Jing Zhang

The development, working mechanisms, and comparison of various micro-nano fabrication techniques are reviewed, with a particular emphasis on their application in metasurfaces. The advantages and disadvantages of each technique are analyzed, and recent advancements are highlighted. This article will provide technical guidance for researchers in the fabrication of metasurfaces.

Abstract

As a popular artificial composite material emerging in recent years, metasurfaces are one of the most likely devices to break through the volume limitation of conventional optical components due to their compact structure, flexible materials, and high modulation resolution of the beam. With a unique arrangement of units or made of special materials, the metasurface can effectively modulate the incident light's amplitude, phase, polarization, and frequency, thus realizing applications such as communication, imaging, sensing, and beam steering. The interaction of high-resolution structure, periodic arrangement, and unique constituent materials makes it possible to realize these applications, so researchers should choose the appropriate micro-nano processing technologies when designing and preparing the metasurface. This review will present micro-nano processing technologies related to the preparation of metasurfaces, such as electron beam lithography (EBL), femtosecond laser processing, focused ion beam lithography (FIB), additive manufacturing, nanoimprinting, and self-assembly, respectively. In addition, classical lithography techniques such as wet lithography, plasma lithography, deep reactive ion etching (DRIE), and photolithography will be introduced. Their development history and functions are described in detail, and examples of these techniques in preparing micro-nano-structures in different branches are presented, as well as some examples of metasurface preparation using these techniques. In addition, this paper has produced several tables describing these technologies, outlining their resolution, processing materials, advantages and disadvantages, and so on. Hopefully, this review will provide researchers with options and ideas for preparing metasurfaces.

This study presents a cleanroom-free toolkit for patterning submicron-resolution flexible bioelectronics, combining two-photon laser writing, mask transfer, and multi-layer patterning assembly. This technique enables precise and scalable patterning of diverse biomaterials on flexible substrates, offering the potential for developing wearable and implantable bioelectronics with excellent functionality and performance.

Abstract

Fabricating flexible bioelectronics remains an ongoing challenge in pursuing a cost-effective, efficient, scalable, and environmentally friendly approach for research and commercial applications. The current dominant method, lithography, presents challenges due to its incompatibility with solvent-sensitive biomaterials and the phase mismatch between the photoresist and flexible substrates, such as elastomers. This study proposes a simplified, cleanroom-free toolkit as a potential alternative to lithography for fabricating intricate bioelectronics on flexible substrates with submicron resolution. This technique integrates a two-photon laser writing mask, mask transfer, and multi-layer/material patterning processes, enabling batch-to-batch processing and making it suitable for scalable production. With excellent conformal patterning capability, different functional and encapsulation biomaterials can be patterned on flexible substrates, including elastomers, parylene-C, polymer sheets, skin, fabric, and plant leaves. The versatility of this toolkit is validated by fabricating various prototypes of wearable and implantable bioelectronics, demonstrating excellent performance.

Flexible cross–linked polymer films with excellent sensor abilities for ultralow temperature is explored. Significantly, the polymer films exhibits thermoresponsive, featuring phosphorescence color rapidly transforming from blue to green between 80 and 280 K, and there is a linear relationship between the RGB values of afterglow color and temperature. Based on these prominent features, an ultralow temperature sensor is achieved by using these flexible cross-linked polymer films as thermoresponsive elements.

Abstract

Ultralow temperature storage has sparked considerable attention with the development of the economy, showing promising applications ranging from biomedical to national defense and other fields. However, the development of ultralow temperature detection is constrained by the brittleness of current materials at low temperatures and the complexity of detection techniques. Consequently, the challenge exists in finding efficient solutions to material tolerance issues and achieving rapid detection of ultralow temperature. Herein, a novel flexible cross–linked polymer TPTA@PU film with long afterglow, high phosphorescence quantum efficiency, and excellent mechanical properties are successfully fabricated. Interestingly, the obtained TPTA@PU films demonstrate a notable thermoresponsive behavior, with the afterglow color shifting rapidly from blue to green within the temperature ranges from 80 to 280 K. Additionally, there is a positive linear correlation between the RGB values of the afterglow color and the corresponding temperature. Based on these prominent features, an ultralow temperature sensor is realized by utilizing TPTA@PU films as thermoresponsive elements. This work can be expected to provide more inspiration and possibilities for using RTP materials in a more cutting-edge field.

