Geometry-programmed self-wrinkling in organo-hydrogels for anisotropic mechanics and adaptive sensing

Domain: biology
Published: 2026-03-10
Editorial outcome: major_revision

Abstract
Gel-based soft materials are attractive for flexible electronics and biointerfaces but are often
limited by insufficient mechanical robustness and constrained functional integration. Here, we
introduce a geometry-programmed self-wrinkling strategy that enables the spontaneous formation
of aligned wrinkle architectures during thermal–evaporative gelation of poly(vinyl alcohol)–based
organo-hydrogels. Without external patterning or post-processing, this process produces materials
with enhanced mechanical robustness and pronounced anisotropy in deformation, fracture, and
ionic transport. By leveraging these intrinsic properties, we demonstrate multiple sensing and
actuation functions, including directional strain sensing, multidirectional sliding detection,
deformation-driven rolling sensors, and temperature-triggered alarms. These results highlight
geometry-programmed self-wrinkling as a scalable route to integrate structural reinforcement and
directional functionality into soft materials through a physically driven formation process.

Introduction
Soft materials play a central role in emerging technologies ranging from biomedical devices and
biointerfaces to flexible robotics and wearable sensing platforms1–3. Among them, gel-based soft
materials, including hydrogels and organo-hydrogels, are particularly attractive owing to their high
ionic conductivity, intrinsic compliance, and tissue-like mechanical properties, positioning them
as promising candidates for biointerfaces and flexible electronic systems4,5. However, the highly
solvated and weakly crosslinked nature of gel networks often leads to limited durability under
repeated deformation, insufficient toughness in dynamic environments, and restricted sensing
performance, which together constrain their long-term reliability and multifunctional
deployment6,7.

Bioinspired structural design has emerged as an effective approach to addressing the mechanical
limitations of gel-based soft materials by introducing architectures that redistribute stress and
enhance energy dissipation efficiency8–10. A representative example is honeycomb-like structured
hydrogels, in which directional freeze casting establishes aligned cellular frameworks while
salting-out–induced polymer aggregation concurrently reinforces the pore walls at the molecular
level, together producing hierarchical networks with exceptional strength, toughness, and fatigue
resistance11. Similarly, bamboo-inspired composite hydrogels exploit evaporation-induced
structuring during gelation to generate aligned, lamellar internal architectures, while
complementary molecular modifications stabilize interfacial interactions within the evolving
network and enhance load transfer across length scales12. Accumulating studies suggest that
bioinspired structural design, when coupled with molecular-level engineering during gel formation,
offers an effective route to improving the mechanical performance of gel-based soft materials.

Wrinkle architectures represent another widely explored bioinspired motif, inspired by textured
natural interfaces such as fingerprints and skin folds13,14. In engineered gel-based systems, surface
wrinkling has been extensively employed to enhance sensing performance; for example, wrinkled
iontronic interfaces substantially improve pressure sensitivity and resolution by promoting
localized deformation and increasing interfacial contact area, while wrinkled nanocomposite
hydrogels exploit surface strain concentration to achieve highly sensitive and robust electrical
responses4,15,16. In most existing implementations, however, such surface wrinkles are introduced
through external or post-forming processes, including stretch–release cycles applied to fully
crosslinked gels17–19, swelling-induced instabilities that develop post-gelation20,21, and externally
imposed patterns using photolithographic or molding techniques on chemically crosslinked
networks22–24. As a result, functional enhancement is primarily achieved through geometric
amplification at the surface, while the underlying molecular network that governs mechanical
integrity and durability remains largely unchanged.

In contrast, wrinkles commonly emerge in situ in natural systems and in soft materials as they form
or evolve, a phenomenon commonly referred to as self-wrinkling25–28. Representative examples
include the spontaneous wrinkling of drying biological tissues, polymer films, and soft coatings,
where surface patterns develop concurrently with solvent loss or phase transitions29–31. Such
wrinkling behavior is commonly attributed to the accumulation of compressive stress during
formation, which is relieved through surface undulation as the system seeks a lower-energy
configuration32,33. Consistently, in exploratory experiments we observed that thermally assisted
evaporation during gelation readily led to the spontaneous formation of surface undulations,
indicating that temperature gradients and solvent loss can promote wrinkle formation in hydrated
gel systems.

In this work, we develop a geometry-programmed self-wrinkling strategy in which thermal–
evaporative gelation drives the spontaneous formation of surface wrinkles, while the planform
boundary of the system governs their macroscopic orientation. Using poly(vinyl alcohol)–based
organo-hydrogels as a model platform, we show that this in situ, physically driven process embeds
aligned wrinkle architectures directly into the evolving gel network, rather than imposing them
through external patterning or post-processing. As a result, the resulting materials exhibit enhanced
mechanical robustness together with pronounced anisotropy in deformation, fracture behavior, and
ionic transport. By leveraging this intrinsic structural anisotropy, we further demonstrate a series
of directional and adaptive functions, including motion-responsive sliding sensors, deformation-
driven rolling sensors, and thermally actuated temperature alarms (Fig. 1a). Together, these results
establish geometry-programmed self-wrinkling as a general materials-level approach for encoding
aligned, multifunctional wrinkle architectures into soft matter systems through spontaneous
formation, coupling mechanical reinforcement with programmable functional responses.

Results
Onset and geometry-guided organization of wrinkles
In this work, we developed a self-wrinkling strategy to fabricate well-aligned wrinkle architectures
in a poly(vinyl alcohol) (PVA)–based organo-hydrogel system, referred to as the wrinkled
structured organo-hydrogel (WSO). As illustrated in Fig. 1b, a PVA solution prepared in a
water/glycerol mixture is cast into a rectangular mold consisting of a thermally conductive copper
base and thermally insulating polylactic acid (PLA) sidewalls. The mold is placed on a
temperature-controlled heating platform (typically 40-90 ℃) with the top surface exposed to
ambient air, allowing evaporation to proceed under controlled laboratory conditions (23 ± 0.5 ℃,
55 ± 2.5% relative humidity (RH), no forced airflow). During heating, the PVA solution receives
heat predominantly from the copper base, while the free surface undergoes evaporative cooling,
establishing a pronounced vertical temperature gradient across the liquid layer (Fig. 1b, left).
Owing to such vertical temperature gradient, convective flow consistent with Rayleigh–Bénard
convection34 is observed, as supported by numerical simulations and thermal imaging
(Supplementary Fig. 1), promoting heat and solvent redistribution prior to surface solidification.
As evaporation proceeds, continuous solvent loss at the free surface increases the local polymer
concentration, triggering a sol–gel transition that leads to the formation of a thin, mechanically
coherent surface skin layer, while the underlying bulk remains fluid (Fig 1b, middle). Thermal
imaging reveals lower surface temperatures near the boundaries of the skin-covered area
(Supplementary Fig. 2; schematized in Fig. 1b), indicating locally enhanced evaporative cooling
and, consequently, spatially non-uniform evaporation across the interface. With further
evaporation, the initially smooth surface skin first exhibits subtle distortions, which evolve into
localized undulations and progressively propagate across the interface, ultimately organizing into
continuous, highly aligned wrinkle bands, as shown in Supplementary Movies 1, 2 and
schematized in Fig. 1b (right).

