Dynamic wrinkling pattern exhibiting tunable fluorescence for anticounterfeiting applications

Light-Controlled Mechanical Self-Assembly for Programmable Surface Micro-Nano Patterning

Mechanical self-assembly is a novel manufacturing principle for programmable surface micro-nano patterning, which can be accurately triggered by interface stress mismatch-induced surface instability and regulated by high-precision boundary constraints. However, existing mechanical self-assembly fabrication strategies for micro-nano surface patterns face challenges in microfabrication compatibility and industrial repeatability. Here, a microfabrication-compatible light-controlled mechanical self-assembly is proposed for programmable and industrially standardized micro-nano surface patterning. By introducing light-controlled high spatial resolution soft-constraint boundaries and surface instability-induced mechanical self-assembly into film/substrate systems, a develop-free and industrially standardized manufacturing process with microfabrication compatibility is demonstrated. Moreover, trans-scale patterns spanning from 5 to 1000µm, 2D highly-ordered patterns, and dynamic patterns mimicking Chinese pandas eating bamboo are achieved. Design criteria for programmablely fabricating trans-scale patterns and the mechanical mechanism of orderliness evolutions in 2D self-assembly under arbitrary exposure angles are explained. Furthermore, by applying the highly-ordered micro-nano patterns, a new self-adaptive wideband gas detection system based on tunable micro-gratings is developed and methane is detected. This study can advance strategies for programmable surface micro-nano patterns and lay the foundation for the applications of surface functional devices.

Large Capacity of Data Storage and Information Encryption in Optical Encoder Disk by Integrating Phase Angle and Time Lock Based on Luminescence Metal Nanoclusters

The traditional "matrix" symbol patterns from the luminescence materials are mainly involved in a 2D plane, which seriously limits the information security and storage capacity. Here, a novel strategy is designed to extend two additional dimensions into a 2D plane by integrating time-gated response and phase angle changes of luminescent patterns. The strong orange fluorescence assemblies in an optical encoder disk are obtained after adding metal ions (Zn2+ or Al3+) and ammonia into copper nanoclusters (CuNCs) mainly due to aggregation-induced emission (AIE) behavior. The number of CuNCs-based aggregates is closely related to rotating angle changes. On the contrary, these aggregates can be reversibly dissembled upon exposing to adenosine triphosphate (ATP) in concomitant with their luminescence quenching. Their different quenching rates are on-demand controlled by the coordination reaction kinetics between ATP and metal ions in different pH value, which is conducive to the design of a series of time-locked information. The encoding patterns comprehensively utilize the static and dynamic characteristics of materials by rotating the phase angle at the specific time. The phase angle and time double locks is added into 2D plane to form a 4D storage models, which realizes higher-level information encryption and larger data storage capacity.

"All-in-One Functionalization and Synergic Ordering" Strategy Enables Multimode Anti-Counterfeiting Patterns

Conventional multimode anticounterfeiting systems usually suffer high cost, complicated structures, and different optical channel interferences. In this study, we demonstrate a simple strategy named "all-in-one functionalization and synergic ordering" to prepare quadruple mode patterns on a photoresponsive alternating copolymer P(DPA-alt-BP) film. Herein, a 9,10-diphenylanthracene (DPA) nonanoate unit serves as the multipurpose moiety with photoresponse and fluorescence, performing photodimerization upon 365 nm UV irradiation. The liquid crystal mesogen biphenyl (BP) caproate units can orderly align along strain for polarized sight and improve the microphase separation. Upon UV irradiation through a photomask followed by solvent annealing, the P(DPA-alt-BP) film is first gradient-cross-linked and then undergoes stress relief and microphase separation, giving rise to a synergic ordering effect that enables fabrication of an anticounterfeiting pattern with quadruple modes, i.e., wrinkled pattern, substructure on a wrinkled surface, distinguishable fluorescent emission, and polarized sight on the film. This strategy is promising for high-level anticounterfeiting applications and provides helpful inspiration to the development of innovative photoresponsive materials.

Dynamic multimodal information encryption combining programmable structural coloration and switchable circularly polarized luminescence

Multimodal optical-materials are highly desirable due to their advantages in enhancing information security, though independent modulation is challenging, especially accurately controlling the orthogonal relationship between the structural coloration (SC) and fluorescence (FL) pattern. Herein, we report a strategy which combines programmable structural coloration and switchable circularly polarized luminescence (CPL) for multimodal information encryption. Using photomask with aligned grating, programmable periodic patterns are fabricated on a polydiacetylene (PDA) gel film, which produces image in tunable structural colors. Introducing a chiral fluorescence layer containing perovskite nanocrystals and twisted-stacking Ag nanowires (NWs) bilayers, which provides stimuli-responsive FL and CPL with high dissymmetry factor (glum, up to 1.3). Importantly, the structural coloration information and FL patterns (including CPL pattern) can be independently modulated without mutual interference, even selectively concealed or exposed by varying microstructure design of the cross-linked PDA gel or by acetonitrile treatment.

Irreproducible SEBS wrinkling based on spin evaporation enabling identifiable artificial finger pad electronics

Irreproducible wrinkling, characterized by randomly arranged ridges or creases on material surfaces, has significant potential for application in entity identification and anti-counterfeiting. However, active research in this field is hindered because the existing wrinkling methods face challenges in realizing discernible patterns and potential applications of submillimeter-scale wavelength wrinkles are yet to be identified. Herein, we propose a strategy to create unique and irreproducible styrene-ethylene-butylene-styrene (SEBS) wrinkles using "spin evaporation", a technique that rapidly removes the solvent by spinning. We demonstrate the realization of SEBS wrinkles with wavelengths of hundreds of micrometers with high randomness, irreproducibility, and resistance to external stimuli. Importantly, to demonstrate the potential application of the wrinkle, we suggest and fabricate a human-finger-like fully soft identifiable artificial finger pad electronics and integrate it with a soft bimodal sensing system. The artificial finger pad mimics human finger pad features such as identification, object recognition, and effective grasping. Further integration of this pad into soft robots, cephalopods, and prosthetic skin offers insightful potential for the proposed wrinkling method in various fields.

