Graphene Transistors Research Articles

Ultraprecise Detection of Influenza Virus by Antibody-Modified Graphene Transistors

Over the past decade, the large-scale spread of influenza viruses has posed an increasing burden on public health. The effective screening of influenza agents requires a fast, precise, on-site and easy-to-operate method. Unfortunately, current screening methods face challenges in speed and accuracy, especially in complex on-site settings. Here, this work develops a nucleoprotein antibody-modified graphene field-effect transistor (NPAb-GFET) for rapid and highly precise detection of influenza A viruses. The functionalized monoclonal antibodies capture influenza virus nucleoprotein within 100 × 10−9 s on the sensing surface. Therefore, the developed NPAb-GFET achieves an average response time of 72.1 s when detecting influenza A viruses in clinical samples. Furthermore, the testing of 106 throat swab samples exhibits an accuracy of 99.1%. This finding provides a valuable diagnostic tool for the control of influenza viruses, accelerating the population-wide control of other epidemics.

Enhanced sensitivity in tanshinol detection using manganese dioxide-doped laser-induced graphene sensor

Enhanced sensitivity in tanshinol detection using manganese dioxide-doped laser-induced graphene sensor

Miniaturized Wearable Biosensors for Continuous Health Monitoring Fabricated Using the Femtosecond Laser-Induced Graphene Surface and Encapsulated Traces and Electrodes.

Wearable sensors are increasingly being used as biosensors for health monitoring. Current wearable devices are large, heavy, invasive, skin irritants, or not continuous. Miniaturization was chosen to address these issues, using a femtosecond laser-conversion technique to fabricate miniaturized laser-induced graphene (LIG) sensor arrays on and encapsulated within a polyimide substrate. The femtosecond laser-converted conductive traces can have a size of 20 to 2 μm compared to the traditionally larger CO2 laser dimensions of around 300 to 100 μm. This marks a 93-98% decrease in trace size when using a femtosecond laser. This miniaturization allows for the ability to process temperature, electrocardiography (ECG), electromyography (EMG), and glucose data in the same space that would have been occupied by a single sensor. The femtosecond laser-converted graphene (FSLIG) electrodes were modified to function as glucose sensors, and comprehensive electrochemical analyses using cyclic voltammetry (CV) and chronoamperometry (CA) were performed. These tests confirmed the capability of the sensors to detect glucose levels, showing a stability of 96.14%. Encapsulation of FSLIG within polyimide was achieved for the first time, demonstrating the ability to nondestructively create FSLIG electrodes within existing materials, thereby protecting them from external environmental factors. The encapsulated FSLIG shows potential as a method to produce LIG-coated Cu traces for improved multilayered printed circuit boards or layered circuits with complex geometries in polyamide to reduce size and increase functionality. Even sterile probes for use inside the body or under dermis polyamide injections and subsequent FSLIG circuit tattoos are possible. This study demonstrates the novel miniaturization and encapsulation capabilities enabled by the femtosecond laser, developing next-generation wearable biosensors focusing on miniaturization, flexibility, continuous monitoring, multifunctionality, and comfort.

Advantages and Challenges of Graphene Transistors for High-Frequency Applications

Graphene is regarded as an ideal material for next-generation high-frequency (HF) electronic devices, attributed to its unique two-dimensional structure, high carrier mobility, and exceptional electrical properties. In recent years, the limitations of conventional silicon-based technologies for high-frequency applications have become increasingly apparent, resulting in heightened interest in graphene transistors, which exhibit significant potential for applications in wireless communications, radar systems, and terahertz technology. These transistors exhibit high cutoff frequency and low noise characteristics, along with favorable bipolar properties, which provide them with significant advantages in radio frequency (RF) applications. However, despite the significant theoretical advantages of graphene materials, their practical application is still restricted by multiple factors. Specifically, insufficient voltage gain from weak current saturation, material uniformity issues, and large-scale production challenges have restricted the widespread adoption of graphene transistors in high-frequency electronic devices. This paper reviews the relevant literature, examines the disparity between the electrical performance and practical applications of graphene transistors, and identifies the key factors influencing their implementation. The results demonstrate that targeted bandgap engineering, innovative device architectures, and the exploration of new materials can help graphene transistors can mitigate existing challenges and position themselves as key components in future HF electronic devices, driving significant advancements and broader integration of related technologies.

Nanoscopic Supercapacitance Elucidations of the Graphene-Ionic Interface with Suspended/Supported Graphene in Different Ionic Solutions.

