneous yes stretchabl 10\nprinting wires\nmaterials) e\nNon-\nActivated Blade Coil and\nNMP PET Partial coupling No stretchabl 11\ncarbon coating MSC\ne\nIn addition to the architectural innovation, our work also introduces significant material-level\nadvances. Conventional MXene synthesis methods based on HCl/LiF etching systems typically\nyield small batch quantities and are not suitable for large-scale fabrication of integrated\nelectronics. To overcome this limitation, we employed a low-temperature molten salt (LTMS)\netching approach, which enables the rapid preparation of over 100 g of high-quality Ti C T\n3 2 X\nMXene within 5 min, ensuring both scalability and reproducibility across device fabrication.\nSupplementary Table 2 compares the LTMS-derived MXene with previously reported etching\nsystems, emphasizing its superior yield, shorter reaction time, and higher scalability12-15.\nSupplementary Table 2 | Comparison of time required between LTMS and other etching\nmethods.\nMAX Etching system Time Temperature Refs.\nTi AlC 12M HCl+50% HF 24 h 35°C 12\n3 2\n3 2 2\nTi AlC 9M HCl + 12M LiF 24 h 40°C 14\n3 2\nTi AlC 1.7M NH HF in PC 196 h 35°C 15\n3 2 4 2\nTi AlC 30% HF 5 h 40°C 14\n3 2\nTi AlC NH HF molten salt 5 min 130°C This work\n3 2 4 2\nIn addition, we further applied a Li+ ion-exchange treatment to replace the bulky TMA+ species\nwith smaller Li+ ions, effectively restoring compact interlayer coupling and achieving an\nexceptionally high conductivity of MXene (≈ 3500 S cm-1).\nAs shown in Figure R2, the Li+-intercalated MXene enabled efficient electromagnetic coupling\nand stable resonance behavior, which is essential for realizing high-efficiency energy harvesting\nand transmission in our sos-MXetronics system. In contrast, the MXene antenna fabricated\nusing TMA+-residual MXene exhibited excessive energy loss and failed to resonate effectively,\nconfirming that the low conductivity severely hampers wireless performance.\nThis material-level optimization therefore ensures lower Joule heating, higher power transfer\nefficiency, and reliable wireless operation under strain, complementing the structural\ninnovation to advance the overall system.\nCollectively, the combined architectural and material innovations enable our sos-MXetronics\nto achieve a truly integrated, scalable, and strain-invariant MXene system beyond the scope of\nprevious studies.\n(a) Schematic illustration of the low-temperature molten-salt (LTMS) etching and post-\ntreatment process. (b) Intercalation and Li+-exchange steps for conductivity enhancement. (c)\nPhotograph of the high-yield MXene powder and dispersion (≈ 100 g batch, 10mg/ml). (d)\nAntenna performance comparison showing that the TMA-MXene antenna exhibits high loss\nand suppressed resonance, while the Li-MXene antenna demonstrates efficient impedance\nmatching and strong resonance at 13.56 MHz.\nComment 2: During the tensile process, which specific interaction forces between MXene\nnanosheets resist slippage to maintain constant resistivity? In situ TEM/SEM during tensile\ntesting could visually confirm the stretching mechanism.\nWe sincerely appreciate your thoughtful question about the microscopic interactions that\nstabilize the electrical resistance of the MXene conductors during stretching. In our architecture,\nthe strain-invariant behavior arises primarily from the combination of strong interfacial bonding\nbetween MXene and the rigid PET island, and the strain-shielding effect provided by the\nhierarchical stiffness design, rather than from the MXene flakes needing to withstand large\ntensile deformation directly.\nFirst, the MXene film is supported on a PET island whose modulus is orders of magnitude\nhigher than that of the surrounding Ecoflex matrix. During tensile deformation, the global strain\nis preferentially absorbed by the soft Ecoflex, while the PET island acts as a rigid load-shielding\nplatform. Consequently, the MXene region experiences only a very small fraction under applied\nstrain. Second, the residual micro-strain that does reach the MXene film is dissipated through\nreversible interlayer sliding. Surface terminations (-O, -OH, -F) provide weak hydrogen-\nbonding and van der Waals interactions that can break and reform during deformation. This\nmechanism accommodates slight lateral displacement between nanosheets without producing\nlong, through-thickness cracks, thereby preserving electrical continuity.\nAs designed, the MXene films are patterned on serpentine-shaped PET islands, which act as\nrigid backbones embedded within a soft Ecoflex matrix. Under tensile deformation, the\nmajority of the applied strain is absorbed by the Ecoflex, while the serpentine PET confines the\nMXene layers to regions of minimal deformation. In our previous in situ mechanical-optical\ntests, we directly observed the evolution of microcracks in the MXene films during stretching\n(Supplementary Fig. 14, The first draft). The results show that visible cracks begin to appear\nonly when the global strain approaches 40%, yet the MXene networks remain electrically\nconnected without complete rupture. It is important to emphasize that the aim of our design is\nnot to induce strain in the MXene itself, but to maintain its electrical integrity by minimizing\ninternal displacement within the MXene network. Within this architecture, the hierarchical\nstiffness gradient (Ecoflex →PDMS→PET → MXene) creates an efficient strain-isolation\nmechanism, allowing the device to sustain stable conductivity without requiring MXene\n9\nnanosheets to bear large deformation.\nSupplementary Fig. 14 Crack evolution behavior of MXene films. (a) and (b) Schematic\nillustration of crack formation and propagation with and without isolation. (c) and (d) Optical\nimages showing crack propagation in MXene films with and without isolation under 0%, 20%,\n40%, 60%, and 100% strain states.\nFollowing your suggestion, we acknowledge that in situ SEM or TEM observation could in\nprinciple provide direct visual evidence of the nanosheet evolution during stretching. However,\nfor our system, this approach is technically challenging and of limited relevance. The sos-\nMXetronics employs a macroscopic serpentine MXene-PET-Ecoflex architecture, rather than a\nthin freestanding MXene film, making in situ electron microscopy under tensile loading\nextremely difficult. Moreover, the mechanical and optical coupling tests we have already\nconducted are able to directly capture the real-time evolution of MXene morphology during\nstretching at the device scale, which provides more representative information than localized\nnanoscale imaging. Therefore, we performed stepwise pre-stretching experiments and\nexamined the MXene films by SEM at different strain levels (0-120%). The films on PET\nislands show only fine, non-propagating micro-cracks even under high global strain, which\nvalidates the sliding-dominated deformation mechanism and confirms the structural integrity\nof the MXene.\nstretching.\nAccording to your suggestion, we have incorporated the SEM observations at different strain\nlevels into the Supplementary Information (Supplementary Fig. 15) and updated the\ncorresponding mechanistic descriptions in the revised main text accordingly:\n“The rigid serpentine PET island effectively shields the MXene film from large global strain,\nenabling the electrode to deform through localized MXene flake sliding rather than catastrophic\ncrack propagation. This prevents the formation of long cut-through cracks and large conductive\nislands, maintaining electrical integrity even under high tensile strain (Supplementary Fig. 14-\n17).” (Page 9-10)\nComment 3: Can the long-cycle performance of the sos-MXetronics, which is prepared solely\nthrough structural design optimization, remain stable under a strain of 40%? Data on\nenvironmental stability (e.g., humidity, temperature) and prolonged mechanical fatigue are\nneeded.\nResponse:\nWe sincerely thank you for emphasizing the importance of long-cycle and environmental\nstability. We fully agree that, beyond instantaneous strain-invariant performance, reliable\nmechanical and environmental robustness is essential for practical wearable applications. In the\n11\nrevised manuscript, we have therefore added comprehensive fatigue and stability evaluations\nat both the device and material levels, as summarized below.\n(1) Long-cycle mechanical fatigue under 40% strain\nTo assess long-cycle durability under large deformation, the fully integrated sos-MXetronics\nwas subjected to repeated stretching between 0% and 40% strain for 15000 cycles. After cycling,\nthe MXene NFC antenna, MSC array, pressure sensor, and temperature sensor were re-\ncharacterized. All modules retained their characteristic responses: the antenna preserved a\nstable output waveform and detection distance, the MSCs exhibited nearly unchanged CV\nbehavior, and both pressure and temperature sensors maintained consistent signal profiles.\nThese results agree with our original in situ tests, which showed <5% signal variation under\nrepeated 40% strain (Fig. 5d), collectively confirming that the hierarchical stiffness design\nsupports long-term cyclic operation without performance degradation.\nSupplementary Fig. 53 Long-term mechanical fatigue performance of the integrated sos-\nMXetronics. (a) Optical images of the integrated device at 0% and 40% tensile strain. (b)\nprofiles at cycle 2,000 and 14,000. (c) Performance of the MXene antenna, (d) MXene MSC\narray, (e) MXene P-sensor and (f) MXene T-sensor at the initial state, after 7500 cycles, and\nafter 15000 cycles.\n(2) Environmental stability under temperature–humidity aging\nMXene oxidation is known to occur only when both water and oxygen are present, and the\ndegradation rate follows Arrhenius-type temperature dependence. For this reason, we selected\ntwo representative environments that together capture the practically relevant oxidation\nenvelope:\n• 60°C, 100% RH – an accelerated aging condition widely used in MXene stability studies\n• 25°C, 50% RH – typical ambient conditions for wearable electronics\nThis pair of conditions is sufficient to evaluate degradation without considering low-\ntemperature environments, as MXene is typically stored only under refrigerated conditions to\nensure long-term aqueous dispersion stability, and actual devices operate under room\ntemperature conditions. Under 60°C and 100% RH, unencapsulated MXene rapidly oxidized,\nwith its resistance increasing by more than seven orders of magnitude within 10 days,\neventually exceeding the 200 MΩ limit of our multimeter and becoming unmeasurable. In\ncontrast, Ecoflex-encapsulated MXene showed only a ~103-fold increase after 15 days\n(Supplementary Fig. 54), demonstrating that the elastomer layers significantly retard moisture\ningress. Under 25°C and 50% RH, unencapsulated MXene exhibited only ~15-fold resistance\nincreases over 30 days, whereas the encapsulated MXene changed by merely ~1-fold. This\nsuggests minimal degradation in normal wearable conditions, consistent with the fact that\nMXene oxidation is strongly humidity- and temperature-dependent.