Template-Guided Nondeterministic Assembly of Organosilica Nanodots for Multifunctional Physical Unclonable Functions

Optical physical unclonable functions (PUFs) are gaining attention as a robust security solution for identification in the expanding Internet of Things (IoT). To enhance the security and functionality of PUFs, integrating multiple optical responses─such as fluorescence and structural color─into a single system is essential. These diverse optical properties enable multilevel authentication, where different layers of security can be verified under varying light conditions, greatly reducing the risk of counterfeiting. However, compactly integrating these photonic components poses significant challenges due to the difficulty of aligning and combining their optical behaviors within a limited space. In this study, we address these challenges by employing a template-guided assembly of organosilica nanodots (OSiNDs), which allows for the simultaneous control of solid-state fluorescence, rainbow holography, and PUF patterns. By precisely tuning the dewetting process, the OSiNDs assemble into nanoisland structures that provide enhanced fluorescence brightness and thermal stability while maintaining distinct holographic properties. Our system produces a 4096-bit key with 3228 bits of entropy, a storage density of 1 Gbit/in2, and a low false positive rate of 10-6. Additionally, it includes multilevel anticounterfeiting features that reveal distinct color patterns under different illumination angles, further boosting security. Comprehensive environmental stability and durability tests, including humidity, thermal, and mechanical abrasion resistance, confirm the robustness of the system, ensuring its functionality under real-world conditions. This multifunctional PUF design establishes a standard for secure, compact optical systems, combining high-performance authentication with practical applications in anticounterfeiting.

Time-Encoded Information Encryption with pH Clock Guided Broad-Spectrum Emission by Dynamic Assemblies

With growing threats from counterfeiting-based security breaches, multi-level and specific stimuli-responsive anti-counterfeiting devices and message encryption methods have attracted immense research interest. Fluorescence-based encryption from aggregation-induced emission (AIE)-based materials solves the problems to a considerable extent. However, the development of smarter patterns with hierarchical security levels alongside dynamic display is still challenging. To screen out this complication, we bring forward a pH-switchable fluorescent assembly of an AIEgen and an aliphatic acid. We later temporally direct the molecular assembly with the aid of a chemical trigger-regulated pH clock, generating a transitory multicolor emission, including transient white light generation. The pH-dependent emissions were further implemented in constructing smart multi-input fluorescent chemical AND gates. Subsequently, we integrate the time-gated emissive system to develop an advanced multi-dimensionally secure data encryption strategy. This novel approach enhances anti-counterfeiting measures by introducing an additional layer of security based on temporal characteristics.

Femtosecond Laser-Induced Recrystallized Nanotexturing for Identity Document Security With Physical Unclonable Functions

Counterfeit identity (ID) documents pose a serious threat to personal credit and national security. As a promising candidate, optical physical unclonable functions (PUFs) offer a robust defense mechanism against counterfeits. Despite the innovations in chemically synthesized PUFs, challenges persist, including harmful chemical treatments, low yields, and incompatibility of reaction conditions with the ID document materials. More notably, surface relief nanostructures for PUFs, such as wrinkles, are still at risk of being replicated through scanning lithography or nanoimprint. Here, a femtosecond laser-induced recrystallized silicon nanotexture is reported as latent PUF nanofingerprint for document anti-counterfeiting. With femtosecond laser irradiation, nanotextures spontaneously emerge within 100 ms of exposure. By introducing a low-absorption metal layer, surface plasmon polariton waves are excited on the silicon-metal multilayer nanofilms with long-range boosting, ensuring the uniqueness and non-replicability of the final nanotextures. Furthermore, the femtosecond laser induces a phase transition in the latent nanotexture from amorphous to polycrystalline state, rather than creating replicable relief wrinkles. The random nanotextures are easily identifiable through optical microscopy and Raman imaging, yet they remain undetectable by surface characterization methods such as scanning electron and atomic force microscopies. This property significantly hinders counterfeiting efforts, as it prevents the precise replication of these nanostructures.

Construction of Heterogeneous Aggregation-Induced Emission Microspheres with Enhanced Multi-Mode Information Encryption

Traditional organic light-emitting materials hinder their anti-counterfeiting application in solid state due to their aggregation-caused quenching effect. A facile and straightforward method was reported to introduce AIE molecules into microspheres and manipulate different reaction parameters to prepare AIE microspheres with different morphologies. In this strategy, fluorescent microspheres with spherical, apple-shaped, and hemoglobin-like types were synthesized. Driven by the photocyclization and oxidation of tetraphenylethene, microspheres can be used as an aqueous fluorescence ink with erasable properties. The fluorescent patterns printed by microsphere ink on paper can be irreversibly erased by prolonged exposure to ultraviolet light (365 nm, 60 mw/cm2). Moreover, the multi-morphology microspheres can be further arranged for multiple-information encryption and anti-counterfeiting of barcodes and two-dimensional codes, in which double validation was carried out through fluorescence spectroscopy and laser confocal microscopy. This approach provides a new method for more reliable anti-counterfeiting and information encryption.

Artificial fingerprints engraved through block-copolymers as nanoscale physical unclonable functions for authentication and identification

Besides causing financial losses and damage to the brand's reputation, counterfeiting can threaten the health system and global security. In this context, physical unclonable functions (PUFs) have been proposed to overcome limitations of current anti-counterfeiting technologies. Here, we report on artificial fingerprints that can be directly engraved on a wide range of substrates through self-assembled block-copolymer templating as nanoscale PUFs for secure authentication and identification. Results show that morphological features can be exploited to encode fingerprint-like nanopatterns in binary code matrices representing a unique bit stream of information characterized by high uniqueness and entropy. A strategy based on computer vision concepts for authentication/identification in real-world scenarios is reported. Long-term reliable operation and robust authentication/identification against thermal treatment at cryogenic and high temperatures of the PUF have been demonstrated. These results pave the way for the realization of PUFs embracing the inherent stochasticity of self-assembled materials at the nanoscale.

Smart Wrinkled Interfaces: Patterning, Morphing, and Coding of Polymer Surfaces by Dynamic Anisotropic Wrinkling

In contrast to traditional static surfaces, smart patterned surfaces with periodical and reversible morphologies offer limitless opportunities for encoding surface functions and properties on demand, facilitating their widespread application as functional building blocks in various devices. Advances in intelligently controlling the macroscopic properties of these smart surfaces have been accomplished through various techniques (such as three-dimensional printing, imprint lithography and femtosecond laser) and responsive materials. In contrast to the sophisticated techniques above, dynamic anisotropic wrinkling, taking advantage of dynamic programmable manipulation of surface wrinkling and its orientation, offers a powerful alternative for fabricating dynamic periodical patterns due to its spontaneous formation, versatility, convenient scale-up fabrication, and sensitivity to various stimuli. This review comprehensively summarizes recent advances in smart patterned surfaces with dynamic oriented wrinkles, covering design principles, fabrication techniques, representative types of physical and chemical stimuli, as well as fine-tuning of wrinkle dimensions and orientation. Finally, advanced applications of these smart patterned surfaces are presented, along with a discussion of current challenges and future prospects in this rapidly evolving field. This review would offer some insights and guidelines for designing and engineering novel stimuli-responsive smart wrinkled surfaces, thereby facilitating their sustainable development and progressing toward commercialization.

