Nanoparticle-based Sensors

Nanoparticles exhibit several unique properties that can be applied to develop chemical and biosensorspossessing desirable features like enhanced sensitivity and lower detection limits. Gold nanoparticles arecoated with sugars tailored to recognise different biological substances. When mixed with a weak solution ofthe sugar-coated nanoparticles, the target substance, e.g., ricin or E.coli, attaches to the sugar, thereby alteringits properties and changing the colour. Spores of bacterium labeled with carbon dots have been found to glowupon illumination when viewed with a confocal microscope. Enzyme/nanoparticle-based optical sensors forthe detection of organophosphate (OP) compounds employ nanoparticle-modified fluorescence of an inhibitorof 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 thatglow when target DNA, e.g., those of anthrax or HIV, are present. Of great importance are tools like goldnanoparticle-enhanced surface-plasmon resonance sensor and silver nanoparticle surface-enhanced portableRaman integrated tunable sensor. Nanoparticle metal oxide chemiresistors using micro electro mechanical systemhotplate are very promising devices for toxic gas sensing. Chemiresistors comprising thin films of nanogoldparticles, encapsulated in monomolecular layers of functionalised alkanethiols, deposited on interdigitatedmicroelectrodes, show resistance changes through reversible absorption of vapours of harmful gases. Thispaper reviews the state-of-the-art sensors for chemical and biological terror agents, indicates their capabilitiesand applications, and presents the future scope of these devices.Defence Science Journal, 2008, 58(5), pp.608-616, DOI:http://dx.doi.org/10.14429/dsj.58.168

LIDAR for Detection of Chemical and Biological Warfare Agents

Remote detection of chemical and biological warfare agents and toxic gases in the atmosphere is of current interest to both the military and civilian agencies. Out of all currently available techniques, no single technique provides efficient detection against such threats at significant standoff distances. Light detection and ranging (LIDAR) technologies, based on the transmission of laser pulses and analysis of the return signals, have demonstrated impressive capabilities in remote detection of such toxic chemicals. LIDAR is a highly sensitive tool to detect the extremely low concentrations of various toxic agents present in the form of thin clouds at distances of few kilometer. The detection of these toxic clouds is based on the approach of first detecting and measuring the range of the clouds using the scattering phenomena and subsequently identifying the composition of toxic clouds using absorption and fluorescence phenomena. Laser Science and Technology Centre (LASTEC), Delhi has been working on the design and development of LIDAR systems for detection of chemical and biological warfare (CBW) agents. In this paper, theoretical analysis of differential absorption LIDAR (DIAL) for detection of chemical agents and fluorescence LIDAR for detection of biological agents has been discussed. For some typical parametric conditions, the received power levels from different ranges to detect specific concentrations of chemical or biological clouds have been computed and discussed. The technical details of the indigenously developed backscattering LIDAR, which detects and measures the distance of cloud layers up to 5 km is also presented.Defence Science Journal, 2011, 61(3), pp.241-250, DOI:http://dx.doi.org/10.14429/dsj.61.55

Use of particle counter system for the optimization of sampling ,identification and decontamination procedures for biological aerosols dispersion in confined environment

Abstract In a CBRNe (Chemical, Biological, Radiological, Nuclear and explosive) scenario, biological agents hardly allow efficient detection/identification because of the incubation time that provides a lag in symptoms outbreak following their dissemination. The detection of atmospheric dispersion of biological agents (i.e.: toxins, viruses, bacteria and so on) is a key issue for the safety of people and security of environment. Another fundamental aspect is related to the efficiency of the sampling method, which leads to the identification of the agent released, in fact an effective sampling method is needed either to identify the contamination and to check for the decontamination procedure. Environmental monitoring is one of the ways to improve fast detection of biological agents; for instance, particle counters with the ability of discriminating between biological and non-biological particles are used for a first warning when the amount of biological particles exceeds a particular threshold. Nevertheless, these systems are not able to distinguish between pathogen and non-pathogen organisms, thus, classical “laboratory” assays are still required to unambiguously identify the particle which triggered the warning signal. In this work, a combination of commercially available equipment for detection and identification of the atmospheric dispersion of biological agents was evaluated in partnership between the Italian Army, the Department of Industrial Engineering and the School of Medicine and Surgery of the University of Rome “Tor Vergata”. The aim of this work, whose results are presented here, was to conduce preliminary studies on the dynamics of biological aerosols fallout after its dispersion, to improve detection, sampling and identification techniques. This will help minimizing the impact of the release of biological agents, guarantee environmental, and people safety and securit

Matched Optical Waveforms for Detection and Identification of Biological Pathogens.

