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Surface plasmon resonance (SPR) sensors have emerged as powerful tools for detecting and analyzing changes in the refractive index (RI) of surrounding media. In this paper, we present a highly sensitive SPR sensor implemented on a graphene metasurface for the detection of low RI variations. We have incorporated glass structure as the substrate in the sensor design. Glass provides a stable and rigid substrate for the creation of the graphene metasurface. It ensures the mechanical support of the sensor and serves as a solid foundation for the subsequent fabrication steps. The results demonstrate remarkable performance characteristics of the proposed graphene metasurface sensor. The maximum sensitivity and detection limit achieved by the sensor are 1100 GHz/RIU and 0.391 RIU−1, respectively. Furthermore, the corresponding sensor resolutions and FOM are determined to be 0.453 and 3.832 RIU−1, respectively. Such high resolutions ensure accurate and precise measurement of even subtle changes in the refractive index. [ABSTRACT FROM AUTHOR]

This paper presents the development of the photocurable resin material based on the graphene reinforced polyethylene glycol diacrylate (gPEGDA) for vascular stent fabrication using a commercial 3D printer. 3D printing with digital light processing (DLP) technique is an attractive alternative for low-cost fast fabrication with high accuracy. Four photocurable resin compositions were prepared by mixing PEGDA and varied composition of graphene and the photoinitiator according to the design of experiment of 22 full factorial design. The diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) photoinitiator was adopted to meet the required 405 nm UV-light source wavelength of the 3D printer for stent fabrication. Material characterization of the UV-absorbance and viscosity tests were conducted and optimized to obtain resin printability. Mechanical characteristics tests were conducted to obtain the best resin composition for stent application. For this purpose, the tensile tests were conducted according to the ASTM D638 standard using the type-V specimen size. The test specimens were 3D printed with varied UV exposure time 20 and 30 seconds. Finally, the stents were successfully fabricated using a commercial 3D printer DLP with the bottom parameter time setting of 60 seconds, and the UV exposure time of 30 seconds. The resin material was applicable for 3D printing of the stent. The result has shown that 3D printer with DLP technique is suitable for stent fabrication with excellent surface quality. Moreover, the innovative bioresorbable stent materials and fabrication approach could open up new possibilities in the development of medical devices, particularly in the treatment of vascular diseases. [ABSTRACT FROM AUTHOR]

This study demonstrates the development of a unique hybrid thermoplastic composite using reduced Graphene oxide (rGO) content and Zirconia (ZrO2) nanoparticles into the Ultra-High Molecular Weight Polyethylene (UHMWPE) biomaterials for continuous loading conditions. Specimens with different loadings of rGO (0 to 1.5 wt.%) and ZrO2 (5 to 10 wt.%) were fabricated using liquid phase ultrasonication followed by the hot press moulding method. The samples were analyzed using Thermogravimetric Analysis (TGA), Impact (Izod) testing, and Dynamic Mechanical Analysis (DMA). The developed material feasibility was assessed using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) analyses. The findings revealed that the 1 wt.% rGO/5 wt.% ZrO2/UHMWPE sample improved the storage modulus by 66.15%, and the Impact absorbed energy by 11.33% compared to the pristine UHMWPE. The proposed nanocomposite could be endorsed for artificial joints, prostheses, and other Artificial Bio-Bearing (ABB) applications. [ABSTRACT FROM AUTHOR]

As data processing volume increases, the limitations of traditional computers and the need for more efficient computing methods become evident. Neuromorphic computing mimics the brain's low‐power and high‐speed computations, making it crucial in the era of big data and artificial intelligence. One significant development in this field is the memristor, a device that exhibits neuromorphic tendencies. The performance of memristive devices and circuits relies on the materials used, with graphene being a promising candidate due to its unique properties. Researchers are investigating graphene‐based memristors for large‐scale, sustainable fabrication. Herein, progress in the development of graphene‐based memristive neuromorphic devices and circuits is highlighted. Graphene and its common fabrication methods are discussed. The fabrication and production of graphene‐based memristive devices are reviewed and comparisons are provided among graphene‐ and nongraphene‐based memristive devices. Next, a detailed synthesis of the devices utilizing graphene‐based memristors is provided to implement the basic building blocks of neuromorphic architectures, that is, synapses, and neurons. This is followed by reviewing studies building graphene memristive spiking neural networks (SNNs). Finally, insights on the prospects of graphene‐based neuromorphic memristive systems including their device‐ and network‐level challenges and opportunities are given. [ABSTRACT FROM AUTHOR]

