Jing Zhang

This work introduces an innovative electrostatic capture-and-release manipulator enabling precise microdroplet emission and transportation. Utilizing electrostatic forces and dielectric pinning, it achieves controlled, contamination-free manipulation of nanoscale droplets. The study explores its application in diverse fields, including microfluidics, chemical reactions, and material fabrication, offering a sustainable and highly accurate platform for droplet-based technologies.

Abstract

The application of physical fields is crucial for droplet generation and manipulation, underpinning technologies like printing, microfluidic biochips, drug delivery, and flexible sensors. Despite advancements, precise micro/nanoscale droplet generation and accurate microfluidic reactions remain challenging. Inspired by the liquid ejection mechanisms in microscopic organisms, an electrostatic manipulator for the precise capture, emission, and transport of microdroplets is proposed. This approach enables the controlled and periodic emission of nanoscale daughter droplets from microscale parent droplets, achieved through dielectric pinning on surfaces and electrostatic field-driven forces. Results show precise nanoscale droplet release on inert polymer surfaces, enabling directional, contamination-free liquid manipulation. Moreover, leveraging surface treatment techniques and robust electrostatic force-driven transportation, a versatile strategy for droplet generation and manipulation, spanning from microfluidic devices to chemical reaction operations. The novel droplet manipulation phenomena and control strategies can advance the fields of electrostatic-based microfluidics, materials fabrication, and beyond.

Nature, Published online: 13 January 2025; doi:10.1038/d41586-025-00060-z

Sang-Wook Han hopes that the technology will spark innovations in materials science, drug development, finance and defence.

This review paper presents a comprehensive collection of approaches to improve gas sensor performance, addressing selectivity challenges in 2D material-based sensors. The strategies are categorized into Material Approaches (surface functionalization, physical barriers, electronic modification, heterostructures), Engineering Approaches (sensor arrays, external condition modification), and Machine Learning Approaches (supervised and unsupervised learning).

Abstract

Two-dimensional (2D) materials have emerged as promising candidates for gas sensing applications due to their exceptional electrical, structural, and chemical properties, which enable high sensitivity and rapid response to gas molecules. However, despite their potential, 2D material-based gas sensors face a significant challenge in achieving adequate selectivity, as many sensors respond similarly to multiple gases, leading to cross-sensitivity and inaccurate detection. This review provides a comprehensive overview of the recent advancements for improving the selectivity of 2D gas sensors. It explores material modification strategies, such as functionalizing the sensing components and tuning adsorption dynamics, to enhance selective gas interactions. Engineering approaches, including field-effect modulation and sensor array design, are also discussed as effective methods to fine-tune sensor performance. Additionally, the integration of machine learning (ML) algorithms is highlighted for their potential to differentiate among multiple analytes. Prospects for further improving selectivity through material optimization, sensor calibration, and drift compensation are explored, along with the incorporation of smart sensing systems into the Internet of Things (IoT). This review outlines key objectives and strategies that pave the way for next-generation gas sensors with enhanced selectivity, reliability, and versatility, poised to impact a wide range of applications from environmental monitoring to industrial safety.

An approach is presented to noninvasively porate neurons on planar MEA electrodes and enable the recording of intracellular-like action potentials without interfering with the spontaneous activity of the network not affecting the neuronal health. In particular, it is shown that the method works on commercial MEA electrodes integrated on both high density and high-throughput MEAs.

Abstract

Presently, the in vitro recording of intracellular neuronal signals on microelectrode arrays (MEAs) requires complex 3D nanostructures or invasive and approaches such as electroporation. Here, it is shown that laser poration enables intracellular coupling on planar electrodes without damaging neurons or altering their spontaneous electrophysiological activity, allowing the process to be repeated multiple times on the same cells. This capability distinguishes laser-based neuron poration from more invasive methods like electroporation, which typically serve as endpoint measurement for cells. It is demonstrated that planar MEA electrodes, when combined with laser cell optoporation and live cell staining, can record spontaneous intracellular signaling from primary neurons in vitro. This approach allows for the detection of attenuated signals resembling positive monophasic intracellular action potentials. Recordings after laser optoporation also reveal subthreshold signals such as post-synaptic potentials that are essential for assessing neuronal network plasticity and connectivity. Moreover, the noninvasiveness of the process enables repeated intracellular recordings over multiple days from the same cells.

