Author
R. K. Verma
Other affiliations: Indian Institute of Technology Delhi, University of Rajasthan
Bio: R. K. Verma is an academic researcher from Central University of Rajasthan. The author has contributed to research in topics: Optical fiber & Surface plasmon resonance. The author has an hindex of 12, co-authored 31 publications receiving 1025 citations. Previous affiliations of R. K. Verma include Indian Institute of Technology Delhi & University of Rajasthan.
Papers
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TL;DR: The present review may provide researchers valuable information regarding fiber optic SPR sensors and encourage them to take this area for further research and development.
Abstract: Surface plasmon resonance technique in collaboration with optical fiber technology has brought tremendous advancements in sensing of various physical, chemical, and biochemical parameters. In this review article, we present the principle of SPR technique for sensing and various designs of the fiber optic SPR probe reported for the enhancement of the sensitivity of the sensor. In addition, we present few examples of the surface plasmon resonance- (SPR-) based fiber optic sensors. The present review may provide researchers valuable information regarding fiber optic SPR sensors and encourage them to take this area for further research and development.
418 citations
TL;DR: In this paper, a surface-plasmon-based fiber optic biosensor with molybdenum disulfide (MoS2) as a bio recognition layer was proposed.
Abstract: We theoretically propose a surface-plasmon-based fiber optic biosensor in metal/graphene/MoS2 configuration with molybdenum disulfide (MoS2) as a bio recognition layer. The proposed configuration works in the visible region of the electromagnetic spectrum with a very high sensitivity. A comparative theoretical study of the sensors with different metallic layers of gold (Au), copper (Cu), and aluminum (Al) has been performed. The sensor has been found to be the most sensitive in both Cu/graphene/MoS2 and Al/graphene/MoS2 configurations with sensitivity of 6.2 μm/RIU. In both of the configurations the thicknesses of Cu and Al layers is 50 nm and the number of layers of graphene is 16 and 27, respectively, while only a single layer of MoS2 has been used. The sensitivity of the sensor in the Au/graphene/MoS2 configuration is 5.0 μm/RIU with comparatively high depth of resonance.
204 citations
TL;DR: In this paper, a theoretical model for surface plasmon resonance (SPR) based tapered fiber optic sensor is proposed with three different taper profiles, namely, linear, parabolic, and exponential-linear.
165 citations
TL;DR: Theoretical modeling of a surface plasmon resonance (SPR) based fiber optic sensor with a conducting metal oxide [indium tin oxide (ITO)] as the SPR active material reveals that the proposed sensing probe can be utilized for sensing in the IR region, where most of the gases show their absorption regime.
Abstract: Theoretical modeling of a surface plasmon resonance (SPR) based fiber optic sensor with a conducting metal oxide [indium tin oxide (ITO)] as the SPR active material is proposed. The theoretical analysis reveals that the proposed sensing probe can be utilized for sensing in the IR region, where most of the gases show their absorption regime. Comparison of sensitivity predicts that an ITO-layer-coated SPR-based fiber optic sensor is about 60% more sensitive than a gold-coated fiber optic sensor. The physical reasons behind sensitivity enhancement are provided. Apart from this, various advantageous features of the ITO over the noble metals, silver and gold, are addressed.
111 citations
TL;DR: In this article, the effect of taper ratio (TR) on the sensitivity of a surface-plasmon-resonance-based fiber-optic sensor with a metal-coated uniform core sensing region sandwiched between two identical tapered fiber regions is studied.
Abstract: Theoretical model for surface-plasmon-resonance-based fiber-optic sensor with a metal-coated uniform core sensing region sandwiched between two identical tapered fiber regions is proposed. The effect of taper ratio (TR) on the sensitivity of the sensor is studied. The study shows that the proposed probe geometry with TR lying between 1.5 and 2.0 provides the best performance. The physical reasons behind sensitivity enhancement due to tapered regions are provided.
