arXiv subjects

Joydip Sengupta

Publications and source records attributed to Joydip Sengupta.

At least 19 recordsLinked to original sources

arXiv2022

Prospective pathways of green graphene-based lab-on-chip devices: the pursuit toward sustainability

At present, analytical lab-on-chip devices find their usage in different facets of chemical analysis, biological analysis, point of care analysis, biosensors, etc. In addition, graphene has already established itself as an essential component of advanced lab-on-chip devices. Graphene-based lab-on-chip devices have achieved appreciable admiration because of their peerless performance in comparison to others. However, to accomplish a sustainable future a device must undergo Green-Screening to check its environmental compatibility. Thus, extensive research is carried out globally to make the graphene-based lab-on-chip green, though it is yet to be achieved. Nevertheless, as a ray of hope, there are few existing strategies that can be stitched together for feasible fabrication of environment-friendly green graphene-based analytical lab-on-chip, and those prospective pathways are reviewed in this paper.

physics.app-ph↗

arXiv2021

Toxicity of Carbon Nanomaterials

The outstanding multidisciplinary applicability of nanomaterials has paved the path for the rapid advancement of nanoscience during the last few decades. Such technological progress subsequently results in an inevitable environmental exposure of nanomaterials. Presently, nanomaterials are employed in an extensive range of commercial products. Safe and sustainable incorporation of nanomaterials in industrial products requires a profound and comprehensive understanding of their potential toxicity. Among different nanomaterials, carbon nanomaterials marked its notable superiority toward the development of state-of-the-art nanotechnology due to the significant contribution of each of the carbon allotropes with varied dimensionality. The zero-dimensional fullerene, one-dimensional carbon nanotube, and two-dimensional graphene possess an exclusive combination of distinctive properties that are utilized in most of the nanotechnology-based products nowadays. However, potential risk factors are associated with the production and the use of carbon nanomaterials. Consequently, the number of studies regarding the assessment of the toxicity of these nanomaterials has increased rapidly in the past decade. This chapter will summarize the recent scientific efforts on the toxicity evaluation of different carbon nanomaterials.

cond-mat.mtrl-sci↗

arXiv2021

Graphene-based analytical lab-on-chip devices for detection of viruses: A review

Lab on a chip (LOC) device intakes fluid and makes it flow through the microchannels, to achieve rapid, highly sensitive and low-cost analysis with significant yield. Graphene has vast potential to be used in LOC devices owing to its remarkable and unique properties. A trustworthy, swift, inexpensive and facile detection scheme is of urgency due to the current situation of COVID-19 to break the chain of transmission and lab-on-chip based biosensor has materialized itself as a realistic solution for this purpose. The addition of Graphene has augmented the sensing capability of the LOC devices to a superior level. Recently, Graphene-based lab-on-chip type biosensor is effectively used for faithful detection of SARS-CoV-2 and this draws the attention of the researchers to review the recent progress in Graphene-based LOC platforms for detection of viruses and the same has been reviewed here.

physics.bio-ph↗

arXiv2020

Carbon Nanomaterials to Combat Virus: A perspective in view of COVID-19

The rapid outbreaks of lethal viruses necessitate the development of novel antiviral substance. Besides the conventional antiviral substances, biocompatible nanomaterials also have significant potential in combating the virus at various stages of infection. Carbon nanomaterials have an impressive record against viruses and can deal with many crucial healthcare issues. In accordance with the published literature, biocompatible carbon nanomaterials have a promising prospect as an antiviral substance. Subsequently, the antiviral properties of different carbon nanomaterials namely fullerene, carbon nanotube, carbon dot and graphene oxide have been reviewed.

cond-mat.mtrl-sci↗

arXiv2020

Graphene-based field-effect transistor biosensors for the rapid detection and analysis of viruses: A perspective in view of COVID-19

