ABSTRACT Wrinkled surfaces, characterized by strictly periodic microstructures, can serve as templates to provide localized, repetitive microdeformations and open routes to controlled deformation properties important for strain engineering. Low‐pressure plasma treatment with various process gases tunes the localized curvature conditions of the microstructures, resulting in adjusted bending radii ranging from 20 to 3200 nm. A key challenge in achieving appropriate bending conditions is predicting the required process conditions. We demonstrate that machine learning techniques solve this prediction problem and allow precise bending adjustments. Therefore, we designed an artificial neural network (ANN) that directly maps the process parameters to the resulting wavelength ( λ ) and amplitude ( A ). By coupling this model with a bisection method, we solved the inverse design problem, allowing the derivation of possible combinations of process parameters to achieve a specific λ or A . This transforms the fabrication process from trial‐and‐error to a precisely controlled engineering workflow. Thus, our finding opens new perspectives for the tailored fabrication of wrinkled surfaces with repetitive, controlled bending in manifold applications, such as strain engineering of 2D‐materials for optical and catalytically active surfaces, or structure‐dependent localized charge accumulation, e.g., for enhanced performance of triboelectric‐based sensors.

The interfaces in cable accessories form the weakest link in the cable system and can be considered as one of the major reasons for its failure. The parameters, such as surface smoothness, contact pressure, and temperature in the interfaces, govern the interfacial electrical withstand strength. An imperfect surface smoothness of the material creates voids at dielectric interfaces, which are inevitable, initiating the partial discharges (PDs). In the present work, different microstructured (rough, triangular, and wrinkled) silicones are investigated with reference to silicone for its interfacial discharge mechanism. The impact of structured silicone with different pressures (0.1, 0.15, and 0.2 MPa) at ambient temperature and 70 degrees C is examined. The dielectric constant of Sylgard 184 observed a deviation of only 6%, whereas the dissipation factor was 5.8 times higher from room temperature to 90 degrees C. The wrinkled structures exhibiting a lower void area (VA) with flat reference observed a higher PD inception voltage (PDIV) at different pressures compared to rough and triangular structures. In comparison to rough and triangular structures, the wrinkled structures with a flat reference and a decreased VA showed a greater PDIV at the selected pressures. The phase-resolved PD (PRPD) pattern of interfaces indicates a uniform distribution of charges at positive and negative half cycles involving the presence of both voids and surface discharges. The interfacial breakdown voltage (BDV) follows a similar trend in its magnitude, exhibited as that of PDIV for different structures.

Triboelectric sensors are known for their ultrahigh sensitivity and wide‐range detectability of tactile force/pressure, all while being self‐powered. However, the energy harvesting efficiency of triboelectric nanogenerators (TENGs) is often limited by relatively low output power density, when compared to other state‐of‐the‐art microgenerators. To address this challenge and achieve high force/pressure detection while maintaining excellent tactile resolution, a hybrid nanogenerator is proposed that comprises of both triboelectric and piezoelectric components within a ferroelectric polyvinylidene fluoride (PVDF) polymer matrix. To enhance tactile sensitivity, a coupled transfer printed‐spin coating technique is introduced to imprint wrinkled silicone structuring with tunable periodicity and amplitude directly onto PVDF. The hybrid output voltage of the wrinkled PVDF‐based TENG utilizing the ferroelectric β phase of PVDF (FE‐TENG_5) shows an impressive ≈200% increase compared to pristine FE‐TENG. The highest power density (0.9 mW cm −2 ) corresponds to FE‐TENG with the periodicity of 5 µm. Remarkably, the imprinted FE‐TENGs can detect even the slightest tactile force (<2 N), while the hybrid mechanism ensures a broad force sensing range, extending up to 100 N before saturation. This exceptional performance establishes the imprinted PVDF‐based FE‐TENG as a versatile tactile sensing platform for a range of cutting‐edge applications, particularly in electronic skin and next‐generation microelectronics.

Two-dimensional polymers (2DPs), comprising mono- or multilayer covalent polymeric networks with long-range order in two orthogonal directions, are of considerable interest due to their unique physicochemical properties. However, achieving precise thickness control from monolayer to bilayer, crucial for exploring proximity effect-driven phenomena beyond the monolayer limit, remains synthetically challenging. Here we report the on-water surface synthesis of crystalline mechanically interlocked monolayer and bilayer 2DP (MI-M2DP and MI-B2DP) films by embedding macrocyclic molecules with one and two cavities into 2DP backbones. The incorporation of bulky macrocyclic molecules introduces periodic mechanical bonds that precisely control interlayer interlocking, enabling selective monolayer or bilayer 2DP formation. Both MI-M2DP and MI-B2DP exhibit homogeneous, large-area films with ordered hexagonal pores and high modulus. MI-B2DP demonstrates an exceptionally high effective Young’s modulus of 151 ± 16 GPa (indentation method), surpassing MI-M2DP (90 ± 14 GPa), van der Waals-stacked MI-M2DPs (46 ± 11 GPa) and other reported multilayer 2DPs (<50 GPa). Modelling confirms that the mechanical interlocking minimizes interlayer sliding and reinforces the structure. Mechanically interlocked monolayer and bilayer two-dimensional polymers (2DPs) are synthesized on the water surface by embedding macrocyclic molecules with one and two cavities into the backbones. The resulting bilayer 2DP displays a high effective Young’s modulus, exceeding other reported multilayer 2DPs.