To identify the conditions required for wrinkle initiation, we varied the heating temperature while
keeping the mold geometry and initial solution composition unchanged. Adjusting the heating
temperature modulates the thermal contrast between the bottom-heated substrate and the
evaporatively cooled free surface. We quantify this contrast using the average maximum
temperature difference, ΔT , defined as the temperature difference between the heating substrate
m
and the free surface, averaged from the early heating stage to the onset of surface wrinkling
(Supplementary Fig. 3). Experiments conducted over a heating range of 40–90 ℃ yield distinct
ΔT values, and the resulting wrinkling behavior is summarized in Fig. 1c by plotting the measured
m
outcomes against ΔT and the surface polymer concentration at the moment when wrinkles first
m
appear. At a heating temperature of 40 ℃, ΔT remains small, evaporation is weak, and no surface
m
wrinkling is observed within the experimental window (Region ②). In contrast, for heating
temperatures of 50 ℃ and above, which produce ΔT values on the order of 3–4 ℃ or higher,
m
surface wrinkling becomes accessible and emerges once evaporation has sufficiently densified the
surface layer to sustain compressive deformation (Region ①). Within this regime, the surface
polymer concentration measured at wrinkle onset increases modestly with ΔT , reflecting
m
enhanced surface enrichment under stronger evaporation conditions.

These experimental trends indicate that wrinkle initiation arises from the coupled effects of thermal
driving and surface skin development. A sufficiently large thermal contrast, imposed by bottom
heating and reflected in ΔT , regulates the evaporation rate at the free surface and thereby sets the
m
magnitude of stress that can develop within the skin. As evaporation progresses, solvent loss
densifies the surface region into a solid-like layer capable of sustaining compressive deformation.
The buildup of stress within this layer is consistent with evaporation-induced pore-pressure effects
(Fig. 1b), for which the thickness-averaged pressure scales as 〈p〉 ∝ Jhη/k , where J is the
evaporation rate, h is the skin thickness, η is the solvent viscosity, and k is the gel permeability32.
The spatially non-uniform surface temperature distributions captured by thermal imaging reflect
this evaporation process and support the presence of heterogeneous stress development across the
interface. From this perspective, Region ③ corresponds to conditions in which the thermal
driving force is already substantial, but the surface skin has not yet fully developed at the time of
observation, resulting in a transient smooth state.

Once surface wrinkling is initiated, we find that the macroscopic wrinkle orientation and domain
organization are governed primarily by the planform geometry of the mold. This effect is most
clearly demonstrated for rectangular molds with varying aspect ratios (Fig. 1b, middle), where
wrinkles consistently align parallel to the short edges, with domain transitions localized near the
corners. Changing the mold size does not alter the global orientation pattern, indicating that
wrinkle direction is dictated by geometry rather than by local material parameters. Side-view
imaging further confirms that the evaporatively formed surface skin exhibits positive Gaussian
curvature (κ > 0 ) throughout the wrinkling process (Supplementary Fig. 4). During wrinkle
formation, this curved skin layer is supported by the underlying fluid bulk and laterally constrained
by the mold boundary. Within this setting, recent theoretical work on confined elastic shells
predicts that wrinkle orientation and domain layout are controlled by the planform boundary
through geometric selection rules35. In the rules, wrinkle organization is described by two key
geometric quantities: a scalar order parameter λ which distinguishes ordered (λ > 0) and
disordered (λ = 0) regions, and a unit director T̂ , which specifies the local principal wrinkle
direction (Fig. 1b, left). We further verified this behavior using additional mold designs, including
circular geometries, all of which exhibit wrinkle organizations consistent with these predictions
(Fig. 1d-f and Supplementary Fig. 5; see Supplementary Note 1 for details). Together, these results
show that thermal–evaporative conditions determine when wrinkles form, while boundary
geometry robustly programs how they are oriented.

Composition-dependent wrinkle size evolution
The wrinkling process in our system can be viewed as comprising two coupled but distinct regimes.
In the initial onset–organization regime, evaporation induces a mechanical instability in the surface
skin, while geometric confinement associated with the planform boundary of the curved surface
establishes the macroscopic wrinkle organization. Following this initial pattern formation, the
system enters a growth–maturation regime in which continued evaporation, gelation, and solvent
redistribution progressively evolve the wrinkle morphology, giving rise to the final wrinkle
wavelength and amplitude. A key implication of this separation is that wrinkle formation persists
across a broad range of material formulations, whereas the characteristic wrinkle dimensions
remain sensitive to material composition and processing parameters that influence the later stages
of evolution.

To examine how composition and processing affect wrinkle development during this growth-
maturation regime, we varied the secondary solvent (glycerol) content, incorporated different
functional additives, and adjusted the precursor mass, while keeping the mold geometry and
heating conditions unchanged. Across all formulations investigated, surface wrinkles reproducibly
emerge under identical thermal–geometric conditions, indicating that wrinkle formation reflects a
general response of the PVA-based organo-hydrogel system rather than a behavior restricted to a
specific composition. As shown in Fig. 2a–c, well-developed wrinkle patterns are consistently
observed in additive-free samples (NA–2%GLY), carbon-nanotube–doped samples (CNT–
2%GLY), and MgB -nanosheet–doped samples (MN–2%GLY), as confirmed by optical imaging
2
and three-dimensional surface reconstructions. While the overall wrinkle organization remains
comparable under the same mold geometry, the characteristic wrinkle dimensions vary with
composition and processing history. To quantitatively capture these variations, wrinkle size was
characterized using the wavelength w and amplitude A extracted from surface height profiles, as
illustrated in Fig. 2c.