Three-dimensional printing is regarded as a future-oriented additive manufacturing technology that is making significant contributions to the field of polymer processing. Among the 3D printing methods, the DLP (digital light processing) technique has attracted great interest because it requires a short printing time and enables high-quality printing through selective light curing of polymeric materials. In this study, we report a fabrication method for ABS-like resin composites containing polyaniline (PANI) nanofibers and graphene flakes suitable for DLP 3D printing. As-prepared ABS-like resin composite inks employing PANI nanofibers and graphene flakes as co-fillers were successfully printed, obtaining highly conductive and mechanically robust products with the desired shapes and different sizes through DLP 3D printing. The sheet resistance of the 3D-printed composites was reduced from 2.50 × 1015 ohm/sq (sheet resistance of pristine ABS-like resin) to 1.61 × 106 ohm/sq by adding 3.0 wt.% of PANI nanofibers and 1.5 wt.% of graphene flakes. Furthermore, the AP3.0G1.5 sample (the 3D-printed composite containing 3.0 wt.% of PANI nanofibers and 1.5 wt.% of graphene flakes) exhibited 2.63 times (22.23 MPa) higher tensile strength, 1.47 times (553.8 MPa) higher Young's modulus, and 5.07 times (25.83%) higher elongation at break values compared to the pristine ABS-like resin with a tensile strength of 8.46 MPa, a Young's modulus of 376.6 MPa, and an elongation at break of 5.09%. Our work suggests the potential use of highly conductive and mechanically robust ABS-like resin composites in the 3D printing industry. This article not only provides optimized DLP 3D printing conditions for the ABS-like resin, which has both the advantages of the ABS resin and the advantages of a thermoplastic elastomer (TPE), but also presents the effective manufacturing process of ABS-like resin composites with significantly improved conductivity and mechanical properties. [ABSTRACT FROM AUTHOR]

Lightweight and flexible electronics have recently emerged at the forefront of optoelectronic applications. In this regard, graphene electrodes enable opportunities for new photodiode devices. In this paper, we formulated and tested graphene ink using the standard inkjet printing technique. It was shown that the maximum conductivity of ink was achieved for 14 print passes of the graphene layer. Moreover, we deposited Molybdenum Disulfide (MoS2) ink in the same pattern and used it as an active layer. We put MoS2 ink on an Indium-Tin-Oxide (ITO) glass substrate and then deposited graphene ink as a top electrode to fabricate an ITO/MoS2/graphene device. The fabricated device showed good rectification behavior and high ON/OFF switching behavior with a max photocurrent of 15 µA at +2 V. The technique thus paves the way for low-cost, low-temperature processing of electronics and one-step fabrication. [ABSTRACT FROM AUTHOR]

In the past few decades, nanometer-scale pores have been employed as a powerful tool for sensing biological molecules. In pursuit of this technology, a variety of nanotechnology-based approaches have been explored and established, especially nanopore sequencing. In comparison to the existing pores in other materials such as Si3N4, carbon nanopores have the ability to rapidly sense various biological molecules at single-molecule resolution and with reduced cost. Different from most reviews about nanopore sequencing, herein, we focus on the nanopore materials employed for sequencing applications. Initially, we provide an overview on the general issues associated with nanopore sequencing, concentrating on the recent progress and achievements in nanopore sequencing, especially using various carbon nanomaterials such as graphene and carbon nanotubes. Finally, the future research directions using carbon nanomaterials for nanopore sequencing are discussed and outlined. [ABSTRACT FROM AUTHOR]