\nMXetronics. (a) Resistance evolution (R/R ) of MXene films with and without Ecoflex\n0\nencapsulation under accelerated aging (60°C, 100%RH) (b) Resistance evolution (R/R ) of\n0\nencapsulation under accelerated aging (25°C,\n50%RH). (c) Photographs showing that the integrated sos-MXetronics remains fully functional,\npowering on normally after 1, 10, and 30 days of storage at room temperature and moderate\nhumidity.\nTo further verify device-level robustness, we evaluated the integrated sos-MXetronics stored at\n25 °C and 50% RH for 1, 10, and 30 days. The system powered on normally, established NFC\ncoupling, and transmitted data without failure at all tested time points (Supplementary Fig. 54).\nWe have added these newly obtained datasets to Supplementary Figs. 53 and 54, and the key\nfindings have been incorporated into the revised main text as follows.\n“Furthermore, the pressure and temperature sensors show minimal variation (<5%) under\n14\nrepeated 40% strain (Fig. 5d and Supplementary Video 6). And device-level fatigue testing up\nto 15,000 stretching cycles reveals no detectable degradation in the electrical or sensing\nperformance of the integrated system (Supplementary Fig. 53), confirming its long-term\nmechanical robustness.” (Page 18)\nComment 4: Do multilayer substrates design ensure adequate breathability in wearable\ndevices? Please provide breathability test data for the wearable devices.\nResponse:\nWe sincerely thank you for raising this important question regarding breathability. We fully\nagree that breathability is a key consideration for certain categories of long-term wearable\nelectronics, particularly those based on textiles or porous membranes.\nHowever, in our system, the multilayer substrate is designed primarily for mechanical strain\nredistribution and protection of the MXene conductive network, rather than for facilitating air\nor moisture transport. The skin-facing layers consist of Ecoflex and PDMS, both of which are\nwidely used in soft bioelectronics and medical-grade epidermal devices. These elastomers offer\nexcellent elasticity, conformability, and biocompatibility, which are essential for achieving the\nomnidirectional strain-invariant behavior that defines the core contribution of this work.\nFigure R3 Water-vapor transmission rate (WVTR) of Ecoflex and PDMS. (a) Schematic of\nthe cup test setup used for WVTR measurement. (b) Comparison of WVTR for open, Ecoflex,\nconditions. Scale bar, 1.5 cm.\nTo provide quantitative evidence, we additionally measured the water-vapor transmission rate\n(WVTR) of Ecoflex and PDMS using a standard cup method (Figure R3). As expected for\nEcoflex or PDMS elastomers, both materials exhibit moderate WVTR values that are higher\nthan glass and lower than open conditions, indicating that they still allow a certain level of\nwater-vapor transmission suitable for short-term skin contact. Importantly, these values are\nconsistent with previously reported ranges for skin-compatible elastomeric membranes that\nhave been successfully used in ECG patches, temperature sensors, and epidermal microfluidic\ndevices (Nature Electronics 2024, 7, 51-65, Nature Electronics 2025, 8, 981-993)16, 17. These\nprecedents indicate that although Ecoflex and PDMS are not highly breathable, they are fully\nsuitable for short- to medium-term wear without causing discomfort or compromising device\nperformance. In our application scenario, the device is designed as a soft, integrated electronic\npatch for medium-term physiological monitoring, where mechanical robustness and electrical\nreliability are far more essential than breathability.\nWe would also like to emphasize that the multilayer configuration provides an additional\npractical benefit for MXene-based electronics. Because an Ecoflex overlayer is added as the\nfinal encapsulation layer, the system becomes even more effective at blocking moisture and\noxygen permeation. This reduced exposure significantly slows MXene oxidation, thereby\nextending the operational lifetime of Ti C T -based devices.\n3 2 x\nWe truly appreciate your insightful perspective. Indeed, integrating the strain-invariant MXene\narchitecture with breathable textiles or porous substrates represents an exciting future direction\nthat could merge mechanical robustness, multifunctional integration, and long-term comfort.\nYour suggestion will be an important inspiration for our subsequent work.\nComment 5: How reliable are the sos-MXetronics during physical activity? Can sos-\nMXetronics maintain good adhesion to the skin during sweating? Would physical activity and\nprofuse sweating impact the accuracy of the sos-MXetronics readings?\nWe sincerely thank you for raising this important question regarding the reliability of the sos-\nMXetronics during physical activity and under sweating conditions. Ensuring stable skin\nadhesion and signal accuracy in realistic scenarios is indeed essential for wearable health\nmonitoring. Following this valuable suggestion, we conducted additional experiments to\nsystematically examine (i) sweat-affected adhesion, (ii) waterproof integrity, and (iii) pulse-\nmonitoring accuracy during daily movements and perspiration.\n(1) Adhesion performance under sweat\nWe fully agree with you that sweat may influence the adhesion of skin-mounted devices.\nBecause the device contacts the skin through the Ecoflex/PDMS elastomer (with the\nMXene/PET layer fully encapsulated and not in direct skin contact), we evaluated its adhesion\nstrength on porcine skin with and without artificial sweat. As shown in Supplementary Fig. 63,\nsweat slightly reduces adhesion. (Ecoflex: 6.7 →4.1 kPa; PDMS: 2.4 →1.5 kPa), but the\nadhesion remains sufficiently strong for reliable wear. Cross-sectional images also confirm\nconformal contact between the elastomer and skin even in the presence of sweat.\nEcoflex/PDMS substrate. (a) Human skin after spraying saline to simulate perspiration. (b)\nCross-sectional image of Ecoflex adhered to pigskin. (c,d) Photographs showing device contact\nunder water flushing. (e) Schematic of the peel-test setup. (f) Adhesion curves and averaged\nadhesion strength of Ecoflex on pigskin with and without sweat. (g) Adhesion curves and\naveraged adhesion strength of PDMS on pigskin with and without sweat.\n(2) Waterproof stability of the integrated device\nYou also raised an important point regarding the effect of sweat on device integrity. After\npatterning, the entire sos-MXetronics is encapsulated with an additional thin Ecoflex overlayer,\nforming a fully sealed and waterproof structure. As demonstrated in Supplementary Fig. 63c-d,\nthe device maintains firm attachment even under continuous water rinsing. This confirms that\nexternal moisture cannot penetrate the encapsulation nor reach the MXene conductor network.\nThe waterproof configuration not only ensures stable operation during sweat exposure but also\nhelps slow MXene oxidation, thereby enhancing long-term device reliability.\n18\n(3) Signal reliability during physical activity and perspiration\nTo directly assess whether movement or sweating affects physiological sensing accuracy, we\nrecorded pulse signals during walking, jumping, and sweating (Supplementary Fig. 64). During\nwalking, the pulse waveform and extracted systolic/diastolic peaks remain nearly unchanged\nfrom the resting state, indicating that mild motion introduces minimal interference. During\njumping, short motion artifacts occur at landing moments, but the waveform rapidly returns to\nits original form, and the estimated blood pressure remains consistent (e.g., 114/76 → 113/76\nmmHg). Under perspiration, pulse waveforms remain stable and nearly identical to dry\nconditions, confirming that neither sweat nor slight moisture accumulation affects sensing\nfidelity. These results collectively demonstrate that the hierarchical stiffness design effectively\nisolates the sensing region from mechanical disturbances and preserves consistent physiological\nsignal acquisition during realistic physical activity and perspiration.\nSupplementary Fig. 64 Pulse monitoring under different motion and perspiration\nconditions. (a) Pulse waveforms measured at rest (top) and during walking (bottom). (b) Pulse\nwaveforms measured at rest (top) and during jumping (bottom). (c) Pulse waveforms measured\nat rest (top) and under simulated sweating (bottom). Systolic and diastolic pressure estimates\n19\n(SBP/DBP) are shown above each waveform.\nTogether, these results confirm that the sos-MXetronics maintain strong adhesion, waterproof\nintegrity, and high-quality physiological signal acquisition during realistic physical activity and\nsweating. We have added these new datasets to the revised Supplementary Information and\nhave updated the corresponding discussion in the manuscript. These two new datasets have\nbeen added to the revised Supplementary Information, and the corresponding discussion has\nbeen incorporated into the main text as follows:\n“In addition, the integrated system maintains stable pulse waveforms and consistent SBP/DBP\nestimation during walking, jumping, and sweating, indicating that daily motion and perspiration\ndo not compromise the sensing performance of the sos-MXetronics (Supplementary Figs. 63\nand 64)” (Page 21)\nComment 6: Does the wearable device exhibit sufficient biocompatibility for prolonged skin\ncontact? This research needs to provide the results of cytotoxicity tests, as well as some data\non the corrosion rate in simulated body fluids.\nResponse:\nWe sincerely thank you for raising this important question regarding biocompatibility and\ncorrosion stability. We fully agree that both aspects are critical for the safe use of wearable\nMXene-based electronics.