Rare-Earth-Metal-Free Solid-State Fluorescent Carbonized-Polymer Microspheres for Unclonable Anti-Counterfeit Whispering-Gallery Emissions from Red to Near-Infrared Wavelengths

Colloidal carbon dots (CDs) have garnered much attention as metal-free photoluminescent nanomaterials, yet creation of solid-state fluorescent (SSF) materials emitting in the deep red (DR) to near-infrared (NIR) range poses a significant challenge with practical implications. To address this challenge and to engineer photonic functionalities, a micro-resonator architecture is developed using carbonized polymer microspheres (CPMs), evolved from conventional colloidal nanodots. Gram-scale production of CPMs utilizes controlled microscopic phase separation facilitated by natural peptide cross-linking during hydrothermal processing. The resulting microstructure effectively suppresses aggregation-induced quenching (AIQ), enabling strong solid-state light emission. Both experimental and theoretical analysis support a role for extended π-conjugated polycyclic aromatic hydrocarbons (PAHs) trapped within these microstructures, which exhibit a progressive red shift in light absorption/emission toward the NIR range. Moreover, the highly spherical shape of CPMs endows them with innate photonic functionalities in combination with their intrinsic CD-based attributes. Harnessing their excitation wavelength-dependent photoluminescent (PL) property, a single CPM exhibits whispering-gallery modes (WGMs) that are emission-tunable from the DR to the NIR. This type of newly developed microresonator can serve as, for example, unclonable anti-counterfeiting labels. This innovative cross-cutting approach, combining photonics and chemistry, offers robust, bottom-up, built-in photonic functionality with diverse NIR applications.

Uncovering the Recent Progress of CNC-Derived Chirality Nanomaterials: Structure and Functions

Cellulose nanocrystal (CNC), as a renewable resource, with excellent mechanical performance, low thermal expansion coefficient, and unique optical performance, is becoming a novel candidate for the development of smart material. Herein, the recent progress of CNC-based chirality nanomaterials is uncovered, mainly covering structure regulations and function design. Undergoing a simple evaporation process, the cellulose nanorods can spontaneously assemble into chiral nematic films, accompanied by a vivid structural color. Various film structure-controlling strategies, including assembly means, physical modulation, additive engineering, surface modification, geometric structure regulation, and external field optimization, are summarized in this work. The intrinsic correlation between structure and performance is emphasized. Next, the applications of CNC-based nanomaterials is systematically reviewed. Layer-by-layer stacking structure and unique optical activity endow the nanomaterials with wide applications in the mineralization, bone regeneration, and synthesis of mesoporous materials. Besides, the vivid structural color broadens the functions in anti-counterfeiting engineering, synthesis of the shape-memory and self-healing materials. Finally, the challenges for the CNC-based nanomaterials are proposed.

What Exactly Can Bionic Strategies Achieve for Flexible Sensors?

Flexible sensors have attracted great attention in the field of wearable electronic devices due to their deformability, lightness, and versatility. However, property improvement remains a key challenge. Fortunately, natural organisms exhibit many unique response mechanisms to various stimuli, and the corresponding structures and compositions provide advanced design ideas for the development of flexible sensors. Therefore, this Review highlights recent advances in sensing performance and functional characteristics of flexible sensors from the perspective of bionics for the first time. First, the "twins" of bionics and flexible sensors are introduced. Second, the enhancements in electrical and mechanical performance through bionic strategies are summarized according to the prototypes of humans, plants, and animals. Third, the functional characteristics of bionic strategies for flexible sensors are discussed in detail, including self-healing, color-changing, tangential force, strain redistribution, and interfacial resistance. Finally, we summarize the challenges and development trends of bioinspired flexible sensors. This Review aims to deepen the understanding of bionic strategies and provide innovative ideas and references for the design and manufacture of next-generation flexible sensors.

Stimuli-responsive mechanically interlocked polymer wrinkles

Artificial wrinkles, especially those with responsive erasure/regeneration behaviors have gained extensive interest due to their potential in smart applications. However, current wrinkle modulation methods primarily rely on network rearrangement, causing bottlenecks in in situ wrinkle regeneration. Herein, we report a dually cross-linked network wherein [2]rotaxane cross-link can dissipate stress within the wrinkles through its sliding motion without disrupting the network, and quadruple H-bonding cross-link comparatively highlight the advantages of [2]rotaxane modulation. Acid stimulation dissociates quadruple H-bonding and destructs network, swiftly eliminating the wrinkles. However, the regeneration process necessitates network rearrangement, making in situ recovery unfeasible. By contrast, alkaline stimulation disrupts host-guest recognition, and subsequent intramolecular motion of [2]rotaxane dissipate energy to eliminate wrinkles gradually. The always intact network allows for the in situ recovery of surface microstructures. The responsive behaviors of quadruple H-bonding and mechanical bond are orthogonal, and their combination leads to wrinkles with multiple but accurate responsiveness.

Designed wrinkles for optical encryption and flexible integrated circuit carrier board

Patterns on polymers usually have different mechanical properties as those of the substrates, causing deformation or distortion and even detachment of the patterns from the polymer substrates. Herein, we present a wrinkling strategy, which utilizes photolithography to define the area of stress distribution by light-induced physical crosslinking of polymers and controls diffusion of residual solvent to redistribute the stress and then offers the same material for patterns as substrate by thermal polymerization, providing uniform wrinkles without worrying about force relaxation. The strategy allows the recording and hiding of up to eight switchable images in one place that can be read by the naked eye without crosstalk, applying the wrinkled polymer for optical anti-counterfeiting. The wrinkled polyimide film was also utilized to act as a substrate for the creation of fine copper circuit by a full-additive process. It generates flexible integrated circuit (IC) carrier board with copper wire density of 400% higher than that of the state-of-the-art in industry while fulfilling the standards for industrialization.

Recent advances in photoresponsive printing inks for security encoding applications

Counterfeiting of banknotes, important documents, and branded goods continues to be a major worldwide problem for governments, businesses, and consumers. This problem has serious financial, security, and health implications. Due to their stability for printing on various substrates, the photochromic anticounterfeiting inks have received important interest. There have been various photochromic agents, such as polymer nanoparticles, quantum and carbon dots, and organic and inorganic fluorophores and luminophores, which have been broadly used for antiforging applications. In comparison to organic agents, inorganic photochromic materials have better stability under reversible/long-term light illumination. Recently, the remarkable optical characteristics and chemical stability of photoluminescent and photochromic agents have led to their extensive usage anticounterfeiting products. There have been also several strategies to tackle the rising problem of counterfeiting. Both of solvent-based and water-based inks have been developed for security encoding purposes. Additionally, the printing methods, including screen printing, labeling, stamping, inkjet printing, and handwriting, that have been used to apply anticounterfeiting inks onto various surfaces are discussed. The limitations of photoluminescent and photochromic agents and the potential for their future preparation to combat counterfeiting were discussed. This review would benefit academic researchers and industrial developers who are interested in the area of security printing.