We discuss the development of electrode surfaces modified with nanostructures for the electrochemical detection of contaminants of environmental concern (CECs) in the environment. The CECs are found in substances we all use in our daily lives such as pharmaceuticals, pesticides, flame retardants, personal care products, and so on. These contaminants pose a threat to human and environmental wellbeing, hence the need for effective methods for the fast and sensitive detection of these contaminants in our ecosystems. We describe the different electrochemical techniques researchers have used in the past for the detection of these pollutants in different environmental matrices. We survey the nanomaterials used to modify the electrodes used such as nanoparticles, nanowires, graphene, nanotubes and others used by researchers to detect these pollutants. The sensitivity of each approach is covered for numerous examples and nanomaterial-modified electrodes typically offer superior performance over more standard electrodes. We review the properties of these modifiers that make them good for the job and we looked at directions that researchers can pursue to further improve the sensitivity and selectivity of these modified electrodes. [ABSTRACT FROM AUTHOR]

This review introduces the technique of helium ion microscopy along with some unique applications of this technology in the fields of electronics and biology, as performed at the National Institute of Advanced Industrial Science and Technology, Japan, over the last several years. Observations of large-scale integrated circuits, analyses of low-dielectric-constant films with minimal damage, and assessments of copper metal in insulating films are discussed. The special characteristics of this technique are explained, including low-energy input to the material and minimal secondary electron energy resulting from helium ion irradiation. Applications to electronic materials, such as tuning the electrical conductivity of graphene films by helium ion beam irradiation and the formation of nanopore arrays on graphene films with nanometer-scale control, are presented. The use of helium ion microscopy to examine cellular tissues based on the low damage imparted by the ion beam is also evaluated. [ABSTRACT FROM AUTHOR]

This review introduces the technique of helium ion microscopy along with some unique applications of this technology in the fields of electronics and biology, as performed at the National Institute of Advanced Industrial Science and Technology, Japan, over the last several years. Observations of large-scale integrated circuits, analyses of low-dielectric-constant films with minimal damage, and assessments of copper metal in insulating films are discussed. The special characteristics of this technique are explained, including low-energy input to the material and minimal secondary electron energy resulting from helium ion irradiation. Applications to electronic materials, such as tuning the electrical conductivity of graphene films by helium ion beam irradiation and the formation of nanopore arrays on graphene films with nanometer-scale control, are presented. The use of helium ion microscopy to examine cellular tissues based on the low damage imparted by the ion beam is also evaluated. [ABSTRACT FROM AUTHOR]

Nanostructured MoS2 grown on reduced graphene oxide (rGO–MoS2) is demonstrated as a lubricating reinforcement material for copper matrix composite. The Cu–rGO–MoS2 nanocomposites having variable dosages of rGO–MoS2 (0.5 to 2.0 wt%) are prepared via a combinational approach of powder metallurgy and then spark plasma sintering at 700 °C. The XRD and Raman analyses suggested the preparation of rGO–MoS2 hybrid, whereas HRTEM images revealed the thorough distribution of MoS2 nanosheets over the rGO. The tribological properties of Cu–rGO–MoS2 nanocomposites were evaluated against the EN 31 steel ball under the variable loads (4–10 N). The coefficient of friction was found to decrease with increasing of rGO–MoS2 content. The Cu–rGO–MoS2 nanocomposite with a 2.0 wt% of rGO–MoS2 hybrid exhibited the lowest and stable coefficient of friction (μ = 0.2) among all the nanocomposites. The high mechanical strength and low shearing properties driven by the lamellar structure of rGO–MoS2 furnished the self-lubricating properties to Cu–rGO–MoS2 nanocomposites. A combination of adhesion, oxidation, abrasion, and delamination of materials are revealed as major events for the wear mechanisms. These wear events are governed by the dosage of rGO–MoS2 reinforcement in the Cu–rGO–MoS2 nanocomposites and applied load. The results indicate that rGO–MoS2 has the potential to be used as a solid lubricant in the metal matrix composites. [ABSTRACT FROM AUTHOR]

A photonic crystal's refractive index sensor is proposed based on the photonic crystal (PC) optical properties and the surface wave resonance principle. The optical Tamm state existing at the interface between one-dimensional (1D) PCs and the metal layer can overcome the disadvantage of the surface plasmon resonance (SPR) sensor in which the incident light can only be TM polarized light. The resonant wavelength can be changed by adjusting the optical parameters of the PC. Through coating the metal surface with graphene, the resolution and sensitivity of the sensor can be improved obviously. The relationship model between the graphene parameters and the reflectivity is established by analyzing the reflective properties of the graphene. In the numerical simulation, the graphene layer is optimized to improve the refractive index sensing properties. The numerical simulation results show that the quality factor ( value) can attain to 1418.2 and the sensitivity is about 1178.6 nm RIU, which can demonstrate the effectiveness of the senor structure and provide some theoretical references for the design of the refractive index sensors with high value and sensitivity. [ABSTRACT FROM AUTHOR]