\nFirst, we would like to clarify that in our sos-MXetronics the skin-contacting layers are Ecoflex\nand PDMS, while the MXene films are fully encapsulated and never directly contact the skin\nor sweat. To quantitatively evaluate the cytocompatibility of these elastomer layers, we\nperformed CCK-8 assays using fibroblast cells cultured with extracts of Ecoflex and PDMS.\nAs shown in Supplementary Fig. 52a, the optical density (OD@450 nm) for Ecoflex and PDMS\ngroups at days 1 and 3 is comparable to that of the control group, with no statistically significant\ndifferences, indicating no detectable cytotoxicity. In addition, live/dead staining\n(Supplementary Fig. 52b) shows uniformly high cell viability and normal cell morphology for\n20\nboth Ecoflex and PDMS over three days of culture. These results confirm that the actual skin-\ncontact materials in our device are cytocompatible and suitable for prolonged epidermal contact.\nSupplementary Fig. 52 Cytocompatibility of Ecoflex and PDMS. (a) CCK-8 assay results\n(OD at 450 nm) of bone-marrow-derived mesenchymal stem cells cultured in the presence of\nEcoflex and PDMS membranes for 1 and 3 days, with untreated cells used as the control. (b)\nFluorescence images of live/dead-stained cells after 1 and 3 days of culture in the three groups\n(control, Ecoflex, and PDMS). Scale bars, 100 µm.\nSecond, to address your concern about corrosion behavior in physiological environments, we\ncompared the stability of MXene films with and without Ecoflex encapsulation. MXene-coated\nsamples were immersed in mildly acidic phosphate buffer (pH ≈ 6) at 37 °C for 10 days. For\neach sample, we measured the mass retention (M/M ) after 10 days and monitored the electrical\n0\nresistance change (R/R ) over time. As shown in Supplementary Fig. R4a, both encapsulated\n0\nand non-encapsulated films exhibit similar mass retention after 10 days. However, the electrical\nresistance of the non-encapsulated MXene increases by nearly three orders of magnitude,\nwhereas the encapsulated MXene shows only about one order of magnitude increase\n(Supplementary Fig. R4b). These results demonstrate that the Ecoflex encapsulation layer\neffectively suppresses electrochemical degradation and greatly slows conductivity loss in\nsimulated body-fluid conditions, consistent with the waterproof behavior observed in our on-\nskin tests.\nretention ratio (M/M ) of MXene films without encapsulation and with Ecoflex encapsulation\n0\nafter 10 days of immersion in phosphate buffer (pH ≈ 6) at 37 °C.(b) Time-dependent resistance\nratio (R/R ) of MXene films without and with encapsulation measured over 10 days under the\n0\nsame conditions.\nTogether, the cytotoxicity evaluation of Ecoflex/PDMS and the corrosion tests of encapsulated\nMXene films confirm that the sos-MXetronics are suitable for prolonged skin contact, because\nthe encapsulation strategy provides robust protection for the MXene components. We have\nadded the new datasets to the Supplementary Information and briefly discussed them in the\nrevised manuscript, as follows:\n“The entire sos-MXetronics could withstand 40% tensile strain deformation without any\nphysical damage (Fig. 5c), enabling conformal and biocompatible contact with the wrist for\nstable, long-term pulse-rate and temperature monitoring. (Fig. 5e and Supplementary Fig.52).”\n(Page 18)\n“Cytotoxicity and Live/Dead Assays\nCytocompatibility of Ecoflex and PDMS was evaluated using bone-marrow–derived\nmesenchymal stem cells. Samples (10 mm diameter) were sterilized and incubated with cells\n(2 × 104 cells per well) in 48-well plates. Cell viability was quantified by a CCK-8 assay\n(OD450, Day 1 & Day 3) and further visualized by Live/Dead fluorescence staining.” (Page\n29)\nComment 7: Provide some discussion on Scalability Limitations due to solvent toxicity and\n22\ncost.\nResponse:\nWe sincerely thank you for raising this important point about scalability, solvent toxicity, and\ncost. We fully acknowledge that large-scale implementation of MXene production still faces\nseveral practical constraints, particularly related to etching chemistry and delamination solvents.\nIn our current process, the low-temperature molten-salt (LTMS) route relies on NH HF as the\n4 2\nfluorine source. Although NH HF is substantially safer and requires far smaller quantities than\n4 2\nconventional direct HF etching, its handling and the resulting fluorinated wastewater still\nimpose environmental and economic burdens at industrial scale. We also recognize that our\ndelamination step employs TMAOH, an organic intercalant that is relatively expensive and\nrequires careful waste-management procedures—representing a non-trivial limitation for large-\nvolume manufacturing. At the same time, we note that the LTMS approach significantly\nimproves the inherent scalability of MXene synthesis. The solid-state etching reduces liquid-\nphase chemical consumption, minimizes by-product generation, and eliminates highly\nconcentrated fluoride solutions. Moreover, only a very small quantity of TMAOH is required\nto achieve high-yield delamination, and the resulting MXene films are only a few micrometers\nthick, meaning the material cost per device remains relatively low.\nLooking ahead, we acknowledge that further improvement is required for practical large-scale\nproduction. In particular, the use of NH HF and TMAOH represents the main sources of\n4 2\ntoxicity and cost in the current workflow. Recent literature has reported several promising\ndirections—such as alternative milder fluorine sources, organic-free intercalation routes, and\nimproved wastewater treatment protocols—that could reduce the environmental and economic\nburden of MXene production. While these strategies are still in early development, they\nhighlight feasible opportunities for future process optimization and greener scale-up.\nWe have incorporated this discussion into the revised manuscript to more explicitly articulate\nthe scalability limitations and future opportunities associated with solvent use and cost, as\nfollows:\n“Despite these benefits, the use of NH HF and TMAH still presents scalability challenges in\n4 2\n23\nterms of solvent toxicity and cost.” (Page 9)\nThis manuscript reports an omnidirectional strain-invariant, fully MXene-based microgrid\nsystem (sos-MXetronics) that seamlessly integrates energy harvesting, storage, sensing, and\nwireless communication within a single architecture. This work represents a substantial\nadvance beyond all previously reported MXene-based integrated devices, both in terms of\nfunctional complexity and mechanical robustness, highlighting the critical role of\nmultifunctional unit integration in advancing next-generation wearable electronics. The\nresearch is comprehensive, the integration strategy is highly innovative, and the\noverall presentation is clear and compelling. Therefore, the manuscript could be published in Nature\nCommunications after minor revision. My specific comments are as follows:\nResponse:\nThank you so much for the positive comments! We sincerely thank you for your thoughtful\nassessment of our manuscript and for acknowledging the strengths of the proposed sos-\nMXetronics system. All specific concerns have been carefully addressed point by point, with\ncorresponding revisions and additional data incorporated into the updated version.\nComment 1: MXene is prone to oxidation in humid or oxygen-rich environments. To more\ncomprehensively understand its performance, it is necessary to determine whether the fully\nintegrated device can operate reliably over the long term, especially given that wearable\ndevices often function in sweat-rich environments.\nResponse:\nWe sincerely appreciate your question regarding long-term stability, especially under humid or\nsweat-rich conditions. To address this concern, we conducted additional temperature–humidity\naging tests and device-level evaluations.\nMXene oxidation requires both water and oxygen and accelerates with temperature. To evaluate\n25\nenvironmental stability, we tested MXene films with and without elastomer encapsulation under\n60 °C/100% RH and 25 °C/50% RH. Unencapsulated MXene degraded rapidly in the\naccelerated condition, with resistance increasing by >107-fold within 10 days, whereas\nencapsulated MXene increased only ~103-fold after 15 days. Under ambient conditions,\nencapsulated MXene showed only minor changes (~1-fold), while unencapsulated MXene\nincreased by ~15-fold (Supplementary Fig. 54). In parallel, the integrated sos-MXetronics\nremained fully operational after 1, 10, and 30 days of ambient storage, with reliable powering,\nNFC coupling, and physiological-signal transmission (Supplementary Fig. 54), confirming\nstable long-term performance.\nSupplementary Fig. 54 Environmental stability of MXene films and integrated sos-\nMXetronics. (a) Resistance evolution (R/R ) of MXene films with and without Ecoflex\n0\nencapsulation under accelerated aging (60°C, 100%RH) (b) Resistance evolution (R/R ) of\n0\nencapsulation under accelerated aging (25°C,\n50%RH). (c) Photographs showing that the integrated sos-MXetronics remains fully functional,\n26\npowering on normally after 1, 10, and 30 days of storage at room temperature and moderate\nhumidity.\nThese results demonstrate that the elastomer encapsulation effectively suppresses MXene\noxidation and enables reliable long-term operation under realistic wearable environments. The\ncorresponding data and discussion have been added to the revised manuscript.\n“In addition, temperature-humidity aging tests demonstrate that the elastomer encapsulation\neffectively suppresses MXene oxidation, enabling stable device operation even after 30 days of\nenvironmental exposure (Supplementary Fig. 54)” (Page 18)\nComment 2: For MXene obtained via molten salt etching, is it possible to directly produce\nMXene nanosheets through ultrasonication to avoid organic intercalation, or to use alkali metal\nsalts for direct intercalation?\nResponse:\nWe sincerely thank you for raising this important question regarding the delamination pathway\nof MXene produced through low-temperature molten-salt (LTMS) etching. To directly address\nyour concern, we systematically compared three possible routes—(i) alkali-metal-salt\nintercalation, (ii) direct ultrasonication, and (iii) organic intercalation followed by Li⁺\nexchange—and summarize our findings below.