Current situation of COVID-19 demands a rapid, reliable, cost-effective, facile detection strategy to break the transmission chain and biosensor has emerged as a feasible solution for this purpose. Introduction of nanomaterials has undoubtedly improved the performance of biosensor and the addition of graphene enhanced the sensing ability to a peerless level. Amongst different graphene-based biosensing schemes, graphene field-effect transistor marked its unique presence owing to its ability of ultrasensitive and low-noise detection thereby facilitating instantaneous measurements even in the presence of small amounts of analytes. Recently, graphene field-effect transistor type biosensor is even successfully employed in rapid detection of SARS-CoV-2 and this triggers the interest of the scientific community in reviewing the current developments in graphene field-effect transistor. Subsequently, in this article, the recent progress in graphene field-effect transistor type biosensors for the detection of the virus is reviewed and challenges along with their strengths are discussed.

physics.app-ph↗

arXiv2020

Effect of growth temperature on the CVD grown Fe filled multi-walled carbon nanotubes using a modified photoresist

Fe filled carbon nanotubes were synthesized by atmospheric pressure chemical vapor deposition using a simple mixture of iron acetylacetonate with a conventional photoresist and the effect of growth temperature from 550 to 950 °C on Fe filled nanotubes has been studied. Scanning electron microscopy results show that, as the growth temperature increases from 550 to 950 °C, the average diameter of the nanotubes increases while their number density decreases. High resolution transmission electron microscopy along with energy dispersive X-ray investigation shows that the nanotubes have a multi-walled structure with partial Fe filling for all growth temperatures. The graphitic nature of the nanotubes was observed via X-ray diffraction pattern. Raman analysis demonstrates that the degree of graphitization of the carbon nanotubes depends upon the growth temperature.

physics.app-ph↗

arXiv2020

Application of carbon nanomaterials in the electronic industry

Nanomaterials have much improved properties compared to their bulk counterparts, which promotes them as ideal material for applications in various industries. Among the various nanomaterials, different nanoallotropes of carbon, namely fullerene, carbon nanotubes, and graphene, are the most important as indicated by the fact that their discoverers gained prestigious awards such as Nobel Prize or Kavli Prize. Carbon forms different nano-allotropes by varying the nature of orbital hybridization. Since all nanoallotropes of carbon possess exotic physical and chemical properties, they are extensively used in different applications, especially in the electronic industry.

physics.app-ph↗

arXiv2020

Pre-heating effect on the catalytic growth of partially filled carbon nanotubes by chemical vapor deposition

The surface reconstruction of the Fe catalyst films due to high temperature processing in hydrogen prior to nanotube nucleation and its effect on the growth morphologies of partially filled carbon nanotubes (CNTs) synthesized using atmospheric pressure chemical vapor deposition (APCVD) of propane was investigated. Results show that pre-heating of the catalyst film deeply influences the particle size distribution, which governs the growth morphologies of the corresponding CNTs. The distribution of the catalyst particles over the Si substrate was analyzed before and after the heat treatment by atomic force microscopy (AFM) which reveals that heat treatment causes clusters of catalyst to coalesce and form macroscopic islands. The X-ray diffraction (XRD) pattern of the grown material indicates that they are graphitic in nature. Scanning electron microscopy (SEM) analysis suggested that the growth density strongly depends on the pre heat treatment of the Fe catalyst film. Multiwalled CNTs with partial catalyst filling were observed via high-resolution transmission electron microscopy (HRTEM) measurements. The degree of graphitization of the CNTs also depends on the pre heating as demonstrated by Raman analysis. A simple model for the growth of partially catalyst filled nanotubes is proposed.

physics.app-ph↗

arXiv2019

Different Synthesis Routes of Graphene-Based Metal Nanocomposites

Nanocomposite material proves to be the best candidate to match todays technological need as fascinating properties can be achieved by combining two or more nanomaterials. Among various nanomaterials, graphene is able to stand out far ahead of all others because of its novel structure and exclusive characteristics. In particular, graphene metal nanocomposites have attracted enormous interest for their prospective use in various fields, including electronics and electrical and energy related areas. However, for the utmost use of potential of graphene, it has to be homogenously embedded into metal matrices. Thus, appropriate synthesis route is decisive to obtain graphene metal nanocomposites with desired properties. This chapter will summarize the different synthesis routes of high quality graphene metal nanocomposites along with their current developments.