Wrinkling, formed by stress-induced energy minimization in thin polymer films, provides a reproducible method for large-area surface patterning. The resulting nano/micro topographies allow controlled spatial organization of nanomaterials for applications in sensing, optoelectronics, photocatalysis, and soft nanofabrication. The anisotropy of these wrinkled patterns can also be tuned for anti-biofouling or directional templating of biomolecules, which is crucial for hybrid bio-interfaces. Complementing this, spider silk-based surface technologies offer a flexible platform for creating biocompatible and biodegradable coatings. Recombinant spider silk protein technologies enable the modification of intrinsic protein properties (e.g., net charge) or incorporation of new functional elements (e.g., affinity peptides, enzymes). Spider silk-based coatings have been engineered for antifouling activities or to support cell adhesion and growth. In terms of biomedical applications, enhanced implant performance is feasible as well as tailored tissue engineering approaches. The synergistic combination of wrinkling and recombinant spider silk technology presents exciting opportunities for creation of surfaces with enhanced or new functionalities. For instance, spider silk wrinkled coatings can provide benefit for bioelectronics by encapsulating sensitive biomolecules within a topographically defined matrix, increasing sensitivity and specificity. This approach also offers innovations in biomedical device coatings, tissue engineering platforms (e.g., for neuronal or muscle tissue), large-scale bio-selective filtration, and switchable sustainable adhesives.

Power cables serve a crucial role in connecting transmission and distribution utilities as a part of expansion in the electricity grid with the recent trend. The electric potential separation in cable applications (joints, bushings and terminations) is controlled by the electrical strength between the solid interfaces. The imperfections in the dielectric insulation caused by surface roughness and assembly inaccuracies at the onsite conditions lead to voids in the interfaces responsible for discharges. These cavities above a critical size could initiate a higher electron avalanche, causing a failure in the insulation at the interface. Our proposed controlled surface structuring of silicone insulation material in the micron range, based on a wrinkleformation process, introduces a controlled cavity volume between the insulation parts, which reduces the number of failuretriggered cavities and extends the interface length simultaneously. All these studies were conducted previously on flat substrates. To more accurately replicate real-world conditions, this work examines the field distribution on a cylindrical surface with a constant gap distance (10 mm) while varying the configuration of the external electrodes. Using COMSOL Multiphysics, theoretical simulations enable the development of an optimal design for investigating the interfacial discharge mechanism in a cylindrical module.

Nanophase mixtures, leveraging the complementary strengths of each component, are vital for composites to overcome limitations posed by single elemental materials. Among these, metal-elastomer nanophases are particularly important, holding various practical applications for stretchable electronics. However, the methodology and understanding of nanophase mixing metals and elastomers are limited due to difficulties in blending caused by thermodynamic incompatibility. Here, we present a controlled method using kinetics to mix metal atoms with elastomeric chains on the nanoscale. We find that the chain migration flux and metal deposition rate are key factors, allowing the formation of reticular nanophases when kinetically in-phase. Moreover, we observe spontaneous structural evolution, resulting in gyrified structures akin to the human brain. The hybridized gyrified reticular nanophases exhibit strain-invariant metallic electrical conductivity up to 156% areal strain, unparalleled durability in organic solvents and aqueous environments with pH 2-13, and high mechanical robustness, a prerequisite for environmentally resilient devices.

Preserving the superior mechanical properties of monolayer two-dimensional (2D) materials when transitioning to bilayer and layer-stacked structures poses a great challenge, primarily arising from the weak van der Waals (vdW) forces that facilitate interlayer sliding and decoupling. Here, we discover that mechanically interlocked 2D polymers (2DPs) offer a means for structural reinforcement from monolayer to bilayer. Incorporating macrocyclic molecules with one and two cavities into 2DPs backbones enables the precision synthesis of mechanically interlocked monolayer (MI-M2DP) and bilayer (MI-B2DP). Intriguingly, we have observed an exceptionally high effective Young's modulus of 222.4 GPa for MI-B2DP, surpassing those of MI-M2DP (130.1 GPa), vdW-stacked MI-M2DPs (2 MI-M2DP, 8.1 GPa) and other reported multilayer 2DPs. Modeling studies demonstrate the extraordinary effectiveness of mechanically interlocked structures in minimizing interlayer sliding ( 0.1 Å) and energy penalty (320 kcal/mol) in MI-B2DP compared to 2 MI-M2DP ( 1.2 Å, 550 kcal/mol), thereby suppressing mechanical relaxation and resulting in prominent structural reinforcement.