Graphene-based supercapacitors have gained significant attention due to their exceptional energy storage capabilities. Despite numerous research efforts trying to improve the performance, the challenge of experimentally elucidating the nanoscale-interface molecular characteristics still needs to be tackled for device optimizations in commercial applications. To address this, we have conducted a series of experiments using substrate-free graphene field-effect transistors (SF-GFETs) and oxide-supported graphene field-effect transistors (OS-GFETs) to elucidate the graphene-electrolyte interfacial arrangement and corresponding capacitance under different surface potential states and ionic concentration environments. For SF-GFET, we observed that the hysteresis of the Dirac point changes from 0.32 to -0.06 V as the ionic concentration increases. Moreover, it results in the interfacial capacitance changing from 4 to 2 F/g. For OS-GFET, the hysteresis of the Dirac point remains negative (-0.15 to -0.07 V). Furthermore, the corresponding capacitance of OS-GFET decreases (53-16 F/g) as the ionic concentration increases. These suggest that the orderly oriented water structure at the graphene-water interface is gradually replaced by ionic hydration clusters and results in the difference of capacitance. The relationship between Dirac-point hysteresis value and ionic concentration can be modeled by using the first-order Hill equation to obtain the half occupation value (K = 1.0131 × 10-4 for KCl solution and K = 6.6237 × 10-5 for MgCl2 solution). This also agrees with the variances of two minerals in ion hydration within the inner water layer at the interface. This work illustrates the influence of interfacial nanoscale arrangement on interface capacitance formation and layout implications for the development of supercapacitors.

Terahertz Saturable Absorption across Charge Separation in Photoexcited Monolayer Graphene/MoS2 Heterostructure.

Unveiling the nonlinear interactions between terahertz (THz) electromagnetic waves and free carriers in two-dimensional materials is crucial for the development of high-field and high-frequency electronic devices. Herein, we investigate THz nonlinear transport dynamics in a monolayer graphene/MoS2 heterostructure using time-resolved THz spectroscopy with intense THz pulses as the probe. Following ultrafast photoexcitation, the interfacial charge transfer establishes a nonequilibrium carrier redistribution, leaving free holes in the graphene and trapping electrons in the MoS2. When probed with intense THz pulses exceeding 34 kV/cm in a peak electric field, significant THz saturable absorption is observed over a period of 20 ps. Furthermore, the photoinduced change in the transmitted THz waveform, linked to the THz-driven nonlinear current, manifests as a substantial self-phase modulation. These nonlinear responses can be attributed to the competition between rapid carrier heating and slow carrier cooling via electron-electron and electron-phonon scattering in the charge-transfer-induced hole system of the graphene layer. This work demonstrates an integration of advantages arising from robust nonlinear absorption in graphene and enhanced photocarrier harvesting in transition metal dichalcogenides by exploiting heterostructure construction.

Linear and nonlinear resonant properties of electron gas in n-InSb and graphene layers in terahertz range in bias magnetic fields

Abstract The nonlinear conductivity of 2D electron gas in graphene and 3D electron gas in the narrow-gap n-InSb semiconductor has been simulated in terahertz (THz) range by various methods including the direct quantum approach, the quasi-classical kinetics, and the quasi-relativistic hydrodynamics. These methods yield the same results under the electron temperatures ≤100 K when the kinetic electron effective mass used in the nonlinear hydrodynamics is equal to the effective mass in n-InSb and it is equal to some nonzero mass that depends on 2D electron concentration in the graphene. The linear resonant dependencies of the complex electron conductivity are simulated both from the kinetic theory and from the hydrodynamic one. The kinetic dependencies of the resonant conductivity on frequency coincide with ones obtained from the hydrodynamic theory under realistic electron concentrations and collision frequencies. Thus, the nonlinear hydrodynamic equations are valid to describe the nonlinear dynamics of the electron gas in graphene and in n-InSb. The nonlinear hydrodynamics has been applied for simulations of nonlinear propagation of THz electromagnetic waves through the multilayer structures dielectric - graphene or n-InSb - dielectric placed in a bias magnetic field. The simplest three-layer structures demonstrate the sharp nonlinear switching of the transparency of THz waves and the bistability under relatively low values of amplitudes of the incident electromagnetic wave.

Enhanced electrochemical performance of sulfur-doped laser-induced graphene supercapacitors: Synergistic effects of doping and plasmochemical surface modification

Enhanced electrochemical performance of sulfur-doped laser-induced graphene supercapacitors: Synergistic effects of doping and plasmochemical surface modification

Boosting flexible laser-induced graphene supercapacitors performance through double pass laser processing.