Systematic variations in wrinkle dimensions are observed upon changing composition and
precursor mass, accompanied by changes in skin-layer and precursor properties (Supplementary
Figs. 7 and 8). Increasing the glycerol concentration leads to a monotonic increase in wrinkle
amplitude A accompanied by a decrease in wavelength w (Fig. 2f). For example, increasing the
glycerol concentration from 0% to 2% in additive-free samples (NA–0%GLY to NA–2%GLY)
results in an increase in A from 0.06 ± 0.02 mm to 0.22 ± 0.06 mm (Fig. 2d). The incorporation of
functional additives further modifies wrinkle development at fixed glycerol content. At 2%GLY
(Fig. 2g), samples containing different additives exhibit distinct wrinkle dimensions, with MN–
2%GLY displaying narrower wavelength distributions and more uniform wrinkle morphology
compared with NA–2%GLY and CNT–2%GLY (Fig. 2c, e). In addition, the precursor mass
influences wrinkle development. For MN–2%GLY–x g samples, increasing the precursor mass
leads to larger wrinkle amplitudes accompanied by a reduction in wavelength (Fig. 2h, i). At higher
masses, the distribution of wrinkle sizes becomes broader, indicating increased spatial variability
in wrinkle growth. Moreover, the mold geometry also modulates wrinkle dimensions: compared
with the rectangular mold, the triangular mold produces a smaller wavelength but a larger
amplitude (Fig. 2j). Together, glycerol content, additive incorporation, and precursor mass provide
experimentally accessible parameters for modulating wrinkle dimensions within a common
formation framework.

Finally, we assessed the post-formation stability of the wrinkle morphology using representative
WSO samples (MN–2%GLY, rectangular mold) under relevant environmental conditions
(Supplementary Fig. 9). Under ambient storage (25 ℃), the wrinkle profiles remain essentially
unchanged over 28 days, with both w and A staying within experimental uncertainty
(Supplementary Fig. 9a, b). Exposure to elevated temperature (80 ℃) leads to a gradual reduction
in amplitude during the first week, accompanied by a smaller decrease in w, after which the
morphology stabilizes (Supplementary Fig. 9c, d), indicating partial relaxation followed by a new
steady state. Stepwise relative-humidity cycling induces reversible changes in both w and A, with
swelling at high humidity and contraction at low humidity and minimal hysteresis upon cycling
(Supplementary Fig. 9e, f). These observations indicate that wrinkle dimensions are responsive to
solvent content and environmental history, while the patterned surface remains structurally intact
after formation.

Wrinkle-induced reinforcement and mechanical anisotropy
To examine how wrinkle formation and alignment influence mechanical performance, we focus
on PVA organo-hydrogels reinforced with MgB nanosheets and containing 2 wt% glycerol, which
2
reproducibly form well-defined wrinkle architectures (denoted WSO–MN). Wrinkle-free
counterparts with identical composition (WFO–MN) were prepared by suppressing the surface
temperature gradient during processing. Thermogravimetric analysis (TGA) confirms that WFO–
MN and WSO–MN contain comparable residual solvent contents (Supplementary Fig. 10),
ensuring that differences in mechanical behavior primarily reflect structural differences introduced
during wrinkle formation rather than variations in solvent content.

Fig. 3a compares the tensile responses of wrinkle-free samples (WFO–MN) and specimens loaded
along an individual wrinkle ridge of the wrinkled organo-hydrogel (WSO–MN–SW). The stress–
strain curve of WSO–MN–SW extends to substantially higher strain while maintaining a
continuously increasing stress level, whereas WFO–MN fails at lower stress and strain.
Quantitatively, the fracture strain increases from 606.07 ± 59.35% for WFO–MN to 997.90 ±
130.14% for WSO–MN–SW, accompanied by increases in fracture strength from 17.12 ± 3.53
MPa to 51.72 ± 3.43 MPa and fracture toughness from 66.05 ± 7.81 to 315.93 ± 63.94 MJ m-3 (Fig.
3b, c). These differences in mechanical response are accompanied by systematic structural
distinctions between wrinkled and wrinkle-free regions. Scanning electron microscopy (SEM)
shows that WFO–MN retains a relatively open porous network, whereas the wrinkled regions in
WSO–MN exhibit a denser and more layered morphology (Fig. 3e). Consistent with this
densification, differential scanning calorimetry (DSC) indicates a higher crystalline fraction within
the wrinkled regions, with the melting peak area of WSO–MN–SW being approximately 1.2 times
that of WFO–MN and also exceeding that of the non-wrinkled regions within WSO–MN (Fig. 3f).
At the molecular level, Fourier-transform infrared spectra of WSO–MN display more pronounced
borate-associated bonding features at ~680 cm-1 (O-B-O)36,37, ~1110 cm-1 (B-O-C), and ~1415 cm-
1 (B-O stretching)37,38, together with a broadened O-H stretching band near 3417 cm-1, compared
with WFO–MN (Fig. 3g). Collectively, these measurements show that regions associated with
wrinkle formation differ structurally from wrinkle-free material despite identical bulk composition,
indicating additional network development localized within the wrinkled surface layer (Fig. 3h).

At the macroscopic scale, the presence and alignment of these reinforced wrinkle regions lead to
a pronounced dependence of mechanical response on loading orientation. When WSO–MN
samples are stretched parallel to the wrinkle direction (WSO–MN–WD), they sustain
exceptionally large deformation while maintaining high stress, reaching fracture strains above
1000% together with elevated fracture strength and toughness (Fig. 3b, c). Notably, these metrics
place WSO–MN among the strongest and toughest hydrogel-based materials reported to date (Fig.
3d and Supplementary Table 1). In addition to these enhanced fracture metrics, the stress–strain
response in this configuration exhibits a non-monotonic, stepwise evolution at large strains,
characterized by successive stress plateaus and drops prior to final failure (Fig. 3a, inset and
Supplementary Movie 3). This response reflects progressive damage events occurring at different
stages of deformation rather than a single abrupt fracture. In contrast, when the same material is
loaded perpendicular to the wrinkle direction (WSO–MN–PWD), the tensile response is markedly
less robust. Fracture strain and strength are comparable to, or lower than, those of the wrinkle-free
sample, and the stress–strain curves show early stress saturation with limited extensibility (Fig.
3a). This behavior indicates that under perpendicular loading, deformation is concentrated within
regions between wrinkle ridges, reducing the effective participation of the reinforced wrinkle
structure in load bearing. Consistent with this behavior, finite-element simulations qualitatively
illustrate a crack-arresting role of the wrinkled architecture. Under uniaxial stretching, loading
along the perpendicular to the wrinkle direction (PWD) leads to pronounced stress localization
within a narrow necking band, which accelerates damage accumulation and promotes premature
failure (Supplementary Fig. 11a). In contrast, loading along the wrinkle direction (WD)
redistributes stress across multiple wrinkle segments, suppressing the formation of a single
dominant localization zone and thereby postponing catastrophic fracture to higher strain levels
(Supplementary Fig. 11b).

