[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Two-dimensional (2D) materials have generated great interest in the past few years as a new toolbox for electronics. This family of materials includes, among others, metallic graphene, semiconducting transition metal dichalcogenides (such as MoS2), and insulating boron nitride. These materials and their heterostructures offer excellent mechanical flexibility, optical transparency, and favorable transport properties for realizing electronic, sensing, and optical systems on arbitrary surfaces. In this paper, we demonstrate a novel technology for constructing large-scale electronic systems based on graphene/molybdenum disulfide (MoS2) heterostructures grown by chemical vapor deposition. We have fabricated high-performance devices and circuits based on this heterostructure, where MoS2 is used as the transistor channel and graphene as contact electrodes and circuit interconnects. We provide a systematic comparison of the graphene/MoS2 heterojunction contact to more traditional MoS2-metal junctions, as well as a theoretical investigation, using density functional theory, of the origin of the Schottky barrier height. The tunability of the graphene work function with electrostatic doping significantly improves the ohmic contact to MoS2. These high-performance large-scale devices and circuits based on this 2D heterostructure pave the way for practical flexible transparent electronics.

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Graphene-MoS2 Hybrid Technology for Large-Scale Two-Dimensional Electronics

Graphene-based nanocomposites for sensitivity enhancement of surface plasmon resonance sensor for biological and chemical sensing: A review.

In this paper, a high-resolution refractive index sensor is proposed based on a novel metal–insulator–metal plasmonic topology. The structure is based on a Si nano-ring located inside a circular cavity. It acts as an optical notch filter with a quality factor equal to 269. The proposed filter topology is numerically simulated using the finite difference time domain method. It is shown that the proposed filter can also act as a refractive index sensor with a sensitivity of 636 nm/RIU and a fairly high figure of merit (FoM) equal to 211.3 RIU−1. It is shown that the sensor can easily detect a refractive index change of ± 0.001 for dielectrics whose refractive index is between 1 and 1.2. For the refractive index range of 1.33 to 1.52, the maximum FoM of the sensor is 191 RIU−1. The simplicity of the design and its high resolution are the two main features of the proposed sensor which make it a good candidate for biomedical applications.

Design of a High-Resolution Metal–Insulator–Metal Plasmonic Refractive Index Sensor Based on a Ring-Shaped Si Resonator

In this paper, a novel nanoscale refractive index sensor topology, which incorporates a ring resonator containing circular tapered defects coupled to a metal-insulator-metal (MIM) plasmonic waveguide with tapered defects, is proposed. For the proposed design, the effect of introduction of defects on transmittance value, shape of magnetic field, and sensor parameters such as sensitivity (S) and figure of merit (FOM) are investigated numerically and simulated using finite-difference time-domain (FDTD) method. By optimizing the ring radius and selecting the appropriate waveguide width, we have achieved a maximum sensitivity of 1295 nm per refractive index unit (RIU) and a fairly high FOM equal to 159.6 RIU−1. The structure can be used as a high accuracy refractive index sensor for refractive indices ranging from 1 to 1.65. Due to the small size, wide detection range, and the high detection resolution of the proposed sensor, it is a good choice for integrated bio-sensing applications.

Design of a Refractive Index Plasmonic Sensor Based on a Ring Resonator Coupled to a MIM Waveguide Containing Tapered Defects

A nanoscale structure which comprises metal-insulator-metal (MIM) waveguide, stub resonator, and hexagonal resonator is proposed to realize plasmon-induced transparency (PIT) response. The characteristics of the device are numerically investigated with different geometrical parameters. Benefitting from the narrow transparency window and long coupling length between two resonators, the proposed devices are able to act as a nanosensor for refractive index (RI) sensing with figure-of-merit (FOM) of 178 and 140 RIU−1 near RI of 1 and 1.33, respectively. Furthermore, the FOM can be further improved by employing symmetric structure.