Nature Reviews Chemistry, Published online: 10 January 2025; doi:10.1038/s41570-024-00680-5

As their applications grow, it is vital to understand how 2D materials degrade in the environment and biological systems. Current knowledge remains limited, and the available methodologies are specific and challenging to carry out. This article aims to identify opportunities for us to better understand the end-of-life characteristics of advanced materials.

In this paper, we present AgErP2Se6, a layered two-dimensional material that produces bright ultra-narrow photoluminescence emission bands across a wide wavelength range (350–1,550 nm). The down- and up-converted emission comes from the octahedrally coordinated Er3+ ions in the lattice. The emission bands can be used for ratiometric sensing of temperature and pressure. We also observe a thickness-dependent Purcell enhancement of some emission bands in exfoliated flakes.

Nature Communications, Published online: 08 January 2025; doi:10.1038/s41467-024-55646-4

Here, authors develop an anti-counterfeiting device using semiconducting polymer nanoparticles embedded in photoresist thin films. The device exhibits high brightness, stability, and encoding capacity, with promising uniqueness and reliability under UV exposure, high humidity, and temperature variations.

Nature Chemistry, Published online: 07 January 2025; doi:10.1038/s41557-024-01703-w

Practical electronics and robotics for chemists

Nature Electronics, Published online: 06 January 2025; doi:10.1038/s41928-024-01306-w

Using a polymer stamp with a period arrangement of micro-posts on its surface and a high surface tension liquid, two-dimensional material films can be patterned and transferred on a large-scale with high yield.

Developing advanced technology to efficiently screen the Dirac materials in transition metal dichalcogenides (TMDCs) is highly critical for achieving advanced photoelectric properties. This work reports the establishment of a comprehensive database including 90 types of TMDCs and investigates their response behaviors under external strains regarding the presence of Dirac cones and electronic structure evolutions, supplying information from electronic perspectives.

Abstract

Discovering and utilizing the unique optoelectronic properties of transition metal dichalcogenides (TMDCs) is of great significance for developing next-generation electronic devices. In particular, research on Dirac state modulations of TMDCs under external strains is lacking. To fill this research gap, it has established a comprehensive database of 90 types of TMDCs and their response behaviors under external strains have been systematically investigated regarding the presence of Dirac cones and electronic structure evolutions. Among all the conditions, 27.3% of the TMDCs are Dirac materials with three distinct types of Dirac cones, which are mainly attributed to the electron localizations induced by external strains. TMDCs based on tellurides with 1H phase favor the formation of Dirac cones under stresses, leading to metallic-like properties and ultra-fast charge transportation. Correlations among Dirac cones, energy, electronic properties, and lattice structures have been revealed, offering critical references for modulating the properties of well-known TMDCs. More importantly, it has confirmed that the phase transition points are not sufficient for the appearance of Dirac cones. This work provides critical guidance to facilitate the development of TMDCs-based superconducting and optoelectronic devices for broad applications.

Nature Photonics, Published online: 06 January 2025; doi:10.1038/s41566-024-01588-8

A chip-integrated laser with 7.5 × 10−14 fractional frequency instability is demonstrated by active stabilization to an on-chip 6.1-m-long spiral resonator. By using this laser to interrogate the narrow-linewidth transition of 88Sr+, a clock instability averaging down as $$3.9\times 1{0}^{-14}/\sqrt{\tau }$$ 3.9 × 1 0 − 14 / τ is achieved.

Nature Nanotechnology, Published online: 02 January 2025; doi:10.1038/s41565-024-01843-7

A metal–semiconductor structure as small as 170 nm in diameter emits lasing light from the lowest-order plasmonic mode across a broad spectral range in the infrared.

Nature Nanotechnology, Published online: 02 January 2025; doi:10.1038/s41565-024-01830-y

An optical-tweezer-based nanorheometer is developed to quantify the viscoelasticity of biomolecular condensates and intracellular compartments in vivo during aging and mutations that cause nuclear envelopathies in a Caenorhabditis elegans model.