Beyond monotonic tensile loading, wrinkle alignment also influences fracture resistance and
damage evolution under deformation modes relevant to practical use. Fig. 3i compares the fracture
energy measured under pure-shear loading for WFO–MN, WSO–MN–PWD, and WSO–MN–WD
(Fig. 3i). The WD configuration exhibits a higher fracture energy than both the PWD configuration
and the wrinkle-free counterpart, indicating increased resistance to crack extension when
deformation is applied along the wrinkle alignment. Cyclic tensile tests on pre-notched specimens
subjected to repeated loading to 20% strain further reveal a pronounced orientation dependence
(Fig. 3j). For WSO–MN–PWD, the crack tip advances progressively from the 1st to the 1000th
and 5000th cycles, accompanied by a reduction in the force–strain hysteresis loops, reflecting
cumulative damage and stiffness loss. In contrast, WSO–MN–WD shows minimal crack extension
over the same number of cycles, with a comparatively stable hysteresis response. These results
further support that aligned wrinkle ridges act as stable load-bearing pathways, limiting stress
localization and crack advancement across different loading modes.

Wrinkle-induced electrical anisotropy and enhanced ion transport
We next examine how the same aligned wrinkle architecture in WSO–MN governs its electrical
transport properties. Variations in fabrication temperature and glycerol content are used as
controlled perturbations to test the effect on the electrical properties. Electrical conductivity and
electromechanical responses are therefore compared along WD and PWD as indicated in Fig. 4a.
As shown in Fig. 4a, the electrical conductivity measured along WD is consistently higher than
that measured along PWD across all tested temperatures (85–95 ℃) and glycerol concentrations
(1–3 wt%). For example, WSO-MN fabricated at 90 ℃ with 2% glycerol exhibits a conductivity
of 0.068 S m⁻¹ along WD, compared with 0.020 S m⁻¹ along PWD. While increasing glycerol
content leads to a modest increase in absolute conductivity (e.g., at 90 ℃, from 0.062 S m⁻¹ at 1%
glycerol to 0.076 S m⁻¹ at 3% glycerol), the conductivity contrast between WD and PWD remains
the dominant and persistent feature. Increasing evaporation temperature reduces the overall
conductivity, consistent with partial solvent loss during drying (Supplementary Fig. 12);
importantly, the directional separation between WD and PWD is preserved, indicating that the
anisotropy is not tied to a specific processing point but reflects the wrinkle-organized internal
structure.

This directional architecture also leads to anisotropic electromechanical sensitivity under
deformation. Fig. 4b compares the strain-dependent resistance change for samples stretched along
different orientations. The gauge factor (GF) is highest for WSO–MN–PWD (GF = 1.404),
intermediate for WSO–MN–WD (GF = 0.671), and lowest for specimens loaded along a single
wrinkle ridge (WSO–MN–SW, GF = 0.446). All configurations exhibit highly linear responses up
to 500% strain, with correlation coefficients of 0.998. The frequency-dependent measurements in
Fig. 4c show that this directional sensitivity is maintained over a range of deformation rates,
indicating a stable electromechanical coupling. In addition to tensile deformation, WSO–MN also
exhibits pressure sensitivity under compression, with two approximately linear response regimes
observed below 20 kPa (Fig. 4d), further reflecting the mechanically compliant.

To evaluate environmental robustness, time-dependent conductivity measurements were
conducted under storage and humidity variations while monitoring both WD and PWD responses.
Under ambient storage for 28 days, the conductivity in both directions remains essentially
unchanged, and the anisotropic contrast is preserved (Supplementary Fig. 13a). Accelerated drying
at 40 ℃ leads to a gradual decrease in absolute conductivity due to solvent loss; however, the WD–
PWD separation remains clearly observable throughout the test (Supplementary Fig. 13b).
Similarly, under stepwise relative-humidity cycling between 30% and 90% RH, both resistance
and calculated conductivity show step-like changes while maintaining directional contrast
(Supplementary Fig. 14). These results indicate that although ionic conductivity depends on
solvent content, the wrinkle-induced anisotropy is structurally encoded and remains stable under
long-term storage and dynamic environmental conditions.

The observed anisotropy in electrical properties originates from the enhanced ionic transport
ability along the wrinkle structures. Nyquist plots (Fig. 4e) show that WSO–MN–WD exhibits a
smaller overall impedance than WSO–MN–PWD, a trend that persists across the measured
frequency range (Fig. 4f) and is also observed for WSO–MN–SW and WSO–MN–NW
(Supplementary Fig. 15). Equivalent-circuit fitting using a Randles-type model39,40
(Supplementary Fig. 16) reveals that the Warburg impedance associated with ion diffusion along
WD is approximately an order of magnitude smaller than that along PWD (Supplementary Table
2), indicating reduced diffusion resistance in the wrinkle-aligned direction. Complementary two-
dimensional small-angle X-ray scattering (2D SAXS) measurements further reveal anisotropic
internal organization in WD samples, characterized by directionally elongated scattering patterns
and a Hermans orientation12 factor of fc = 0.51 (Fig. 4g–j). This intermediate degree of alignment
suggests reduced transport tortuosity and enhanced directional connectivity of ion-conductive
domains along WD41–43. Together, these electrical and structural measurements indicate that the
wrinkled architecture not only concentrates conductive pathways locally but also organizes them
directionally, enabling efficient ionic transport along WD and giving rise to the observed electrical
anisotropy.

Wrinkle-induced multidirectional sliding sensing
The combination of wrinkle-induced mechanical and electrical anisotropy enables WSO–MN to
function as a platform for detecting complex, direction-dependent mechanical stimuli. To
demonstrate this capability, we constructed a sliding sensor using a WSO–MN film featuring a
curved wrinkle arrangement, with the concave vertex oriented downward (Fig. 5a). During finger
sliding, the local contact pressure and shear direction relative to the wrinkle orientation modulate
the conductive pathways, producing characteristic resistance responses that depend on the
direction of motion. Resistance changes were recorded for four sliding directions (up, down, left,
and right) using three electrode configurations: PWD, WD, and a combined WD–PWD
configuration (Fig. 5c–e). In the PWD configuration, sliding across the wrinkle ridges generates
pronounced resistance variations, whereas sliding parallel to the ridges produces weaker responses.
In contrast, the WD configuration exhibits stronger signals for sliding along the WD and reduced
sensitivity to perpendicular motion. The combined WD–PWD configuration integrates both
response modes, yielding clearer and more distinguishable signal patterns for all sliding directions.
The directional nature of these signals is further illustrated by the time-resolved resistance change
rates (Fig. 5f–i), which show stable and repeatable waveforms for repeated sliding in the same
direction, alongside clear differences between different directions. To evaluate the practical
usability of these anisotropic signals, the sensor was mounted on the index finger, and resistance
signals generated by thumb sliding were collected in real time (Supplementary Movie 4 and Fig.
5j). A pre-trained artificial neural network (ANN) was used to classify the sliding directions and
convert the recognized signals into control commands for a robotic arm (Fig. 5b). The system
achieved a recognition accuracy exceeding 92% across four sliding directions (Supplementary Fig.
17), demonstrating that the wrinkle-induced signal anisotropy is sufficiently robust and separable
for real-time motion decoding. Independent validation using sensors fabricated from different
wrinkle batches, analyzed via t-distributed stochastic neighbor embedding (t-SNE), further
confirms consistent clustering of sliding signals by direction (Supplementary Fig. 18), indicating
good reproducibility across devices.