\nMolten-salt-etched MXenes are known to exhibit densely packed, accordion-like multilayers\nwith much stronger interlayer coupling than MXenes produced by traditional HCl/LiF routes\n(Chemistry of Materials 29.18 (2017): 7633-7644). Consequently, direct ultrasonication of these\nmultilayer MXenes results in extremely low yields, because their interlayer bonding is\nsignificantly stronger than that in graphite or bulk MoS₂, making sonication alone insufficient\nfor effective delamination. To overcome this limitation, polar organic molecules such as\nhydrazine, urea, dimethyl sulfoxide (DMSO), isopropylamine, and larger organic bases (e.g.,\n27\ntetrabutylammonium hydroxide, choline hydroxide, or n-butylamine) are commonly used as\nintercalants. Intercalation with these species followed by mechanical shaking or ultrasonication\nin water effectively expands the interlayer spacing, enabling the formation of single- or few-\nlayer colloidal MXene dispersions. Furthermore, some well-studied MXenes such as Ti C T\n3 2 x\ncan also be delaminated through metal-cation intercalation using aqueous solutions of ionic\ncompounds (e.g., halide salts or metal hydroxides). In fluoride-containing etching systems (e.g.,\nHCl/LiF), additional organic intercalants are not strictly necessary because metal cations are\nintroduced in situ during synthesis, allowing delamination simply by increasing the pH to near-\nneutral and applying mild mechanical agitation.\nBased on these mechanistic insights, we systematically compared the three practical routes for\nLTMS-derived MXene, as described below.\n(i) Alkali-metal-salt intercalation:\nWhen 1 g of LTMS-derived MXene was treated with 1 mol/L LiCl, the resulting dispersion\nreached only ~0.35 mg/mL with a yield < 5 %. Such poor exfoliation arises because Li+ can\neffectively intercalate only when Cl- surface terminations are present, which are largely absent\nin molten-salt-etched MXene. The dense multilayer morphology and limited ion mobility of\nsmall inorganic cations further hinder effective intercalation.\n(ii) Direct ultrasonication:\nFor 1 g of MXene obtained from the LTMS etching process, direct ultrasonication in 100 mL\nof deionized water yielded a colloidal concentration of approximately 0.8 mg/mL,\ncorresponding to a monolayer yield below 10 %. Most of the product remained in a multilayer\nstate because the molten-salt environment produces tightly stacked MXene with strong\ninterlayer coupling, which resists delamination by sonication alone. This is consistent with\nprevious reports that molten-salt-etched MXenes possess much stronger interlayer interactions\nthan van-der-Waals solids such as graphite or MoS .\n2\nmolten-salt (LTMS) etching. (a–c) Schematic illustration of three exfoliation approaches:\n(d, e) Photographs of the resulting dispersions after reaction and after centrifugation. (f)\nQuantitative comparison of single- and few-layer MXene yields from the three routes.\n(iii) Organic intercalation and Li⁺ exchange (optimized route):\nUsing 1 mol/L TMAOH as the intercalant produced a stable colloidal dispersion of ~5.3 mg\nmL-1 (in 100 mL), corresponding to a monolayer yield >50 %. This expansion allows efficient\ndelamination and printing of uniform conductive films. To restore electrical conductivity\nreduced by residual TMA+ species, a Li+ exchange step was subsequently introduced, yielding\ncompact stacking and high conductivity (~3500 S/cm).\nThese experimental results and mechanistic considerations show that organic intercalation is\nnot only effective but necessary for LTMS-derived MXene, whereas alkali-metal-salt\nintercalation and direct ultrasonication alone are insufficient to generate high-quality, large-area\nnanosheets.\nWe have added this discussion to the Supplementary Information (Supplementary Note 3) to\nclarify the rationale behind our exfoliation strategy. As follow:\n“MXenes obtained from LTMS etching show densely stacked multilayers that cannot be\n29\neffectively delaminated by ultrasonication or simple alkali-metal-salt intercalation, both\nproducing only a very small amount of single/few-layer flakes” (Supplementary Information\nPage 8)\nComment 3: The authors mention that the modulus of MXene is close to the GPa range and cite\nprevious literature for support. Given that different preparation methods can greatly influence\nthe modulus of MXene, it is recommended that the authors measure and present the tensile\nstress–strain curves of their MXene to substantiate this claim.\nResponse:\nWe sincerely appreciate your insightful comment. You are absolutely correct that the modulus\nof MXene is strongly dependent on the synthesis route, surface terminations, and film assembly\nprocess, and therefore literature values alone cannot fully substantiate our claim. To directly\nvalidate the mechanical properties of the MXene used in this work, we measured the tensile\nstress-strain behavior of our LTMS-derived, Li+-exchanged MXene films.\nFreestanding MXene films were prepared by spray-coating concentrated MXene dispersions\n(~10 mg/mL) and subsequently releasing the films to obtain uniform test specimens. The\nobtained MXene membranes were laser-cut into rectangular specimens (15 mm × 5 mm, 2-3\nμm). SEM imaging revealed a dense lamellar microstructure with tightly stacked nanosheets\nand strong interlayer coupling, indicative of a highly ordered architecture (Figure R6).\n(a) Photograph of the freestanding MXene specimen (15 mm × 5 mm) mounted on the micro-\ntensile tester. (b) Representative tensile stress-strain curve showing a linear elastic region\nfollowed by brittle fracture. (c) Summary of the mechanical parameters extracted from multiple\nsamples. (d) Cross-sectional SEM image of the MXene film after fracture.\nTensile testing was conducted on a precision micro-mechanical tester (FET-60) at a strain rate\nof 1 mm/min under ambient conditions. The stress-strain curves display a distinct linear elastic\nregion followed by brittle fracture. The extracted Young’s modulus of the MXene films was\nfound to be 6-7 GPa, with a fracture strength of ~80 MPa and an elongation at break of\napproximately 2% (Figure R6).\nThese experimentally obtained values confirm that our LTMS-derived, Li+-exchanged MXene\nfilms indeed possess GPa-level stiffness, directly substantiating the claim in the main text.\nThe modulus is also slightly higher than that of vacuum-filtered MXene films reported previously\n(typically 3-5 GPa; J. Mater. Chem. C 2020, 8.21, 7170-7180; Adv. Mater. Interfaces 2021, 8,\n2002043.)18, 19, which attributes to the compact stacking and removal of bulky organic residues\nthrough Li+-exchange process.\nOverall, these results confirm that our MXene films possess robust mechanical strength and\n31\nstiffness consistent with the GPa-level modulus assumed in our analysis. The high in-plane\nmodulus ensures that the MXene regions within the hierarchical stiffness microgrid act as rigid\nconductive domains, thereby preserving electrical continuity and enabling the strain-invariant\nbehavior of the sos-MXetronics system during deformation.\nAccordingly, we have revised relevant discussions in the manuscript, and the tensile\ncharacterization of the MXene films has been added in the Supplementary Information to\ncomplement the discussion of their mechanical properties. As follow:\n“We used PET as the substrate to support the MXene layers. The PET (modulus of 1.78 GPa,\nSupplementary Fig. 9) was selected for its close mechanical match to our MXene films\n(measured modulus of 6.39 GPa).” (Page 9)\n“PDMS and Ecoflex were cast into dumbbell-shaped molds for tensile testing, while PET was\nlaser-cut into dumbbell-shaped specimens from available rectangular sheets. Serpentine PET\nand serpentine PET/Ecoflex were directly stretch according to the original pattern. A strain rate\nof 50 mm·min-1 was applied during stretching, with force and displacement values recorded\nby the tensile testing machine (LDW-1). For MXene films, These films were laser-cut into\nrectangular strips (15 mm × 5 mm) for tensile testing under the same conditions.” (Page 29-30)\nPhotograph of the tensile specimen. (b) Stress-stretch curves of samples. (c) Photograph of the\ntensile specimen of MXene. (d) Stress-stretch curves of MXene films. (e)Young's modulus and\nfracture elongation of PDMS, Ecoflex, PET and MXene. (d) Stress-strain curves of PDMS with\nvarying curing agents.\nComment 4: The authors propose unifying all components with MXene and have demonstrated\nits feasibility. Could this approach also be applicable to other materials?\nResponse:\nWe sincerely thank you for raising this important question regarding the generalizability of our\nsingle-material integration strategy. The selection of MXene was based on its unique\ncombination of several critical features: (i) metallic-level conductivity, suitable for antennas\nand current collectors, (ii) rich surface terminations, enablig the electrochemical activity for\nenergy storage, (iii) solution processability for printing and coating, and (iv) mechanical\nflexibility, compatible with stretchable systems. These attributes collectively make MXene an\nideal platform for integrating all components within one architecture.\nImportantly, the underlying hierarchical stiffness engineering strategy is fundamentally\nmaterial-agnostic. In principle, any material that can be processed into continuous thin films,\npatterned into functional structures, and integrated with elastomeric substrates while providing\ntunable modulus contrasts could be adopted within this framework. Examples include graphene\nfilms, CNT papers, PEDOT:PSS, metal nanowire networks, and other emerging multifunctional\nconductors.\nThat said, most alternative systems exhibit inherent trade-offs that hinder true single-material\nintegration. For example, a recent study based on graphite paper (Nat. Commun. 2021, 12,\n2647)11 demonstrated energy harvesting and storage functionalities within a carbon-based\nsystem. However, these approaches generally face limitations in either multifunctionality (for\ninstance, achieving good conductivity but insufficient electrochemical performance) or\nprocessability (difficulty in forming both structural and functional components within a single\nframework)\nWe have clarified this discussion in the revised manuscript, emphasizing the following addition:\n“However, such a strategy is often constrained by the intrinsic limitations of individual\nmaterials, which generally fail to satisfy the broad spectrum of performance criteria required\nby different functional devices (for example, although copper and liquid metals are commonly\nused in electrical wiring, they are unsuitable for energy storage applications due to inherent\ntrade-offs among electrical conductivity, electrochemical activity, and processability)” (Page 3)\n“MXene-based electronics, utilizing monolayer Ti3C2Tx MXene flakes with superior\nmechanical properties9, exhibit exceptional intra-layer conductivity enabled by the\nhybridization of transition metal and carbon atoms.10-12. This unique electronic structure\nfacilitates the efficient spread of electronic states, enabling the development of epidermal soft\nelectronics, “MXetronics”13, and provides a versatile foundation for single-material integration.”