Metasurfaces, a catalog of optical components, offer numerous novel functions on demand. They have been integrated with vertical cavity surface-emitting lasers (VCSELs) in previous studies. However, the performance has been limited by the features of the VCSELs such as low output power and large divergence angle. Although the solution of the module of VCSEL array could solve these issues, the practical application is limited by extra lens and large size. In this study, we experimentally demonstrate reconstruction of a holographic images using a compact integration of a photonic crystal surface-emitting laser and metasurface holograms designed for structured light generation. This research showcases the flexible design capabilities of metasurfaces, high output power (on the order of milliwatts), and the ability to produce well-uniformed images with a wide field of view without the need for a collection lens, making it suitable for 3D imaging and sensing.

Two-dimensional (2D) ferroelectric transistors hold unique properties and positions, especially talking about low-power memories, in-memory computing, and multifunctional logic devices. To achieve better functions, appropriate design of new device structures and material combinations is necessary. We present an asymmetric 2D heterostructure integrating MoTe2, h-BN, and CuInP2S6 as a ferroelectric transistor, which exhibits an unusual property of anti-ambipolar transport characteristic under both positive and negative drain biases. Our results demonstrate that the anti-ambipolar behavior can be modulated by external electric field, achieving a peak-to-valley ratio up to 103. We also provide a comprehensive explanation for the occurrence and modulation of the anti-ambipolar peak based on a model describing linked lateral-and-vertical charge behaviors. Our findings provide insights for designing and constructing anti-ambipolar transistors and other 2D devices with significant potential for future applications.

The development of oligonucleotide nanoassemblies with small molecules has shown great potential in bio-medical applications. However, the interaction of negatively charged oligonucleotides with halogenated small molecules represents a scientific challenge. Here, we introduced a distinct allyl bromide halogenated scaffold, which exhibits specific interaction with adenine nucleic bases of the oligonucleotides, thus leading to the formation of self-assembled nanostructures. Graphical abstract

AbstractIn this work, Sulfur and Nitrogen co-doped carbon nanoparticles (SN-CNPs) were synthesized by hydrothermal method using dried beet powder as the carbon source. TEM and AFM images indicated that these SN-CNPs form a round-shape ball with an approximate diameter of 50 nm. The presence of Sulfur and Nitrogen in these carbon-based nanoparticles was confirmed by FTIR and XPS analyses. These SN-CNPs were found to have strong phosphatase-like enzymatic activity. The enzymatic behavior of SN-CNPs follows the Michaelis–Menten mechanism with greater vmax and much lower Km values compared to alkaline phosphatase. Their antimicrobial properties were tested on E. coli and L. lactis, with MIC values of 63 μg mL−1 and 250 μg mL−1, respectively. SEM and AFM images of fixed and live E. coli cells revealed that SN-CNPs strongly interacted with the outer membranes of bacterial cells, significantly increasing the cell surface roughness. The chemical interaction between SN-CNPs and phospholipid modeled using quantum mechanical calculations further support our hypothesis that the phosphatase and antimicrobial properties of SN-CNPs are due to the thiol group on the SN-CNPs, which is a mimic of the cysteine-based protein phosphatase. The present work is the first to report carbon-based nanoparticles with strong phosphatase activity and propose a phosphatase natured antimicrobial mechanism. This novel class of carbon nanozymes has the potential to be used for effective catalytic and antibacterial applications.Graphical abstract