A novel approach to in situ visualization of carbon dioxide (CO₂) reduction within living cells is presented, using rhenium coated gold nanoflower (Re@Au)  catalysts and three dimensional (3D) surface-enhanced Raman spectroscopy (SERS) imaging. The Re@Au catalysts enable precise, light-controlled carbon monoxide (CO) generation under physiological conditions, while offering therapeutic benefits, including enhanced neurite outgrowth and reduced amyloid-beta levels. This work highlights the potential of plasmonic nanocatalysts for applications in neurodegenerative disease treatment, providing real-time insights into catalytic activity at the molecular level.

Abstract

The advancement of catalytic processes for therapeutic applications is pivotal to the development of next-generation medical technologies. One of the major challenges in this field lies in elucidating the intracellular generation of small molecules, such as carbon monoxide (CO), nitric oxide (NO), and others, which possess significant therapeutic potential. In this study, in situ surface-enhanced Raman spectroscopy (SERS) is employed to visualize and monitor the carbon dioxide (CO₂) reduction process mediated by a rhenium coated gold nanoflower (Re@Au) catalyst within living cells. The findings provide direct spectroscopic evidence of CO₂ reduction under intracellular conditions, demonstrating that CO can be catalytically generated from CO₂ in the cellular environment. These results position SERS as an indispensable tool for investigating catalytic processes in biological systems, providing molecular-level insights through the analysis of molecular fingerprint spectra that are typically beyond the capabilities of conventional microscopy techniques.

A novel strategy is demonstrated for in situ generation and dynamic modulation of circularly polarized luminescence (CPL) signals based on the combination of controllable magnetic field-assisted assembly, photo-patterning of diacetylene assemblies, and the twisted stacking chiral heterostructure. Multi-responsivity and arbitrary programmable patterning of CPL can be achieved based on the phase transition of polydiacetylene.

Abstract

Circularly polarized luminescence (CPL) material has been widely exploited in 3D display, information encryption, etc. However, in situ generation and dynamic modulation of CPL signals to achieve programmable CPL patterns remains challenging due to elusory interactions between fluorescence and the chiral microstructures. A novel strategy is proposed combining the controllable magnetic field-assisted assembly and photo-patterning technique to form the twisted stacking chiral heterostructure, consisting of orientated magnetic Ag@Fe₃O₄ nanowires (NWs) and polydimethylsiloxane (PDMS) film embedded with achiral dyes and orientated polydiacetylene (PDA) chains. In a designed chiral system, the orientated PDA chains after in situ photo-polymerization can serve as the polarizer to produce linear polarized fluorescence, while the aligned Ag@Fe₃O₄ NWs on the surface of PDMS films act as phase retarder, favoring in situ CPL generation. Furthermore, the CPL characteristics, including the wavelength and handedness, can be switched by the thermo-chromatic transition of PDA, thus, the programmable micropatterns with tailorable CPL distributions can be achieved. By employing the above fluorescence and CPL signals as two orthogonal information channels, the system possesses brilliant information storage capabilities, favoring multistage information encryption. This study proposes a novel strategy for the fabrication of programmable CPL micropatterns toward multiple information storage and encryption.

Nature Materials, Published online: 05 March 2025; doi:10.1038/s41563-025-02142-9

Inch-sized bulk lanthanide oxychloride single crystals and single-crystalline thin films with thickness down to the monolayer are synthesized through flux-enabled oriented attachment, providing a library of van der Waals materials with interesting dielectric and quantum properties.

“Light-Flashable” 2D polymeric fluorescent lifetime microbarcodes with excellent control of size, components, and functionalities are prepared to optimize for nanoscale spatial programmability of encoding patterns, light-triggered dynamic output, and quantitative fluorescence lifetime output, which will be essential for achieving extremely high data densities.

Abstract

The output signals of dynamic microbarcodes with precise control over dimensions can be reversibly altered in response to external stimuli, which have emerged as a promising alternative to information encoding. However, the complexity of multi-dimensional encoding and the high requirements for precision in nano/microscale fabrication still present significant challenges. Herein, “Light-Flashable” two-dimensional (2D) polymeric fluorescent lifetime microbarcodes are prepared with excellent control of size, components, and functionalities using the technique known as living crystallization-driven self-assembly seeded growth method, optimizing for nanoscale spatial programmability of encoding patterns, light-triggered dynamic output, and quantitative fluorescence lifetime output. By carefully modulating the output signals, the integration of photoswitchable spiropyrans facilitates “Light-Flashable” dynamic signaling by controlling energy transfer between the fluorescent components and spiropyrans on the 2D platelet surfaces. This energy transfer enables the manipulation of light-responsive fluorescence lifetimes and enhances the robustness of information storage. Consequently, the development of such state-of-the-art information carriers, capable of managing complex light patterns and storing data in 3D space, will be essential for achieving extremely high data densities.