\n(Page 3-4)\nComment 5: The authors discuss the sensitivity range of the MXene pressure sensor; however,\nthere is a lack of discussion on the sensor’s consistency and long-term cyclic stability, which\nare crucial for stable pulse measurement.\nResponse:\nWe sincerely thank you for highlighting the importance of device-to-device consistency and\nlong-term cyclic stability, which are indeed essential for reliable pulse acquisition. To address\nyour concern, we have now conducted additional statistical and durability evaluations of the\nMXene pressure sensor, and the results confirm excellent reproducibility and stability.\nFirst, to assess intra-device repeatability, we measured the pressure-response curves of the same\nsensor across three independent runs. As shown in Supplementary Fig. 27a, the three curves\nnearly overlap, and the 90% confidence/prediction bands remain narrow across the entire\npressure range, demonstrating high measurement consistency. Second, to evaluate device-to-\ndevice reproducibility, we examined three sensors fabricated in different batches. As shown in\nSupplementary Fig. 27b, all sensors exhibit highly similar response profiles and saturation\nbehaviors within the low-pressure regime (<40 kPa) relevant to pulse monitoring, confirming\nrobust fabrication uniformity.\nSupplementary Fig. 27 Consistency and reproducibility of the MXene P-sensor. (a)\nRepeated pressure-response measurements. (b) Pressure-response curves from three\nindependently fabricated MXene P-sensor.\nThird, we performed a long-term cyclic compression test under ~2 kPa for 25000 cycles. The\nsensor maintains stable current outputs without noticeable signal drift or amplitude decay, and\nrepresentative cycles at the 10th, 10000th, and 20000th cycles show nearly identical waveforms\n(Figure. R7). These results verify that the MXene-PDMS active layer remains structurally and\nelectrically stable under repeated low-pressure operation.\nkPa loading for 25000 cycles.\nWe sincerely thank the reviewer for this important comment. We fully agree that consistency\nand long-term cyclic stability are indispensable metrics for reliable pressure sensing, especially\nfor continuous physiological signal monitoring such as pulse detection. In the original\nmanuscript, our focus was mainly on the sensitivity range, but we realize that the absence of\nexperimental evidence on repeatability and durability might leave concerns about the\nrobustness of the device performance.\nWe have included the new data in the Supplementary Information (Supplementary Fig. 30) and\nadded corresponding descriptions in the revised manuscript:\n“Extensive experimental data (Fig. 3c) show that the incorporation of intermittent structure also\nenhanced the electrical performance of the sensing film, with the sensitivity of 56.1 kPa-1 in the\nlow-pressure region, which is about 120 times greater than planar film-based P-sensor\n(Supplementary Fig. 26)” (Page 13)\n“Additionally, the sensor demonstrates fast and accurate responses to subtle pressures below 10\nkPa, as displayed in Figure 3d, and maintains highly stable performance over 25000 cyclic\ncompressions (Supplementary Fig. 30).” (Page 13)\nspecific voltage chosen? Could it be higher or lower? In this regard, what considerations are\ninvolved in the matching design between the coil and the capacitor?\nResponse:\nWe thank you for this insightful question. The charging voltage of ~2.8 V is determined jointly\nby the electrochemical window of our MXene micro-supercapacitors (MSCs) and the load\ncharacteristics of the integrated MXene NFC coil. Each MSC operates safely within a 0.6 V\nwindow. By connecting five MSCs in series, the total working voltage extends to 3.0 V, which\nis close to the maximum value that can be applied without electrolyte decomposition or\nelectrode polarization. Meanwhile, the MXene coil exhibits an open-circuit voltage of 3.1-3.3\nV. When the MSC array is connected, the system naturally stabilizes at 2.6-2.9 V under load,\nmaking the measured 2.8 V the highest stable charging voltage achievable without exceeding\nthe MSCs’ electrochemical limit.\nIn principle, this voltage could be tuned. As illustrated in Figure R8, a step-up (boost)\ncircuit can raise the coil output to ~5 V, while a step-down regulator can reduce it to ~1 V depending\non the device requirements. However, our intent in this work is to demonstrate that the MXene\ncoil and MSC array are inherently compatible and can operate without any additional power-\nmanagement circuits.\nThe matching between the coil and the MSCs considers both structural and electrical factors.\nThe coil dimensions were selected so that the entire MSC array lies within the high-coupling\nregion, ensuring uniform wireless power transfer. The MSCs were connected in series\nspecifically to match the coil’s open-circuit voltage and avoid over-voltage stress, thereby\nachieving safe, efficient, and circuit-free wireless charging.\nComment 7: The current system radius is 3.3 cm. For broader adoption, especially in wearable\nhealth monitoring, integration into smaller form factors may be desired. A brief discussion on\npossible scaling strategies or design modifications for miniaturization would strengthen the\nimpact.\nResponse:\nWe sincerely appreciate your thoughtful comment regarding the device size and its relevance\nto practical wearable applications. You are absolutely correct that miniaturization is important\nfor expanding the usability of our system, especially in scenarios that require compact,\nunobtrusive form factors for continuous physiological monitoring. In our initial demonstration,\nthe radius of approximately 3.3 cm was selected to ensure optimal NFC coupling and sufficient\narea for integrating the MSC array and sensing modules, but we fully agree that this dimension\ndoes not represent a fundamental limit of our approach.\nTo directly address your concern, we have now fabricated a substantially miniaturized version\nof the sos-MXetronics system. As shown in Fig. R9, the overall radius was reduced to about\n1.6 cm. The smaller system can even be mounted on a fingertip, illustrating that the hierarchical\nstiffness architecture and MXene-based integration strategy remain fully effective at much\nsmaller scales.\n3.3cm) (b-c) Photographs of a reduced-diameter device (approximately 1.6 cm). The compact\ndevice can be comfortably mounted on a fingertip, highlighting the scalability of the proposed\ndesign.\nFurthermore, the underlying design principles naturally support additional size reduction. The\nNFC coil can be further miniaturized by adjusting the turn density or adopting multilayer coil\nlayouts to preserve inductance within a smaller footprint. The MSC array can also be compacted\nby increasing areal capacitance or stacking multiple MSC layers. Importantly, the hierarchical\nstiffness design is inherently geometry-independent; proportionally scaling the elastiff island\nand the surrounding meandering interconnects preserves the same strain isolation mechanism,\nensuring omnidirectional strain invariance even in compact layouts.\nWe have added the newly obtained miniaturized-device data to the Supplementary Information\nas Supplementary Fig. 1, as follow:\nsos-MXetronics. (a) The PET substrate is first treated with plasma and APTES, followed by\nspray-coating of MXene. The PDMS/Ecoflex substrate with elastically reinforced regions is\nthen fabricated through a sequence of scraping-cutting-rescraping. After transfer printing and\npatterning of the PET/MXene structures, a final Ecoflex over-coating is applied as\nencapsulation, yielding the strain-invariant MXene-integrated electronics. (b) Photographs of\nsos-MXetronics (radius: 3.3cm) (c-d) Photographs of a reduced-diameter device\n(approximately 1.6 cm). The compact device can be comfortably mounted on a fingertip,\nhighlighting the scalability of the proposed design.\nintegrated devices and highlight an in-depth comparative analysis with other integrated\nsystems, which would help enhance the depth of the paper and its relevance from a forward-looking perspective.\nResponse:\nWe sincerely thank you for this valuable suggestion. We fully agree that a systematic\ncomparison with previously reported MXene-based integrated electronics is essential for\nplacing our work in proper context and for highlighting its technical significance. Following\nyour recommendation, we have added an expanded comparative discussion in the revised\nmanuscript and compiled a comprehensive summary table (Supplementary Table 1)\nbenchmarking our sos-MXetronics against representative MXene-based and hybrid integrated\nsystems.\nTo date, most reported MXene systems have achieved partial integration of specific components\nsuch as energy storage and sensing or energy harvesting and storage. However, these\nsubsystems typically function in isolation and are interconnected through external wiring or\nmeasurement equipment rather than forming a fully coupled, self-contained architecture. For\ninstance, MXene-based microsupercapacitor/sensor hybrids can simultaneously store and sense\nsignals, but the sensing units still require external readout circuits and independent power\nsources (Adv. Mater. 2021, 33, 2005449; Energy Storage Mater. 2022, 50, 444–453). Similarly,\nsystems combining MXene energy-storage units with rigid photovoltaic harvesters (Adv.\nEnergy Mater. 2021, 11, 2100746) or textile-integrated MXene sensors (Sci. Adv. 2024, 10(40):\neadp8866, Materials Today, 2024, 81: 59-69) demonstrate partial multifunctionality, yet they\ndo not achieve real-time wireless communication or strain-invariant system operation.