Agricultural crops are subject to a variety of biotic and abiotic stresses that adversely affect growth and reduce the yield of crop plantss. Traditional crop stress management approaches are not capable of fulfilling the food demand of the human population which is projected to reach 10 billion by 2050. Nanobiotechnology is the application of nanotechnology in biological fields and has emerged as a sustainable approach to enhancing agricultural productivity by alleviating various plant stresses. This article reviews innovations in nanobiotechnology and its role in promoting plant growth and enhancing plant resistance/tolerance against biotic and abiotic stresses and the underlying mechanisms. Nanoparticles, synthesized through various approaches (physical, chemical and biological), induce plant resistance against these stresses by strengthening the physical barriers, improving plant photosynthesis and activating plant defense mechanisms. The nanoparticles can also upregulate the expression of stress-related genes by increasing anti-stress compounds and activating the expression of defense-related genes. The unique physico-chemical characteristics of nanoparticles enhance biochemical activity and effectiveness to cause diverse impacts on plants. Molecular mechanisms of nanobiotechnology-induced tolerance to abiotic and biotic stresses have also been highlighted. Further research is needed on efficient synthesis methods, optimization of nanoparticle dosages, application techniques and integration with other technologies, and a better understanding of their fate in agricultural systems.

Many promising applications of surface-enhanced Raman scattering (SERS), such as microfluidic SERS and electrochemical (EC)-SERS, require immersion of plasmonic nanostructured films in aqueous media. Correlational investigations of the optical response and SERS efficiency of solid SERS substrates immersed in water are absent in the literature. This work presents an approach for tuning the efficiency of gold films over nanospheres (AuFoN) as SERS substrates for applications in aqueous environment. AuFoN are fabricated by convective self-assembly of colloidal polystyrene nanospheres of various diameters (300–800 nm), followed by magnetron sputtering of gold films. The optical reflectance of the AuFoN and Finite-Difference Time-Domain simulations in both water and air reveal the dependence of the surface plasmon band on nanospheres’ diameter and environment. SERS enhancement of a common Raman reporter on AuFoN immersed in water is analyzed under 785 nm laser excitation, but also using the 633 nm line for the films in air. The provided correlations between the SERS efficiency and optical response in both air and water indicate the best structural parameters for high SERS efficiency and highlight a route for predicting and optimizing the SERS response of AuFoN in water based on the behavior in air, which is more practical. Finally, the AuFoN are successfully tested as electrodes for EC-SERS detection of the thiabendazole pesticide and as SERS substrates integrated in a flow-through microchannel format. The obtained results represent an important step toward the development of microfluidic EC-SERS devices for sensing applications.

A tunable metamaterial nanograting coupler (MNC) is presented that is composed of a one-dimensional surface nanograting coupler with a bottom reflector and the metamaterial atop. For a single nanograting coupler, by introducing a reflector and optimizing nanograting parameters, the spatial coupling efficiency exceeds 97% around near-infrared wavelength of 1.43 μm. The metamaterial can be tuned by using micro-electro-mechanical system (MEMS) technique. The relative height or lateral offset between metamaterial and coupling nanograting can be controlled, that the light-emitting efficiency can be separated into two different directions. In addition, the coupling efficiency is as high as 91% at the optical C-band communication window. Therefore, the proposed MEMS-based MNC not only has the possibility of coupling optical fibers with high-density integrated optoelectronic chips, but also has potential application prospects in light path switching, variable optical attenuation, and optical switch.

Malaria is a life-threatening, blood-borne disease with over two hundred million cases throughout the world and is more prevalent in Sub-Saharan Africa than anywhere else in the world. Over the years, several treatment agents have been developed for malaria; however, most of these active pharmaceutical ingredients exhibit poor aqueous solubility and low bioavailability and may result in drug-resistant parasites, thus increasing malaria cases and eventually, deaths. Factors such as these in therapeutics have led to a better appreciation of nanomaterials. The ability of nanomaterials to function as drug carriers with a high loading capacity and targeted drug delivery, good biocompatibility, and low toxicity renders them an appealing alternative to conventional therapy. Nanomaterials such as dendrimers and liposomes have been demonstrated to be capable of enhancing the efficacy of antimalarial drugs. This review discusses the recent development of nanomaterials and their benefits in drug delivery for the potential treatment of malaria.

