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

Biomimetic Fingerprint-like Unclonable Optical Anticounterfeiting System with Selectively In Situ-Synthesized Perovskite Quantum Dots Embedded in Spontaneous-Phase-Separated Polymers

Anticounterfeiting technologies meet challenges in the Internet of Things era due to the rapidly growing volume of objects, their frequent connection with humans, and the accelerated advance of counterfeiting/cracking techniques. Here, we, inspired by biological fingerprints, present a simple anticounterfeiting system based on perovskite quantum dot (PQD) fingerprint physical unclonable function (FPUF) by cooperatively utilizing the spontaneous-phase separation of polymers and selective in situ synthesis PQDs as an entropy source. The FPUFs offer red, green, and blue full-color fingerprint identifiers and random three-dimensional (3D) morphology, which extends binary to multivalued encoding by tuning the perovskite and polymer components, enabling a high encoding capacity (about 108570000, far surpassing that of biometric fingerprints). The strategy is compatible with mainstream production techniques that are widely used in traditional low-cost printed anticounterfeiting labels including spray printing, stamping, writing, and laser printing, avoiding complicated fabrication. Macrographical patterns and micro/nanofingerprint patterns with multiscale-tailorable inter-ridge sizes can be fused into a single FPUF label, satisfying different levels of anticounterfeiting requirements. Furthermore, a smart fused scheme of enhanced deep learning and fingerprint characteristic comparison is leveraged, by which high-efficiency, high-accuracy authentication of our FPUFs is achieved even for the increasingly huge FPUF databases and imperfectly captured images from users.

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.

3D printing hydrogel with homogeneous structural color induced by ZnS colloidal spheres for customized multi-channel spatial information encryption

The utilization of structural colors in 3D printing was anticipated due to their eco-friendliness and sustainability. However, the manufacturing of homogeneous structural colors with intricate 3D architectures remains a great challenge, particularly in hydrogels. Herein, we added 0.5 wt% ZnS colloidal spheres supporting Mie scattering into photocurable inks to generate vibrant and homogeneous structural color in the hydrogel, representing 40-100 times decrease of the reported dosage of colloidal spheres in previous work. Through optical simulation, gradient experiments, and evaluation in HSV color space, the ink composition was meticulously optimized for a commercial light-based 3D printer. Our experiments validate the high-throughput manufacturing of structural colored hydrogels with intricate 3D architectures and polychromatic objects, enabling the 1000 prints within 17 min and achieving 200 μm precision. We have also demonstrated the utilization of customizable 3D hydrogels with both structural and luminescent colors, thereby expanding their applications in the multi-channel spatial information encryption.

Bright and stable anti-counterfeiting devices with independent stochastic processes covering multiple length scales

Physical unclonable functions (PUFs) are considered the most promising approach to address the global issue of counterfeiting. Current PUF devices are often based on a single stochastic process, which can be broken, especially since their practical encoding capacities can be significantly lower than the theoretical value. Here we present stochastic PUF devices with features across multiple length scales, which incorporate semiconducting polymer nanoparticles (SPNs) as fluorescent taggants. The SPNs exhibit high brightness, photostability and size tunability when compared to the current state-of-the-art taggants. As a result, they are easily detectable and highly resilient to UV radiation. By embedding SPNs in photoresists, we generate PUFs consisting of nanoscale (distribution of SPNs within microspots), microscale (fractal edges on microspots), and macroscale (random microspot array) designs. With the assistance of a deep-learning model, the resulting PUFs show both near-ideal performance and accessibility for general end users, offering a strategy for next-generation security devices.

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.

Robust and Versatile Biodegradable Unclonable Anti-Counterfeiting Labels with Multi-Mode Optical Encoding Using Protein-Mediated Luminescent Calcite Signatures

Physical unclonable functions (PUFs) are emerging as a cutting-edge technology for enhancing information security by providing robust security authentication and non-reproducible cryptographic keys. Incorporating renewable and biocompatible materials into PUFs ensures safety for handling, compatibility with biological systems, and reduced environmental impact. However, existing PUF platforms struggle to balance high encoding capacity, diversified encryption signatures, and versatile functionalities with sustainability and biocompatibility. Here, all-biomaterial-based unclonable anti-counterfeiting labels featuring multi-mode encoding, multi-level cryptographic keys, and multiple authentication operations are developed by imprinting biomimetic-grown calcites on versatile silk protein films. In this label, the inherent non-clonability comes from the randomized characteristics of calcites, mediated by silk protein during crystal growth. The successful embedding of photoluminescent molecules into calcite lattices, assisted by silk protein, allows the resulting platform to utilize fluorescence patterns alongside birefringence for high-capacity encoding. This design facilitates easy and rapid authentication through Hamming distance and convolutional neural networks using standard cameras and portable microscopes. Moreover, angle-dependent polarization patterns enable multi-level key generation, while multi-spectral fluorescence signals offer multi-channel keys. The developed anti-counterfeiting labels combine biodegradability, green manufacture, easy authentication, high-level complexity, low cost, robustness, patternability, and versatility, offering a practical and high-security solution to combat counterfeiting across various applications.