This article treats finite element simulations of controlled wrinkle formation experiments of a soft bulk material with a thin, stiff layer on top. The wrinkling process is triggered by a stress mismatch between the bulk material and the thin layer. For the finite element simulations, we model the bulk material using a three‐dimensional hyperelastic material and the thin layer with a geometrically nonlinear elastic Cosserat shell. For the finite element simulations, we model the bulk material using a three‐dimensional hyperelastic material and the thin layer with a geometrically nonlinear elastic Cosserat shell. We use Lagrange finite elements for the bulk material and geodesic finite elements for the shell. The resulting minimization problem is nonlinear and nonconvex. We prove existence of minimizers in the continuous and the discrete function space. Finally, we solve the resulting nonconvex minimization problem numerically using a Riemannian trust‐region algorithm and compare our simulations to real experiments.

The energy transition towards a carbon-free economy requires an increased expansion of the electrical grid. Applications such as joints, bushing and terminations with electrical potential separation are limited in their electrical strength caused by discharges. Especially in cable accessories involving medium to extra-high voltage applications, where the surface roughness and assembly inaccuracies lead to cavities between the insulation parts are critical for electrical strength. These cavities, if above a certain size, initiate discharges and trigger damage processes of the insulating material at the interface. Controlled surface structuring of silicone insulation material in the micron range based on a wrinkle-formation process introduces a controlled cavity volume between the insulation parts, which reduces the number of failure-trigged cavities and extends the interface length simultaneously. Discharge measurements show a clear tendency towards higher breakdown (BD) voltages for reduced wrinkle-controlled cavity sizes with BD values of 45.9 kV compared to 26.5 kV for an undefined microstructured (rough) and 38.0 kV for a triangular structured silicone. The resulting compressed cavity size was analyzed and used for electric field simulations, which shows the dependency between the structure feature and the field magnitudes. The partial discharge inception voltage (PDIV) measurements indicated a lower voltage for triangular structures compared to wrinkle-controlled structures reflecting the severity of the ionization process.

Metal‐semiconductor nanostructures in various configurations are extensively used in photodetection, photocatalysis, and photovoltaics. For photodetection purposes, the working principle is straightforward; on illumination, generated charge carriers in excess lead to a decrease in resistance. Notably, using an interconnected metal‐semiconductor grating, it is observed and now reported an opposite response, an increase in the resistance. Such photoresistors are fabricated through wrinkle structuring and oblique angle material deposition methods. It is found that the controlled wrinkling leads to large‐area 1D periodic structures with coexisting cracking perpendicular to the grating direction—such cracks are used as connections between the two‐point contact measurement through the associated gold layer deposition. An enhanced current reduction is further observed on photoexcitation for an additional deposition of an amorphous titania layer. Subsequently, a discussion on the mechanisms and interaction between hot electron injection, charge carrier recombination, and thermalization is presented. Supported by numerical modeling, the angle‐resolved plasmonic modes with the photoresistance can be correlated. The ease of layered deposition of the materials allows one to extend the studies on cavity‐based structures with sandwiched titania layers as hotspots. This simple, scalable, and robust fabrication method thus promises an efficient routeway toward photosensor development in which plasmon‐mediated hot electrons play a crucial role.

We demonstrate a novel approach for controlling the line defect formation in microscopic wrinkling structures by patterned plasma treatment of elastomeric surfaces. Wrinkles were formed on polydimethylsiloxane (PDMS) surfaces exposed to low-pressure plasma under uniaxial stretching and subsequent relaxation. The wrinkling wavelength λ can be regulated via the treatment time and choice of plasma process gases (H2, N2). Sequential masking allows for changing these parameters on micron-scale dimensions. Thus, abrupt changes of the wrinkling wavelength become feasible and result in line defects located at the boundary zone between areas of different wavelengths. Wavelengths, morphology, and mechanical properties of the respective areas are investigated by Atomic Force Microscopy and agree quantitatively with predictions of analytical models for wrinkle formation. Notably, the approach allows for the first time the realization of a dramatic wavelength change up to a factor of 7 to control the location of the branching zone. This allows structures with a fixed but also with a strictly alternating branching behavior. The morphology inside the branching zone is compared with finite element methods and shows semi-quantitative agreement. Thus our finding opens new perspectives for "programming" hierarchical wrinkling patterns with potential applications in optics, tribology, and biomimetic structuring of surfaces.

A scalable method for the assembly of oriented bacterial cellulose (BC) films is presented based on using wrinkled thin silicone substrates of meter-square size as templates during biotechnological syntheses of BC. Control samples, including flat templated and template-free bacterial cellulose, along with the oriented BC, are morphologically characterized using scanning electron microscopy (SEM). Multiple functional properties including wettability, birefringence, mechanical strength, crystallinity, water retention, thermal stability, etc., are being characterized for the BC samples, where the wrinkling-induced in situ BC alignment not only significantly improved material mechanical properties (both strength and toughness) but also endowed unique material surface characteristics such as wettability, crystallinity, and thermal stability. Owing to the enhanced properties observed, potential applications of wrinkle templated BC in printing and cell culture are being demonstrated as a proof of concept, which renders their approach promising for various biomedical and packaging applications.