The flexible pressure sensor is expected to be applied in the new generation of sports wearable electronic devices. Developing flexible pressure sensors with a wide linear range and great sensitivity, however, remains a significant barrier. In this work, we propose a hybrid conductive elastomeric film oxide-based material with a concave-shape micro-patterned array (P-HCF) on the surface that sustainably shows the necessary sensing qualities. To enhance sensing range and sensitivity, one-dimensional carbon fibers and two-dimensional MXene are incorporated into the polydimethylsiloxane matrix to form a three-dimensional conductive network. Micro-patterns with a curved shape in P-HCFs can be able to linear sensitivity across the sensing range by controlling the pressure distribution inside the material. Besides, the sensitivity of P-HCF pressure sensor can reach 31.92 kPa−1, and meanwhile, the linear band of P-HCF pressure sensor can arrive at 24 Pa–720 kPa, which makes it a good choice for sports monitoring. The designed pressure sensor can be used to monitor the foot pressure during running. By analyzing the gait information during running, it can provide data support and strategy improvement for running. This new dual working mode pressure P-HCF sensor will provide a new way for the development of intelligent sports.

The influence of self-assembled short-period superlattices (SPSLs) on the structural and optical properties of InGaN/GaN nanowires (NWs) grown by PAMBE on Si (111) was investigated by STEM, EDXS, µ-PL analysis and k·p simulations. STEM analysis on single NWs indicates that in most of the studied nanostructures, SPSLs self-assemble during growth. The SPSLs display short-range ordering of In-rich and In-poor InxGa1-xN regions with a period of 2–3 nm that are covered by a GaN shell and that transition to a more homogenous InxGa1-xN core. Polarization- and temperature-resolved PL analysis performed on the same NWs shows that they exhibit a strong parallel polarized red-yellow emission and a predominantly perpendicular polarized blue emission, which are ascribed to different In-rich regions in the nanostructures. The correlation between STEM, µ-PL and k·p simulations provides better understanding of the rich optical emission of complex III-N nanostructures and how they are impacted by structural properties, yielding the significant impact of strain on self-assembly and spectral emission.Graphical abstract

A high-performance gas sensor operating at room temperature is always favourable since it simplifies the device fabrication and lowers the operating power by eliminating a heater. Herein, we fabricated the ammonia (NH3) gas sensor by using Au nanoparticle-decorated TiO2 nanosheets, which were synthesized via two distinct processes: (1) preparation of monolayer TiO2 nanosheets through flux growth and a subsequent chemical exfoliation and (2) decoration of Au nanoparticles on the TiO2 nanosheets via hydrothermal method. Based on the morphological, compositional, crystallographic, and surface characteristics of this low-dimensional nano-heterostructured material, its temperature- and concentration-dependent NH3 gas-sensing properties were investigated. A high response of ~ 2.8 was obtained at room temperature under 20 ppm NH3 gas concentration by decorating Au nanoparticles onto the surface of TiO2 nanosheets, which generated oxygen defects and induced spillover effect as well.

In this study, systematic development of a portable sensor for the rapid detection of Escherichia coli (E. coli) and Exiguobacterium aurantiacum (E. aurantiacum) was reported. A conductive glass was utilized as a substrate and developed the electrode patterns on it. Trisodium citrate (TSC) and chitosan-stabilized gold nanoparticles (AuNPs) (CHI-AuNP-TSC) and chitosan-stabilized AuNPs (CHI-AuNP) were synthesized and utilized as a sensing interface. The morphology, crystallinity, optical properties, chemical structures, and surface properties of immobilized AuNPs on the sensing electrodes were investigated. The sensing performance of the fabricated sensor was evaluated by using an electrochemical method to observe the current changes in cyclic voltammetric responses. The CHI-AuNP-TSC electrode has higher sensitivity toward E. coli than CHI-AuNP with a limit of detection (LOD) of 1.07 CFU/mL. TSC in the AuNPs synthesis process played a vital role in the particle size, the interparticle spacing, the sensor’s effective surface area, and the presence of CHI around AuNPs, thus enhancing the sensing performance. Moreover, post-analysis of the fabricated sensor surface exhibited the sensor stability and the interaction between bacteria and the sensor surface. The sensing results showed a promising potential for rapid detection using a portable sensor for various water and food-borne pathogenic diseases.