High Defect Tolerance Breaking the Design Limitation of Full-Spectrum Multimodal Luminescence Materials

With the development of optical anti-counterfeiting and the increasing demand for high-level information encryption, multimodal luminescence (MML) materials attract much attention. However, the discovery of these multifunctional materials is very accidental, and the versatile host suitable for developing such materials remains unclear. Here, a grossite-type fast ionic conductor CaGa4O7, characterized by layered and tunnel structure with excellent defect tolerance, is found to meet the needs of various luminescent processes. Almost all luminescent modes, including down/up-conversion luminescence (DCL/UCL), long persistent luminescence (LPL), mechanoluminescence (ML), and X-ray excited optical luminescence (XEOL), are realized in this single host. Full-spectrum (from violet to near-infrared) photoluminescence and ML as well as multicolor XEOL are achieved by simply changing the doped luminescent center. A series of anti-counterfeiting devices, including the quasi-dynamic display of famous paintings, digital information encryption, and multi-color handwritten signatures, are designed to show the encryption of information in temporal and spatial dimensions. This study clarifies the importance of defect tolerance of the host for the development of MML materials, and provides a unique insight into the cross-field applications of special functional materials, which is a new strategy to accelerate the development of novel MML materials.

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.

High-dimensional anticounterfeiting nanodiamonds authenticated with deep metric learning

Physical unclonable function labels have emerged as a promising candidate for achieving unbreakable anticounterfeiting. Despite their significant progress, two challenges for developing practical physical unclonable function systems remain, namely 1) fairly few high-dimensional encoded labels with excellent material properties, and 2) existing authentication methods with poor noise tolerance or inapplicability to unseen labels. Herein, we employ the linear polarization modulation of randomly distributed fluorescent nanodiamonds to demonstrate, for the first time, three-dimensional encoding for diamond-based labels. Briefly, our three-dimensional encoding scheme provides digitized images with an encoding capacity of 109771 and high distinguishability under a short readout time of 7.5 s. The high photostability and inertness of fluorescent nanodiamonds endow our labels with high reproducibility and long-term stability. To address the second challenge, we employ a deep metric learning algorithm to develop an authentication methodology that computes the similarity of deep features of digitized images, exhibiting a better noise tolerance than the classical point-by-point comparison method. Meanwhile, it overcomes the key limitation of existing artificial intelligence-driven classification-based methods, i.e., inapplicability to unseen labels. Considering the high performance of both fluorescent nanodiamonds labels and deep metric learning authentication, our work provides the basis for developing practical physical unclonable function anticounterfeiting systems.

Amorphous Photonic Structure Patterns with Thin Film Interference Effects for Multilevel Anticounterfeiting

Colloidal photonic structures with the ability to control and manipulate light propagation offer long-term color stability, low optical loss, and angle-dependent color properties, while combinations of different photonic structures across multiple scales provide an extensive color range and enhanced optical functionalities, presenting significant potential for advanced anticounterfeiting applications. However, the proper design or manufacture of such complex structures is still challenging. In this study, amorphous photonic structures (APSs) with thin film interference (TFI) effects were fabricated for multilevel anticounterfeiting. The APSs inherit the isotropic resonant scattering and render partial TFI effects, resulting in unprecedented dynamic specular and diffuse color-shifting features as the viewing or incident direction shifts. Additionally, incorporating a certain concentration of fluorescent microspheres into the colloidal ink adds a third layer of fluorescent anticounterfeiting mode to the APSs. Enabled by infiltration-assisted (IFAST) colloidal assembly technologies, the sophisticated color distributions and randomly arranged fluorescent microspheres on the microscale of APSs grant unique and inherent fingerprint features. The unique and unpredictable optical and structural characteristics of APSs provide physical unclonable functions (PUFs) to prevent replication and tampering, demonstrating their potential as optical PUF security labels for anticounterfeiting applications through artificial intelligence (AI) reading and authentication.