A 3D spatial map for human cancer cells is developed using the designed multiplexed THz metachip with superior Q factors and sensitivity. This method for screening and quantifying cancer cells based on such a 3D spatial map has been experimentally validated to achieve high accuracies (93.33%) under several selected cancer cells from different parts of the human body.

Abstract

In this paper, compact terahertz (THz) metachips for hyperspectral screening and quantitative evaluation of human cancer cells is reported. This pixelated resonant metachips feature the resonance channel from 1 and 3 THz frequency with a record-high quality factor (up to 230). Through the interactions of various cancer cells of different concentrations, high-dimensional spectral signatures are obtained, which are further transformed into a spatial map for labelling and quantification purposes. The screening of up to 15 cancer cells is experimentally reported, with very high detecting accuracy of 93.33% and with attractive quantitative concentration sensitivity up to 1320 kHz cell mL⁻¹. This hyperspectral metachips are low-cost, highly compact, and label-free for fast, high-throughput and high-sensitivity detections and evaluation of human cancer cells. This technology does not require clinical experience, representing an accessible technology for early diagnosis of cancer.

The nonlinear response of spiral 2D transition-metal dichalcogenides can be tailored on-demand through novel structural designs (such as aligned- and twisted-triangular spiral nanosheets) with scalable and reproducible method, which is beneficial to the integrated photonics and lab-on-a-chip quantum devices.

Abstract

Spiral transition-metal dichalcogenides with broken crystal inversion symmetry and significant second-order nonlinear responses have shown great promise for further nonlinear optical applications. However, various spiral structures will be formed during their synthesis process, their second harmonic generation (SHG) varying with the layer thickness and which of them manifesting the most promising SHG response are still unresolved. Here, the layer-dependent SHG response is investigated for four representative spiral WS₂ with different screw and twist angles, including aligned- and twisted-triangular spiral structures, aligned- and twisted-hexagonal spiral structures, respectively. Experimental results demonstrate that both aligned- and twisted-hexagonal spiral WS₂ present weak SHG response. In contrast, the SHG signal of the aligned-triangular spiral WS₂ almost quadratically increases with the lift of their thickness, which is two orders of magnitude stronger than hexagonal structures. Moreover, an oscillating layer-dependence SHG response for twisted-triangular spiral WS₂ has been attributed to the restored inversion symmetry. The underlying mechanism has been explored by the evolution of their crystal symmetry. The results not only disclose that the nonlinear response of the spiral WS₂ can be tailored on-demand through the novel structural designs, but also pave the way to scalable integrated photonics and lab-on-a-chip quantum devices based on spiral layered materials.

A thickness series of epitaxial rare-earth iron garnet thin films on the (110) plane is prepared to investigate the surface effect on magnetic anisotropy. Here, the out-of-plane inversion symmetry breaking at a surface with C_2v symmetry shows a temperature-dependent surface contribution to anisotropy with both an in-plane and out-of-plane component and a magnitude comparable with bulk anisotropy.

Abstract

Ferrimagnetic oxide thin films are important material platforms for spintronic devices. Films grown on low symmetry orientations such as (110) exhibit complex anisotropy landscapes that can provide insight into novel phenomena such as spin-torque auto-oscillation and spin superfluidity. Using spin-Hall magnetoresistance measurements, the in-plane (IP) and out-of-plane (OOP) uniaxial anisotropy energies are determined for a thickness series (5–50 nm) of europium iron garnet (EuIG) and thulium iron garnet (TmIG) films epitaxially grown on a gadolinium gallium substrate with (110) orientation and capped with Pt. Pt/EuIG/GGG exhibits an (001) easy plane of magnetization perpendicular to the substrate, whereas Pt/TmIG/GGG exhibits an (001) hard plane of magnetization perpendicular to the substrate with an IP easy axis. Both IP and OOP surface anisotropy energies comparable in magnitude to the bulk anisotropy are observed. The temperature dependence of the surface anisotropies is consistent with first-order predictions of a simplified Néel surface anisotropy model. By taking advantage of the thickness and temperature dependence demonstrated in these ferrimagnetic oxides grown on the low symmetry (110) orientations, the complex anisotropy landscapes can be tuned to act as a platform to explore rich spin textures and dynamics.