Silicon quantum dot multilayer (Si-QDML) is a promising material for a light absorber of all silicon tandem solar cells due to tunable bandgap energy in a wide range depending on the silicon quantum dot (Si-QD) size, which is possible to overcome the Shockley–Queisser limit. Since solar cell performance is degenerated by carrier recombination through dangling bonds (DBs) in Si-QDML, hydrogen termination of DBs is crucial. Hydrogen plasma treatment (HPT) is one of the methods to introduce hydrogen into Si-QDML. However, HPT has a large number of process parameters. In this study, we employed Bayesian optimization (BO) for the efficient survey of HPT process parameters. Photosensitivity (PS) was adopted as the indicator to be maximized in BO. PS (σp/σd) was calculated as the ratio of photoconductivity (σp) and dark conductivity (σd) of Si-QDML, which allowed the evaluation of important electrical characteristics in solar cells easily without fabricating process-intensive devices. 40-period layers for Si-QDML were prepared by plasma-enhanced chemical vapor deposition method and post-annealing onto quartz substrates. Ten samples were prepared by HPT under random conditions as initial data for BO. By repeating calculations and experiments, the PS was successfully improved from 22.7 to 347.2 with a small number of experiments. In addition, Si-QD solar cells were fabricated with optimized HPT process parameters; open-circuit voltage (VOC) and fill factor (FF) values of 689 mV and 0.67, respectively, were achieved. These values are the highest for this type of device, which were achieved through an unprecedented attempt to combine HPT and BO. These results prove that BO is effective in accelerating the optimization of practical process parameters in a multidimensional parameter space, even for novel indicators such as PS.

This study presents a gate-all-around InAs–Si vertical tunnel field-effect transistor with a triple metal gate (VTG-TFET). We obtained improved switching characteristics for the proposed design because of the improved electrostatic control on the channel and the narrow bandgap source. It shows an Ion of 392 μA/μm, an Ioff of 8.8 × 10−17 A/μm, an Ion/Ioff ratio of about 4.4 × 1012, and a minimum subthreshold slope of 9.3 mV/dec at Vd = 1 V. We also analyze the influence of the gate oxide and metal work functions on the transistor characteristics. A numerical device simulator, calibrated to the experimental data of a vertical InAs–Si gate all around TFET, is used to accurately predict different features of the device. Our simulations demonstrate that the proposed vertical TFET, as a fast-switching and very low power device, is a promising transistor for digital applications.

In this work, we demonstrated Ga2O3-based power MOSFETs grown on c-plane sapphire substrates using in-situ TEOS doping for the first time. The β-Ga2O3:Si epitaxial layers were formed by the metalorganic chemical vapor deposition (MOCVD) with a TEOS as a dopant source. The depletion-mode Ga2O3 power MOSFETs are fabricated and characterized, showing the increase of the current, transconductance, and breakdown voltage at 150 °C. In addition, the sample with the TEOS flow rate of 20 sccm exhibited a breakdown voltage of more than 400 V at RT and 150 °C, indicating that the in-situ Si doping by TEOS in MOCVD is a promising method for Ga2O3 power MOSFETs.

The modern-day computing technologies are continuously undergoing a rapid changing landscape; thus, the demands of new memory types are growing that will be fast, energy efficient and durable. The limited scaling capabilities of the conventional memory technologies are pushing the limits of data-intense applications beyond the scope of silicon-based complementary metal oxide semiconductors (CMOS). Resistive random access memory (RRAM) is one of the most suitable emerging memory technologies candidates that have demonstrated potential to replace state-of-the-art integrated electronic devices for advanced computing and digital and analog circuit applications including neuromorphic networks. RRAM has grown in prominence in the recent years due to its simple structure, long retention, high operating speed, ultra-low-power operation capabilities, ability to scale to lower dimensions without affecting the device performance and the possibility of three-dimensional integration for high-density applications. Over the past few years, research has shown RRAM as one of the most suitable candidates for designing efficient, intelligent and secure computing system in the post-CMOS era. In this manuscript, the journey and the device engineering of RRAM with a special focus on the resistive switching mechanism are detailed. This review also focuses on the RRAM based on two-dimensional (2D) materials, as 2D materials offer unique electrical, chemical, mechanical and physical properties owing to their ultrathin, flexible and multilayer structure. Finally, the applications of RRAM in the field of neuromorphic computing are presented.