To assess reliability under conditions relevant to wearable use, we examined the sliding sensor
response after exposure to sweat, frictional wear, and repeated bending. Following immersion in
artificial sweat for up to 60 min, the wrinkle topography remains intact apart from moderate
swelling-induced dimensional changes, and the direction-dependent sliding signals remain clearly
distinguishable (Supplementary Figs. 19–22). After 5000 friction cycles along WD and 5000
cycles along PWD, the wrinkle morphology and characteristic signal waveforms are largely
preserved, with only a modest reduction in decoding accuracy (Supplementary Figs. 23–26).
Similar stability is observed after cyclic bending along both directions (Supplementary Figs. 27–
30). Together, these results show that the anisotropic sliding-sensing functionality arises from the
intrinsic wrinkle-organized architecture and is retained under mechanical and environmental
perturbations relevant to long-term, on-body operation.

Mechanical deformation enables rolling strain sensors and temperature alarms
In addition to the anisotropic mechanical and electrical properties of WSO-MN, the wrinkle
architecture introduces spatial heterogeneity in stiffness and stress distribution across the film
thickness. This leads to a mechanical instability of the surface layer, especially under thermal
stimulation, this heterogeneity gives rise to pronounced out-of-plane deformation, enabling
spontaneous and programmable rolling behavior. As shown in Fig. 6d, when WSO–MN is heated
to elevated temperature (80 ℃), the wrinkled film undergoes rapid inward rolling, forming a
cylindrical geometry with its rolling axis aligned parallel to the wrinkle direction. Quantitative
curvature analysis shows that the initial curvature increases from 0.176 ± 0.014 mm⁻¹ to 0.371 ±
0.017 mm⁻¹ within 5 min of heating (Supplementary Fig. 31). This rolling behavior originates from
the modulus mismatch between the reinforced wrinkle ridges and the comparatively softer matrix,
which generates internal stress upon thermal activation. As solvent redistribution and thermal
softening proceed, this stress imbalance drives bending and self-rolling, with the wrinkle
alignment dictating the rolling direction. Importantly, the rolling response is robust and repeatable,
and its geometry can be tailored by the wrinkle pattern, providing a mechanically programmable
deformation mode.

Leveraging this rolling behavior, we designed a rolling strain sensor by assembling two parallel
wrinkled WSO–MN strips joined at both ends with a pure PVA solution and thermally activating
the structure at 80 ℃ (Supplementary Movie 5 and Fig. 6a, b). Upon rolling, the wrinkle ridges of
the inner layer come into contact with the smooth surface of the outer layer, forming multiple
parallel conductive pathways and establishing a low-resistance initial state (Fig. 6c). When tensile
strain is applied, progressive separation of the wrinkle contacts occurs, leading to stepwise
increases in resistance (Fig. 6e). This contact-mediated sensing mechanism is reversible; upon
release, the sensor returns to its rolled configuration with minimal hysteresis (3.86%). The rolling
sensor maintains stable performance over 2,500 loading cycles at 300% strain (Fig. 6f),
outperforming most reported hydrogel-based and structural strain sensors in terms of durability
and signal stability (Fig. 6g, h and Supplementary Table 4). Owing to its low activation force and
large deformation range, the rolling sensor is particularly suited for detecting localized and subtle
motions. When mounted across finger joints, bending-induced elongation of the sensor produces
clear resistance changes that enable recognition of distinct hand gestures and real-time control of
a robotic hand (Supplementary Movie 6, Fig. 6i and Supplementary Fig. 32).

The same thermally driven rolling behavior also enables simple temperature-triggered actuation.
To demonstrate this capability, we constructed a temperature alarm in which a metal rod suspended
from a rolled WSO–MN film functions as a mechanical switch within an LED circuit (Fig. 6j, k).
The rod, with a mass 5.7 times that of the WSO–MN film, initially remains separated from a copper
contact, keeping the circuit open. As the ambient temperature increases from 33 ℃ to 58 ℃, the
WSO–MN rolls further, lifting the rod and closing the circuit within approximately 2 min (Fig. 6l).
This design illustrates how wrinkle-enabled thermal deformation can be directly translated into
functional actuation without additional power sources or complex circuitry.

Methods
Materials
PVA (Mw 146,000~186,000, 99+% hydrolyzed), ethylenediaminetetraacetic acid (EDTA), sodium
hydroxide (NaOH, pellets), and glycerol were purchased from Sigma. Multi-walled carbon
nanotubes (MWCNTs, OD: 10~20 nm, Length: 10~30 μm, Purity: >95%) were purchased from
XFNANO Inc., China. PLA filaments were purchased from 3D AURA Pte Ltd, Singapore. MgB
2
powder was brought from Xiaohuang nanotech, Chinaand MN were prepared following previous
work40. In short, EDTA (12.89g) and NaOH (3.95g) were dissolved in 90 mL of H O, and the pH
2
was adjusted to 10. MgB powders (2g) were then added to this solution at 25 °C. After 3 days of
2
exfoliation, the suspension was washed with deionized water and centrifuged multiple times to
separate the powders. The precipitate was dispersed in water and delaminated using probe
sonication for 30 min. The mixture was then centrifuged at 10,000 rpm for 10 min. Finally, after
freeze-drying and annealing at 750 °C, MgB nanosheets were obtained.
2

Fabrication of PVA solution (2% glycerol concentration)
First, 1 g glycerol was added into 48 g DIW. AftNer that, 1 g of PVA was added to the glycerol-DIW
solution at 95 ℃ and stirred at 450 rpm for 1 h. The glycerol concentration of the final solution
should be 2 wt%. For glycerol-dependent experiments, the glycerol concentration was varied as
specified in the corresponding sections.

Fabrication of PVA-MgB
2
solution (2% glycerol concentration)
First, 0.1 g NaOH was dissolved in 48 g deionized water (DIW). Then 1 g glycerol and 0.04 g MN
were added into alkaline DIW and ultrasonicated with 200 W power for 20 min to obtain a well-
dispersed solution. After that, 1 g of PVA was added to the glycerol-MgB solution at 95 ℃ and
2
stirred at 450 rpm for 1 h. The glycerol concentration of the final solution should be 2 wt%.

