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 | Nanoparticle-based Sensors
Author : Khanna, V.K.
Source : Defence Science Journal ; Vol:58(5) ; 2008 ; pp 608-616
Subject :
Keywords : Nanoparticles;Nanomaterials;Chemical warfare;Biological warfare;Toxins;Sensors;Biosensors;Quantum dots;Chemiresistors
Abstract : Nanoparticles exhibit several unique properties that can be applied to develop chemical and biosensors possessing desirable features like enhanced sensitivity and lower detection limits. Gold nanoparticles are coated with sugars tailored to recognise different biological substances. When mixed with a weak solution of the sugar-coated nanoparticles, the target substance, e.g., ricin or E.coli, attaches to the sugar, thereby altering its properties and changing the colour. Spores of bacterium labeled with carbon dots have been found to glow upon illumination when viewed with a confocal microscope. Enzyme/nanoparticle-based optical sensors for the detection of organophosphate (OP) compounds employ nanoparticle-modified fluorescence of an inhibitor of the enzyme to generate the signal for the OP compound detection. Nanoparticles shaped as nanoprisms, built of silver atoms, appear red on exposure to light. These nanoparticles are used as diagnostic labels that glow when target DNA, e.g., those of anthrax or HIV, are present. Of great importance are tools like gold nanoparticle-enhanced surface-plasmon resonance sensor and silver nanoparticle surface-enhanced portable Raman integrated tunable sensor. Nanoparticle metal oxide chemiresistors using micro electro mechanical system hotplate are very promising devices for toxic gas sensing. Chemiresistors comprising thin films of nanogold particles, encapsulated in monomolecular layers of functionalised alkanethiols, deposited on interdigitated microelectrodes, show resistance changes through reversible absorption of vapours of harmful gases. This paper reviews the state-of-the-art sensors for chemical and biological terror agents, indicates their capabilities and applications, and presents the future scope of these devices. |
| | Sol-gel Technology for Sensor Applications
Author : Chaudhury, N. K.;Gupta, R.;Gulia, S.
Source : Defence Science Journal ; Vol:57(3) ; 2007 ; pp 241-253
Subject : 681.586 Sensors
Keywords : Sol-gel technology;Defence applications;Healthcare;Nanomaterials;Sensors
Abstract : Sol-gel processes refer to the transition of predefined compositions of inorganic alkoxides precursors from liquid sol phase to solid gel phase. The phenomenon of sol-gel was known to mankind for more than 150 years. It is because of concerted efforts of researchers from multidisciplinary fields, sol-gel science transformed to technology. Several products are already commercially available for applications in optical coatings, nanocomposites, and public healthcare. Potential applications in the areas of biosensors and environmental monitoring are expected. Newer applications with nanotechnology appear too exciting. An attempt has been made to address important applications of sol-gel technology, particularly in sensing techniques from the defence perspective. |
| | Carbon Nanotubes and Related Structures
Author : Mukhopadhyay, Kingsuk;Kanik Ram;Rao, K.U. Bhasker
Source : Defence Science Journal ; Vol:58(4) ; 2008 ; pp 437-450
Subject : 620.1 Material Science and Technology
Keywords : Carbon nanotubes;Nanomaterials;Nanotechnology;Nanostructures;CNTs;Chirality
Abstract : Carbon nanotubes have attracted the fancy of many scientists worldwide. The small dimensions, strength, and the remarkable physical properties of these structures make them a unique material with a whole range of promising applications. In this review, the structural aspects, the advantages and disadvantages of different for their procedures synthesis, the qualitative and quantitative estimation of carbon nanotubes by different analytical techniques, the present status on their applications as well as the current challenges faced in the application field, national, in particular DRDO-DMSRDE status, and interest in this field, have been discussed. |
| | Nanomaterials in Pyrotechnics
Author : Sarawadekar, R.G.;Agrawal, J.P.
Source : Defence Science Journal ; Vol:58(4) ; 2008 ; pp 486-495
Subject : 620.1 Material Science and Technology
Keywords : Nanomaterials;Pyrotechnics;Nanocomposites;Nanometal powders;Nanooxidisers
Abstract : Pyrotechnics consist of metallic powders as fuels and different oxidisers which generally have particle size of > 5 m. The use of nano materials is expected to increase intimate contact between fuel oxidiser, and therefore, development of nano pyrotechnics based on nano fuels oxidizers along with their synthetic routes is considered of great interest. In this review, methods for the preparation of powders of nanometals: aluminium (Al), nickel (Ni), copper (Cu), titanium (Ti), iron (Fe), silver (Ag), and cobalt (Co) and; metallic oxides: molybdenum trioxide (MoO3), tungsten trioxide (WO3), iron (III) oxide (Fe2O3), copper (I) oxide (Cu2O), antimony trioxide (Sb2O3), nickel oxide (NiO), manganese dioxide (MnO2), and zirconium dioxide (ZrO2) along with their characterisation are discussed. Some nano oxidisers such as PbCO3, Mg(OH)2 , NH4ClO4, NH4NO3 have also been reported. Further, some nano pyrotechnic formulations Al-MO3, Al-WO3, Al- Fe2O3, Al-AP, Al-Bi2O3, Al-CaO based on nanofuels oxidisers have also been formulated. |
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