On-Demand Picoliter-Level-Droplet Inkjet Printing for Micro Fabrication and Functional Applications

With the advent of Internet of Things (IoTs) and wearable devices, manufacturing requirements have shifted toward miniaturization, flexibility, environmentalization, and customization. Inkjet printing, as a non-contact picoliter-level droplet printing technology, can achieve material deposition at the microscopic level, helping to achieve high resolution and high precision patterned design. Meanwhile, inkjet printing has the advantages of simple process, high printing efficiency, mask-free digital printing, and direct pattern deposition, and is gradually emerging as a promising technology to meet such new requirements. However, there is a long way to go in constructing functional materials and emerging devices due to the uncommercialized ink materials, complicated film-forming process, and geometrically/functionally mismatched interface, limiting film quality and device applications. Herein, recent developments in working mechanisms, functional ink systems, droplet ejection and flight process, droplet drying process, as well as emerging multifunctional and intelligence applications including optics, electronics, sensors, and energy storage and conversion devices is reviewed. Finally, it is also highlight some of the critical challenges and research opportunities. The review is anticipated to provide a systematic comprehension and valuable insights for inkjet printing, thereby facilitating the advancement of their emerging applications.

Confined Flash Printing and Synthesis of Stable Perovskite Nanofilms under Ambient Conditions

The fabrication of stable perovskite nanofilm patterns is important for the development of functional optical devices. However, current production approaches are limited by the requirement for strict inert gas protection and long processing times. Here, a confined flash printing synthesis method is presented to generate perovskite nanofilms under ambient conditions, combining precursor transfer, perovskite synthesis, crystallization, and polymer protection in a single step within milliseconds. A laser simultaneously prints and induces the flash synthesis, confined in a polymer nanofilm, under normal ambient conditions. Due to its simplicity and flexibility, the method enables the combination and screening of many different perovskite precursor materials on various substrates. Besides for the development of novel perovskite materials and devices, the nanofilms can be applied for biodetection. The unique H2O2-responsive property of the ultrathin perovskite quantum dot film is applied for biomolecule detection based on oxidase-catalyzed enzymatic reactions.

Scalable Multistep Imprinting of Multiplexed Optical Anti-counterfeiting Patterns with Hierarchical Structures

Multiplexed optical techniques with multichannel patterns provide powerful strategies for high-capacity anti-counterfeiting. However, it is still a big challenge to meet the demands of achieving high encryption levels, excellent readability, and simple preparation simultaneously. Herein, we use a multistep imprinting technique, leveraging surface work-hardening to massively produce multiplexed encrypted patterns with hierarchical structures. These patterns with coupled nano- and microstructures can be instantaneously decoded into different pieces of information at different view angles under white light illumination. By incorporating perpendicular nano- and microgratings, we achieve four-channel encoded patterns, enhancing anti-counterfeiting capacity. This versatile method works on various metal/polymer materials, offering high-density information storage, direct visibility, broad material compatibility, and low-cost mass production. Our high-performance anti-counterfeiting patterns show significant potential in real-world applications.

Scalable Photo-Responsive Physical Unclonable Functions via Particle Kinetics

The increasing menace of counterfeiting and information theft underscores the urgent need for security platforms compatible with both micro- and nanoelectronics. Existing methods for anticounterfeiting labeling and cryptographic systems rely on unclonable patterns derived from the unpredictable variability of physical phenomena. However, these approaches impose limitations on the scalability of security components. Here we present a scalable platform for photoresponsive physically unclonable functions based on oxide particle kinetics in polymer solutions. The stochastic agglomeration process occurring during the formation of polymer films with dispersed oxide particles yields random patterns, with pixel sizes scalable from micro to nanoscales. We produce mechanically flexible and self-destructible optical unclonable function patterns utilizing oxide aggregates on a polymer film. Moreover, we establish a strategy for generating electrical unclonable patterns on a conducting polymer film. This involves covering the polymer film with an aggregate pattern mask, which serves as an ultraviolet-blocking layer for randomly exposing the film to ultraviolet ozone treatment. These unclonable patterns constitute robust and compact security systems, exhibiting effective resilience against machine-learning attacks (∼50% prediction error for training data sets of 1000). The developed scalable platforms for physically unclonable functions provide a hardware solution for robust cryptographic applications.

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.