Bioinspired Carbonized Polymer Microspheres for Full-Color Whispering Gallery Mode Emission for White Light Emission, Unclonable Anticounterfeiting, and Chemical Sensing Applications

Light-element-based fluorescent materials, colloidal graphene quantum dots, and carbon dots (CDs) have sparked an immense amount of scientific interest in the past decade. However, a significant challenge in practical applications has emerged concerning the development of solid-state fluorescence (SSF) materials. This study addresses this knowledge gap by exploring the unexplored photonic facets of C-based solid-state microphotonic emitters. The proposed synthesis approach focuses on carbonized polymer microspheres (CPMs) instead of conventional nanodots. These microspheres exhibit remarkable SSF spanning the entire visible spectrum from blue to red. The highly spherical shape of CPMs imparts built-in photonic properties in addition to its intrinsic CD-based attributes. Leveraging their excitation-dependent photoluminescence property, these microspheres exhibit amplified spontaneous emission, assisted by the whispering gallery mode resonance across the visible spectral region. Remarkably, unlike conventional semiconductor quantum dots or dye-doped microresonators, this single microstructure showcases adaptable resonant emission without structural/chemical modifications. This distinctive attribute enables a plethora of applications, including microcavity-assisted energy transfer for white light emission, highly sensitive chemical sensing, and secure encrypted anticounterfeiting measures. This interdisciplinary approach, integrating photonics and chemistry, provides a robust solution for light-element-based SSF with inherent photonic functionality and wide-ranging applications.

Ultradurable Embedded Physically Unclonable Functions

Physically unclonable functions (PUFs) have attracted growing interest for anticounterfeiting and authentication applications. The practical applications require durable PUFs made of robust materials. This study reports a practical strategy to generate extremely robust PUFs by embedding random features onto a substrate. The chaotic and low-cost electrohydrodynamic deposition process generates random polymeric features over a negative-tone photoresist film. These polymer features function as a conformal photomask, which protects the underlying photoresist from UV light, thereby enabling the generation of randomly positioned holes. Dry plasma etching of the substrate and removal of the photoresist result in the transfer of random features to the underlying silicon substrate. The matching of binary keys and features via different algorithms facilitates authentication of features. The embedded PUFs exhibit extreme levels of thermal (∼1000 °C) and mechanical stability that exceed the state of the art. The strength of this strategy emerges from the PUF generation directly on the substrate of interest, with stability that approaches the intrinsic properties of the underlying material. Benefiting from the materials and processes widely used in the semiconductor industry, this strategy shows strong promise for anticounterfeiting and device security applications.

A Shape Memory Hydrogel with Excellent Mechanical Properties, Water Retention Capacity, and Tunable Fluorescence for Dual Encryption

Information encryption platforms with reliable encryption performance, excellent mechanical performance, and high water retention capacity are highly desired. In this study, a tough double-network hydrogel is designed using the first network of a polyion complex containing lanthanide complexes via one-pot polymerization and the second network of a poly (N-hydroxyethyl acrylamide) (PHEAA) obtained by deep eutectic solvent (DES)-assisted introduction and subsequent photopolymerization. In this system, the pH-induced shape memory function and pH-/wavelength-dependent fluorescence allow the use of the prepared hydrogel as a dual-encryption platform. Owing to its high response reversibility, the hydrogel-based platform exhibits both a high security level and the advantages of rewritability, reprogrammability, and reusability. Additionally, the excellent mechanical properties and water retention capacity owing to the solvent exchange process involving the low-volatility solvent DES and the resulting introduction of the second network of PHEAA offer high practical application value for the hydrogel-based dual encryption platform, demonstrating its potential for information security protection.

Light-Responsive Shape- and Color-Changing Block Copolymer Particles with Fast Switching Speed

Polymer particles capable of dynamic shape changes in response to light have received substantial attention in the development of intelligent multifunctional materials. In this study, we develop a light-responsive block copolymer (BCP) particle system that exhibits fast and reversible shape and color transitions. The key molecular design is the integration of spiropyran photoacid (SPPA) molecules into the BCP particle system, which enables fast and dynamic transformations of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) particles in response to light. The SPPA photoisomerization, induced by 420 nm light irradiation, lowers the pH of the aqueous surroundings from 5.5 to 3.3. The protonated P4VP block substantially increases in domain size from 14 to 39 nm, resulting in significant elongation of the BCP particles (i.e., an increase in the aspect ratio (AR) of the particles from 1.8 to 3.4). Moreover, SPPA adsorbed onto the P4VP surface induces significant changes in the luminescent properties of the BCP particles via photoisomerization of SPPA. Notably, the BCP particles undergo fast, dynamic shape and color transitions within a period of 10 min, maintaining high reversibility over multiple light exposures. Functional dyes are selectively incorporated into different domains of the light-responsive BCP particles to achieve different ranges of color responses. Thus, this study showcases a light-responsive hydrogel display capable of reversible and multicolor photopatterning.

Direct in Situ Fabrication of Multicolor Afterglow Carbon Dot Patterns with Transparent and Traceless Features via Laser Direct Writing

Multicolor afterglow patterns with transparent and traceless features are important for the exploration of new functionalities and applications. Herein, we report a direct in situ patterning technique for fabricating afterglow carbon dots (CDs) based on laser direct writing (LDW) for the first time. We explore a facile step-scanning method that reduces the heat-affected zone and avoids uneven heating, thus producing a fine-resolution afterglow CD pattern with a minimum line width of 80 μm. Unlike previous LDW-induced luminescence patterns, the patterned CD films are traceless and transparent, which is mainly attributed to a uniform heat distribution and gentle temperature rise process. Interestingly, by regulating the laser parameters and CD precursors, an increased carbonization and oxidation degree of CDs could be obtained, thus enabling time-dependent, tunable afterglow colors from blue to red. In addition, we demonstrate their potential applications in the in situ fabrication of flexible and stretchable optoelectronics.