Fabrication of PVA-CNT solution (2% glycerol concentration)
First, 1 g glycerol and 0.04 g MWCNT were added into 48 g DIW and ultrasonicated with 200 W
power for 20 min to obtain a well-dispersed solution. After that, 1 g of PVA was added to the
glycerol-DIW solution at 95 ℃ and stirred at 450 rpm for 1 h. The glycerol concentration of the
final solution should be 2 wt%.

Fabrication of 3D printed molds
All samples used for mechanical and electrical tests were prepared with rectangular molds (40 mm
wide and 80 mm long). To investigate the effect of mold shape on wrinkle patterns, we also
employed other rectangular molds (20–80 mm wide and 80 mm long), a circular mold (64 mm in
diameter), and an equilateral triangular mold (86 mm side length). All models were designed in
SolidWorks and exported as STL files for 3D printing. The molds were fabricated using an
Adventure 3 (Flashforge, China), a fused deposition modeling 3D printer with PLA filaments.

Fabrication of WSO
Unless otherwise specified, all samples characterized and utilized in this study were prepared using
a heating temperature of 90 ℃. Specifically, a PLA mold (area: 3200 mm²) was securely attached
to a copper plate and placed onto a uniformly heated platform maintained at 90 ℃. Subsequently,
12 g of the prepared PVA composite solution was poured into the mold, and WSO was obtained
after a 40 min heating process. The heating duration was determined based on the evaporation
mass-loss curve (Supplementary Fig. 33). For mass-dependent experiments, the precursor mass
was varied as specified in the corresponding sections.

Fabrication of WFO
For comparison, WFO were fabricated by eliminating the temperature gradient during evaporation.
Specifically, 12 g of the PVA composite solution was poured into a plastic petri dish (area: 3200
mm²) and heated at 90 ℃ for 6 h in an oven to obtain WFO.

Characterization of the emergence time of wrinkles, temperature differences
The emergence time of wrinkles was determined through visual observation. The moment when
distinct wrinkle patterns first appeared on the surface was recorded as the emergence time of
wrinkles. Surface temperature measurements were obtained using an infrared thermal camera
(iRay, USA). For samples with wrinkle formation (heated above 50 ℃), the average temperature
difference was calculated by subtracting the minimum surface temperature from the maximum
surface temperature over a 1 min interval immediately before wrinkle emergence. For samples
without wrinkle formation (heated at 40 ℃), the average temperature difference was determined
by averaging the difference between the highest and lowest surface temperatures recorded over the
30 min interval immediately before complete evaporation of the polymer solution.

Characterization of PVA concentration in the skin layer at the time when wrinkle emerge
The PVA concentration at the time when wrinkles emerge was assessed by isolating the skin layer
from the PVA solution. The wet mass of the skin layer (m ) was first recorded. The sample was
wet
then dried in an oven at 80 ℃ for 48 h to ensure complete solvent removal, after which the dry
mass (m ) was measured. The PVA concentration (C ) was calculated using the following
dry PVA
formula:
m
dry
C = (1)
PVA m
wet

Characterization of microstructure, wrinkle size, cross-section image of wrinkles, bonding
energy, and viscosity
The microstructure images of WSO were taken by a field-emission scanning electron microscope
(FE-SEM, Hitachi S-4300, Japan). The optical ultra-depth images were taken by a confocal
microscope (KEYENCE, Japan). The amplitude of wrinkles was directly obtained from optical
ultra-depth images, and the wavelength of wrinkles were collected using ImageJ (National
Institutes of Health, USA). Representative cross-sectional images of the wrinkles were captured
using an optical charge-coupled device (CCD) microscope (Luosi, China). The bonding of WSO
and WFO was analyzed by FTIR (Thermo Scientific, USA). Viscosity tests were performed using
a rheometer (Thermo Scientific, USA) in viscosity mode. The mixture solution was placed on the
test platform with a gap of 0.1 mm between the platform and the detector, and the platform
temperature was kept constant at 90 ℃.

Thermal analysis
Thermogravimetric analysis (TGA Q500, TA Instruments) was used to quantify the solvent content
of the samples. Measurements were performed from room temperature to 350 ℃ at a heating rate
of 10 ℃ min-1. DSC (DSC 25, TA Instruments) was employed to examine the crystalline domains.
The testing was conducted at a heating rate of 20 ℃ min-1, in the presence of an argon atmosphere
with a flow rate of 50 mL min-1. Prior to testing, organo-hydrogel slices were initially submerged
in a cross-linking solution consisting of 5 mL glutaraldehyde (50 vol%), 500 μL hydrochloric acid
(37 wt%), and 50 mL of water. Subsequently, any surplus hydrochloric acid was thoroughly rinsed
from the stabilized hydrogels over a period of 2 h, after which they were dried in a 50 ℃ blast
oven for the duration of the night.

Characterization of skin layers' modulus and relaxation
The skin layer was prepared following previous work30. After 30 min of evaporation, the container
was tilted to drain the liquid. At this time, the skin layer on the upper layer of the solution would
be attached to the bottom of the container. Then, this layer was peeled off and sealed for storage.
A universal tensile machine (Instron 5500, USA) was used to test the modulus of the peeled skin
layer.

Mechanical characterizations
The mechanical performances of WSO and WFO were tested by a universal tensile machine
(Instron 5500, USA). The samples were cut into standard shapes (width: 12 mm, length: 6 mm),
the thickness of the samples was calculated through adding the cross-sectional area of the wrinkles
and the cross-sectional area of the wrinkle-free area at the bottom. The tensile speed was 20 mm
min-1. The fracture toughness was obtained by integrating the stress-strain curve.

For single-edge notch tension tests, the pair of notched and unnotched samples with a standard
shape (width: 21 mm; length: 10.5 mm; notch width: 7 mm) were prepared to measure the tearing
energy under a tensile speed of 20 mm min-1. The fracture energy can be calculated as:
εc
Fracture energy = H∫ σdε, (2)
0
where H is the sample height, ε is the critical crack strain of notched specimens, 𝜀 is applied
Ic
strain, and σ is the normal stress of the unnotched sample.

For fatigue tests, pre-notched specimens (width: 7.5 mm; length: 15 mm; notch width: 2.5 mm)
were mounted on a universal testing machine (Instron 5500, USA) and subjected to 5000 tensile
loading cycles at a maximum strain of 20%.