Functional graphene optical sensors are now viable due to the recent developments in hand-held Raman spectroscopy and the chemical vapor deposition (CVD) of graphene films. Herein, the strain in graphene/poly (methyl methacrylate) sensor coatings is followed using Raman band shifts. The performance of an 'ideal' mechanically-exfoliated single crystal graphene flake is compared to a scalable CVD graphene film. The dry-transferred mechanically exfoliated sample has no residual stresses, whereas the CVD sample is in compression following the solvent evaporation during its transfer. The behavior of the sensors under cyclic deformation shows an initial breakdown of the graphene-polymer interface with the interface then stabilizing after several cycles. The Raman 2D band shift rates per unit strain of the exfoliated graphene are ≈35% higher than CVD graphene making the former more strain sensitive. However, for practical wide-area applications, CVD graphene coatings are still viable candidates as a Raman system can be used to read the strain in any 5 μm diameter spot in the coating to an absolute accuracy of ≈0.01% strain and resolution of ≈27 microstrains (μs), which compares favorably to commercial photoelastic systems. [ABSTRACT FROM AUTHOR]

In this work, we report the deposition of graphene flakes exfoliated through graphite dispersion in N-methyl-pyrrolidone using non-vacuum electrohydrodynamic atomization (EHDA) technique. Stable cone jet mode of EHDA is used to deposit graphene flakes on silicon substrate. The deposited graphene flakes film is characterized by Raman spectroscopy, microscopy, 3D-Nanomap, scanning electron microscope, and UV–visible spectroscopy. Through characterizations it is evident that a randomly oriented graphene flakes film has shown good transparency, conductivity and suitable work function. For electrical characterization of film, it is employed as cathode in a simple diode indium tin oxide/(poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate)/polydioctylfluorene-benzothiadiazole/graphene. It is observed that at voltage of 0.3 V, the current density in device is at low value of 2.67 A/cm 2 however as the voltage is increased to a value of 4 V the current density is increased by almost 100 times and reaches up to 2.65 × 10 2 A/cm 2. We believe that by further optimizing parameters of EHDA techniques for graphene deposition, more uniform and defect free graphene film can be obtained. [ABSTRACT FROM AUTHOR]

We report on a thermal diffusivity study of suspended graphene foam (GF) using the transient electro-thermal technique. Our Raman study confirms the GF is composed of two-layer graphene. By measuring GF of different lengths, we are able to exclude the radiation effect. Using Schuetz’s model, the intrinsic thermal diffusivity of the free-standing two-layer graphene is determined with a high accuracy without using knowledge of the porosity of the GF. The intrinsic thermal diffusivity of the two-layer graphene is determined at 1.16–2.22 × 10−4 m2 s−1. The corresponding intrinsic thermal conductivity is 182–349 W m−1 K−1, about one order of magnitude lower than those reported for single-layer graphene. Extensive surface impurity defects, wrinkles and rough edges are observed under a scanning electron microscope for the studied GF. These structural defects induce substantial phonon scattering and explain the observed significant thermal conductivity reduction. Our thermal diffusivity characterization of GF provides an advanced way to look into the thermal transport capacity of free-standing graphene with high accuracy and ease of experimental implementation. [ABSTRACT FROM AUTHOR]

Platinum nanoparticles (Pt NPs) on carbon black (CB) have been used as catalysts for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells for a while. However, this catalyst has suffered from aggregation and dissolution of Pt NPs as well as CB dissolution. In this study, we resolve those issues by developing perfluorosulfonic acid (PFSA)-functionalized Pt/graphene as a high-performance ORR catalyst. The noncovalently bonded PFSA remarkably decreases the dissolution and aggregation of Pt NPs. Moreover, unlike typical NP functionalization with other capping agents, PFSA is a proton conductor and thus efficiently develops a triple-phase boundary. These advantageous features are reflected in the improved cell performance in electrochemical active surface area, catalytic activity, and long-term durability, compared to those of the commercial Pt/C catalysts and graphene-based catalysts with no such treatment. [ABSTRACT FROM AUTHOR]