Controlled Preparation of Highly Stretchable, Crack-Free Wrinkled Surfaces with Tunable Wetting and Optical Properties

Constructing wrinkles by utilizing strain-driven surface instability in film-substrate systems is a general method to prepare micronano structures, which have a wide range of applications in smart surfaces and devices such as flexible electronics, reversible wetting, friction, and optics. However, cracks generated during the preparation and use process significantly affect the uniformity of wrinkled surfaces and degrade the functional properties of the film devices. The realization of crack-free wrinkles with high stretchability in hard film systems is still a great challenge. Here, we report on a facile technique for controllable preparation of large-area, highly stretchable, crack-free wrinkled surfaces by ultraviolet ozone (UVO) treatment of Ecoflex. The thickness dependence of the wrinkles and the in situ wrinkling process during mechanical loading are investigated. The wrinkles including striped, labyrinth-like, herringbone, and transitional structures are controllable by changing strain mode (uniaxial or biaxial), loading history (simultaneous or sequential), strain anisotropy, and gradient loading. The wrinkled surfaces obtained using UVO-treated Ecoflex have tunable wetting and optical properties and can maintain excellent mechanical stability under large strains. This study provides a facile method for the preparation of large-area, crack-free wrinkles, which is simple, fast, low-cost, and robust. The resulting wrinkled surfaces remain stable under high stretching, which is beneficial for many practical applications, especially in the cases of large strains.

Light-Responsive Supramolecular Liquid-Crystalline Metallacycle for Orthogonal Multimode Photopatterning

The development of multimode photopatterning systems based on supramolecular coordination complexes (SCCs) is considerably attractive in supramolecular chemistry and materials science, because SCCs can serve as promising platforms for the incorporation of multiple functional building blocks. Herein, we report a light-responsive liquid-crystalline metallacycle that is constructed by coordination-driven self-assembly. By exploiting its fascinating liquid crystal features, bright emission properties, and facile photocyclization capability, a unique system with spatially-controlled fluorescence-resonance energy transfer (FRET) is built through the introduction of a photochromic spiropyran derivative, which led to the realization of the first example of a liquid-crystalline metallacycle for orthogonal photopatterning in three-modes, namely holography, fluorescence, and photochromism.

Stimulus-responsive polymer materials toward multi-mode and multi-level information anti-counterfeiting: recent advances and future challenges

Information storage and security is one of the perennial hot issues in society, while the further advancements of related chemical anti-counterfeiting systems remain a formidable challenge. As emerging anti-counterfeiting materials, stimulus-responsive polymers (SRPs) have attracted extensive attention due to their unique stimulus-responsiveness and charming discoloration performance. At the same time, single-channel decryption technology with low-security levels has been unable to effectively prevent information from being stolen or mimicked. As a result, it would be of great significance to develop SRPs with multi-mode and multi-level anti-counterfeiting characteristics. This study summarizes the latest achievements in advance anti-counterfeiting strategies based on SRPs, including multi-mode anti-counterfeiting (static information) and multi-level anti-counterfeiting (dynamic information). In addition, the promising applications of such materials in anti-counterfeiting labels, identification platforms, intelligent displays, and others are briefly reviewed. Finally, the challenges and opportunities in this emerging field are discussed. This review serves as a useful resource for manipulating SRP-based anti-counterfeiting materials and creating cutting-edge information security and encryption systems.

Green syntheses of silk fibroin/wool keratin-protected AuAg nanoclusters with enhanced fluorescence for multicolor and patterned anti-counterfeiting

Counterfeiting is a serious worldwide issue that threatens human health and economic security. How to apply anti-counterfeiting techniques to textile materials remains a great challenge. Herein, we report bimetallic AuAg nanoclusters (NCs) synthesized by one-step reduction of chloroauric acid (HAuCl4) and silver nitrate (AgNO3) with wool keratin (WK) as reducer and silk fibroin (SF) as stabilizer. The strongest orange-red fluorescence under ultraviolet light as well as the highest zeta potential absolute values of -27.97 mV were simultaneously realized in the optimal proportion Au-AgNCs2 (WK/SF is 3/2), which was further processed to a series of anti-counterfeiting films by blending with SF, silk sericin (SS), and polyvinyl alcohol (PVA). After successfully being numbered into fifteen colors, a dark blue-orange-dark red-dark blue cyclic fluorescent anti-counterfeiting color chart was designed. In addition, a two-Maxwell-unit model was constructed to assist with the microstructure analysis, which found that the formation of hydrogen bonds and the secondary structure transition from α-helices to β-sheets during stretching were responsible for improving the mechanical properties and the two-staged fracture curves of films, respectively. Finally, a patterned and multicolor fluorescence anti-counterfeiting fabric application was demonstrated by combining the color chart and screen printing, indicating the great potential in textile anti-counterfeiting.

Electron-beam writing of a relaxor ferroelectric polymer for multiplexing information storage and encryption

To meet the strong demand for high-level encryption security, several efforts have been focused on developing new encryption techniques with high density and data security. Herein we employed a template-free electron beam lithography (EBL) technique to write various nanopatterns on poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CTFE)) films and applied it to electron-beam/electric multiplexing memory. Furthermore, electron beams can arbitrarily tailor down the domain structure evolutions and dipole directions, as proved by a combination of AFM-IR and PFM. Finally, our devices could function concurrently as an electron-beam write-only-memory (EB-WOM) and FeRAM, where the information could be encoded with the metastable phase evolutions from the ferroelectric phase to the paraelectric phase and variable bi-level ferroelectric signals. Our systematic study provides an inspiring idea for the design of information encryption devices with high-security requirements in flexible electronic fields.

Light and Humidity Dual-Responsive Anti-Counterfeiting Films Based on Hydrogen-Bonded Cholesteric Liquid Crystal Polymers with Spiropyran

There is still significant room for improvement when combining structural color with fluorescence patterns in dual anti-counterfeiting and dynamic anti-counterfeiting labels. In this study, we achieved significant breakthroughs under dual anti-counterfeiting conditions by using the structural color properties of the hydrogen-bonded cholesteric liquid crystal (HBCLC) and combining them with the fluorescence dye spiropyran (SP) to create anti-counterfeiting patterns. The anti-counterfeiting label can only display storage information after meeting the conditions of humidity and ultraviolet light (UV) and has the functions of dynamic encryption and repeated reading. We adjusted the center of the reflection band of the HBCLC film to transition from red to infrared under 40-90% relative humidity (RH) conditions and used it as a background film to draw anti-counterfeiting patterns with SP. Since these fluorescence dyes can switch between merocyanine (MC) (red) and SP (colorless) under UV and visible light conditions, when combined with the HBCLC, orthogonal dynamic encryption was achieved. Additionally, with the adsorption of SP, the reflection band of HBCLC films under the same humidity range increased from around 160 nm to around 260 nm, greatly improving the sensitivity to humidity changes. Furthermore, under UV conditions, it can still emit red fluorescence, demonstrating a polymorphic encryption feature, which greatly increased the complexity of the anti-counterfeiting pattern with significant significance to dynamic anti-counterfeiting and information storage.