physics.app-ph↗

arXiv2019

Well-Ordered "Ripple-Shaped" Microstructures of Mn Thin Films on GaAs Substrates

This study was aimed to investigate the thickness dependent morphological changes of Mn films deposited on GaAs substrates by thermal evaporation technique. Ni films were deposited under same conditions to perform comparative study of the morphological changes with respect to the Mn films. The scanning electron microscopy and atomic force microscopy studies revealed ripple-shaped structure of Mn film with good periodicity, while Ni film only exhibited small granules deposited throughout the surface. The influence of the thickness of the Mn film in producing the ripple structure was clearly observed. In addition, the annealing time was considered as the major parameter to control the ordering of the ripple structure. X-ray diffraction pattern indicated the formation of different phases of Ga-Mn and Mn-As due to diffusion of atoms during annealing. A model for the creation of stress-driven microstructure is proposed which indicates that Mn thin films grow on GaAs substrates in three stages: in the primary stage, the growth occurs via two-dimensional nucleation process; as the thickness increases, the stress is released by the film via creation of additional surface roughness which produce ripples; and finally an island-like growth occurs because of the non-uniform distribution of stress along the surface of the film.

physics.app-ph↗

arXiv2019

Graphene and its derivatives for Analytical Lab on Chip platforms

Since last decade, graphene has materialized itself as one of the phenomenal materials to modern researchers because of its remarkable thermal, optical, electronic, and mechanical properties. Graphene holds enormous potentials for lab on chip (LOC) devices and can provide diverse fabrication routes and structural features due to their special electronic and electrochemical properties. A LOC device can manipulate fluids using microchannels and chamber structures, to accomplish fast, highly sensitive and inexpensive analysis with high yield. Hence, the graphene based LOC devices can constitute a well-controlled microenvironment for both advanced chemical/biological evaluation and low-cost point-of-care analysis etc. This review critically debates the graphene as a prime candidate for microfluidic devices and their future applicability towards various practical applications. Finally, the opportunities and challenges for the future of graphene with respect to their commercial challenges and sustainability perspectives are discussed.

physics.app-ph↗

arXiv2019

Substrate free synthesis of graphene nanoflakes by atmospheric pressure chemical vapour deposition using Ni powder as a catalyst

Graphene nanoflakes (GNFs) were synthesized by atmospheric pressure chemical vapour deposition of propane (C3H8) employing Ni (salen) powder without the introduction of a substrate. The graphitic nature of the GNFs was examined by an X-ray diffraction method. Scanning electron microscopy results revealed that GNFs were stacked on top of one another and had a high aspect ratio. Transmission electron microscopy studies suggested that the GNFs were made up of a number of crystalline graphene layers, some of which were even single crystalline as evident from the selected area diffraction pattern. Finally, Raman spectroscopy confirmed the high quality of the GNFs.

physics.app-ph↗

arXiv2019

Structural and optical properties of post annealed Mg doped ZnO thin films deposited by the sol gel method

Thin films of magnesium doped zinc oxide (MZO) were synthesized using the sol gel method and annealed at different temperatures under ambient condition. The morphological properties of the post annealed MZO films were investigated using X ray diffraction (XRD) while atomic force microscopy (AFM) was employed to probe the topographical alteration of the films. The optical properties of the post annealed MZO films were examined by UV visible spectroscopy and the Tauc method was used to estimate the optical band gap. The studies revealed that, with the rise of annealing temperature the crystallinity and the surface roughness of the MZO films were increased whereas the optical transmittance and the energy bandgap were decreased.

cond-mat.mtrl-sci↗

arXiv2019

Effect of annealing on the structural, topographical and optical properties of sol gel derived ZnO and AZO thin films