\nIn contrast, our sos-MXetronics represents the first fully MXene-based, functionally unified\nmicrogrid, in which energy harvesting, micro-supercapacitor storage, pressure sensing, and\nnear-field communication (NFC) modules are seamlessly integrated through a common MXene\nnetwork. All modules are co-designed to share the same conductive backbone and mechanical\nload path, ensuring both electrical and mechanical coherence. To clearly illustrate this\nadvancement, Supplementary Table 1 presents a quantitative comparison of material systems,\nfabrication methods, substrate types, functional scope, degree of functional coupling, wireless\ncapability, and strain-invariant performance across prior reports and our work. As summarized\nin the table:\nSupplementary Table 1 | Comparison of representative MXene-based multifunctional electronic\nsystems (Strain-invariant performance is expressed as the relative change in electrical signal\nunder the indicated tensile strain).\nFunctional Wireless Strain-\nMaterial Method Solvent Substrate function Ref\nCoupling Capability invariant\nFully coupled\nEcofelx/ Antenna, MSC, 40%\n(self-powered This\nTi3C2TX Spraying Water PDMS T/P sensors and Yes (change:\nand wirelessly work\n/PET wires < 5%)\ncommunicative)\nMSC, P Independent No Non-\nScreen\nTi3C2TX water A4 paper Sensor and (external signal (external stretchabl 1\nprinting\nwires readout required) source) e\nAntenna, Non-\nExtrusion\nTi3C2TX water PDMS MSC, and Sequential Yes stretchabl 2\nprinting\nsensors e\nNominally\nSensors, coupled (no Non-\nDrop-\nTi3C2TX water Parylene heater and demonstrated No stretchabl 3\ncasting\nstimulator wireless or e\nenergy linkage)\nPartial coupling\nNon-\nExtrusion T/P sensors (heterogeneous\nTi3C2TX water SBS Yes stretchabl 4\nprinting and MSC materials, limited\ne\nintegration)\n42\n100%\nTransfer- Independent\nTi3C2TX water PDMS Sensor No (change: 5\nprinting (only sensor)\n~ 60%)\nNon-\nDIW Coil，sEMG\nTi3C2TX water Textile Sequential No stretchabl 6\nprinting electrodes\ne\nAcetone Non-\nDrop- MScs and\nTi3C2TX -water Si Independent No stretchabl 7\ncasting wires\nmixture e\nPartial coupling\n600%\nExtrusion Coil and (heterogeneous\nEGaIn DMF IBA No (change: 8\nprinting wires materials, limited\n~ 100%)\nintegration)\nPartial coupling 400%\nStencil Electrode and\nEGaIn / SBS (heterogeneous yes (change: 9\nprinting wires\nmaterials) ~ 40%)\nPartial coupling Non-\nExtrusion TENG and\nGO water paper (heterogeneous yes stretchabl 10\nprinting wires\nmaterials) e\nNon-\nActivated Blade Coil and\nNMP PET Partial coupling No stretchabl 11\ncarbon coating MSC\ne\nWe sincerely appreciate your suggestion, which has significantly strengthened the forward-\nlooking perspective of the manuscript. In addition, we have revised the corresponding\nparagraph in the main text, as follow:\n“Comparative analysis (Supplementary Table 1) reveals that the sos-MXetronics system\nexhibits superior strain-invariant performance (<5% variation under 40% strain),\noutperforming previously reported integrated electronics based on MXenes and other materials\nacross all key functional metrics (Fig. 1f).” (Page 6)\nIn this manuscript, the authors fabricate strain-invariant omnidirectional stretchable\nMXetronics (sos-MXetronics) through hierarchical stiffness engineering by introducing\npatterned elastiff regions and achieving strong bonding with an elastomeric substrate. The\nauthors demonstrate the potential of sos-MXetronics for human physiological signal\nmonitoring using fully MXene-based near-field communication (NFC) antennas, micro-\nsupercapacitors (MSCs), and resistive-type pressure and temperature sensors. Specifically, the\nsos-MXetronics successfully acquire pulse and body-temperature signals while minimizing the\ninfluence of wrist deformation, thereby improving data reliability. Overall, I think that the\nauthors have effectively demonstrated the potential of sos-MXetronics for human physiological\nsignal monitoring with convincing experimental results. However, the manuscript lacks\nsufficient explanation regarding the operating mechanism of the pressure sensor (P-sensor) and\nleaves some questions about the omnidirectional stability of fabricated electrode. Therefore, I\nrecommend that the authors address the following issues, as detailed below:\nResponse:\nThank you so much for the positive comments! We sincerely thank you for your positive\nevaluation of our work and for highlighting the potential of the proposed sos-MXetronics\nsystem. We also greatly appreciate your constructive comments regarding the pressure-sensing\nmechanism and the omnidirectional stability of the MXene electrodes. These suggestions have\nbeen extremely helpful. To address your concerns, we have added new experiments and\nmechanistic analyses, including cyclic compression tests, multidirectional stretching\nmeasurements, and enlarged microscopic observations. These revisions substantially clarify the\ndeformation behavior and operating principles of the pressure sensor and MXene interconnects.\nAll corresponding updates have been incorporated into the revised manuscript and\nSupplementary Information. Below, we provide detailed, point-by-point responses.\nshould be analyzed.1.1. As mentioned in Figure 1, conventional stretchable devices without a\nhierarchical structure composed of elastiff and rigid layers often lose their electrical properties\nupon deformation. From this conclusion, the MXene spin-coated PDMS (PDMS–MXene) can\nbe inferred to be unstable under compressive deformation. Therefore, the stability of the\nPDMS–MXene should be verified through cyclic loading tests.\nResponse:\nWe thank you for this valuable suggestion. To verify the intrinsic stability of the MXene-coated\nPDMS layer, we first examined the interfacial adhesion strength after plasma activation of\nPDMS, which introduces silanol groups and significantly enhances bonding with MXene flakes.\nPeel-off tests using pressure-sensitive tapes with different adhesion levels show that the MXene\nlayer remains fully intact under low and medium-adhesion PI tapes, whereas only partial\nremoval occurs under high-adhesion tapes (Fig. S30a-b), confirming that the MXene-PDMS\ninterface is sufficiently robust for deformation levels relevant to physiological pressure sensing.\nSupplementary Fig. 30. Adhesion of MXene to PDMS and cyclic stability of the P-sensor.\n(a) Adhesion test of the MXene-coated PDMS film using medium-adhesion PI tape, showing\nno noticeable MXene removal, confirming strong MXene-PDMS interfacial bonding. Scale\nbars, 2 cm. (b) Adhesion test using a high-adhesion tape, where partial MXene detachment is\nobserved. Scale bars, 2 cm. (c) Cyclic compression test of the assembled MXene/PDMS\npressure sensor under ~2 kPa loading for 25000 cycles, demonstrating stable electrical output.\nInsets: Representative cycles at the 10th, 10,000th, and 20,000th cycles.\nfurther evaluated the long-term durability of the assembled pressure sensor under repeated\ncompression. Because the device operates primarily within a low-pressure regime (<10 kPa)\nfor pulse detection, we applied a cyclic compressive load of ~2 kPa for 25000 cycles. As shown\nin Fig. S30c, the sensor maintains highly stable current output without signal attenuation and\nbaseline drift, and the representative cycles collected at the 10th, 10000th, and 20000th cycles\nexhibit nearly identical amplitudes and waveforms. These results verify that both the MXene–\nPDMS active layer and the fully assembled pressure sensor possess excellent mechanical and\nelectrical durability under practical working conditions. Together, the adhesion measurements\nand cyclic fatigue tests clearly demonstrate the robustness of the MXene-PDMS system.\nWe have added these newly conducted adhesion and cyclic compression stability tests to the\nSupplementary Information as Supplementary Fig. 30, and have updated the corresponding\ndescriptions in the main text.\n“Additionally, the sensor demonstrates fast and accurate responses to subtle pressures below 10\nkPa, as displayed in Figure 3d, and maintains highly stable performance over 25000 cyclic\ncompressions (Supplementary Fig. 29).” (Page 13)\nComment 2: 1.2. The observation that the intermittent pattern exhibits high pressure sensitivity\nbut low strain sensitivity is an interesting and unique characteristic. However, the underlying\nmechanism for the enhanced sensitivity of the intermittent pattern compared to the\nhomogeneous pattern should be clarified for better reader understanding, which is likely\nrelated to changes in contact area under applied pressure. In addition, presenting the sensor’s\nperformance under strain would help elucidate its strain-insensitive behavior. Moreover, in\nSupplementary Figure 24, the authors state that the intermittent pattern exhibits good hysteresis\nbehavior as reported in previous studies; however, the relevant reference is not provided and\nshould be cited.\nResponse:\nsensitivity of the intermittent pattern, we performed finite element simulations comparing the\nintermittent and homogeneous structures. As shown in Figure. R10a, the homogeneous pattern\nundergoes a monotonic densification process during compression, whereas the intermittent\npattern exhibits a multi-stage contact evolution. Owing to its initially smaller contact area and\nthe sequential engagement of neighboring microstructures, the intermittent pattern produces a\nmuch larger change in effective contact area under identical displacement, which is also\nreflected in the significantly steeper simulated S/S –displacement curve (Figure. R10b). These\n0\nresults directly support your interpretation that the superior sensitivity arises from pressure-\ninduced contact area modulation.\nFigure R10 Finite element analysis of the intermittent and homogeneous microstructures\nunder compression. (a) Simulated deformation profiles of the intermittent (top row) and\nhomogeneous (bottom row) structures at compression displacements of 0, 6, and 13.5 μm,\nrespectively. (b) Simulated normalized contact area variation (S/S ) as a function of\n0\ncompression displacement for the intermittent and homogeneous patterns, highlighting the\nmulti-stage contact evolution of the intermittent design.\nWe have now incorporated this newly performed finite element analysis into the Supporting\nInformation as Supplementary Fig. 24 to explicitly support the mechanism you highlighted. A\nconcise discussion reflecting this mechanism has been incorporated into the revised main text,\nas detailed below.