Physical Unclonable Functions with Hyperspectral Imaging System for Ultrafast Storage and Authentication Enabled by Random Structural Color Domains

Physical unclonable function (PUF) is attractive in modern encryption technologies. Addressing the disadvantage of slow data storage/authentication in optical PUF is paramount for practical applications but remains an on-going challenge. Here, a highly efficient PUF strategy based on random structural color domains (SCDs) of cellulose nanocrystal (CNC) is proposed for the first time, combing with hyperspectral imaging system (HIS) for ultrafast storage and authentication. By controlling the growth and fusion behavior of the tactoids of CNC, the SCDs display an irregular and random distribution of colors, shapes, sizes, and reflectance spectra, which grant unique and inherent fingerprint-like characteristics that are non-duplicated. Based on images and spectra, these fingerprint features are used to develop two sets of PUF key generation methods, which can be respectively authenticated at the user-end and the manufacturer-front-end that achieving a high coding capacity of at least 22304. Notably, the use of HIS greatly shortens the time of key reading and generation (≈5 s for recording, 0.5-0.7 s for authentication). This new optical PUF labels can not only solve slow data storage and complicated authentication in optical PUF, but also impulse the development of CNC in industrial applications by reducing color uniformity requirement.

Fast and Accurate Recognition of Perovskite Fluorescent Anti-counterfeiting Labels Based on Lightweight Convolutional Neural Networks

Anti-counterfeiting technology has always been a key issue in the field of information security. Physical Unclonable Function (PUF) labels, which are random patterns produced by a stochastic process, emerge as an effective anti-counterfeiting strategy due to the inherent randomness of their physical patterns. In this study, we developed a high-throughput droplet array generation technique based on surface tension confinement to prepare perovskite crystal films with controllable shapes and sizes. We utilized the random distribution of perovskite nanocrystal particles to construct the PUF textures of the labels. Compared to other anti-counterfeiting labels, our labels not only possess fluorescent properties but also feature microscale dimensions (less than 5.3 × 10-2mm2), low cost (less than 3 × 10-4 USD), and high encoding capacity (1.7 × 101956), providing support for multilevel anti-counterfeiting protection. Additionally, we introduce an innovative PUF recognition method based on a Partial Convolutional Network (PaCoNet), effectively addressing the limitations of previous methods, in terms of recognition accuracy and speed. Experimental validation on a data set of perovskite nanocrystal films with up to 60 different macroscopic shapes and unique microscopic textures demonstrates that our method achieves a recognition accuracy of up to 99.65% and significantly reduces the recognition time per image to just 0.177 s, highlighting the potential application of these labels in the field of anti-counterfeiting.

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.

Silicon Vacancies Diamond/Silk/PVA Hierarchical Physical Unclonable Functions for Multi-Level Encryption

Physical unclonable functions (PUFs) have emerged as a promising encryption technology, utilizing intrinsic physical identifiers that offer enhanced security and tamper resistance. Multi-level PUFs boost system complexity, thereby improving system reliability and fault tolerance. However, crosstalk-free multi-level PUFs remain a persistent challenge. In this study, a hierarchical PUF system that harnesses the spontaneous phase separation of silk fibroin /PVA blend and the random distribution of silicon-vacancy diamonds within the blend is presented. The thermodynamic instability of phase separation and inherent unpredictability of diamond dispersion gives rise to intricate random patterns at two distinct scales, enabling time-efficient hierarchical authentication for cryptographic keys. These patterns are complementary yet independent, inherently resistant to replication and damage thus affording robust security and reliability to the proposed system. Furthermore, customized authentication algorithms are constructed: visual PUFs authentication utilizes neural network combined structural similarity index measure, while spectral PUFs authentication employs Hamming distance and cross-correlation bit operation. This hierarchical PUF system attains a high recognition rate without interscale crosstalk. Additionally, the coding capacity is exponentially enhanced using M-ary encoding to reinforce multi-level encryption. Hierarchical PUFs hold significant potential for immediate application, offering unprecedented data protection and cryptographic key authentication capabilities.

Dual Challenge-Response Systems of a Three-Dimensional "Bionic" Fluorescent Physically Unclonable Function Label

Inspired by the light and dark variations observed in natural cloud clusters under sunlight, we propose a three-dimensional (3D) "bionic" fluorescent physically unclonable function (PUF) label. The minimalist preparation process eliminates the need for expensive traditional instruments, thus offering new insight into the widespread adoption of 3D PUF labels. The Eu(CCA)3(H2O)2 powder, which is the first to propose its secondary building unit, was chosen as the fluorescent material. Its 3D morphology is preserved in the resin to mimic cloud-like structures. Furthermore, the luminescent properties are elucidated through experimental tests and first-principles calculations. To overcome the coding capacity limitation of traditional two-dimensional (2D) fluorescent PUF labels, a dual challenge-response system model is proposed. The shallow and deep models provide anticounterfeiting information from macro and micro perspectives, respectively. This successfully increases the encoding capacity from 210×10 to 2100×10000 for a 10 × 10 pixel binary code. Therefore, 3D "bionic" fluorescent PUF labels strike a balance between the simple usage of PUF labels and enhanced label security.