Plasmon-Induced Transparency and Refractive Index Sensing in Side-Coupled Stub-Hexagon Resonators

Gas drainage is carried out based on output from each coal bed throughout commingling production of coalbed methane (CBM). A reasonable drainage process should therefore initially guarantee main coal bed production and then enhance gas output from other beds. Permanent damage can result if this is not the case, especially with regard to fracture development in the main gas-producing coal bed and can greatly reduce single well output. Current theoretical models and measuring devices are inapplicable to commingled CBM drainage, however, and so large errors in predictive models cannot always be avoided. The most effective currently available method involves directly measuring gas output from each coal bed as well as determining the dominant gas-producing unit. A dynamic evaluation technique for gas output from each coal bed during commingling CBM production is therefore proposed in this study. This technique comprises a downhole measurement system combined with a theoretical calculation model. Gas output parameters (i.e., gas-phase flow rate, temperature, pressure) are measured in this approach via a downhole measurement system; substituting these parameters into a deduced theoretical calculation model then means that gas output from each seam can be calculated to determine the main gas-producing unit. Trends in gas output from a single well or each seam can therefore be predicted. The laboratory and field test results presented here demonstrate that calculation errors in CBM outputs can be controlled within a margin of 15% and therefore conform with field use requirements.

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A dynamic evaluation technique for assessing gas output from coal seams during commingling production within a coalbed methane well: a case study from the Qinshui Basin

The traditional downhole drilling vibration measurement methods which use cable or battery as power supplies increase the drilling costs and reduce the drilling efficiency. This paper proposes a spherical triboelectric nanogenerator, which shows the potential to collect the downhole vibration energy and measure the vibration frequency in a self-powered model. The power generation tests show that the output signal amplitude of the spherical triboelectric nanogenerator increases as the vibration frequency increases, and it can reach a maximum output voltage of 70 V, a maximum current of 3.3 × 10-5 A, and a maximum power of 10.9 × 10-9 W at 8 Hz when a 10-ohm resistor is connected. Therefore, if the power generation is stored for a certain period of time when numbers of the spherical triboelectric nanogenerators are connected in parallel, it may provide intermittent power for the low-power downhole measurement instruments. In addition, the sensing tests show that the measurement range is 0 to 8 Hz, the test error is less than 2%, the applicable working environment temperature is below 100 degrees Celsius, and the installation distance between the spherical triboelectric nanogenerator and the vibration source should be less than the critical value of 150 cm because the output signal amplitude is inversely proportional to the distance.

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Research on the Potential of Spherical Triboelectric Nanogenerator for Collecting Vibration Energy and Measuring Vibration.

The heterostructures of two-dimensional (2D) materials have broad application prospects in surface plasmon resonance (SPR) biosensor. In order to enhance the sensitivity, we propose new a configuration of SPR biosensor based on Cu/Au/Ag-indium tin oxide (ITO)-graphene/two-dimensional transition metal dichalcogenide (TMDC) hybrid structures for highly sensitive sensors. The highest angular sensitivity with 219.4°/RIU for the Ag-ITO-WS2 is obtained. In addition, the SPR biosensor can also be used to detect analytes with different refractive index. The phase sensitivity of Cu-ITO-MoSe2 structure is 30.18 times higher than that of the single Cu thin film and 1.51 times higher than that of the Cu-ITO hybrid structure. It is believed that the SPR sensor has potential application prospects in environmental monitoring, chemical examination, and biological and gas detection.

Comprehensive Study of SPR Biosensor Performance Based on Metal-ITO-Graphene/TMDC Hybrid Multilayer

Surface plasmon resonance (SPR) biosensor is widely used for its high precision and real-time analysis. In this paper, SPR biosensor based on the hybrid structure of metal–indium tin oxide (ITO)–WS2 are proposed and investigated. By optimizing the thickness of metals (Au, Cu, Ag), ITO and WS2, the reflectivity of 2.932 × 10−7 a.u and highest phase sensitivity of 1.711 × 106 deg/RIU are obtained by using Ag–ITO–WS2-dielectric structure. Compared with the traditional metal-based SPR sensor, the performance of the proposed one is improved up to ~ 25.8 times. The results show that ITO and WS2 have an important effect on enhancing SPR sensing performance.

Chuan Wu

Papers

Plasmon-Induced Transparency and Refractive Index Sensing in Side-Coupled Stub-Hexagon Resonators

A dynamic evaluation technique for assessing gas output from coal seams during commingling production within a coalbed methane well: a case study from the Qinshui Basin

Research on the Potential of Spherical Triboelectric Nanogenerator for Collecting Vibration Energy and Measuring Vibration.

Comprehensive Study of SPR Biosensor Performance Based on Metal-ITO-Graphene/TMDC Hybrid Multilayer

Comprehensive Study of Phase-Sensitive SPR Sensor Based on Metal–ITO Hybrid Multilayer