GF and hysteresis measurements
The resistance signal was collected by a digital multimeter (DMM6500, Keithley, USA) and the
GF was characterized by GF = (∆R/R )/𝜀, here ∆R and R are the resistance change and initial
0 0
resistance, respectively, and 𝜀 is the applied strain. Electrical hysteresis is calculated as follows:
∫ εmax|R̂ -R̂ |dε
Hysteresis = 0 load unload , (3)
∫
εmax|R̂
|dε
0 load
where R̂ = (∆R/R ) represents the relative resistance change, R̂ represents the relative
0 load
resistance change measured during sample loading, R̂ represents the relative resistance
unload
change measured during unloading, and ε denotes the maximum strain applied to the tested
max
sample.

Conductivity
Apparent conductivity was calculated from the measured resistance using conductivity = L/(SR),
where L is the projected electrode spacing along the macroscopic current direction, R is the
measured resistance, and S is the effective cross-sectional area normal to the macroscopic current
direction. Because the wrinkled film has a non-uniform cross section, S is defined direction-
dependently to enable consistent device-level comparison (Supplementary Fig. 34). For current
flow along WD, the effective area S was obtained from the measured ridge geometry, calculated
WD
as the base-film cross-sectional area plus the summed semi-elliptic ridge areas (Supplementary
Fig. 34a). For current flow PWD, the local thickness varies along the current path (Supplementary
Fig. 34b). We therefore defined the effective area using the average cross section based on the total
conductive volume: S = V/W , where V = S L , where W is the sample width
PWD WD WD PWD
perpendicular to the current direction.

Electrochemistry study
To determine the impedance of materials, we used two carbon electrodes to clamp the two ends of
the material, with a clamping distance of 5.5 mm in all tests. We adopted a Biologic Potentiostat
(VMP3, France) to test the material impedance ranging from 100 kHz to 1 Hz. After obtaining the
test results, we performed scaling, as follows:
S
Z = Z , (4)
scaling testedL
where S is the sample cross section area, L is the clamping distance, and Z is the tested
tested
impedance of the sample.

X-ray scattering characterizations
The two-dimensional (2D) small-angle X-ray scattering (SAXS) measurements were conducted
on an Anton Paar SAXSpoint2.0 (Anton Paar, Austria). The wavelength was Λ = 1.54 Å, and an
ELGER R 1M detector is employed. An exposure time of 10 min was used for the measurement,
with a sample-to-detector distance of 542 mm. The degree of structural orientation was quantified
using the Hermans orientation factor (fc), calculated following previous work12.

Fabrication of the sliding sensor
To fabricate a sliding sensor, strips of silver conductive tapes (BJS tapes, China) were affixed to a
3M VHB tape (3M, USA) measuring 12 mm × 12 mm, with each silver tape having a width of 5
mm. Except for the silver portion, the rest of the region was coated with super glue. A 12 mm × 12
mm WSO-MN organo-hydrogel slice was then placed on a VHB tape to finish the fabrication.

Deep learning for sliding-gesture recognition
To evaluate the feasibility of recognizing and classifying sliding gestures from the collected sensor
signals, we developed a five-layer feedforward ANN. The primary objective of the ANN was to
recognize the type of slide gesture represented by a continuous input data stream. Each layer
extracted features via fully connected nodes with rectified linear unit (ReLU) activation functions.
The network was trained using a dataset comprising four distinct sliding signal classes,
consistently collected with a bench multimeter (DMM6500, Keithley, USA). Each input sample
contained 51 data points. The complete dataset was randomly divided into training (80%),
validation (10%), and testing (10%) subsets. The ANN was trained for 20 epochs, and
classification performance was assessed using accuracy, classification rate, and loss function
metrics. Following training, the ANN was deployed on a laptop connected to the DMM6500 to
perform real-time recognition of sliding gestures.

Curvature measurement
The curvature change of WSO with temperature was measured using a caliper. The diameter of the
innermost circle (Dinner) of the gel in the rolled state was measured. The curvature was calculated
as follows:
1
Curvature = . (5)
D
inner

Fabrication of the rolling sensor
The rolling sensor was made using two slices of WSO-MN, with each slice measuring 5 mm × 12
mm. A single droplet of PVA-MgB solution with a glycerol content of 2% was utilized as an
2
adhesive to join the terminals of two slices. The rolling sensor was finally acquired after being
placed in an oven at a temperature of 80 ℃ for a duration of 5 min.