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.

All-silicon multidimensionally-encoded optical physical unclonable functions for integrated circuit anti-counterfeiting

Integrated circuit anti-counterfeiting based on optical physical unclonable functions (PUFs) plays a crucial role in guaranteeing secure identification and authentication for Internet of Things (IoT) devices. While considerable efforts have been devoted to exploring optical PUFs, two critical challenges remain: incompatibility with the complementary metal-oxide-semiconductor (CMOS) technology and limited information entropy. Here, we demonstrate all-silicon multidimensionally-encoded optical PUFs fabricated by integrating silicon (Si) metasurface and erbium-doped Si quantum dots (Er-Si QDs) with a CMOS-compatible procedure. Five in-situ optical responses have been manifested within a single pixel, rendering an ultrahigh information entropy of 2.32 bits/pixel. The position-dependent optical responses originate from the position-dependent radiation field and Purcell effect. Our evaluation highlights their potential in IoT security through advanced metrics like bit uniformity, similarity, intra- and inter-Hamming distance, false-acceptance and rejection rates, and encoding capacity. We finally demonstrate the implementation of efficient lightweight mutual authentication protocols for IoT applications by using the all-Si multidimensionally-encoded optical PUFs.

Advanced Nanomaterials in Medical 3D Printing

3D printing is now recognized as a significant tool for medical research and clinical practice, leading to the emergence of medical 3D printing technology. It is essential to improve the properties of 3D-printed products to meet the demand for medical use. The core of generating qualified 3D printing products is to develop advanced materials and processes. Taking advantage of nanomaterials with tunable and distinct physical, chemical, and biological properties, integrating nanotechnology into 3D printing creates new opportunities for advancing medical 3D printing field. Recently, some attempts are made to improve medical 3D printing through nanotechnology, providing new insights into developing advanced medical 3D printing technology. With high-resolution 3D printing technology, nano-structures can be directly fabricated for medical applications. Incorporating nanomaterials into the 3D printing material system can improve the properties of the 3D-printed medical products. At the same time, nanomaterials can be used to expand novel medical 3D printing technologies. This review introduced the strategies and progresses of improving medical 3D printing through nanotechnology and discussed challenges in clinical translation.

Printed smart devices for anti-counterfeiting allowing precise identification with household equipment

Counterfeiting has become a serious global problem, causing worldwide losses and disrupting the normal order of society. Physical unclonable functions are promising hardware-based cryptographic primitives, especially those generated by chemical processes showing a massive challenge-response pair space. However, current chemical-based physical unclonable function devices typically require complex fabrication processes or sophisticated characterization methods with only binary (bit) keys, limiting their practical applications and security properties. Here, we report a flexible laser printing method to synthesize unclonable electronics with high randomness, uniqueness, and repeatability. Hexadecimal resistive keys and binary optical keys can be obtained by the challenge with an ohmmeter and an optical microscope. These readout methods not only make the identification process available to general end users without professional expertise, but also guarantee device complexity and data capacity. An adopted open-source deep learning model guarantees precise identification with high reliability. The electrodes and connection wires are directly printed during laser writing, which allows electronics with different structures to be realized through free design. Meanwhile, the electronics exhibit excellent mechanical and thermal stability. The high physical unclonable function performance and the widely accessible readout methods, together with the flexibility and stability, make this synthesis strategy extremely attractive for practical applications.

Highly stretchable and self-healing photoswitchable supramolecular fluorescent polymers for underwater anti-counterfeiting

Thanks to the non-destructiveness and spatial-controllability of light, photoswitchable fluorescent polymers (PFPs) have been successfully applied in advanced anti-counterfeiting and information encryption. However, most of them are not suitable for use in harsh underwater environments, including high salinity seawater. In this study, by integrating photochromic molecules into a hydrophobic polymer matrix with the fluorine elastomer, including dipole-dipole interactions, we describe a class of novel photoswitchable supramolecular fluorescent polymers (PSFPs) that can adaptively change their fluorescence between none, green and red by the irradiation of different light. The PSFPs not only exhibited excellent photoswitchable properties, including fast photo-responsibility, prominent photo-reversibility, and photostability, but also exhibited some desired properties, including exceptional stretchability, hydrophobicity, antifouling, self-healing ability, simple preparation process, and processability. We thus demonstrated their applications in underwater data encryption and anti-counterfeiting labels.