This study reports a new antifouling strategy based on a bioinspired design. Mucin coating enhances biofilm control by active topography with beating micron-sized pillars. Besides the mechanical force of beating pillars, the antibiofilm activities also involve biological factors since mucin coating inhibits swarming motility and c-di-GMP synthesis in Pseudomonas aeruginosa but enhances its twitching motility.

Abstract

In the innate immune system of mammalians, beating cilia of epithelial cells and the attached mucin proteins prevent the colonization of microbial pathogens. Abiotic biomaterials of medical implants lack such protection and thus are susceptible to microbial colonization, leading to biofilm formation and persistent infections with high-level antibiotic tolerance. To address this challenge, the team further develops its new strategy of biofilm control by magnetically driven oscillation of micron-sized pillars on biomaterials. This study is based on a bioinspired design by covalently coating the pillars with mucin, a glycoprotein found ubiquitously in mammalian innate immune systems. The results show that mucin coating significantly enhances the antifouling effects of active topography in both the inhibition of Pseudomonas aeruginosa biofilm formation and removal of its mature biofilms. Analysis using scanning electron microscopy (SEM) reveals that mucin coating inhibits bacterial attachment near the pillar base, the area protected from the direct force of beating pillars. In addition, mucin coating enhances the twitching motility of P. aeruginosa but represses its swarming motility and the synthesis of cyclic di-GMP. These effects further contribute to the antifouling activities. Overall, these findings demonstrate the feasibility of engineering bioinspired antifouling materials for safer medical devices.

It is demonstrated that AgBiS₂ quantum dots exhibit unique photoinduced pseudocapacitive charge transfer properties, enabling efficient light-to-electrical energy conversion. These quantum dots facilitate enhanced light absorption and transduction when integrated with ZnO nanowires, which serve as an effective charge transport medium. Directly interfaced with neurons, the device achieves effective photostimulation, showcasing its potential for advanced neurostimulation applications.

Abstract

Optoelectronic biointerfaces have emerged as a promising platform for controlling the nervous system at the cellular, tissue, and organ levels with potential clinical applications via transduction of light energy to ionic currents. To improve charge injection, supercapacitor materials like IrO_x, TiN, and PEDOT have been incorporated as an additional layer on the photodiodes at electrode–electrolyte interfaces. Here, a bioelectronic design is demonstrated where AgBiS₂ quantum dots (QDs) serve as the photoabsorption material, hole transport medium, and pseudocapacitive electrode–electrolyte interface. The power-law behavior of the anodic and cathodic peaks suggests that diffusion-controlled and capacitive processes contribute to the charge storage mechanism. Furthermore, 3D Bode capacitance maps and phase angle responses indicate a high capacitance of 3.3 mF cm⁻² at the half-wave potential (0.044 V vs Ag/AgCl) in artificial cerebrospinal fluid (aCSF). For efficient transduction of light to electrical stimulation, AgBiS₂ QDs are embedded onto ZnO nanowires (NWs) in a photovoltaic device architecture, which produces twice the photocurrent (1.9 ± 0.3 mA cm⁻²) and nearly three times the charge injection (29 ± 2.3 µC cm⁻²) compared to the planar devices without NWs. Moreover, photostimulation of hippocampal neurons is demonstrated on the device without inducing significant oxidative stress. This study demonstrates an unconventional and efficient bioelectronic device via pseudocapacitive optoelectronic nanocrystals.

Multi-layered printed electronics are generally fabricated by overprinting with multiple stamps. Herein, a novel printing approach is introduced by modifying stamp with patterned surface energy. This enables the fabrication of multiple functional layers using only one stamp. Using this method, the fabrication of flexible light-emitting devices and high-denstiy transistor array are demonstrated (with over 17,900 transistors on an 8-inch wafer).

Abstract

Beyond its role in cultural communication, printing technology has emerged as one of the most important approaches to distributing and patterning functional materials for advanced manufacturing. In a printing process, a stamp is employed to transfer functional inks to a target surface, generating a specific pattern that exactly replicates the stamp. Through precise manipulation of different inkdrops, herein, a “one stamp, diverse patterns” printing strategy is developed and achieves deposition of varied patterns utilizing a single stamp. This stamp features patterned surface energy, achieved through regioselective energy injection treatment of an ultralow surface energy solid. It is revealed that inks with different surface tensions can selectively exhibit Cassie or Wenzel state on the stamp to generate diverse ink distributions, which enables the printing of distinct patterns on target surfaces. Leveraging this approach, flexible light-emitting devices and high-density transistor array are successfully printed using single stamps. These findings advance the understanding of finely tuning and patterning surface energy for precise liquid manipulation and offer a leap forward in efficient and versatile printing methodology that will boost the innovative integration of functional materials in a simplified manner.