Photoswitchable and Reversible Fluorescent Eutectogels for Conformal Information Encryption

Smart fluorescent materials that can respond to environmental stimuli are of great importance in the fields of information encryption and anti-counterfeiting. However, traditional fluorescent materials usually face problems such as lack of tunable fluorescence and insufficient surface-adaptive adhesion, hindering their practical applications. Herein, inspired by the glowing sucker octopus, we present a novel strategy to fabricate a reversible fluorescent eutectogel with high transparency, adhesive and self-healing performance for conformal information encryption and anti-counterfeiting. Using anthracene as luminescent unit, the eutectogel exhibits photoswitchable fluorescence and can therefore be reversibly written/erased with patterns by non-contact stimulation. Additionally, different from mechanically irreversible adhesion via glue, the eutectogel can adhere to various irregular substrates over a wide temperature range (-20 to 65 °C) and conformally deform more than 1000 times without peeling off. Furthermore, by exploiting surface-adaptive adhesion, high transparency and good stretchability of the eutectogel, dual encryption can be achieved under UV and stretching conditions to further improve the security level. This study should provide a promising strategy for the future development of advanced intelligent anti-counterfeiting materials.

Mechanically Ultra-Robust Elastomers Integrating Self-Healing and Recycling Properties Enable Information Encryption and Hierarchical Decryption

Developing high-performance elastomers with distinctive features opens up new vistas and exciting possibilities for information encryption but remains a daunting challenge. To surmount this difficulty, an unprecedented synthetic approach, "modular molecular engineering", was proposed to develop tailor-made advanced elastomers. The customized hydrophobic poly(urea-urethane) (HPUU-R) elastomer perfectly integrated ultrahigh tensile strength (∼75.3 MPa), extraordinary toughness (∼292.5 MJ m-3), satisfactory room-temperature healing, high transparency, puncture-, scratch-, and water-resistance; and miraculously, its 0.20 g film could lift objects over 100 000 times its weight without rupture. Intriguingly, we unexpectedly discovered that the elastomers fluoresce brightly at the optimal excitation wavelength attributed to the "clusterization-triggered emission". Based on the gradient hydrophobicity and fluorescent properties of HPUU-R, a hierarchical information encryption/decryption mode was innovatively established. Using high-performance HPUU-R as a double encryption platform makes the information highly stable and persistent, thus providing a stronger guarantee for the encrypted information. More attractively, given the impressive recyclability and self-healing of HPUU-R, information encryption can be realized by using recycled elastomers, injecting new vitality into green and sustainable development.

Food-Grade Physically Unclonable Functions

Counterfeit products in the pharmaceutical and food industries have posed an overwhelmingly increasing threat to the health of individuals and societies. An effective approach to prevent counterfeiting is the attachment of security labels directly on drugs and food products. This approach requires the development of security labels composed of safely digestible materials. In this study, we present the fabrication of security labels entirely based on the use of food-grade materials. The key idea proposed in this study is the exploitation of food-grade corn starch (CS) as an encoding material based on the microscopic dimensions, particulate structure, and adsorbent characteristics. The strong adsorption of a food colorant, erythrosine B (ErB), onto CS results in fluorescent CS@ErB microparticles. Randomly positioned CS@ErB particles can be obtained simply by spin-coating from aqueous solutions of tuned concentrations followed by transfer to an edible gelatin film. The optical and fluorescence microscopy images of randomly positioned particles are then used to construct keys for a physically unclonable function (PUF)-based security label. The performance of PUFs evaluated by uniformity, uniqueness, and randomness analysis demonstrates the strong promise of this platform. The biocompatibility of the fabricated PUFs is confirmed with assays using murine fibroblast cells. The extremely low-cost and sustainable security primitives fabricated from off-the-shelf food materials offer new routes in the fight against counterfeiting.

An all-in-one nanoprinting approach for the synthesis of a nanofilm library for unclonable anti-counterfeiting applications

In addition to causing trillion-dollar economic losses every year, counterfeiting threatens human health, social equity and national security. Current materials for anti-counterfeiting labelling typically contain toxic inorganic quantum dots and the techniques to produce unclonable patterns require tedious fabrication or complex readout methods. Here we present a nanoprinting-assisted flash synthesis approach that generates fluorescent nanofilms with physical unclonable function micropatterns in milliseconds. This all-in-one approach yields quenching-resistant carbon dots in solid films, directly from simple monosaccharides. Moreover, we establish a nanofilm library comprising 1,920 experiments, offering conditions for various optical properties and microstructures. We produce 100 individual physical unclonable function patterns exhibiting near-ideal bit uniformity (0.492 ± 0.018), high uniqueness (0.498 ± 0.021) and excellent reliability (>93%). These unclonable patterns can be quickly and independently read out by fluorescence and topography scanning, greatly improving their security. An open-source deep-learning model guarantees precise authentication, even if patterns are challenged with different resolutions or devices.

Design of a self-cleanable multilevel anticounterfeiting interface through covalent chemical modulation

Counterfeit products have posed a significant threat to consumers safety and the global economy. To address this issue, extensive studies have been exploring the use of coatings with unclonable, microscale features for authentication purposes. However, the ease of readout, and the stability of these features against water, deposited dust, and wear, which are required for practical use, remain challenging. Here we report a novel class of chemically functionalizable coatings with a combination of a physically unclonable porous topography and distinct physiochemical properties (e.g., fluorescence, water wettability, and water adhesion) obtained through orthogonal chemical modifications (i.e., 1,4-conjugate addition reaction and Schiff-base reaction at ambient conditions). Unprecedentedly, a self-cleanable and physically unclonable coating is introduced to develop a multilevel anticounterfeiting interface. We demonstrate that the authentication of the fluorescent porous topography can be verified using deep learning. More importantly, the spatially selective chemical modifications can be read with the naked eye via underwater exposure and UV light illumination. Overall, the results reported in this work provide a facile basis for designing functional surfaces capable of independent and multilevel decryption of authenticity.

Heat-Resistant and Color-Changing Luminescent Polysulfone for Information Encryption and Fire Alarming

An intrinsic difficulty with thermally responsive photoluminescent materials is that high temperatures usually destroy luminance due to the notorious thermal quenching effect. Limited by the vulnerable chemical structure and soft skeleton, most of the existing photoluminescent responsive materials fail to indicate or work at a surging temperature over 100 °C, thus limiting application in display and alarming in harsh conditions. Herein, enlightened by chameleon's adaptive nature to external stimulus, we introduce a topologically optimized electron donor-acceptor (DA) structure and supramolecular interactions of lanthanide ions into the polymer backbone. The emission color determined by the DA structure is stable at high temperatures, and metal-ligand interaction phosphorescence is temperature-adjustable. Owing to the excellent reproducibility and heat resistance of composite films, the sensors can be bent into different three-dimensional structures and adhered to metal surfaces as flexible thermometers with superior display resolution. The polymer composite film could be directly applied as a photoluminescent quick response (QR) code, with patterns simultaneously variable to a temperature from 30 to 150 °C free of manual operation. More importantly, the polymeric composite could be in-situ-oxidized to a "sulfone" structure with an enhanced glass transition temperature of 297-304 °C. The heat- and flame-resistant characteristics of the oxidized films give rise to the application of fire alarming devices since it can locate the fire source and respond exactly depending on the distance from the fire. The unique display, encryption, and alarming functions of the polymeric composite studied in this work bring forward a new concept of developing a great information security and disaster monitoring system with the application of temperature-responsive materials.