Digital light processing (DLP)-type 3D printing ensures several advantages, such as an easy solution process, a short printing time, high-quality printing, and selective light curing. Furthermore, polyurethane (PU) is among the promising candidates for 3D printing because of its wide range of applications. This work reports comparative studies on the fabrication and optimization of PU composites using a polyaniline (PANI) nanomaterial and a graphene sheet (GS) for DLP-type 3D printing. The morphologies and dispersion of the printed PU composites were studied by field emission scanning electron microscope (FE-SEM) images. Bonding structures in the PU composites were investigated by Fourier-transform infrared (FT-IR) spectroscopy. As-prepared PU/PANI and PU/GS composites with different filler contents were successfully printed into sculptures with different sizes and shapes. The PU/PANI and PU/GS composites exhibit the improved sheet resistance, which is up to 8.57 × 104 times (1.19 × 106 ohm/sq) lower and 1.27 × 105 times (8.05 × 105 ohm/sq) lower, respectively, than the pristine PU (1.02 × 1011 ohm/sq). Moreover, the PU/PANI and PU/GS composites demonstrate 1.41 times (44.5 MPa) higher and 2.19 times (69.3 MPa) higher tensile strengths compared with the pristine PU (31.6 MPa). This work suggests the potential uses of highly conductive PU composites for DLP-type 3D printing. [ABSTRACT FROM AUTHOR]

Due to the promising utilizations in nanoelectronics, doping‐tunable graphene is paid extensive attentions. Nevertheless, a harmless approach to dope/co‐dope graphene in a controllable and easy way with low cost is still unattainable. Herein, through seeding of 0D N & S dual‐doped graphene quantum dots (N & S dual‐doped GQDs) on a catalytic substrate and then dynamic chemical vapor deposition (CVD), a monolayered dual‐doped graphene film is demonstrated. The concentrations of dopants in graphene are strictly discerned in accordance with preliminary seeding for dual‐doped GQDs. Through the monitoring of growing process, the research elucidates the growth mechanism of the graphene, and unveils that dual‐doped GQDs can serve as the nucleation centers for creating doped‐graphene films by 2D epitaxial growth and thus graphene with designed dopant concentration can be obtained. Finally, the photodetector built on N & S dual‐doped graphene film is found to perform satisfactorily, accompanying high detectivity (≈1.42 × 1010 cm Hz1/2 W−1) and responsivity (61 mA W−1), at wavelength of 1550 nm. The research proposes a dexterous approach for synthesizing tunably doped graphene films by the combination of locally controlled nucleation seeds and in situ CVD, which lays the foundation for applying graphene in industries of photonic and electronic devices. [ABSTRACT FROM AUTHOR]

Imaging materials and biological structures in a liquid environment pose a significant challenge for conventional transmission electron microscopy (TEM) due to stringent requirement of ultrahigh vacuum design in the microscope column. The most recent liquid‐cell TEM technique, graphene liquid‐cell (GLC) microscopy, employs only layers of graphene to encapsulate liquid specimens. Recent efforts with GLC–TEM have demonstrated superior imaging resolution of beam‐sensitive specimens. Herein, the parameters that affect the quality of GLC analysis, including the graphene transfer onto TEM grids, are reviewed. Several important factors that affect the in situ TEM imaging of specimens, including the variations in GLC geometries and capillary pressure are discussed. The interaction between the electron beam and the liquid along with the possibility for artifacts or the formation of radical ions is also highlighted in this review. The scientific discoveries enabled by GLC–TEM in the areas of nucleation and growth of crystals, corrosion, battery science, as well as high‐resolution imaging of organelles and proteins are also briefly discussed. Finally, possible future research directions of GLC–TEM and the associated challenges are discussed. The synergistic effort to accomplish the proposed research directions has the potential to yield new discoveries in both materials and life sciences. [ABSTRACT FROM AUTHOR]