Here, the adhesion strength of CVD-grown bilayer WS₂ is directly measured using the nano scratch technique on three different substrates - Sapphire, SiO₂/Si, and fused quartz. The critical delamination load is lowest for the Sapphire substrate (10 µN) (due to oxide layer) and highest for the SiO₂/Si substrate (29 µN). MD simulation results also agree with experimental observations.

Abstract

The interfacial adhesion between transition metal dichalcogenides (TMDs) and the growth substrate significantly influences the employment of flakes in various applications. Most previous studies have focused on MoS₂ and graphene, particularly their interaction with SiO₂/Si substrates. In this work, the adhesion strength of CVD-grown bilayer WS₂ is directly measured using the nano scratch technique on three different substrates—Sapphire, SiO₂/Si, and fused quartz. The scratch test is performed using a Berkovich tip of ≈100 nm radius, mounted to a 2D transducer, capable of measuring normal and lateral forces simultaneously. The critical load is calculated from the Atomic Force Microscopy (AFM) images. The critical load for delamination is lowest for the Sapphire substrate (10 µN) and highest for the SiO₂/Si substrate (29 µN). MD simulation has also been performed, and the results agree with experimental observations. The pull-off force, an essential indicator for the easy removal and transfer of 2D materials, shows the least pull-off force of 2.56 nN for WS₂ on sapphire and the highest, 2.83 nN, for WS₂ on SiO₂/Si.

The investigation into the enhancing mechanisms of black phosphorus-based heterogeneous interface engineering will be approached from two fundamental points: the atomic and electronic interface. By adjusting the contact area and establishing diverse charge transfer mechanisms, the separation and transfer of photogenerated electron–hole pairs are promoted, which provide a novel strategy for devising highly efficient BP-based photocatalysts.

Abstract

Photocatalysis has garnered significant attention as a sustainable approach for energy conversion and environmental management. 2D black phosphorus (BP) has emerged as a highly promising semiconductor photocatalyst owing to its distinctive properties. However, inherent issues such as rapid recombination of photogenerated electrons and holes severely impede the photocatalytic efficacy of single BP. The construction/stacking mode of BP with other nanomaterials decreases the recombination rate of carriers and extend its functionalities. Herein, from the perspective of atomic interface and electronic interface, the enhancement mechanism of photocatalytic performance by heterogeneous interface engineering is discussed. Based on the intrinsic properties of BP and corresponding photocatalytic principles, the effects of diverse interface characteristics (point, linear, and planar interface) and charge transfer mechanisms (type I, type II, Z-scheme, and S-scheme heterojunctions) on photocatalysis are summarized systematically. The modulation of heterogeneous interfaces and rational regulation of charge transfer mechanisms can enhance charge migration between interfaces and even maximize redox capability. Furthermore, research progress of heterogeneous interface engineering based on BP is summarized and their prospects are looked ahead. It is anticipated that a novel concept would be presented for constructing superior BP-based photocatalysts and designing other 2D photocatalytic materials.

III-V semiconductors, known for their exceptional optoelectronic properties, are critical in advancing Micro-light-emitting diode (Micro-LED) technologies. This review explores strategies to enhance performance, including passivation, distributed Bragg reflectors (DBRs), metamaterials, plasmonics, and two-dimensional (2D) materials. It also covers fabrication techniques and key factors such as external quantum efficiency (EQE), emission wavelength, and electrical injection, along with applications and future directions, spanning from deep-ultraviolet (DUV) to long-wavelength infrared (LWIR).

Abstract

III-V semiconductors, known for their optoelectronic properties and versatile engineering capabilities, play a crucial role in the fabrication of Micro light-emitting diodes (Micro-LEDs). Recent advances in research underscore that the optoelectronic performance of Micro-LEDs can be significantly enhanced using various strategies, such as passivation and distributed Bragg reflectors (DBRs), the incorporation of metamaterials and plasmonics, and the integration of 2D materials. By implementing these diverse integration strategies, Micro-LEDs based on III-V semiconductors have demonstrated remarkably high External Quantum Efficiency (EQE) spanning orders of magnitude across the spectrum, from deep-ultraviolet (DUV) to the long-wavelength infrared (LWIR) regions. In this review, the main III-V semiconductors used in Micro-LEDs are discussed. Additionally, an overview of the fabrication processes and integration techniques relevant to Micro-LED-based technologies is provided. Furthermore, the factors that influence the figure of merit in a wide range of Micro-LEDs based on III-V semiconductors, taking into account quantum efficiency, emission wavelength, and electrical injection, are examined. Finally, the discussion highlights several applications of Micro-LEDs, provides a summary, and outlines future directions for the development of Micro-LEDs based on III-V semiconductors.