Swing-out opening of stromal interaction molecule 1

Stromal interaction molecule 1 (STIM1) resides in the endoplasmic reticulum (ER) membrane and senses luminal calcium (Ca2+ ) concentration. STIM1 activation involves a large-scale conformational transition that exposes a STIM1 domain termed "CAD/SOAR", - which is required for activation of the calcium channel Orai. Under resting cell conditions, STIM1 assumes a quiescent state where CAD/SOAR is suspended in an intramolecular clamp formed by the coiled-coil 1 domain (CC1) and CAD/SOAR. Here, we present a structural model of the cytosolic part of the STIM1 resting state using molecular docking simulations that take into account previously reported interaction sites between the CC1α1 and CAD/SOAR domains. We corroborate and refine previously reported interdomain coiled-coil contacts. Based on our model, we provide a detailed analysis of the CC1-CAD/SOAR binding interface using molecular dynamics simulations. We find a very similar binding interface for a proposed domain-swapped configuration of STIM1, where the CAD/SOAR domain of one monomer interacts with the CC1α1 domain of another monomer of STIM1. The rich structural and dynamical information obtained from our simulations reveals novel interaction sites such as M244, I409, or E370, which are crucial for STIM1 quiescent state stability. We tested our predictions by electrophysiological and Förster resonance energy transfer experiments on corresponding single-point mutants. These experiments provide compelling support for the structural model of the STIM1 quiescent state reported here. Based on transitions observed in enhanced-sampling simulations paired with an analysis of the quiescent STIM1 conformational dynamics, our work offers a first atomistic model for CC1α1-CAD/SOAR detachment.

Smart Polymer Surfaces with Complex Wrinkled Patterns: Reversible, Non-Planar, Gradient, and Hierarchical Structures

This review summarizes the relevant developments in preparing wrinkled structures with variable characteristics. These include the formation of smart interfaces with reversible wrinkle formation, the construction of wrinkles in non-planar supports, or, more interestingly, the development of complex hierarchically structured wrinkled patterns. Smart wrinkled surfaces obtained using light-responsive, pH-responsive, temperature-responsive, and electromagnetic-responsive polymers are thoroughly described. These systems control the formation of wrinkles in particular surface positions and the reversible construction of planar-wrinkled surfaces. This know-how of non-planar substrates has been recently extended to other structures, thus forming wrinkled patterns on solid, hollow spheres, cylinders, and cylindrical tubes. Finally, this bibliographic analysis also presents some illustrative examples of the potential of wrinkle formation to create more complex patterns, including gradient structures and hierarchically multiscale-ordered wrinkles. The orientation and the wrinkle characteristics (amplitude and period) can also be modulated according to the requested application.

High-contrast reversible multiple color-tunable solid luminescent ionic polymers for dynamic multilevel anti-counterfeiting

Dynamic color-tunable luminescent materials, which possess huge potential applications in advanced multilevel luminescence anti-counterfeiting, are of considerable interest. However, it remains challenging to develop simple high-contrast reversible multiple (triple or more than triple) color-tunable high-efficiency solid luminescent materials with low cost, facile synthesis, and good processability. Herein, by simply grafting charged multi-color AIEgen-based chromophores into polymers, a series of high-efficiency multiple color-tunable luminescent single ionic polymers are constructed through tuning feed ratios, counter anions and reaction solvents. Remarkably, some ionic polymers can not only achieve rare high-contrast reversible multiple color-tunable emission in solid states in response to different solvent stimuli, but also could realize excitation-dependent color-tunable emission. To the best of our knowledge, such charming multiple (triple or more than triple) color-tunable solid polymers responding to multiple external stimuli are still rare. Based on comparative studies of emission spectra, excitation spectra and fluorescence lifetimes before and after swelling, it could be inferred that solvent stimuli could induce microstructure changes of these ionic polymers and then change the aggregated-states of their corresponding AIE-active emission centers. Moreover, the different solvent stimuli could induce to produce different degrees of microstructure changes, resulting in their unique multiple color-tunable emission. More significantly, these smart color-tunable ionic polymers show great promise for applications in dynamic multilevel (three-level or even more than three-level) anti-counterfeiting.

Photo-induced stress relaxation in reconfigurable disulfide-crosslinked supramolecular films visualized by dynamic wrinkling

Stress relaxation in reconfigurable supramolecular polymer networks is strongly related to intermolecular behavior. However, the relationship between molecular motion and macroscopic mechanics is usually vague, and the visualization of internal stress reflecting precise regulation of molecules remains challenging. Here, we present a strategy for visualizing photo-driven stress relaxation induced by infinitesimal perturbations in the intermolecular exchange reaction via reprogrammable wrinkle patterns. The supramolecular films exhibit visible changes in microscopic wrinkle topography through ultraviolet (UV)-induced dynamic disulfide exchange reaction. In accordance with the trans-scale theoretical models, which quantitatively evaluate the chemical-dependent mechanical stresses in the supramolecular network, the unexposed disordered wrinkles evolved into highly oriented patterns and underwent subsequent mutations after thermal treatment. The stress-sensitive wrinkle macro-patterns can be repetitively written/erased through network topology rearrangement using different stimuli. This strategy provides an approach for visualizing and understanding the molecular behavior from dynamic chemistry to mechanical changes, and directly programming wrinkle patterns with regulated structures.

Novel Stimuli-Responsive Spiropyran-Based Switch@HOFs Materials Enable Dynamic Anticounterfeiting

Developing smart fluorescent materials having very advanced levels, showing dynamic displays of encrypted messaging, remains a huge challenge. In this paper, we present a unique method based on combining a common photochromic molecule spiropyran (SP) with hydrogen-bonded organic frameworks (HOFs), which allows for reversible switching of SP in solid states and shows dynamic displays of encrypted information. With the irradiation time extended, the fluorescence emission undergo an evident transformation from yellow-green to orange to red, because of the fluorescence resonance energy transfer (FRET) process between the unique HOFs and merocyanine (MC) isomer. By doping with polydimethylsiloxane (PDMS), we obtained free-standing membranes with high flexibility and mechanical strength, which can be reversibly and repeatedly bent and folded at angles of >90°. Notably, the comparison of fatigue resistance between SP2/PDMS (can be used for no more than 5 times) and SP2 ⊂ HOF2/PDMS (can be used for more than 100 times) further proved the importance of HOFs. This composite system has many advantages: (1) it has diverse dynamic fluorescence emission and visible colors regulated by ultraviolet radiation with high contrast and can be reversibly converted; (2) these changes in behavior can be achieved by simple UV illumination; and (3) compared with previous work, this work not only shows the dynamic fluorescence emission, but also shows the dynamic information during the decryption.