This study proposes a simple and cost-effective approach to enhance the performance of supercapacitors based on laser-induced graphene (LIG). The use of two consecutive laser passes using the same CO2 engraver on polyimide film led to the expansion in the size of the pores, the increase in the graphitization degree, and the densification of the produced material. These changes in the morphology and chemical structure of the LIG impacted positively its electrochemical performance when it was used as an electrode for supercapacitors. The best achieved material displayed the following results: (a)an enhancement of the areal energy density from 0.77 to 2.20μWh/cm2 at 0.05 mA/cm2, (b)a reduction of 60% in the equivalent series resistance, (c)high cycling stability with a capacitance retention rate of 91% after 10.000 cycles, (d)high performance stability under mechanical tests at different angles, and (e)green LED illumination under configuration in series.

Laser repeat scanning preparation of nitrogen sulfur doped graphene supercapacitor

Laser repeat scanning preparation of nitrogen sulfur doped graphene supercapacitor

Electroanalytical overview: the use of laser-induced graphene sensors.

Laser-induced graphene, which was first reported in 2014, involves the creation of graphene by using a laser to modify a polyimide surface. Since then, laser-induced graphene has been extensively studied for application in different scientific fields. One beneficial approach is the use of laser-induced graphene coupled with electrochemistry, where there is a growing need for disposable, conductive, reproducible, flexible, biocompatible, sustainable, and economical electrodes. In this mini overview, we explore the use of laser-induced graphene as the basis of electroanalytical sensors. We first introduce laser-induced graphene, before moving to the use of laser-induced graphene electrodes highlighting the various approaches and different laser parameters used to produce different graphene micro and macro structures, whilst describing how these structures are characterised and benchmarked for those working in the field of laser-induced graphene electrodes for comparison aspects. Next, we turn to the use of laser-induced graphene electrodes as the basis of electrochemical sensing platforms towards key analytes and its use in the development of biosensors. We provide a critical overview of the use of laser-induced graphene sensors compared to screen-printed and additive manufactured electrodes, providing future suggestions for the field.

The research on the structure and application analysis of graphene electronics

The research on the structure and application analysis of graphene electronics

Unveiling the future: the potential of graphene electronics

Unveiling the future: the potential of graphene electronics

Application of Graphene Composites in Flexible Electrons

With the development of science and technology, graphene materials have come into the public view, especially in flexible electronics and play a key role, which has attracted the public’s attention. Because of its good electrical conductivity, high light transmittance and good flexibility, it has a high application value in the research and development of supercapacitors and epidermal electronics.This paper summarizes the structure and properties of graphene, discusses the application of graphene in supercapacitors and other aspects, describes the research progress and direction of graphene composite in flexible electrons in recent years, and the future development and prediction of graphene composite in flexible electrons. It is found that graphene has significant technical advantages and broad application prospects in the field of flexible electronics. The future prospects of graphene are still broad, and the joint efforts of scientific research and industry are expected to promote the further development and wide application of graphene technology.

Graphene Applications in Sensors: Performance Optimization and Prospects

A sensor, as a detection device, is able to receive information and convert it into an electrical signal or other form of signal for output. In today's era of rapid development of intelligence, digitalization and networking, sensors have become the core tool for obtaining information. As technology advances, higher standards have been set for sensor sensitivity and application breadth. Graphene, a single-layer thin film material composed of carbon atoms arranged in a hexagonal honeycomb, has attracted much attention in the engineering industry because of its unique structure and its excellent electrical and mechanical properties. Among the many potential applications, sensors are seen as one of the most promising application areas for graphene.In this paper, the basic structural characteristics and unique properties of graphene are first outlined, and then the specific application cases in many fields such as biomedical sensors, flexible pressure sensors and photoelectric chemical sensors are discussed in detail, and the wide use of graphene materials is demonstrated by examples. At the same time, the different preparation methods of graphene are compared and analyzed, and the challenges faced by graphene sensors in the commercialization process are pointed out. Finally, a series of suggestions and prospects are put forward for the future development path of graphene sensors.

Direct-detection of glyphosate in drinking water via a scalable and low-cost laser-induced graphene sensor.

The use of pesticides has significantly increased and proliferated following the technological advancements established by the green revolution, aimed at boosting agricultural productivity. The extensive use of man-made chemicals as fertilizer and pesticides has consequently led to large-scale application, which has led to a number of environmental and human health problems. This study has helped to develop a laser-induced graphene (LIG) sensor for the detection of the most widely used herbicide in the world, glyphosate. The electrochemical sensor developed is based on a three-dimensional porous and fibrous structure with nanosheets, making it suitable for scalable manufacture. The study was conducted utilising a linear voltammetry technique and demonstrates the potential to identify glyphosate with good sensitivity. The sensor exhibited detection and quantification limits of 2.7 μmol L-1 and 9.0 μmol L-1, respectively, and showed good selectivity without significant interference from other elements. The sensor presents advantages suitable for scalable production, with case studies in screening of glyphosate-contaminated samples.