A new class of microfastener geometries is proposed, coming from biomimetic considerations and design optimization based on an original theoretical framework that is validated through testing and simulations. Demonstrators are assembled to present the impact that this technology can have on multiple fields: From precision grasping to drug delivery applications and underwater adhesives.

Abstract

Achieving adhesion under unfavorable conditions, such as when van der Waals interaction is not available or in dust environments, is crucial in applications ranging from surgical sutures to wound-healing tapes, underwater adhesives, robotic grippers, and space grasping. Interestingly, plants, animals, and microorganisms living in such environmental conditions show surface morphological traits optimized to achieve mechanical interlocking. Thus, they achieve an effective work of adhesion thanks to the interplay of friction and interfacially-storable elastic energy, which otherwise typically suppress adhesion. In this work, the design and fabrication fundamentals for achieving tunable, switchable, and robust mechanical adhesion is provided under a general environmental condition, such as wet or dusty, bio-mimicking natural solutions. A theoretical framework for the design of mechanical adhesion, based on mean-field continuum contact mechanics, is suggested and validated experimentally. This study can pave the way for the development of new technologies to be employed in situations where conventional adhesives may be ineffective, such as for surfaces exposed to water, solvent vapors, lubricants, high temperatures, dusty environments, high vacuum, or aerospace applications, or processes where switching and selective adhesion is needed such as grasping and sorting applications in the semiconductor industry.

In the present work, an artificial light-harvesting system with three-step energy transfer mechanism is developed, which can be constructed by using the supramolecular assembly of PPTPy and WP[5] through host-guest interactions serve as energy donors, and three distinct fluorescent dyes RhB, SR101, and Cy5 as energy acceptors. The three-step light-harvesting systems with sequential energy transfer not only exhibit high efficiency of energy transfer and strong ability of ROS generation but also can be used as photocatalysts to promote the photocatalyzed Minisci-type alkylation reactions with aldehydes for late-stage functionalization in water.

Abstract

The natural process of photosynthesis involves a series of consecutive energy transfers, but achieving more steps of efficient energy transfer and photocatalytic organic conversion in artificial light-harvesting systems (ALHSs) continues to pose a significant challenge. In the present investigation, a range of ALHSs showcasing a sophisticated three-step energy transfer mechanism is designed, which are meticulously crafted using pillar[5]arene (WP[5]) and p-phenylenevinylene derivative (PPTPy), utilizing host-guest interactions as energy donors. Three distinct types of fluorescent dyes, namely Rhodamine B (RhB), Sulforhodamine 101 (SR101), and Cyanine 5 (Cy5), are employed as acceptors of energy. Starting from PPTPy-2WP[5], energy is sequentially transferred to RhB, SR101, and Cy5, successfully constructing a multi-step continuous energy transfer system with high energy transfer efficiency. More interestingly, as energy is progressively transferred, the efficiency of superoxide anion radical (O₂ ^•−) generation gradually increased, while the efficiency of singlet oxygen (¹O₂) generation decreased, achieving the transformation from type II photosensitizer to type I photosensitizer. Furthermore, in order to fully utilize the energy harvested and reactive oxygen species (ROS) obtained, the ALHSs employ a multi-step sequential energy transfer process to enhance Minisci-type alkylation reactions with aldehydes through photocatalysis for late-stage functionalization in an aqueous environment, achieving a 91% yield.

This study explores the potential applications of antiphase ferroelectric boundaries (APFBs) in PbTiO₃ films due to the sharp, straight morphology and the interlocking feature between antiphase boundaries and 180° conventional domain walls. AFPBs retain a high degree of similarity to conventional domain walls, which may serve as dividers of domains and be used in promising strategy for miniaturizing ferroelectric devices.