Preparation of photoluminescent nanocomposite ink for detection and mapping of fingermarks

Simple and efficient detection and mapping method based on a strong turn-on fluorescent pigment was developed for fingerprint analysis. We present a phosphor powder characterized by strong emission which is useful to achieve better fingerprint detection on multicolored or photoluminescent surfaces, such as currency notes characterized by optically changeable inks and highly fluorescent positions, because it offers better contrast and reduce the difficulty of background interference. Novel photochromic ink was prepared to establish a fingerprinted colorless film onto cellulose documents with green emission for anticounterfeiting applications as illustrated by photoluminescence spectra. Inorganic/organic nanoscale composite ink was prepared from rare-earth doped aluminate phosphor nanoparticles (PNPs; 27-49 nm) dispersed in a polyacrylic acid binding agent. PNPs were dispersed efficiently in polyacrylic acid to generate a colorless mark. The produced photochromic inks were spray-coated onto off-white paper sheets enclosing invisible fingermarks, and then exposed to thermofixation. Photochromic film was detected on paper surface presenting a transparent appearance under visible daylight and switchable to green under UV light. The CIE Lab parameters and photoluminescence spectra were studied under visible light and ultraviolet irradiation. The fingerprinted sheets showed fluorescence band at 517 nm upon excitation at 366 nm, showing a bathochromic shift and reversible photochromism without fatigue. The morphologies of pigment phosphor particles and fingerprinted sheets were inspected. The rheological properties of ink and mechanical behavior of the fingerprinted paper samples were explored. HIGHLIGHTS: Novel smart ink with alkaline-earth aluminate and polyacrylic acid was developed. Dual-mode fluorescent photochromism was presented for latent fingerprint analysis. Off-white fingerprinted films under daylight showed color change to green under UV. Fluorescence band monitored at 517 nm upon excitation at 366 nm. Fluorescent fingermark on paper sheets demonstrated good photostability.

Optical Absorption on Electron Quantum-Confined States of Perovskite Quantum Dots

In the framework of the dipole approximation, it is shown that in the perovskites quantum dots (QDs) FAPbBr3 and {en} FAPbBr3 interacting with low-intensity light, the oscillator strengths of transitions, as well as the dipole moments allowing transitions between one-particle electron quantum-confined states, attain values considerably (by two orders of magnitude) exceeding the typical values of the corresponding quantities in semiconductors. It has been established that the maximum values of the cross-section optical absorption of perovskite QDs are reached at the resonant frequencies of electron transitions. This makes it possible to use such nanosystems as of strong absorption nanomaterials in a wide range of infrared waves.

Spatial Patterning of Fluorescent Liquid Crystal Ink Based on Inkjet Printing

Fluorescent cholesteric liquid crystal materials (FCLC) with aggregation-induced emission (AIE) properties can effectively solve the contradiction between aggregation-induced quenching (ACQ) and liquid crystal self-assembly when light-emitting materials are aggregated, and they have great application value in the fields of anti-counterfeit detection and information hiding. However, generating a visually appealing design, logo, or image in the application typically requires an intricate fabrication process, such as the use of prefabricated molds and photomasks, which greatly limits the practical application of FCLC materials. Herein is reported a new method for spatially patterned liquid crystal (LC) microdroplet arrays using drop-on-demand inkjet printing technology. Through rational composition design, a spatial array composed of different liquid crystal microdroplets was established, and the array contains two entirely distinct but intact patterns at the same time, which can be reversibly switched under the irradiation of UV and natural light. This study provides a new method for the integrated preparation of different component liquid crystal materials.

3D printing of nanowrinkled architectures via laser direct assembly

Structural wrinkles in nature have been widely imitated to enhance the surface functionalities of objects, especially three-dimensional (3D) architectured wrinkles, holding promise for emerging applications in mechanical, electrical, and biological processes. However, the fabrication of user-defined 3D nanowrinkled architectures is a long-pending challenge. Here, we propose a bottom-up laser direct assembly strategy to fabricate multidimensional nanowrinkled architectures in a single-material one-step process. Through the introduction of laser-induced thermal transition into a 3D nanoprinting process for leading the point-by-point nanoscale wrinkling and the self-organization of wrinkle structures, we have demonstrated the program-controlled and on-demand fabrication of multidimensional nanowrinkled structures. Moreover, the precise control of wrinkle morphology with an optimal wavelength of 40 nanometers and the regulation of the dynamic transformation of wrinkled cellular microstructures via interfacial stress mismatch engineering have been achieved. This study provides a universal protocol for constructing nearly arbitrary nanowrinkled architectures and facilitates a new paradigm in nanostructure manufacturing.

Strain Modulation of Perpendicular Magnetic Anisotropy in Wrinkle-Patterned (Co/Pt)5/BaTiO3 Magnetoelectric Heterostructures

The rapid development of spintronics requires the devices to be flexible, to be used in wearable electronics, and controllable, to be used with magnetoelectric (ME) structures. However, the clamping effect inevitably leads to a decreased ME effect on the rigid substrate, and it remains challenging to directly prepare high-quality ferroelectric (FE) membranes on the widely used flexible substrate such as MICA or polyimide (PI). Here, periodic wrinkle-patterned flexible (Co/Pt)₅/BaTiO₃ (BTO) perpendicular magnetic anisotropy (PMA) heterostructures were prepared using the water-soluble method. The high-quality single-crystal BTO membrane ensures that intricate wrinkles do not fracture and a high ME coefficient is achievable. The transferred sample that is released from the clamping effect shows an enhanced ME effect in both in-plane and out-of-plane directions, with the ME coefficient reaching up to 68 Oe °C^-1. The ferromagnetic resonance (FMR) field of the flexible sample can be tuned by tensile strain up to 272 Oe. The finely controlled wrinkle shows periodic strain variations at peak and valley regions that switch the PMA magnetic domain motion as an effective control method. The proposed ultraflexible wrinkle sample shows great potential for combining multiple magnetization tuning approaches, allowing it to potentially serve as a tunable high-density 3D storage prototype.