A method is provided for identifying a contaminant in a gaseous space. The method includes: generating a broadband optical waveform; shaping the optical waveform to match an expected waveform for a known contaminant; and transmitting the shaped optical waveform towards an unknown contaminant. Upon receiving a reflected optical waveform from the unknown contaminant, determining whether the unknown contaminant correlates to the known contaminant based on the reflected waveform

Infrared: A Key Technology for Security Systems

Infrared science and technology has been, since the first applications, mainly dedicated to security and surveillance especially in military field, besides specialized techniques in thermal imaging for medical diagnostic and building structures and recently in energy savings and aerospace context. Till recently the security applications were mainly based on thermal imaging as surveillance and warning military systems. In all these applications the advent of room temperature, more reliable due to the coolers avoidance, low cost, and, overall, completely integrable with Silicon technology FPAs, especially designed and tailored for specific applications, smart sensors, has really been impacted with revolutionary and new ideas and system concepts in all the infrared fields, especially for security applications. Lastly, the advent of reliable Infrared Solid State Laser Sources, operating up to the Long Infrared Wavelength Band and the new emerging techniques in Far Infrared Submillimeter Terahertz Bands, has opened wide and new areas for developing new, advanced security systems. A review of all the items with evidence of the weak and the strong points of each item, especially considering possible future developments, will be reported and discussed

A review on the role of emerging revolutionary nanotechnology in forensic investigations

Due to the unique properties of nanoparticles, it has gained prominence in lots of fields with extensive research being carried around it. With lots of novel applications arising from this field, Forensic science seems to be one of the fast-growing fields in nano research applications. The growing and extensive use of nanotechnology being applied in forensic investigations is promising and could soon be the tipping point in the discipline. Applications mainly have been related to evidence identification and analysis in the broad major fields in Forensic Science such as single-crystalline semiconductor CdS nano slabs for explosives detection, functionalized TiO2 nanorods for organophosphorus chemical warfare agents in Forensic Chemistry, the use of Nanopowders for latent print visualization in Forensic physics and Gold nanoparticle protein nanopore for detection of single-stranded DNA in Forensic biology. Nanotechnology has also been employed in illegal drug detection in recent times. These and other applications of Nanotechnology provides prompt and precise results with reduced methods due to the limited instruments used for analyzing evidence as well as providing sensitive and selective ways of detecting evidence. As evidence is notable in forensic investigations, nanotechnology’s use in identifying and detecting these has potential in enhancing and providing efficient and rapid means for investigations and unravelling leads into crimes. This review emphasizes some disciplines in forensic sciences in which nanotechnology is having an impact, novel methods and newly developed instruments and also takes into account its challenges as well as perspectives into the future

Standoff Detection via Single-Beam Spectral Notch Filtered Pulses

We demonstrate single-beam coherent anti-Stokes Raman spectroscopy (CARS), for detecting and identifying traces of solids, including minute amounts of explosives, from a standoff distance (>50 m) using intense femtosecond pulses. Until now, single-beam CARS methods relied on pulse-shapers in order to obtain vibrational spectra. Here we present a simple and easy-to-implement detection scheme, using a commercially available notch filter, that does not require the use of a pulse-shaper.Comment: 3 pages, 3 figure

Observational Signatures of Self-Destructive Civilisations

We address the possibility that intelligent civilisations that destroy themselves could present signatures observable by humanity. Placing limits on the number of self-destroyed civilisations in the Milky Way has strong implications for the final three terms in Drake's Equation, and would allow us to identify which classes of solution to Fermi's Paradox fit with the evidence (or lack thereof). Using the Earth as an example, we consider a variety of scenarios in which humans could extinguish their own technological civilisation. Each scenario presents some form of observable signature that could be probed by astronomical campaigns to detect and characterise extrasolar planetary systems. Some observables are unlikely to be detected at interstellar distances, but some scenarios are likely to produce significant changes in atmospheric composition that could be detected serendipitously with next-generation telescopes. In some cases, the timing of the observation would prove crucial to detection, as the decay of signatures is rapid compared to humanity's communication lifetime. In others, the signatures persist on far longer timescales.Comment: 35 pages, 2 figures, accepted for publication in the International Journal of Astrobiolog

Molecular Imprinting Applications in Forensic Science.

Producing molecular imprinting-based materials has received increasing attention due to recognition selectivity, stability, cast effectiveness, and ease of production in various forms for a wide range of applications. The molecular imprinting technique has a variety of applications in the areas of the food industry, environmental monitoring, and medicine for diverse purposes like sample pretreatment, sensing, and separation/purification. A versatile usage, stability and recognition capabilities also make them perfect candidates for use in forensic sciences. Forensic science is a demanding area and there is a growing interest in molecularly imprinted polymers (MIPs) in this field. In this review, recent molecular imprinting applications in the related areas of forensic sciences are discussed while considering the literature of last two decades. Not only direct forensic applications but also studies of possible forensic value were taken into account like illicit drugs, banned sport drugs, effective toxins and chemical warfare agents in a review of over 100 articles. The literature was classified according to targets, material shapes, production strategies, detection method, and instrumentation. We aimed to summarize the current applications of MIPs in forensic science and put forth a projection of their potential uses as promising alternatives for benchmark competitors