Abstract

The ferroelectric domain wall, serving as the boundary between separate data carriers based on domains, has attracted widespread interest due to its distinctive physical properties. Although the domain walls in ferroelectric materials are narrower than those in magnetic materials due to their higher lattice anisotropy, they still account for a considerable proportion in ultrathin films, reducing storage efficiency to some extent. Here, ultrathin antiphase ferroelectric boundaries (APFBs) are presented and validated their feasibility as ferroelectric domain walls. The naturally formed APFB shows a sharp and straight morphology, with the characteristic of interlocking between the antiphase boundary (APB) and conventional 180° domain wall. The calculations from the density functional theory demonstrate that the APFBs undergo a significant but localized change in electronic structure. They largely retain the characteristics that are consistent with those of conventional domain walls, such as enhanced conductivity, irregular oxygen vacancy trapping energy, and vacancy-tunable physical properties. Finally, as techniques for precisely controlling the nucleation of APB developing, configurations with out-of-plane APFBs used as dividers may provide a promising strategy for miniaturizing ferroelectric devices.

Chemical vapor transport-synthesized RETe₃ (RE = La, Ce, Pr, Nd, Sm, and Dy) single crystals enable broadband photodetection and mid-wave infrared transmission imaging at room temperature. This research underscores the exceptional potential of RETe₃ charge density wave materials for high-performance, self-powered photodetection. This work advances the development of next-generation room-temperature mid-wave infrared detection strategies.

Abstract

Charge density wave (CDW), as an ordered electronic state, typically leads to the opening of a narrow bandgap, which can be excited by relatively low-energy photons, such as infrared light. Compounds with CDW, therefore, hold significant potential for high-performance broadband photodetectors. In this work, rare-earth tritellurides (RETe₃, where RE = La, Ce, Pr, Nd, Sm, and Dy), a well-known series with CDW transitions above room temperature, are investigated for the first time for room-temperature, broadband, and self-powered photodetection. RETe₃-based photodetectors demonstrate a broadband response spanning 380 to 4400 nm, covering the ultraviolet to mid-wave infrared range. Notably, the DyTe₃-based photodetector achieves a responsivity of 27 mA W⁻¹ at 3500 nm in the mid-wave infrared region, with a detectivity of 1.26 × 10⁹ Jones and a response time of 78 ms, comparable to photodetectors dominated by the photothermoelectric effect based on graphene. This work establishes RETe₃ as a promising new family for low-power, room-temperature, and broadband photodetection applications.

This article presents a hybrid metal-dielectric metasurface in transmission mode for mid-infrared (MIR) spectroscopy. Composed of germanium on aluminium cylinders atop a calcium fluoride substrate, the metasurface achieves 80% transmission efficiency at λ = 2.6 µm with a narrow full-width-half-maximum of 0.4 µm. Numerical simulations, straightforward fabrication method, characterization, and implementation for CO₂ gas detection are presented.

Abstract

Mid-infrared (MIR) spectroscopy is widely applied in many applications such as gas sensing, industrial inspection, astronomy, and imaging. While thin-film narrowband interference filters are cost-effective for MIR sensing, their complex fabrication limits their suitability for miniaturized systems. Plasmonic nanostructures, though explored for MIR applications, suffer from broad spectral responses and low efficiencies due to the ohmic losses inherent in metals. All-dielectric metasurfaces, with low intrinsic losses, have been proposed as alternatives for MIR spectroscopy. However, their operation is typically limited to reflection mode. In this work, a hybrid metal-dielectric metasurface operating in transmission mode for MIR spectroscopy is introduced. Composed of germanium (Ge) atop aluminium (Al) cylinders on a calcium fluoride (CaF₂) substrate, the metasurface achieves high transmission efficiency (80%) at λ = 2.6 µm and a narrow full-width-half-maximum of 0.4 µm. The transmission response arises due to the hybridization of modes between the Ge and Al structures. Numerical simulations are demonstrated, a straightforward fabrication method, and successful deployment as an in-line optical filter for CO₂ gas detection, achieving a detection limit of ≈0.04% (≈400 ppm). This work highlights the potential of hybrid metasurfaces as in-line gas sensing filters in MIR spectroscopy.

The oxygen vacancies engineering, achieved by the synergistic strategy of Rb doping and lattice strain, promotes the chemical adsorption of DEG on the TiO₂ surface for hole scavenging. Surface modification using composite siloxanes ensures the monodispersion of nanoparticles and improves organic-inorganic compatibility. The designed Rb-TiO₂/TB-CS structure exhibits remarkable potential as a responsive material in reversible photochromic systems for various color-switching applications.