\n“Compared with planar and uniform structured films, the intermittent architecture significantly\nreduces the compressive stress required during deformation (Fig. 3b), with a compressive\n47\nstrength below 50 kPa across the 0-28% strain range. By effectively transmitting pressure from\nthe film surface to the micropillars, this design maintains a low equivalent modulus even under\nlarge strains and facilitates greater contact-area changes (Supplementary Figs. 25 and 26)”\n(Page 12-13)\nSupplementary Fig. 24 Mechanical response and deformation mechanism of intermittent,\nhomogeneous, and planar MXene/PDMS structured films. (a-c) Compression test results of\nthe intermittent structured films at different strains (2%-28%). (d-f) Compression test results of\nthe homogeneous structured films at different strains (2%-28%). (g-i) Compression test results\nof the planar films at different strains (2%-28%). Notably, at the same 10% strain, the maximum\n48\nstress of the intermittent structured films is less than 2 kPa, while the stress of the homogeneous\nstructure is approximately twice that of the intermittent structure, and the stress of the planar\nfilm is 30 times greater than that of the intermittent structured film. This indicates that the\nmicrostructure plays a crucial role in regulating mechanical compression behavior.\nAdditionally, we observed that films with microstructures exhibit lower mechanical hysteresis,\na conclusion consistent with previous reports. (j) Finite-element simulations of the intermittent\n(top row) and homogeneous (bottom row) structures under increasing compressive\ndisplacements. (k) Simulated relative contact-area change (S/S ) as a function of compressive\n0\ndisplacement for intermittent and homogeneous structures.\nRegarding strain-insensitive behavior, we would like to note that the main text already includes\ntwo sets of experimental results capturing the sensor response under different strain levels.\nAs shown in Fig. 3g-h, both the sensitivity curves and the dynamic pressure-response profiles\nexhibit nearly overlapping behavior at 0%, 20%, and 40% strain, confirming that the\nintermittent pattern maintains stable performance even under substantial mechanical stretching.\nWe apologize if these results were not sufficiently highlighted previously, and we have now\nclarified this point in the revised manuscript.\nFigure 3 Design and characterizations of MXene P-sensor (g) Current responses to pressures\nfrom fabricated MXene P-sensor when they are at 0, 20% and 40% strains. (h) Typical\nperformance of the sensor under pressure loading and stretching cycle between 0 and 40%\nstrains.\nWe have updated the corresponding descriptions in the main text, as follow:\n49\n“In contrast, the partially reinforced sensor exhibits negligible performance variation when\nstretched from 0% to 40% strain (Supplementary Fig. 34). Quantitative analysis reveals a strain\ninsensitivity of approximately 96% (Fig. 3g). Moreover, this strain-invariant pressure sensing\nperformance is well maintained over repeated stretching cycles to 40% strain (Fig. 3h)” (Page\n14-15)\nFinally, as you pointed out, the description of Supplementary Fig. 24 refers to the low hysteresis\nbehavior of the intermittent pattern. We have now added the appropriate citations, including\nprior reports showing that microstructured sensing layers substantially reduce viscoelastic\nrelaxation times and thus minimize hysteresis, as demonstrated in previous studies by Bao et\nal. (Nature Materials,2010, 9, 859–864, Advanced Functional Materials, 2020, 30, 1903100).\nThese references have been incorporated into the revised Supplementary Information. As\nfollow:\n“Additionally, we observed that films with microstructures exhibit lower mechanical hysteresis,\na conclusion consistent with previous reports9, 10.” (Page 34, Supplementary Information)\nComment 3: Additional analysis of line-pattern stability and deformation behavior is\nrequired.2.1. The interdigitated MXene patterns used in the pressure sensor and MSCs consist\nof line electrodes that are likely to be significantly influenced by the direction of applied strain.\nHowever, the manuscript only analyzes unidirectional deformation. To validate the omni-\ndirectional stability of sos-MXetronics, additional tests under multi-directional deformation\nshould be conducted.\nResponse:\nWe thank you for pointing out that the line-shaped MXene electrodes in the pressure sensor and\nMSCs could, in principle, be sensitive to the direction of applied strain. To directly examine the\nomni-directional stability, we have now performed multi-directional stretching tests along two\northogonal in-plane directions (X and Y) at 40% strain. For the pressure sensor, the ripple-like\nmeandering interconnects around the active region share the same geometry as the temperature\n50\nsensor electrodes used in the main text. As shown in Supplementary Fig 34, the P-sensor\ndelivers nearly identical current responses under 0%, X-40%, and Y-40% strain, indicating that\nits pressure-sensing performance is essentially unaffected by the stretching direction. Similarly,\nfor the MXene MSCs, the interdigitated line electrodes were tested under 0%, X-40%, and Y-\n40% strain; the CV curves at all three conditions almost overlap (Supplementary Fig. 46),\nconfirming that the electrochemical behavior remains stable under multi-directional\ndeformation.\nSupplementary Fig. 34. Multi-directional stretching stability of the MXene-based pressure\nsensor. (a) Photographs of the P-sensor under 0% strain, 40% strain along the X direction, and\n40% strain along the Y direction. (b) Current responses of the P-sensor to applied pressure\nunder these three strain states, showing nearly identical signal amplitudes and waveforms.\nSupplementary Fig. 46 Multi-directional stretching stability of the MXene MSCs. (a)\nstrain. (b) CV curves of the MSC at 0%, X-40%, and Y-40% strain, exhibiting almost\noverlapping profiles.\nThese results are consistent with the mechanical design of our system. The electrodes adopt a\nripple-like meandering layout, which accommodates strain in multiple directions without\nconcentrating stress along a single axis. In addition, the high-modulus PDMS elastiff island is\ncentrally located and has a larger area than the interdigitated electrode region, so the applied\nstrain is primarily distributed within the surrounding low-modulus Ecoflex substrate rather than\nin the functional MXene/PDMS regions. As a result, both the pressure sensor and the MSCs\nexhibit negligible performance variation under multi-directional stretching.\nWe have added these new data to the Supporting Information as Supplementary Figs. 34 and\n46 and have clarified this point in the revised manuscript.\n“In contrast, the partially reinforced sensor exhibits almost no performance variation when\nstretched from 0% to 40% strain (Supplementary Fig. 34).” (Page 15)\n“Compared with omnidirectional strain-unconstrained MXene MSCs (Supplementary Fig. 45),\nour device exhibits negligible capacitance change across the 0-40% strain range (Fig. 4c and\nSupplementary Fig. 46), demonstrating a high capacitance retention rate of 98% (Fig. 4d).”\n(Page 17)\nComment 4: 2.2. In Figure 2h, the relative resistance change of the straight-line structure with\nrigid isolation should also be evaluated to further support the stability of the line-patterned\nelectrodes. Moreover, resistance variation under different strain directions should be examined\nto confirm the claimed omni-directional mechanical stability.\nResponse:\nWe thank you for raising this important point. Following your suggestion, we first evaluated\nthe relative resistance change (ΔR/R ) of the straight-line MXene electrode with rigid PET\n0\nisolation, which was not included in the original Fig. 2h. As shown in the new Fig. 2h, the\nstraight-line electrode with rigid isolation maintains ΔR/R below 5% up to ~60% strain,\n0\n52\ndemonstrating substantially enhanced stability compared with the version without isolation.\nThe sharp increase in ΔR/R beyond ~60% strain can be attributed to the intrinsic non-\n0\nstretchable nature of straight-line conductors, where large interfacial shear stresses eventually\ninduce partial delamination. Nevertheless, within the practical strain window relevant to our\ndevice operation, rigid isolation effectively stabilizes the line-patterned electrodes.\nFig 3. h, Relative resistance changes of the four structures under tensile strain.\nTo further validate the omni-directional mechanical robustness, we examined the ΔR/R of both\n0\nthe straight-line and serpentine electrodes under stretching along the X and Y directions. As\nshown in Supplementary Fig. 14, the rigid-isolated straight-line electrode shows low resistance\nvariation up to ~60% strain in both directions, whereas the rigid-isolated serpentine electrode\nmaintains ΔR/ R below 5% even under strains exceeding 70% along both axes. These results\n0\nconfirm that the serpentine geometry, combined with the rigid PDMS island, efficiently\naccommodates multi-directional deformation without inducing electrical degradation.\nSupplementary Fig. 14. Uniaxial stretching of straight-line and serpentine MXene electrodes\n53\nwith and without rigid isolation. (a) Relative resistance change (ΔR/ R ) of straight-line MXene\n0\nelectrodes with rigid isolation under uniaxial tension. (b) Relative resistance change (ΔR/ R )\n0\nof serpentine MXene electrodes without rigid isolation under uniaxial tension.\nWe have incorporated these new datasets into the revised Fig. 3h and added the full\nmeasurements to the Supporting Information as Supplementary Fig. 14. In addition, we have\nupdated the corresponding descriptions in the main text to reflect these results. As follow:\n“The serpentine interconnections maintain a relative resistance change below 5% within the\nfunctional strain range (up to 75%) in both X and Y directions, while the structure itself can\nwithstand nearly 160% strain before mechanical failure (Fig. 2h, Supplementary Fig. 13 and\n14)” (Page 9)\nComment 5: The effect of the serpentine electrode pattern is not clearly demonstrated in Figure\n2h. Presenting a larger-scale graph would help clarify its role in mechanical stability, and the\ninset image should be described in greater detail for better reader understanding.\nResponse:\nWe thank you for your suggestion that the effect of the serpentine electrode pattern was not\nsufficiently clear in the original Fig. 2h. To address this point, we have reconstructed the\nanalysis with a larger and more mechanistic comparison, now provided in Supplementary Fig.\n15, which clarifies the distinct deformation pathways of straight-line and serpentine MXene\nelectrodes both with and without rigid PET isolation.