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Optimization of polymer coated silicon microcantilever for chemical sensing applications
No full textThe mechanical design and optimization of polymer coated silicon microcantilever (MC) for chemical sensing application have been studied through simple mass sensitivity factor. For this theoretical modeling, silicon is the base layer (substrate) and the functional layer can be selected according to the chemical detection. The mass sensitivity factor and spring constant change before and after chemical reactions have been analyzed theoretically by taking minimum of four hundred samples in each case study. Finally, the specific dimensions and guidelines for designing high sensitivity polymer coated microcantilever for chemical sensing application based on the case study have been suggested. The optimized microcantilever is theoretically analyzed with detection of water vapour and primary alcohols
A new Middle Path Approach for alignments in BLAST
No full textThis paper deals with a new middle path approach developed for reducing alignment calculations in BLAST algorithm. This is a new step which is introduced in BLAST algorithm in between the ungapped and gapped alignments. This step of middle path approach between the ungapped and gapped alignments reduces the number of sequences going for gapped alignment. This results in the improvement in speed for alignment up to 30 percent
Binding of Carbon Nanotubes Dispersed by optical tweezer on Silicon Surface
No full textEffective dispersion and selective positioning of carbon nanotubes is necessary for future integration with conventional microelectronics as well as the development of novel functional devices. Limited progress has been reported in the dispersion and controlled placement of carbon nanotubes. In the present study, we dispersed carbon nanotubes using an optical tweezer cum microdissector system and then binded them onto a silicon surface. –OH groups were created on the silicon surface. Carbon nanotubes were processed to form a carboxylic group at their ends. Fourier transform infrared (FTIR) spectra were recorded to confirm the functionalization. These carbon nanotubes were made to react with silicon surface. The silicon surface was investigated under scanning electron microscope (SEM). The image showed the presence of a number of carbon nanotubes binded to the silicon surface. This kind of binding onto substrates will open up the path to applications like chemical sensors, scanning probe tips etc. based on carbon nanotubes
Holographic optics based two-channel interferometer.
Get PDFThe paper describes a simple and cost effective method for making a two-channel interferometer based on holographic optics, which is suitable for performing optical test studies on two different phase objects simultaneously and independently. The optical arrangement in the proposed method involves a simple alignment procedure and inexpensive recording material is used in the formation of holographic optical elements. Recording schemes for the formation of holographic optical elements and the related techniques for the realization of the proposed interferometer along with the effect of misalignment of holographic optical elements and typical experimental results are presented
Demonstration of a new biosensing concept for immunodiagnostic applications based on change in surface conductance of antibodies after biomolecular interactions
No full textWe report an important observation that the surface conductivity of antibody layer immobilized on polylysine-coated glass substrate decreases upon the formation of complex with their specific antigens. This change in conductivity has been observed for both monoclonal and polyclonal antibodies. The conductance of monoclonal mouse IgG immobilized on polylysine-coated glass substrate changed from 1.02×10−8 Ω−1 to 1.41×10−11 Ω−1 at 10 V when complex is formed due to the specific biomolecular interactions with rabbit anti-mouse IgG F(ab′)2. Similar behavior was observed when the same set up was tested in two clinical assays: (1) anti-Leishmania antigen polyclonal antibodies taken from Kala Azar positive patient serum interacting with Leishmania promastigote antigen, and (2) anti-p21 polyclonal antibodies interacting with p21 antigen. The proposed concept can represent a new immunodiagnostic technique and may have wide ranging applications in biosensors and nanobiotechnology too
Fibre Bragg grating-based sensing device for petrol leak detection
No full textFibre Bragg gratings (FBGs) have emerged in recent years as important sensor elements for various applications. In this communication application of an FBG sensor using a surgical rubber as transducer element for petrol leak detection in pipelines and tanks is presented. The rubber, which is in tubular form and is bonded with the fibre containing FBG, reversibly swells in the presence of petrol thus resulting in Bragg wavelength shift. The shift is measured using an interrogator with a swept fibre laser source (1520-570 nm). The design aspects and experimental procedure along with analysis of results obtained and the potential for distributed sensing have been discussed
Interferometric moiré pattern encoded security holograms
No full textThis paper describes a simple method for making interferometric moiré pattern encoded security holograms. These security holograms contain multi-fold concealed and encoded anti-counterfeit security features which can only be decoded by using an encoded key hologram in the final reading process. The concealed codes in these holograms are recorded with an encoded feature, so that they remain invisible to the counterfeiters, thereby enhancing the anti-counterfeiting ability of security holograms. In the final reading process, a specific moiré-like fringe pattern is formed on the security hologram only when a reconstructing beam generated from the encoded key hologram illuminates this hologram. Further, a careful spatial filtering results in the generation of a specific moiré pattern in the observation plane and it disappears when perfectly repositioned. These can also be used as security codes for better protection against counterfeiting in embossed holograms. Recording schemes for the formation of such security holograms and typical experimental results have been presented
Folding mirror schlieren diffraction interferometer
No full textWe demonstrate the use of a mirror as a viewing diaphragm to generate a built-in diffracted reference beam in schlieren diffraction interferometry (SDI). The use of a mirror edge as a diffracting element instead of a conventional knife edge considerably enhances the contrast of the schlieren pattern, and it is shown to be equal to that of a phase knife edge. This increase in contrast is due to the fact that the otherwise unutilized diffracted beam in SDI is recombined in the described folding mirror geometr
Design improvements in digital seismograph for recording long duration seismic events & after shocks
Get PDFThe paper highlights a new design approach to overcome technical limitations of digital seismographs by incorporating optimum hardware and efficient software modules etc. The paper illustrates how the new design approach has enhanced the limited 64 kbytes addressing capability of 8-bit microprocessor based seismograph to 16 Mbytes capacity. Instrument based on this design philosophy can now record many long duration seismic events and the series of subsequent aftershocks, which need storage of several mega bytes. The technique has enabled uninterrupted data acquisition and processing even when the data of earlier recorded events is being transferred from main storage to PC hard disk. The design concept has been validated successfully by operating the instrument based on this technique for long time in the field
An optoelectronic instrument for the determination of sulphite in beverages.
No full textThe paper describes an optoelectronic device that has been designed and developed to measure the sulphite concentration in beverages for quality evaluation. A selective and sensitive method for determination of sulphite is based on the reaction with pararosaniline acid bleached dye and formaldehyde solution, which gives violet colored complex having absorption maxima at 560 nm. Lambert–Beer’s law is obeyed in the concentration range up to 25 μg/ml (25 ppm) of test solution within an accuracy of ±0.05μg/ml (0.05 ppm). The instrument involves the use of high intensity green light emitting diode (LED) of wavelength 565 nm as light source. BPW21 photodiode having the relative spectral sensitivity above 90% in the range of 500–600 nm has been used as a detector, for the determination of sulphite concentration