A lanthanide-doped freestanding perovskite oxide scroll (SrTiO₃:Er) with an average strain gradient of 9.5 × 10⁴ m⁻¹ exhibits a 7.4-fold enhancement in upconversion luminescence at 548 nm. This enhancement, driven by synergistic effects of ferroelectricity and flexoelectricity, is analyzed using a strain distribution model, providing a versatile 3D tubular platform for advanced luminescent and photonic applications.

Abstract

Lanthanide-doped phosphors have garnered significant attention in the field of optics due to their robust upconversion luminescence capabilities. Enhancing the upconversion luminescence of these phosphors is of paramount importance. The recent advancements in fabricating ultrathin freestanding perovskite oxides present new opportunities for exploring coupled properties such as flexoelectricity. A lanthanide-doped freestanding perovskite oxide scroll, specifically an SrTiO₃:Er scroll is introduced herein, exhibiting an average strain gradient of 9.5 × 10⁴ m⁻¹. The developed scroll structure achieves a remarkable enhancement in upconversion luminescence, with a maximum increase of 7.4 times at the wavelength of 548 nm, driven by the synergistic effects of ferroelectricity and flexoelectricity. Theoretical model is adopted to elucidate the relationship between the scroll structure and strain, further investigating the mechanisms underlying the photoluminescence enhancement. This work unveils a novel three–dimensional (3D) tubular platform for enhancing the luminescence of phosphors without structural constraints, facilitating integration with silicon photonics.

Graph theory modeling of RGD nano inter-relation inversely proportional to the shortest path distance and proportional to the corresponding number of possible instances is harnessed. RGD nano inter-relation can be regulated by modulating the aspect ratio of magnetic nanobars, which can be increased by unidirectionally aligning or reversibly lifting magnetic nanobars, thereby promoting integrin-bearing filopodia penetration and adhesion-mediated pro-regenerative polarization of host macrophages.

Abstract

Graph theory has been widely used to quantitatively analyze complex networks of molecules, materials, and cells. Analyzing the dynamic complex structure of extracellular matrix can predict cell-material interactions but has not yet been demonstrated. In this study, graph theory-based mathematical modeling of RGD ligand graph inter-relation is demonstrated by differentially cutting off RGD-to-RGD interlinkages with flexibly conjugated magnetic nanobars (MNBs) with tunable aspect ratio. The RGD-to-RGD interlinkages are less effectively cut off by MNBs with a lower aspect ratio, which decreases the shortest path while increasing the number of instances thereof, thereby augmenting RGD nano inter-relation. This facilitates integrin recruitment of macrophages and thus actin fiber assembly and vinculin expression, which mediates pro-regenerative polarization, involving myosin II, actin polymerization, and rho-associated protein kinase. Unidirectional pre-aligning or reversibly lifting highly elongated MNBs both increase RGD nano inter-relation, which promotes host macrophage adhesion and switches their polarization from pro-inflammatory to pro-regenerative phenotype. The latter approach produces nano-spaces through which macrophages can penetrate and establish RGD links thereunder. Using graph theory, this study presents the example of mathematically modeling the functionality of extracellular-matrix-mimetic materials, which can help elucidate complex dynamics of the interactions occurring between host cells and materials via versatile geometrical nano-engineering.

Precise and efficient treatment of orthotopic small-size glioblastoma is realized in this work by fully taking advantage of two-photon excitation and an aggregation-induced emission photosensitizer. The proposed photosensitizer with a large two-photon absorption cross-section, the second near-infrared excitation, the first near-infrared emission, and prominent ROS generation, contributes to remarkable tumor growth inhibition and an ultra-deep imaging depth in the brain.

