MXene-Based Elastomer Mimetic StretchableSensors: Design, Properties, and Applications

Flexible sensors based on MXene-polymer composites are highly prospective for next-generation wearable electronics used in human-machine interfaces.One of the motivating factors behind the progress of flexible sensors is the steady arrival of new conductive materials.MXenes,a new family of 2D nanomaterials,have been draw-ing attention since the last decade due to their high electronic conduc-tivity,processability,mechanical robustness and chemical tunability.In this review,we encompass the fabrication of MXene-based polymeric nanocomposites,their structure-property relationship,and applications in the flexible sensor domain.Moreover,our discussion is not only lim-ited to sensor design,their mechanism,and various modes of sensing platform,but also their future perspective and market throughout the world.With our article,we intend to fortify the bond between flexible matrices and MXenes thus promoting the swift advancement of flexible MXene-sensors for wearable technologies.

Active pixel image sensor array for dual vision using large-area bilayer WS_(2)

Transition metal dichalcogenides(TMDs)are a promising candidate for developing advanced sensors,particularly for day and night vision systems in vehicles,drones,and security surveillance.While traditional systems rely on separate sensors for different lighting conditions,TMDs can absorb light across a broad-spectrum range.In this study,a dual vision active pixel image sensor array based on bilayer WS2 phototransistors was implemented.The bilayer WS2 film was synthesized using a combined process of radio-frequency sputtering and chemical vapor deposition.The WS2-based thin-film transistors(TFTs)exhibit high average mobility,excellent Ion/Ioff,and uniform electrical properties.The optoelectronic properties of the TFTs array exhibited consistent behavior and can detect visible to near-infrared light with the highest responsivity of 1821 A W1(at a wavelength of 405 nm)owing to the photogating effect.Finally,red,green,blue,and near-infrared image sensing capabilities of active pixel image sensor array utilizing light stencil projection were demonstrated.The proposed image sensor array utilizing WS2 phototransistors has the potential to revolutionize the field of vision sensing,which could lead to a range of new opportunities in various applications,including night vision,pedestrian detection,various surveillance,and security systems.

Electron beam lithography on nonplanar and irregular surfaces

E-beam lithography is a powerful tool for generating nanostructures and fabricating nanodevices with fine features approaching a few nanometers in size.However,alternative approaches to conventional spin coating and development processes are required to optimize the lithography procedure on irregular surfaces.In this review,we summarize the state of the art in nanofabrication on irregular substrates using e-beam lithography.To overcome these challenges,unconventional methods have been developed.For instance,polymeric and nonpolymeric materials can be sprayed or evaporated to form uniform layers of electron-sensitive materials on irregular substrates.Moreover,chemical bonds can be applied to help form polymer brushes or self-assembled monolayers on these surfaces.In addition,thermal oxides can serve as resists,as the etching rate in solution changes after e-beam exposure.Furthermore,e-beam lithography tools can be combined with cryostages,evaporation systems,and metal deposition chambers for sample development and lift-off while maintaining low temperatures.Metallic nanopyramids can be fabricated on an AFM tip by utilizing ice as a positive resistor.Additionally,Ti/Au caps can be patterned around a carbon nanotube.Moreover,3D nanostructures can be formed on irregular surfaces by exposing layers of anisole on organic ice surfaces with a focused e-beam.These advances in e-beam lithography on irregular substrates,including uniform film coating,instrumentation improvement,and new pattern transferring method development,substantially extend its capabilities in the fabrication and application of nanoscale structures.

A highly sensitive chemical gas detecting transistor based on highly crystalline CVD-grown MoSe2 films

Layered semiconductors with atomic thicknesses are becoming increasingly important as active elements in high-performance electronic devices owing to their high carrier mobilities, large surface-to-volume ratios, and rapid electrical responses to their surrounding environments. Here, we report the first implementation of a highly sensitive chemical-vapor-deposition-grown multilayer MoSe2 field-effect transistor （FET） in a NO2 gas sensor. This sensor exhibited ultra-high sensitivity （S = ca. 1,907 for NO2 at 300 ppm）, real-time response, and rapid on-off switching. The high sensitivity of our MoSe2 gas sensor is attributed to changes in the gap states near the valence band induced by the NO2 gas absorbed in the MoSe2, which leads to a significant increase in hole current in the off-state regime. Device modeling and quantum transport simulations revealed that the variation of gap states with NO2 concentration is the key mechanism in a MoSe2 FET-based NO2 gas sensor. This comprehensive study, which addresses material growth, device fabrication, characterization, and device simulations, not only indicates the utility of MoSe2 FETs for high-performance chemical sensors, but also establishes a fundamental understanding of how surface chemistry influences carrier transport in layered semiconductor devices.

Fabrication and Characterizations of Metallic Mg Containing PMMA-Based Partially Degradable Composite Bone Cements

Inadequate strength at the bone/cement interface is one of the main drawbacks of poly(methylmethacrylate)(PMMA) bone cement in the current orthopedic surgeries. In the present work, a partially degradable PMMA/Mg composite bone cement (PMC) was developed for enhancing the bone/cement interfacial strength, which is proposed to be accomplished by increasing the osteo-conductivity of PMMA and enhancing the mechanical interlocking between bone tissue and the porous PMMA surface formed by the degradation of Mg on the surface of the cement. PMCs were prepared with various concentrations of Mg particles with different sizes and alloy compositions. The effects of Mg particle size, composition and content on the injectability, mechanical and degradation properties, and biocompatibility of PMCs were evaluated. The results show that these parameters affected the properties of the PMCs simultaneously. The good injectability and compressive strengths of PMMA were preserved, while the compatibility to osteoblasts was enhanced when adding Mg particles in a proper manner. The PMCs degraded at the surface with time and formed porous surface structures in the physiological environment, while maintaining the original compressive strengths. This preliminary study shows that the PMC is promising for minimally invasive orthopedic surgery;however, it still requires to be optimized and evaluated in the future.

Effect of doping order on metal-free heteroatoms dual-doped carbon as oxygen reduction electrocatalyst

Metal-free heteroatoms dual-doped carbon has been recognized as one of the most promising Pt/C-substitutes for oxygen reduction reaction(ORR).Herein,we optimize the preparation process by doping order of metal-free heteroatoms to obtain the best electrocatalytic performance through three types of dual-doped carbon,including XC-N(first X doping then N doping),NC-X(first N doping then X doping) and NXC(N and X doping)(X=P,S and F).XC-N has more defect than the other two indicated by Raman spectra.X-ray photoelectron spectrom(XPS) measurements indicate that N and X have been dual-doped into the carbon matrix with different doping contents and modes,Electrocatalytic results,including the potential of ORR peak(Ep),the half-wave potential,the diffusion-limiting current density mainly follows the order of XC-N>NC-X> NXC,Furthermore,the synergistic effect of second atom doping are also compared with the single doped carbon(NC,PC,SC and FC).The differences in electronegativity and atomic radius of these metal-free heteroatoms can affect the defect degree,the doping content and mode of hete roatoms on carbon matrix,induce polarization effect and space effect to affect O2 adsorption and product desorption,ultimately to the ORR electrocatalytic performance.

Erratum to： A highly sensitive chemical gas detecting transistor based on highly crystalline CVD-grown MoSe2 films

AIMS ＆ SCOPENano Research is a peer-reviewed, international and interdisciplinary journal that focuses on all aspects of nanoscience and nanotechnology. Submissions are solicited in all topical areas, ranging from basic aspects of the science of nanoscale materials to practical applications of such materials.