Abstract

The utilization of TiO₂ for the fabrication of transparent photochromic materials is both cost-effective and environmentally friendly. However, it still poses challenges due to the rapid recombination of electron-hole pairs and poor organic-inorganic compatibility. Oxygen vacancies play a crucial role in sustaining sacrificial electron donors for hole scavenging, demonstrating great potential in enhancing photochromic performance. Herein, Rb doping and lattice strain are applied to synergistically engineer oxygen vacancies, considering lattice oxygen release is influenced by charge neutrality and oxygen atom coordination environment. Furthermore, the particle surface is modified using composite siloxanes to ensure monodispersion and enhance organic-inorganic compatibility. Structural analyses and theoretical calculations indicate that Rb doping and epitaxial strain synergistically reduce the oxygen vacancy formation energy and promote the chemical adsorption of diethylene glycol (DEG) on the TiO₂ surface for hole scavenging. The designed DEG-added Rb-TiO₂/TB-CS (TB means extra titanium butoxide, CS means composite siloxanes) nanodispersion exhibits a significant optical modulation amplitude exceeding 90% at 650 nm, rapid response within 60 s, and stable reversibility in color-switching (50 cycles). Moreover, utilizing Rb-TiO₂/TB-CS with DEG ligands as a responsive material enables the fabrication of transparent photochromic polyacrylate-based hybrid films, polyvinyl alcohol-based hydrogels, and hydroxyethyl cellulose-based rewritable papers, showcasing its immense potential for diverse applications.

A vertical Schottky photodiode based on black phosphorus with near-perfect absorption is designed for mid-infrared photodetection. Both electrical and optical designs are involved to support photogenerated carrier collection and light absorption enhancement, respectively. The ultrahigh external quantum efficiency (42%) is achieved for photodetector operating in mid-infrared region under room temperature.

Abstract

Infrared (IR) photodetectors play a crucial role in various fields such as medical imaging, communication, and surveillance. However, the majority of commercial infrared detectors require low-temperature operation, which limits their broader applications. Recently, room temperature infrared photodetectors based on 2D materials have shown potential for expanding their use, yet their performance is often constrained by low quantum efficiency. In this study, a vertical black phosphorus (BP) Schottky photodiode designed for room temperature mid-IR photodetection with enhanced quantum efficiency is reported. By optimizing both optical and electrical aspects of the design, near-perfect absorption is achieved through a resonant cavity and improve carrier separation and collection efficiency via Schottky and ohmic contacts, respectively. The photodetector demonstrates high sensitivity, with a specific detectivity of 2.2 × 10⁹ cm Hz^1/2 W⁻¹, and a maximal external quantum efficiency of 42% at 3.6 µm. Additionally, due to BP's intrinsic anisotropic absorption, the device exhibits an exceptionally high polarization sensitivity with a polarization ratio of 10 and a polarization angle sensitivity of 0.01 A W⁻¹ degree⁻¹ is achieved at 3.8 µm. This device design provides a promising approach for high-performance, room-temperature infrared photodetectors, combining low power consumption with polarization imaging capabilities.

Au substrate induces a strain in the adhered bottommost MoS₂ layer. The strain weakens the coupling at the first MoS₂-MoS₂ interface, making it the weakest point in the system, therefore MoS₂ crystal preferentially cleaves at this interface, facilitating the selective exfoliation of large-area monolayers with size comparable to that of the parent crystal.

Abstract

Gold-assisted exfoliation (GAE) is a groundbreaking mechanical exfoliation technique that produces centimeter-scale single-crystal monolayers of 2D materials. Such large, high-quality films offer unparalleled advantages over the micron-sized flakes typically produced by conventional exfoliation techniques, significantly accelerating the research and technological advancements in the field of 2D materials. Despite its wide applications, the fundamental mechanism of GAE remains poorly understood. In this study, using MoS₂ on Au as a model system, ultra-low frequency Raman spectroscopy is employed to elucidate how the interlayer interactions within MoS₂ crystals are impacted by the gold substrate. The results reveal that the coupling at the first MoS₂-MoS₂ interface between the adhered layer on the gold substrate and the adjacent layer is substantially weakened, with the binding force being reduced to nearly zero. This renders the first interface the weakest point in the system, thereby the crystal preferentially cleaves at this junction, generating large-area monolayers with sizes comparable to the parent crystal. Biaxial strain in the adhered layer, induced by the gold substrate, is identified as the driving factor for the decoupling effect. The strain-induced decoupling effect is established as the primary mechanism of GAE, which can also play a significant role in general mechanical exfoliations.

