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Gas sensing with heterostructures based on two-dimensional nanostructured materials: a review
Bag, Atanu,Lee, Nae-Eung The Royal Society of Chemistry 2019 Journal of Materials Chemistry C Vol.7 No.43
<P>Gas sensors are being used in diverse applications in security, food safety, environmental monitoring, indoor air quality monitoring, personal healthcare, <I>etc.</I> During the past decade, two-dimensional (2D) nanostructured materials have attracted intense attention because of their unique chemical and physical properties. They have demonstrated promising potential for gas sensing devices because of their large surface-to-volume ratio, high surface sensitivity, and excellent semiconducting properties. Combining 2D nanostructured materials with other dimensional materials also holds great promise for developing high-performance gas sensors. This review presents a comprehensive summary of recent progress in gas sensors with advanced heterostructures based on 2D nanostructured materials. Furthermore, the fundamental sensing mechanisms of different types of gas sensors are systematically discussed, and key device architectures and their performances are summarized. Finally, the challenges and prospects for the future development of each type of gas sensor are addressed to promote better sensing-device architectures.</P>
Bag, Atanu,Choi, Shi-Hoon Elsevier 2017 Materials science & engineering. properties, micro Vol.708 No.-
<P><B>Abstract</B></P> <P>The initiation and propagation of microcracks in the copper thin film on flexible polyimide substrates was examined through the thickness direction following cyclic bending test using a focused ion beam (FIB) and electron backscatter diffraction (EBSD) technique. The EBSD observations of the cross-sectional plane clearly indicated that intergranular fracture was predominant during the initiation and propagation of microcracks. During the cyclic bending testing, through the thickness direction microcracks were propagated mostly along the high-angle grain boundaries (HAGBs) that separated the neighboring grains with a high Schmid factor (SF), instead of at the twin boundaries (TBs).</P>
BAG ATANU,박기성,최시훈 대한금속·재료학회 2017 METALS AND MATERIALS International Vol.23 No.4
Cyclic-bend testing was conducted on flexible Cu-clad laminate (FCCL) to investigate the correlation betweenelectrical resistance and the evolution of microcracks. During the test, the change in the electrical resistance of theFCCL was monitored using two-point probe method. The variation in the electrical resistance of the FCCL withrespect to the bending cycle can be divided into three stages according to the slope. In order to reveal the microcracksin Cu thin film and how they contribute to the variation in electrical resistance, quantitative analysis of themicrocracks was conducted on the surface and cross-section of the deformed Cu thin films using field emissionscanning electron microscopy. Analysis showed that the simultaneous extensive evolution of microcracks in thetension and compression zones were main contributors to increase the electrical resistance following specificcritical bending cycles.
Atanu Bag,Ki‑Seong Park,Shi‑Hoon Choi 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.1
The effect that the deformation state exerts on both the electrical and the mechanical degradation of Cu thin film on a flexiblePI substrate was investigated via cyclic sliding test. Two opposite types of deformation (tension and compression) wereapplied to Cu thin film depending on its outward or inward placement in the cyclic sliding test system. During the cyclicsliding test, the change in electrical resistance of the Cu thin films was monitored using a two-point probe method. Systematicsurface observation of deformed Cu thin film under the two opposite types of deformation was performed following specificcycles of sliding motion. Surface observation based on field emission scanning electron microscopy and 3D confocal laserscanning microscopy had been done to quantify the evolution of intrusion extrusions and surface roughness on the deformedCu thin film. The distribution of microcracks significantly depended on the type of stress/strain applied to the Cu thin filmon a flexible PI substrate during the cyclic sliding test. Finite element analysis was performed to explain the deformationbehavior of the Cu thin film on a flexible PI substrate during the cyclic sliding test.
Kale, Amol B.,Bag, Atanu,Hwang, Ji-Hyun,Castle, Elinor G.,Reece, Mike J.,Choi, Shi-Hoon Elsevier 2017 Materials science & engineering. properties, micro Vol.707 No.-
<P><B>Abstract</B></P> <P>In this study, 316L stainless steel (SS) specimens with different relative densities were fabricated using the spark plasma sintering (SPS) technique. These SPS specimens were used to capture the effect of microstructure heterogeneity on deformation and fracture behaviors during uniaxial tension. Microstructure analysis indicated that the SPS specimens consisted of fully sintered and partially sintered regions and contained initial pores which are located at the grain boundaries. Mini-tension tests combined with the digital image correlation (DIC) technique were carried out at room temperature to measure the mechanical properties of the SPS specimens and the evolution of strain heterogeneity on tensile specimens during uniaxial tension. In order to reveal the fracture mechanisms of the SPS specimens, the surfaces of the fractured specimens were analyzed via field emission scanning electron microscope (FE-SEM). The fracture mechanism in the fully sintered region was identified as a ductile fracture by the formation of cup-like dimples, while the fracture mechanism in the partially sintered region was identified as a decohesion of the interface between the powder and the matrix.</P>