A comparative study of the physical properties of undoped Zinc Oxide (ZnO) and Al doped Zinc Oxide (AZO) thin films were performed as a function of annealing temperature. The structural properties were analyzed using X-ray diffraction and the recorded patterns indicated that the crystallinity of the films always enhanced with increasing annealing temperature while it degrades with Al doping. The topographical modification of the films due to heat treatment was examined by atomic force microscopy which revealed that annealing roughened the surface of all the films; however the AZO films always exhibited smoother morphology than ZnO. Study of the optical properties by UV-Visible spectrophotometer demonstrated that the transmittance was gradually diminished with the rise in annealing temperature. In addition, a notable increase in the optical band gap was also observed for the AZO films.

physics.app-ph↗

arXiv2019

Carbon Nanotube Fabrication at Industrial Scale: Opportunities and Challenges

Careful research on different materials reveals that the material properties are mostly affected by the size of it. Material size down to nanometer scale exhibits some remarkable properties, resulting in unique physical and chemical characteristics. In todays world of nanotechnology, carbon nanotubes (CNTs) have become a high priority material because of their exclusive structure, novel characteristics with enormous potential in many technological applications. Till date chemical vapor deposition (CVD) is the preferred and widely used technique among different CNT growth methods, because of its potential advantage to produce CNTs of high purity, large yield with ease of scale up and low setup cost. This article provides an overview of different CVD methods for industrial scale fabrication of CNTs. The influence of material aspect, viz. catalyst type, catalyst support, and growth control aspect, viz. process temperature, pressure, catalyst concentration, are discussed. Additionally, possible growth mechanisms concerning CNT formation are described. Finally, the key challenges of the process are addressed with future perspective.

physics.app-ph↗

arXiv2019

Influence of annealing temperature on the structural, topographical and optical properties of sol gel derived ZnO thin films

This investigation deals with the effect of annealing temperature on the structural, topographical and optical properties of Zinc Oxide thin films prepared by sol gel method. The structural properties were studied using X-ray diffraction and the recorded patterns indicated that all the films had a preferred orientation along (002) plane and the crystallinity along with the grain size were augmented with annealing temperature. The topographical modification of the films due to heat treatment was probed by atomic force microscopy which revealed that annealing roughened the surface of the film. The optical properties were examined by a UV visible spectrophotometer which exhibited that maximum transmittance reached nearly 90% and it diminished with increasing annealing temperature.

physics.app-ph↗

arXiv2019

Site selective synthesis of in situ Ni filled multiwalled carbon nanotubes using Ni(salen) as a catalyst source

The synthesis of Ni filled multiwalled carbon nanotubes was performed by atmospheric pressure chemical vapor deposition with propane on Si at 850 C using a simple mixture of Ni(salen), and a conventional photoresist. Analysis of the carbon nanotubes using scanning electron microscopy together with high resolution transmission electron microscopy show that the nanotubes have grown by a tip growth mechanism and exhibit a multi walled structure with partial Ni filling. The high quality of the Ni filled nanotubes is evidenced by Raman spectroscopy. The magnetic properties of Ni filled nanotubes were analyzed using a superconducting quantum interference device which revealed their ferromagnetic behavior with large coercivity. A scalable as well as site selective growth of high quality Ni filled carbon nanotubes is achieved by a simple photolithographic method.

physics.app-ph↗

arXiv2019

Lithographically defined site-selective growth of Fe filled multi-walled carbon nanotubes using a modified photoresist

Partially Fe filled multi-walled carbon nanotubes (MWCNTs) were grown by chemical vapor deposition with propane at 850 °C using a simple mixture of iron (III) acetylacetonate (Fe(acac)3) powder and conventional photoresist. Scanning electron microscopy revealed that catalytic nanoparticles with an average diameter of 70 nm are formed on the Si substrate which governs the diameter of the MWCNTs. Transmission electron microscopy shows that the nanotubes have a multi-walled structure with partial Fe filling. A site-selective growth of partially Fe filled MWCNTs is achieved by a simple photolithographic route.

physics.app-ph↗