InAs quantum dashes (Qdash) engineered to emit near 2 μm are envisioned to be promising quantum emitters for next-generation technologies in sensing and communications. In this study, we explore the effect of punctuated growth (PG) on the structure and optical properties of InP-based InAs Qdashes emitting near the 2-μm wavelength. Morphological analysis revealed that PG led to an improvement in in-plane size uniformity and increases in average height and height distribution. A 2 × boost in photoluminescence intensity was observed, which we attribute to improved lateral dimensions and structural stabilization. PG encouraged formation of taller Qdashes while photoluminescence measurements revealed a blue-shift in the peak wavelength. We proposed that the blue-shift originates from the thinner quantum well cap and decreased distance between the Qdash and InAlGaAs barrier. This study on the punctuated growth of large InAs Qdashes is a step toward realizing bright, tunable, and broadband sources for 2-μm communications, spectroscopy, and sensing.

Recent years have witnessed the emergence of several viruses and other pathogens. Some of these infectious diseases have spread globally, resulting in pandemics. Although biosensors of various types have been utilized for virus detection, their limited sensitivity remains an issue. Therefore, the development of better diagnostic tools that facilitate the more efficient detection of viruses and other pathogens has become important. Nanotechnology has been recognized as a powerful tool for the detection of viruses, and it is expected to change the landscape of virus detection and analysis. Recently, nanomaterials have gained enormous attention for their value in improving biosensor performance owing to their high surface-to-volume ratio and quantum size effects. This article reviews the impact of nanotechnology on the design, development, and performance of sensors for the detection of viruses. Special attention has been paid to nanoscale materials, various types of nanobiosensors, the internet of medical things, and artificial intelligence-based viral diagnostic techniques.

In order to solve the problem of near-infrared (NIR) absorbance attenuation of silicon, a method of preparing gold nanoparticles (AuNPs) on the micro–nano-structured black silicon (B-Si) is proposed. In this study, the local surface plasmon resonance (LSPR) of AuNPs excited by a light field is used to achieve B-Si materials with broad spectrum and high absorption. The results show that nanometer B-Si composited with 25-nm AuNPs has an average absorption of 98.6% in the spectral range of 400–1100 nm and 97.8% in the spectral range of 1100–2500 nm. Compared with ordinary B-Si, the absorption spectrum is broadened from 400–1100 nm to 400–2500 nm, and the absorption is increased from 90.1 to 97.8% at 1100–2500 nm. It is possible to use the B-Si materials in the field of NIR-enhanced photoelectric detection and micro-optical night vision imaging due to the low cost, high compatibility, and reliability.

A novel 2-transistor (2T) pixel EUV detector is proposed and demonstrated by advanced CMOS technology. The proposed 2T detector also exhibits high spectral range (< 267 nm) and spatial resolution (67 μm) with high stability and CMOS Compatibility. The compact 2T EUV detector pixels arranged in a test array are capable of on-wafer recording the 2D EUV flux distribution without any external power. The compact 2T EUV detector pixels arranged in a test array are capable of on-wafer recording the 2D EUV flux distribution without any external power. Through proper initialization process, EUV induced discharging mechanism is fully investigated and an EUV induced electron emission efficiency model is established. Finally, a 2D array for in-situ EUV detection is demonstrated to precisely reflect the pattern projected on the chip/wafer surface.