Fabrication of the WSO temperature alarm
The temperature alarm was fabricated using a 4.5 mm × 24 mm WSO as the switching module.
One end of the WSO was attached to the top of an acrylic rectangular container (100 mm × 100
mm) using VHB tapes, and a convex metal ring was positioned at the opposite end. The entire
circuit was connected with silver tape. The assembled acrylic container was then placed in a
variable-temperature oven (Lichen, China) set to heat to 60 ℃. A thermometer (Omega, USA) was
used to record the temperature variation during the heating process.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "This manuscript reports a thermal gradient–programmed self-wrinkling strategy to fabricate aligned wrinkle structures in organo-hydrogels during evaporation, enabling simultaneous control of surface architecture and bulk properties. The strength of this work lies in the conceptual novelty: how to harness evaporation-induced stress together with a tailored design to create wrinkles with certain orientation and morphology without external templates. The authors achieve remarkable results: 1. wrinkled organo-hydrogels with enhanced fracture strength (25.3 MPa) and toughness (180.5 MJ/m³) and 2. mechanical and electrical anisotropy that enables directional ion transport and deformation sensing. What really adds to the strength of the manuscript is that the work goes beyond material characterization to demonstrate sliding sensors integrated with NNs for robotic arm actuation, rolling strain sensors with low hysteresis, and temperature-responsive alarms. Compared to the state of the art, which often relies on post-gelation swelling, mechanical pre-straining, or lithographic templating to induce surface patterns, this new approach is simpler, template-free, and can yield structures of similar functionalities.\nOverall, the concept and results seem really novel and important. The experimental characterization is thorough and the results nicely articulated. Based on the above, I find that the, the manuscript presents conceptually novel and broadly relevant findings that align well with the scope of Nature Communications.\nOne minor suggestion:\nThe authors have clearly demonstrated mechanical anisotropy in tension by comparing loading along, perpendicular to, and within wrinkle directions, and they nicely link these results to the microstructural and molecular features of the wrinkled gels. For broader relevance to applications such as soft robotics or wearable electronics, it would be valuable if the authors could expand the discussion to consider how such anisotropy might manifest under other loading modes, including multiaxial deformation, shear, or fatigue. A perspective on these scenarios would help contextualize the findings in the applications arena.", "reviewer_2": "The manuscript presents a new strategy of inducing directional wrinkling in PVA-based organo-hydrogels via thermal gradient–programmed evaporation. The work is well motivated and addresses an important challenge in integrating structural anisotropy into hydrogels. The potential impact on flexible electronics, robotics, and soft biointerfaces is significant. This reviewer suggests a major revision before it can be accepted for publication.\n1. Wrinkle formation and alignment are only qualitatively explained. Mechanical finite element simulations or analytical buckling models should be added to predict critical wrinkling conditions, wrinkle wavelength, and orientation, and compared with experimental results.\n2. The role of wrinkle structures in reinforcing fracture resistance is discussed but not proven. Simulations of stress distribution, crack propagation, or energy release rate would strengthen the claims.\n3. The anisotropy in both mechanical performance (strength and toughness along vs. perpendicular to wrinkles) and electrical behavior (conductivity, gauge factor, strain sensitivity) is important. The authors should provide an analysis showing how wrinkle orientation governs stress distribution and conductive pathways, thereby clarifying the link between structure and function.\n4. Since conductivity relies on water/glycerol retention, how stable are the electrical properties under long-term exposure, drying, or varying humidity? Time-dependent conductivity tests would be helpful.\n5. For biointerface use, issues such as sweat, friction, or repeated bending should be addressed. How would these affect wrinkle stability and sensor performance?\n6. Is there any in situ observation or tracking of wrinkle evolution during formation? How long can the wrinkles remain stable once formed? Are they permanent under ambient conditions, or do they evolve dynamically with time, temperature, or humidity changes?\n7. How does the thickness of the hydrogel layer affect wrinkle wavelength, amplitude, and mechanical performance?", "reviewer_3": "In the manuscript titled “Thermal Gradient-Programmed Wrinkling in Organo-Hydrogels for Directional Mechanics and Adaptive Sensing”, Qi and coworkers developed a self-wrinkling technique that induces the spontaneous formation of aligned wrinkle patterns during evaporation. Through this approach, the PVA-based organo-hydrogels with wrinkle structure exhibits enhanced tensile strength and pronounced anisotropy in both mechanical deformation and ionic conduction. This endows the WSO with sensitive directional force detection capabilities. However, there are still some issues that need to be resolved before acceptance.\n1. The key to the growth and control of wrinkle structures lies in the thermal gradient induced during evaporation. However, your manuscript only provides detailed information on controlling the temperature at the bottom of the mold. The control of ambient temperatures on the side walls and the solution surface should also be elaborated upon.\n2. To better understand the relationship between wrinkle amplitude and film thickness, a cross-sectional image of the wrinkled PVA-based organo-hydrogel should be provided (optical microscope or SEM image).\n3. In the section “Tailoring wrinkle size…”, the mechanism by which glycerol content regulates wrinkle morphology remains unclear. According to your cited reference [35], glycerol reduces PVA crystallinity and enhances chain dynamics, which favors increased gel elasticity. Supplementary Fig. 12 also shows that the stress-strain curve at 8% glycerol exhibits more typical elastic rubber-like mechanical behavior. Additionally, the analysis of stress relaxation (Fig. 2b) in the paper contains certain errors. A long relaxation time does not necessarily imply a decrease in elasticity. Therefore, the mechanism governing wrinkle shape regulation requires further characterization and analysis.\n4. Considering that PVA-based wrinkled materials are formed through DIW evaporation, if water is not completely evaporated, the moisture content of different samples should be measured, as it significantly affects the mechanical properties of hydrogels. When analyzing the enhancement of material mechanical properties by wrinkled structures, the interference from water content should be excluded.\n5. In the calculation of electrical conductivity, considering the irregularity of the wrinkled material's cross-sectional area, how is the cross-sectional area S determined for different wrinkle orientations?\n6. In Fig. 4a, higher evaporation temperatures result in an overall decrease in conductivity. However, can this decrease be simply attributed to “higher evaporation temperatures reducing conductivity due to glycerol loss”? Characterization data is required to support this claim. Differences in water content within the samples could also account for variations in conductivity.\n7. On page 12, the statement “the conductivity along the wrinkle direction is significantly higher than that perpendicular to it, attributed to the tighter wrinkle structure facilitating ion transport” raises the question: Why does a tighter wrinkle structure enhance ion transport? This requires supporting evidence from characterization data or literature to elucidate the mechanism by which it enhances ion transport.\n8. The statement on page 8, “This enhancement is attributed to strong dynamic covalent interactions between MN and PVA, simultaneously elevating viscosity and modulus” is confusing at this point because it lacks supporting literature or evidence.\n9. The layout and visual appeal of figures should be considered. For example, in Fig. 2, the pictures labeled a, b, c, d, and e are of varying sizes and not aligned. Additionally, there are numerous similar instances that require adjustment."}, "author_response": "Response to referees\nMs. Ref. No.: NCOMMS-25-65837A\nGeometry-Programmed Self-Wrinkling in Organo-Hydrogels for Anisotropic\nMechanics and Adaptive Sensing\nHaobo Qi†, Hang Yang†, Tian Li, Min Li, Wei Zhou, Xinyu Dong, Lailai Zhu*, Wei Zhai*\nWe are grateful to the reviewer for assessing our paper and providing constructive\ncomments reported below in black. To address them, we have now revised the manuscript\nand provide detailed responses (blue) along with the newly added text (blue italics), which\nis also marked in the revised manuscript (yellow highlighted text).\nReviewer #1 (Remarks to the Author):\n[...]\nResponse: Thank you for this constructive suggestion. We have expanded the Discussion\nto clarify how the wrinkle-programmed anisotropy may manifest under multiaxial\ndeformation and fatigue, and we further support these perspectives with new multiaxial\nsimulations and cyclic fatigue tests (Supplementary Fig. 11c and Fig. 3j).\n[...]\nReviewer #2 (Remarks to the Author):\n[...]\nResponse: Thank you for this important suggestion. We agree that our earlier description\nof wrinkle formation relied too heavily on qualitative interpretation. In the revised\nmanuscript, we restructured the wrinkling mechanism into two coupled stages and added a\nclearer, more quantitative framework that addresses the reviewer’s three requests—critical\nconditions, orientation, and wavelength/amplitude—with direct comparison to\nexperimental results.\n[...]\nReviewer #3 (Remarks to the Author):\n[...]\nResponse: Thank you for this important point. In addition to controlling the bottom\ntemperature, we ensured reproducible thermal boundary conditions at both the side walls\nand the solution free surface, and we have clarified these details in the revised manuscript.\n[...]"}, {"round": 2, "reviewer_comments": {"reviewer_1": "The authors have addressed all my comments; the manuscript is ready for publication.", "reviewer_2": "The authors have addressed the comments and questions well. This reviewer recommends accepting this manuscript.", "reviewer_3": "The raised concerns have been well addressed. Please consider to accept the revised ms."}, "author_response": ""}]

Decision letter