This review highlights advances in micro/nanorobots-enabled light-based biosensing and imaging. Untethered and remotely controlled micro/nanorobots enable precision biosensing using colorimetric and surface-enhanced Raman spectroscopy methods. They also provide cutting-edge in vitro intracellular and in vivo bioimaging in complex biological environments and organs. Furthermore, micro/nanorobots facilitate the development of point-of-care optical biosensors, enhancing disease diagnosis and prognosis capabilities in medical applications.

Abstract

Sensing and imaging of biomolecules are crucial to disease diagnosis, prognosis, and therapy where optical techniques have essential utility. Untethered and remotely controlled micro/nanorobots have shown promising sensing and imaging capabilities, especially in complex biological environments. In this review, how micro/nanorobots are used for optical biosensing and imaging while highlighting the significant developments in the field is discussed. Starting is done by exploring colorimetric biosensing methods enabled by micro/nanorobots. Significant advancements in surface-enhanced Raman spectroscopy-integrated micro/nanorobots are reviewed. Further, state-of-the-art optical bio-imaging applications by micro/nanorobots at in vitro intracellular level are highlighted. Novel in vivo bio-imaging assisted by optical micro/nanorobot sensors is examined. Furthermore, innovations in micro/nanorobots are assessed where motion augmentation is used as a detection mechanism, with applications in point-of-care molecular diagnostics. Finally, the challenges associated with micro/nanorobots-assisted advanced optical biosensing and imaging while discussing insights about potential research directions for this rapidly progressing field are summarized.

The alignment of electrospun fibers regulates cellular mechanotransduction through spatial guidance mechanisms. Smaller cells, constrained within interfiber space, exhibit attenuated stress fiber formation and diminished intracellular traction force, while activating lamellipodia-mediated adhesion. Larger cells adhere predominantly to the scaffold surface, circumventing spatial confinement to achieve expansive cytoskeletal reorganization and amplified contractile force generation.

Abstract

The geometric properties of extracellular matrix (ECM) fibers play a crucial role in regulating cellular behaviors and functions. Although extensive research has examined the effects of fiber alignment, conflicting results have often arisen, leaving the precise mechanisms by which electrospun fiber alignment affects cellular behavior still unclear. This study investigates how the arrangement of polycaprolactone (PCL) electrospun fiber substrates affects cellular mechanosensing by modulating cell positioning. Larger cells, whose width on a coverslip exceeds 5 times the width of the aligned fiber gaps (≈8 µm in this study) and that span multiple aligned fibers, demonstrate enhanced spreading and mechanotransduction. Conversely, smaller cells, whose width is less than or equal to 2.5 times the width of the aligned fiber gaps and are confined within fiber interstices, exhibit limited mechanotransductive signaling. These findings are further supported by manipulating cell size and, more importantly, have led to the fabrication of semi-aligned fiber networks that enhance both cell spreading and mechanotransduction. This research emphasizes the importance of optimizing fiber architecture to improve cellular interactions, offering valuable insights for the design of biomimetic scaffolds in tissue regeneration.

This study explores ultrathin epitaxial La₂Ti₂O₇ films, a layered perovskite from the Carpy-Galy family, grown on various substrates. Remarkably, high epitaxial strain promotes layer-by-layer growth and stabilizes the correct phase. The films exhibit a polarization significantly higher than previously reported, exceeding 18 µCcm⁻², and retain ferroelectricity down to a single-unit-cell thickness, highlighting their potential for advanced nanoscale devices.

Abstract

Layered perovskite-based compounds offer a range of unconventional properties enabled by their naturally anisotropic structure. Among these, the Carpy-Galy phases (A _n B _n O_3n+2), characterized by (110)-oriented perovskite planes interleaved with additional oxygen layers, stand out for robust in-plane polarization. However, the challenges associated with the synthesis of ultrathin Carpy-Galy films and understanding the impact of strain on their properties limit their integration into devices. Here, La₂Ti₂O₇ (n = 4) films grown on substrates imposing tensile, compressive, or negligible epitaxial strains are investigated. Surprisingly, a 3% tensile strain from DyScO₃ (100) substrates facilitates layer-by-layer growth mode, whereas compressive (LaAlO₃-Sr₂TaAlO₆ (110)) or negligible (SrTiO₃ (110)) epitaxial strains require post-deposition annealing to reach comparable crystallinity. Using density-functional theory calculations, scanning probe microscopy, X-ray diffraction, scanning transmission electron microscopy, and polarization switching experiments, it is confirmed that these films possess exceptional ferroelectric properties, including a polarization of 18 µCcm⁻² – more than three times higher than previously reported – as well as persistence of ferroelectricity down to a single-unit-cell thickness. This study not only advances the understanding of Carpy-Galy phases as epitaxial thin films but also lays a foundation for their integration into advanced ferroelectric device architectures.