Abstract

The existence of residual small-size tumors after surgery is a major factor contributing to the high recurrence rate of glioblastoma (GBM). Conventional adjuvant therapeutics involving both chemotherapy and radiotherapy usually exhibit unsatisfactory efficacy and severe side effects. Recently, two-photon photodynamic therapy (TP-PDT), especially excited by the second near-infrared (NIR-II) light, offers an unprecedented opportunity to address this challenge, attributed to its combinational merits of PDT and TP excitation. However, this attempt has not been explored yet. On the other hand, the lack of high-performance photosensitizers (PSs) also hinders the progress of TP-PDT on GBM. Based on those, a robust TP-PS, termed MeTTh, is constructed intendedly through elaborately integrating multiple beneficial design strategies into a single molecule, which simultaneously achieves excellent NIR-II excitation, large absorption cross-section, aggregation-induced NIR-I emission, and prominent Type I/II reactive oxygen species generation. Aided by nanofabrication, an impressive brain structure imaging depth of 940 µm is realized. Moreover, MeTTh nanoparticles smoothly implement precise and efficient treatment of small-size GBM in vivo under a 1040 nm femtosecond laser irradiation. This study represents first-in-class using TP-PDT on GBM, offering new insights for the therapy of small-size tumors in complex and vital tissues.

A supramolecular 3D printing strategy is reported for the one-step generation of 3D structurally colored objects via direct ink writing supramolecular colloidal inks without post-treatment. The dynamic supramolecular interactions provide supramolecular colloidal inks with unique rheological behaviors for direct ink writing and endow 3D structurally colored objects with healability and recyclability.

Abstract

Structurally colored objects with 3D geometries are intriguing in optical devices and visual sensors, but their preparation is bottlenecked by complicated procedures and limited material choices. Herein, a facile supramolecular 3D printing strategy is proposed via direct ink writing (DIW) supramolecular colloidal inks (SCIs) consisting of polymers and colloids based on supramolecular interactions to construct healable and recyclable structurally colored objects. Optimized supramolecular interactions balance the rheological requirements for DIW and the high particle volume fraction for the one-step and immediate generation of structural color. The shear-thinning and thixotropy features of the SCIs, characterized by a two-order-of-magnitude decrease in viscosity during the printing process and 50% storage modulus recovery thereafter, ensure the reversible solid–liquid transition during the extrusion and deposition process. The short-range ordered arrangements of colloids within the matrix give rise to angle-independent structural color. Moreover, 3D structurally colored objects from the SCIs are healable and, more importantly, can be closed-looped recycled thanks to the reversibility of supramolecular interactions. Leveraging optimized supramolecular interactions, various SCIs with a wide range of material choices meeting the DIW process are extended to construct 3D structurally colored objects directly. This study paves the way for constructing advanced 3D materials with a supramolecular strategy.

Translation of recombinant spider silks as fillers for nerve guidance conduits in long-segment nerve reconstruction demands a detailed examination of native counterparts. Thus, this study conducts a comprehensive analysis of the material properties of four phylogenetically diverse spider silks and their impact on Schwann cell adhesion, pinpointing key factors for material design in tissue engineering.

Abstract

Reconstruction of long-segment peripheral nerve gaps remains a clinical challenge, as neither autografts nor FDA-approved nerve conduits achieve satisfactory functional recovery. Conduits filled with native Trichonephila dragline silk show promise for nerve defects exceeding the critical length, but translating natural silk to clinical use has limitations, necessitating research into recombinant silk replica. The search for optimal silk templates is ongoing, with numerous spider species still unexplored. This study aims to compare the ability of four native silk fibers from phylogenetically diverse spider families to support nerve regeneration. The influence of fiber morphology, primary and secondary protein structures, surface charge, chemical composition, and mechanical properties on the initial cell attachment is studied. Results demonstrate that silk collected from Peucetia lucasi do not adequately support Schwann cell adhesion, which is caused by the lack of a lipid layer and the limited fiber wettability. This reduced wettability, governed by the ratio of hydrophilic and hydrophobic amino acids of silk, is particularly relevant when considering the deployment of uncoated artificial silk fibers for neural tissue engineering. This knowledge is crucial for paving the way toward full functional recovery after peripheral nerve injury via implanting advanced synthetic nerve guidance conduits enhanced with luminal silk alternatives.