Browsing by Author "Korposh, Serhiy O."

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    Development of sensitive elements based on photochromic bacteriorhodopsin for fibre optic sensors
    (Cranfield University, 2007-01) Korposh, Serhiy O.; Ramsden, J. J.
    This work focuses on the development of sensitive elements incorporating bacteriorhodopsin thin films for fibre optic sensors. The sensing principle is based on monitoring optical properties of the bacteriorhodopsin thin films during changes of environmental conditions. The photochromic properties of the bR films change in response to the presence of different chemical species and this effect can be employed for the development of sensitive elements for optical sensors. For practical sensing applications, one can monitor changes (in the presence of chemical species) of the spectral and kinetic parameters of bR films incorporated into a matrix. The main topic of this thesis is to study the possibility of using bacteriorhodopsin thin films for the construction of fibre-optic sensors for monitoring ammonia and humidity. The possibility to control sensitivity and selectivity of the sensor to the presence of ammonia and humidity by adding chemicals to the bR film and by employing different materials as a matrix for the creation of bR films is reported. The examples based on ammonia and relative humidity are used to show how using a broad range of different chemical additives bR can be sensitized to a wide spectrum of species, and thus possesses the potential to be a universal film material for optical sensors.
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    Films based on bacteriorhodopsin in sol-gel matrices
    (International Society for Optical Engineering; 1999, 2005-09-26T00:00:00Z) Korposh, Serhiy O.; Sichka, M. Y.; Trikur, I. I.; Sharkan, Y. P.; Yang, D. H.; Lee, Seung-Woo; Ramsden, Jeremy J.
    The bacteriorhodopsin film in gelatin matrixes which are used as sensitive elements of integrated optic and fibre-optic sensors of various vapor and gases components will not be able to carry out the chemical control of aqueous solutions. In the given paper the results of technological development of obtaining the bacteriorhodopsin (bR) films in a sol-gel matrix are represented. The films are obtained in a broad thickness range (from 0.5 to 20 microns) with various bR concentrations and photosensitize additives. The optimal technological conditions of obtaining of uniform films with given optical parameters are defined. The surface morphology and cross section of the obtained films was studied using an AFM and SEM. The films have a reasonable surface roughness (~ 100 nm) and a uniform distribution of the purple membrane fragments in the nanostructured sol-gel glass matrix along the films surface and thickness. The transmission spectrums have the characteristic for bR the absorption band, the value of which depends on bR concentration and technological features of the films deposition. The investigated photosensitive properties of the obtained films and influence on them of chemical components of aqueous solutions, allow recommending the thin bR films in sol-gel matrixes for creation of planar waveguides in the role of components of the chemical sensors of liquid solutions.
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    Nano-assembled thin film gas sensors. 1. Ammonia detection by a porphyrin-based multilayer film.
    (Association of Modern Scientific Investigation, 2006-09) Korposh, Serhiy O.; Takahara, Naoki; Ramsden, Jeremy J.; Lee, Seung-Woo; Kunitake, Toyoki
    A thin film of porphyrin deposited by the layer-by-layer method is employed as the active element for an optical sensor. The usefulness of this film technology and the resulting nanoscale matrix for the detection of volatile organic compounds (VOCs), aromatics and amine-containing substances has been studied. The sensing principle is based on monitoring the optical changes of the Q band at 700 nm, as induced by the analyte in the electrostatic interaction between tetrakis(4-sulfophenyl)porphine (TSPP) and poly(diallyldimethylammonium chloride) (PDDA) layers. Three thin film samples with different thicknesses were prepared to assess the effect of film thickness on the sensitivity. For ammonia, the sensor shows a linear sensitivity in the concentration range 0–100 ppm and the sensor response was within 30 seconds. Sensor response could be regenerated by rinsing in distilled water.