76 citations
Cited by
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TL;DR: Long-range surface plasmon polaritons (LRSPPs) are optical surface waves that propagate along a thin symmetric metal slab or stripe over an appreciable length as discussed by the authors.
Abstract: Long-range surface plasmon polaritons (LRSPPs) are optical surface waves that
propagate along a thin symmetric metal slab or stripe over an appreciable length
(centimeters). Vigorous interest in LRSPPs has stimulated a large number of studies
over three decades spanning a broad topical landscape. Naturally, a good segment of
the literature covers fundamentals such as modal characteristics, excitation, and
field enhancement. But a large portion also involves the LRSPP in diverse phenomena,
including nonlinear interactions, molecular scattering, fluorescence,
surface-enhanced Raman spectroscopy, transmission through opaque metal films and
emission extraction, amplification and lasing, surface characterization, metal
roughness and islandization, optical interconnects and integrated structures,
gratings, thermo-, electro- and magneto-optics, and (bio)chemical sensing. Despite
the breadth and depth of the research conducted to date, much remains to be
uncovered, and the scope for future investigations is broad. We review the properties
of the LRSPP, survey the literature involving this wave, and discuss the prospects
for applications. Avenues for further work are suggested.
864 citations
TL;DR: An overview of the technologies used to implement surface plasmon resonance (SPR) effects into fiber-optic sensors for chemical and biochemical applications and a survey of results reported over the last ten years is presented.
Abstract: This paper presents a brief overview of the technologies used to implement surface plasmon resonance (SPR) effects into fiber-optic sensors for chemical and biochemical applications and a survey of results reported over the last ten years. The performance indicators that are relevant for such systems, such as refractometric sensitivity, operating wavelength, and figure of merit (FOM), are discussed and listed in table form. A list of experimental results with reported limits of detection (LOD) for proteins, toxins, viruses, DNA, bacteria, glucose, and various chemicals is also provided for the same time period. Configurations discussed include fiber-optic analogues of the Kretschmann–Raether prism SPR platforms, made from geometry-modified multimode and single-mode optical fibers (unclad, side-polished, tapered, and U-shaped), long period fiber gratings (LPFG), tilted fiber Bragg gratings (TFBG), and specialty fibers (plastic or polymer, microstructured, and photonic crystal fibers). Configurations involving the excitation of surface plasmon polaritons (SPP) on continuous thin metal layers as well as those involving localized SPR (LSPR) phenomena in nanoparticle metal coatings of gold, silver, and other metals at visible and near-infrared wavelengths are described and compared quantitatively.
555 citations
Journal Article•
TL;DR: In this paper, the authors demonstrate a novel technology for constructing large-scale electronic systems based on graphene/molybdenum disulfide (MoS2) heterostructures grown by chemical vapor deposition.
Abstract: 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.
439 citations
TL;DR: This paper presents a meta-anatomy of the response of the immune system to PNA-Based Biosensors (DNA, Aptamers) and some of the mechanisms leading to cell reprograming and apoptosis.
Abstract: ■ CONTENTS Books, Reviews, and Articles of General Interest 488 Sensors for (Dissolved) Gases and Vapors 489 Hydrogen 489 Hydrocarbons 490 Oxygen 491 Ammonia 493 Carbon Dioxide 494 Nitrogen Oxides 494 Vapors of Organic Solvents 495 Sensors for Humidity, Water Fractions, Hydrogen Peroxide, and Hydrazine 495 Humidity 495 Water Fractions 496 Hydrogen Peroxide and Hydrazine 496 Sensors for pH Values, Ions, and Salinity 496 pH Values 496 Ions 497 Salinity and Ionic Strength 499 Sensors for Organic Species 499 Biosensors 500 Immunosensors 500 PNA-Based Biosensors (DNA, Aptamers) 501 Other Affinity Sensors 501 Enzymatic Biosensors 502 Whole Cell Sensors 502 Advanced Optical Sensing Schemes and Materials 503 Author Information 505 Corresponding Author 505 Notes 505 Biographies 505 Acknowledgments 505 References 505
419 citations