\nand without PET isolation. (a) Schematic illustration of straight and serpentine MXene\npatterns directly supported on Ecoflex. (b) With the incorporation of a rigid PET island beneath\nthe MXene, most of the applied strain is shielded by the stiffness gradient, allowing only limited\ninterlayer sliding and preventing catastrophic cracking. (c-d) Optical images showing crack\npropagation in MXene films with and without isolation under 0%, 20%, 40%, 60%, and 100%\nstrain states. Scale bars: 100 μm.\nIn Supplementary Fig. 14a, we show that without rigid isolation, straight-line electrodes\ndevelop severe longitudinal cracking and large disconnected conductive islands during\nstretching. Because the applied strain is directly transferred to the MXene layer, the inherent\nsliding mechanism and hydrogen-bond interactions between MXene flakes are insufficient to\nwithstand such large stresses. This macroscopic failure is accompanied by microscale MXene-\nsheet fracture, which is clearly visible in the enlarged optical micrographs. Serpentine\nelectrodes also experience stress concentration in the absence of isolation, although the\ngeometric deformation provides partial buffering. Supplementary Fig. 14b further compares the\nbehavior of straight-line and serpentine electrodes when rigid PET isolation is introduced. The\nstiff island effectively shields the active region from global strain, preventing any macroscopic\ncracking in either geometry. At the microscopic level, a small residual strain still reaches the\nundergo reversible sliding mediated by hydrogen-bond interactions, producing only localized\nand non-propagating microcracks. This sliding-dominated deformation mechanism explains the\nmarkedly improved electrical stability observed in rigid-isolated electrodes.\nTo directly visualize these distinct failure pathways, Supplementary Figs. 14c-f present high-\nresolution optical micrographs under tensile strains from 0% to 100%. The non-isolated\nsamples show progressive crack growth and MXene-sheet rupture, whereas the rigid-isolated\nsamples maintain structural integrity, exhibiting only minor, uniformly distributed micro-\nsliding. These microstructural observations clearly differentiate MXene fracture from MXene\nsliding and highlight how serpentine geometry and rigid PET isolation work synergistically to\nenhance mechanical robustness.\nWe believe that this expanded mechanistic comparison, together with the clearer, higher-\nresolution illustrations, fully clarifies the stabilizing role of the serpentine electrode design\nunder tensile deformation. We have updated the corresponding descriptions in the main text to\nreflect these results. As follow:\n“The rigid serpentine PET island effectively shields the MXene film from large global strain,\nenabling the electrode to deform through localized MXene flake sliding rather than catastrophic\ncrack propagation. This mechanism prevents the formation of long cut-through cracks and large\nconductive islands, thereby maintaining electrical integrity even under repeated high tensile\nstrain (Supplementary Figs. 15-18).” (Page 9-10)\nComment 6: The authors successfully demonstrate the advantage of a fully MXene-based\nplatform by employing MXene electrodes as NFC antennas, micro-supercapacitors (MSCs),\nand multifunctional sensors. However, it raises concerns about the long-term stability of the\ndevice, since MXene materials are prone to oxidation, which can significantly reduce their\nelectrical conductivity over time. Therefore, a discussion or experimental verification of the\ndevice’s durability under ambient or operational conditions would be beneficial.\nResponse:\nWe sincerely thank you for raising this important point. We fully agree that the oxidation\nsensitivity of MXene requires careful evaluation of long-term device stability under realistic\noperating conditions. In the revised manuscript, we have therefore performed additional\nenvironmental aging tests and device-level stability studies to directly address this concern.\nMXene oxidation is known to occur only when both water and oxygen are present, and the\ndegradation rate is strongly temperature dependent. To capture the practically relevant\ndegradation envelope, we evaluated MXene films with and without Ecoflex encapsulation\nunder two representative environments: 60°C/100% RH (accelerated oxidation) and 25°C/50%\nRH (normal wearable conditions). Under 60°C/100% RH, unencapsulated MXene showed a\nresistance increase of over seven orders of magnitude within 10 days and exceeded the\nmultimeter’s measurement limit, whereas encapsulated MXene increased only by ~103-fold\nafter 15 days. Under 25°C/50% RH, unencapsulated MXene increased by ~15-fold over 30\ndays, while encapsulated MXene changed by only ~1-fold, indicating minimal degradation\nunder typical ambient conditions (Supplementary Fig. 54).\nTo further verify operational reliability, we tested the fully integrated sos-MXetronics after 1,\n10, and 30 days of storage at room temperature and moderate humidity. The device consistently\npowered on, maintained NFC coupling, and transmitted physiological signals without failure\n(Supplementary Fig. 54), demonstrating that the elastomer encapsulation effectively protects\nthe MXene circuitry from environmental exposure.\nMXetronics. (a) Resistance evolution (R/R ) of MXene films with and without Ecoflex\n0\nencapsulation under accelerated aging (60°C, 100%RH) (b) Resistance evolution (R/R ) of\n0\nencapsulation under accelerated aging (25°C,\n50%RH). (c) Photographs showing that the integrated sos-MXetronics remains fully functional,\npowering on normally after 1, 10, and 30 days of storage at room temperature and moderate\nhumidity.\nTogether, these results confirm that the encapsulation strategy robustly suppresses MXene\noxidation and enables stable device operation over extended periods. The new datasets and\ncorresponding discussion have been added to the revised manuscript.\n“In addition, temperature-humidity aging tests demonstrate that the elastomer encapsulation\neffectively suppresses MXene oxidation, enabling stable device operation even after 30 days of\nenvironmental exposure (Supplementary Fig. 54)” (Page 18)\n1. Zheng, S. et al. Multitasking MXene inks enable high-performance printable\nmicroelectrochemical energy storage devices for all-flexible self-powered integrated\nsystems. Adv. Mater. 33, 2005449 (2021).\n2. Shao, Y. et al. Room-temperature high-precision printing of flexible wireless\nelectronics based on MXene inks. Nat. Commun. 13, 3223 (2022).\n3. Wu, Y. et al. Orbit symmetry breaking in MXene implements enhanced soft\nbioelectronic implants. Sci. Adv 10, eadp8866 (2024).\n4. Song, Y. et al. 3D-printed epifluidic electronic skin for machine learning-powered\nmultimodal health surveillance. Sci. Adv 9, eadi6492 (2023).\n5. Chen, W., Liu, L.-X., Zhang, H.-B. & Yu, Z.-Z. Kirigami-Inspired highly stretchable,\nconductive, and hierarchical Ti C T MXene films for efficient electromagnetic\n3 2 x\ninterference shielding and pressure sensing. ACS Nano 15, 7668-7681 (2021).\n6. Inman, A. et al. MXene-enabled textile-based energy grid utilizing wireless charging.\nMater. Today 81, 59-69 (2024).\n7. Huang, H. et al. Ti C T MXene-based micro-supercapacitors with ultrahigh\n3 2 x\nvolumetric energy density for all-in-one Si-electronics. ACS Nano 16, 3776-3784\n(2022).\n8. Liu, X. et al. Stiffness and interface engineered soft electronics with large-scale robust\ndeformability. Adv. Mater. 36, 2407886 (2024).\n9. Yao, K. et al. A fully integrated breathable haptic textile. Sci. Adv 10, eadq9575 (2024).\n10. Peng, P., Yang, F., Wang, Z. & Wei, D. Integratable paper-based iontronic power source\nfor all-in-one disposable electronics. Adv. Energy Mater. 13, 2302360 (2023).\n11. Gao, C. et al. A seamlessly integrated device of micro-supercapacitor and wireless\ncharging with ultrahigh energy density and capacitance. Nat. Commun. 12, 2647 (2021).\n12. Lipatov, A. et al. High electrical conductivity and breakdown current density of\nindividual monolayer Ti C T MXene flakes. Matter 4, 1413-1427 (2021).\n3 2 x\n13. Li, Y. et al. A general Lewis acidic etching route for preparing MXenes with enhanced\nelectrochemical performance in non-aqueous electrolyte. Nat. Mater. 19, 894-899\n(2020).\n14. Alhabeb, M. et al. Guidelines for synthesis and processing of two-dimensional titanium\ncarbide (Ti C T MXene). Chem. Mater. 29, 7633-7644 (2017).\n3 2 x\n15. Natu, V. et al. 2D Ti C T MXene synthesized by water-free etching of Ti AlC in polar\n3 2 z 3 2\norganic solvents. Chem 6, 616-630 (2020).\n16. Zhao, C. et al. Skin-like drift-free biosensors with stretchable diode-connected organic\nfield-effect transistors. Nat. Electron. 8, 981-993 (2025).\n17. Lu, Y. et al. Stretchable graphene-hydrogel interfaces for wearable and implantable\nbioelectronics. Nat. Electron. 7, 51-65 (2024).\n18. Liu, Z. et al. Bioinspired ultra-thin polyurethane/MXene nacre-like nanocomposite\nfilms with synergistic mechanical properties for electromagnetic interference shielding.\nJ. Mater. Chem. C 8, 7170-7180 (2020).\n19. Usman, K.A.S. et al. Sequentially bridged Ti C T MXene sheets for high performance\n3 2 x\n59\napplications. Adv. Mater. Interfaces 8, 2002043 (2021).\n60"}, {"round": 2, "reviewer_comments": {"reviewer_1": "The authors have addressed all issues. This version is fine to be accepted.", "reviewer_2": "The authors addressed my concerns. Accept!", "reviewer_3": "Authors addressed all the comments raised by the reviewers."}, "author_response": "List of Responses to the Reviewers’ Comments\nWe would like to thank the reviewers for their valuable comments and suggestions on this\nmanuscript\nReviewer #1 (Remarks to the Author):\nThe authors have addressed all issues. This version is fine to be accepted.\nResponse:\nWe sincerely thank the reviewer for the positive assessment and recommendation for\nacceptance. We are pleased that the revised manuscript meets the reviewer’s expectations.\nReviewer #2 (Remarks to the Author):\nThe authors addressed my concerns. Accept!\nResponse:\nWe greatly appreciate the reviewer’s careful evaluation and supportive comments. We are\ngrateful for the recommendation to accept the manuscript.\nReviewer #3 (Remarks to the Author):\nAuthors addressed all the comments raised by the reviewers.\nResponse:\nWe thank the reviewer for the constructive review and for confirming that all comments have\nbeen satisfactorily addressed in the revised version.\n1"}]

Decision letter