Owing to their atomic-scale thickness and dangling-bond-free surfaces, 2D materials have become promising alternatives for electronic devices operating at high temperatures. This review comprehensively summaries the recent progresses on the interface engineering of 2D materials toward high-temperature electronic devices, including FETs, optoelectronic devices, sensors, and neuromorphic devices.

Abstract

High-temperature electronic materials and devices are highly sought after for advanced applications in aerospace, high-speed automobiles, and deep-well drilling, where active or passive cooling mechanisms are either insufficient or impractical. 2D materials (2DMs) represent promising alternatives to traditional silicon and wide-bandgap semiconductors (WBG) for nanoscale electronic devices operating under high-temperature conditions. The development of robust interfaces is essential for ensuring that 2DMs and their devices achieve high performance and maintain stability when subjected to elevated temperatures. This review summarizes recent advancements in the interface engineering of 2DMs for high-temperature electronic devices. Initially, the limitations of conventional silicon-based materials and WBG semiconductors, alongside the advantages offered by 2DMs, are examined. Subsequently, strategies for interface engineering to enhance the stability of 2DMs and the performance of their devices are detailed. Furthermore, various interface-engineered 2D high-temperature devices, including transistors, optoelectronic devices, sensors, memristors, and neuromorphic devices, are reviewed. Finally, a forward-looking perspective on future 2D high-temperature electronics is presented. This review offers valuable insights into emerging 2DMs and their applications in high-temperature environments from both fundamental and practical perspectives.

Nature, Published online: 17 February 2025; doi:10.1038/s41586-025-08755-z

Ambient-pressure superconductivity onset above 40 K in (La,Pr)₃Ni₂O₇ films

A novel self-rolling integration strategy mounts ultrathin (≈2 µm) poly(N-isopropylacrylamide)/Au microactuators onto optical fiber tapers, achieving unprecedented bending angles (>800°) and rapid response (≈0.55 s). This waveguide microactuator enables dynamic capture of fast-moving microorganisms and provides a high-performance, versatile platform for biomedical applications in confined, unstructured environments.

Abstract

Precisely capturing and manipulating microscale objects, such as individual cells and microorganisms, is fundamental to advancements in biomedical research and microrobotics. Photoactuators based on optical fibers serving as flexible, unobstructed waveguides are well-suited for these operations, particularly in confined locations where free-space illumination is impractical. However, integrating optical fibers with microscale actuators poses significant challenges due to size mismatch, resulting in slow responses inadequate for handling motile micro-objects. This study designs microactuators based on hydrogel/Au bilayer heterostructures that self-roll around a tapered optical fiber. This self-rolling mechanism enables the use of thin hydrogel layers only a few micrometers thick, which rapidly absorb and release water molecules during a phase transition. The resulting microactuators exhibit low bending stiffness and extremely fast responses, achieving large bending angles exceeding 800° within 0.55 s. Using this technique, this study successfully captures rapidly swimming Chlamydomonas and Paramecium, and demonstrates programmable non-reciprocal motion for effective non-contact manipulation of yeast cells. This approach provides a versatile platform for microscale manipulations and holds promise for advanced biomedical applications.

Schematic depicting topics of multifaceted applications of gallium liquid metal: a wide range of explorations from fundamental property research to innovative applications such as photodetectors and neuromorphic systems.

Abstract

Gallium (Ga) liquid metal has become highly suitable for the preparation of 2D materials due to its unique physical and chemical properties, such as high surface tension, low-melting-point, and ease of oxidization. Ga has a very low melting point and becomes a silver-white liquid at 29.76 °C. In the air, the surface of Ga can spontaneously undergo a Cabrera-Mott oxidation reaction to form an ultra-thin oxide layer. This self-formed oxide layer is considered a natural 2D material, and other 2D materials can be derived by post-processing the oxide layer. In recent years, advancements in surface oxidation techniques for Ga have led to the successful preparation of various Ga-based 2D materials. These materials possess unique electronic and optical properties along with a simple, low-cost preparation process, offering broad potential for advancing new electronic devices. This review examines recent research on the preparation of Ga-based 2D materials derived from Ga and its alloys. It discusses the potential applications of different kinds of Ga-based 2D devices across multiple fields. Therefore, it can be expected that Ga will play a more significant role in the development of material science in the future.