Inkjet Printed Multifunctional Graphene Sensors for Flexible and Wearable Electronics

AbstractThe exceptional electrical properties of graphene with high sensitivity to external stimuli make it an ideal candidate for advanced sensing technologies. Inkjet printing of graphene (iGr) can provide a versatile platform for multifunctional sensor manufacturing. Here the multifunctional sensor enabled by combining the design freedom of inkjet printing with the unique properties of graphene networks is reported on. A fully inkjet printed multimaterial device consists of two layers of iGr stripes separated by a dielectric polymeric layer of tripropylene glycol diacrylate (TPGDA). In these devices, the bottom iGr layer, capped with TPGDA, provides temperature sensing, the top uncapped iGr is sensitive to the external atmosphere, while the capacitance between the two iGr layers is sensitive to the applied pressure. The fast, sensitive, and reproducible performance of these sensors are demonstrated in response to environmental stimuli, such as pressure, temperature, humidity, and magnetic field. The devices are capable of simultaneous sensing of multiple factors and are successfully manufactured on a variety of substrates, including Si/SiO2, flexible Kapton films and textiles, demonstrating their potential impact in applications compatible with silicon technologies as well as wearable and healthcare devices.

Quantum Navier–Stokes equations for electrons in graphene

AbstractThe Chapman–Enskog method, in combination with the quantum maximum entropy principle (QMEP), is applied to the Wigner equation in order to obtain quantum Navier–Stokes equations for electrons in graphene in the isothermal case. The derivation is based on the quantum version of the maximum entropy principle and follows the lines of Ringhofer–Degond–Méhats' theory (J. Stat. Phys. 112, 2003 and Z. Angew. Math. Mech. 90, 2010). The model obtained in this way is then semiclassically expanded up to .

Highly Sensitive and Selective SnO2-Gr Sensor Photoactivated for Detection of Low NO2 Concentrations at Room Temperature.

Chemical nanosensors based on nanoparticles of tin dioxide and graphene-decorated tin dioxide were developed and characterized to detect low NO2 concentrations. Sensitive layers were prepared by the drop casting method. SEM/EDX analyses have been used to investigate the surface morphology and the elemental composition of the sensors. Photoactivation of the sensors allowed for detecting ultra-low NO2 concentrations (100 ppb) at room temperature. The sensors showed very good sensitivity and selectivity to NO2 with low cross-responses to the other pollutant gases tested (CO and CH4). The effect of humidity and the presence of graphene on sensor response were studied. Comparative studies revealed that graphene incorporation improved sensor performance. Detections in complex atmosphere (CO + NO2 or CH4 + NO2, in humid air) confirmed the high selectivity of the graphene sensor in near-real conditions. Thus, the responses were of 600%, 657% and 540% to NO2 (0.5 ppm), NO2 (0.5 ppm) + CO (5 ppm) and NO2 (0.5 ppm) + CH4 (10 ppm), respectively. In addition, the detection mechanisms were discussed and the possible redox equations that can change the sensor conductance were also considered.

Specific gFET-Based Aptasensors for Monitoring of Microbiome Quality: Quantification of the Enteric Health-Relevant Bacterium Roseburia Intestinalis.

Roseburia intestinalis, enriched in the gut, is closely associated with obesity, intestinal inflammation, and other diseases. A novel detection method for R.intestinalis to replace the commonly used 16S rRNA sequencing technique is aim to developed, thus enabling real-time and low-cost monitoring of gut microbiota. The optimal solution is to utilize rGO-FET (reduced graphene oxide field-effect transistor) functionalized with aptamers. Due to the high sensitivity of graphene sensors to electronic changes in the system, it is anticipated to achieve detection sensitivity that traditional fluorescence detection techniques cannot attain. The previous work reported a nucleic acid aptamer library, Ri 7_2, capable of quantitatively tracking R. intestinalis in complex systems. However, due to the complexity of the aptamer library itself, large-scale industrial synthesis is challenging, significantly limiting its further commercial application potential. Therefore, in this study, through Next-Generation Sequencing analysis, four representative single aptamers from the aptamer library is strategically selected, named A-Rose 1, A-Rose 2, A-Rose 3, and A-Rose 4, and confirmed their excellent performance similar to the aptamer library Ri 7_2. Furthermore, aptamer-modified rGO-FET demonstrated universality in detecting R. intestinalis in a series of biochemical analyses, providing a novel and powerful diagnostic tool for the clinical diagnosis of R.intestinalis.