Vol 12 No 2&3

Asian Journal of Physics

Vol 12, Nos 2&3 (2003) 183-354

CONTENTS

Novel signal processing for advanced optical sensors

M N Taib and R Narayanaswamy 183

Long period grating sensors to monitor fuel quality

R Falate, JL Fabris, M Muller

Effects of temperature on glued fiber Bragg grating sensors,

Riccardo Falciai and Cosimo Trono 213

Ruthenium-based optical fiber sensor for gaseous oxygen detection

Gaetano Di Marco, Maurizio Lanza, Giuseppe Calogero. Patrizia Bizzarri and Anna Grazia Mignani 219

Trace detection of nitriles in water using long period gratings in multimode optical fiber

P Suresh Kumar, Diesh Kumar, R S Thomas Lee, CPG Vallabhan, VPN Nampoori and P Radhakrishnan 233

Fiber optic chemical sensor for air pollutant measurement: design, development and applications

Ang Soo Seng, M S John and Anand Asundi 237

H₂S sensing properties of H2SO₄ treated Sn02:Pd thin films in temperature cycling mode.

S C Gadkari, V R Katti, Manmeet Kaur, K P Muthe, A K Debnath, A K Dua,S K Gupta and V C Sahni 303

Comparative studies of surface modified SnO₂ as pellet and thin film for LPG sensing.

Niranian S Ramgir and Initiaz S Mulla 311

Porous silicon: a natural nano structure for vapour sensing applications.

H Saha, J Das, S M Hossain 323

Au-polyaniline nanocomposite: sensor for methanol vapours.

Anjali A Athawali, S V Bhagawat and Prachi P Katre 331

Electrical conductivity, humidity sensing properties of SnW04-SnO2 composites synthesized by in situ method.

R Sundaram, O M Sreedharan, C Mallika and K S Nagaraja 339

TCNQ-functionalized ormosil based electrochemical biosensors.

P C Pandey, S Upadhyay, N K Shukla and S Sharma 345

Preface

The field of optical and solid state sensors has emerged during the past twenty years as an important part of modern instrumentation and control systems. The continuous progress of the optoelectronic and microelectronic technologies together with developments in material science has sustained the sensor area growth for many years. Contributing to sensor progress are advances in chemistry, biology, surface science, chaos and information theory, signal processing, nanotechnology, and simulation tools. All of these aspects, which are stronglypluridiscip linary in character, together with promising markets on the horizon in the fields of medicine, industrial processes, transportation, space, and food and beverage control, are contributing to the birth of the sensor science discipline. The sensors have been developed into commercial products, and new sensing and transduction methods have been developed that will lead to new products and system approaches. The global market for sensors is expected to reach more than $50 billion by 2008. Much innovation in sensor technology has occurred in recent years. The related material is spread among various publications, hiding the big picture. The purpose of this special issue is to put together a set of original research papers that represent the best in optical and solid state sensors area, showing the State of Art as well as breadth and depth of current research. I am grateful to authors for responding to my call for papers and for their help in returning the revised papers fairly rapidly. My sincere thanks are due to the publisher of Asian Journal of Physics and the Chief Editor, Professor V.K. Rastogi, for appointing me the Guest Editor of this special issue.

B D Gupta

Guest Editor

Physics Department, Indian Institute of Technology Delhi, Hauz Khas, New Delhi-110 016, India

bdgupta@physics.iitd.ernet.in;banshigupta@hotmail.com

Asian Journal of Physics Vol. 12, Nos 2&3 (2003) 183-204

Novel signal processing for advanced optical sensors

M N Taib¹ and R Narayanaswamy²

¹Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM)

40450 Shah Alam, Selangor D E Malaysia

² Department of Instrumentation, and Analytical Science,UMIST, P O Box 88

Manchester M60 1QD, U K

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A novel technique for processing signals of an optical fibre sensor has been demonstrated in this paper. A multilayer artificial neural network (ANN), with only one hidden layer, was trained via the recursive prediction error (PRE) algorithm to adapt to the input-output signals from a Light Emitting Diode used in conjunction with a reflectance fibre optic sensor. Three LEDs (red, Orange and yellow) operating in the visible region at peak wavelengths of 660nm, 620nm and 590nm,respectively were employed as light source, the optical signals reflected from the tip of a fibre optic sensor based on immobilized thymol blue were correlated directly to pH measurements. A network architecture of 3-input neuros, 13-hidden neurons and 1-output neuron was found most suitable for this application and a linear calibration output was produced for a pH measurement range of 0.90 to 10.28.The application of (ANN) to the optical fibre sensor also exhibited a very robust system where fluctuations in the sensor signals of upto 7.0% can be tolerated before the prediction error magnitude becomes larger than 1.0pH.

Total Refs: 23

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Asian Journal of Physics Vol. 12, Nos 2&3 (2003) 205-211

Long Period Grating Sensor to monitor Fuel Quality

Rosane Falate, José Luís Fabris, Márcia Müller and Hypolito José Kalinowski

Centro Federal de Educação Tecnológica do Paraná

Av. Sete de Setembro, 3165 – 80230-901 Curitiba, Brazil

e-mail:rfalate@cefetpr.br

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We describe the production and characterisation of Long Period Gratings in fibre optics. The gratings are written in standard single-mode fibre using the electrical arc technique while their transmission spectrum is used to control the grating length. Optical characterisation and wavelength dependence with temperature and refractive index of the external medium are shown. An application of the LPG as a sensor to monitor the fuel quality (Brazilian standard mixture of ethanol and gasoline) is presented.

Total refs: 16

Cited: 11 times

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Asian Journal of Physics Vol 12, Nos 2&3 (2003) 213-217

Effects of temperature on glued fiber Bragg grating sensors

Riccardo Falciai* and Cosimo Trono

IFAC-CNR, Optics and Photonics Dept., Via Panciatichi 64, 50127 Firenze, Italy

Phone: +39 055 4235233, Fax: +39 055 410893,e-mail: falciai@iroe.fi.cnr.it

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Fiber Bragg grating sensors are often utilised for the control of structures to which the fiber can be attached or within which it can be embedded. The procedure of fixing or embedding the fiber to the structure under control is a critical point. Measurements were performed on gratings glued on different samples made of strips of commercial glass or iron. The samples were heated or cooled inside an oven or a thermo-cryostat. The Bragg wavelength shift was detected by means of an optical spectrum analyzer. The results of measurements made under different experimental conditions will be reported. These show a good linear relation between the temperature variation and the Bragg wavelength shift, but also reveal problems related to the glue hardening or to the partial ungluing of the gratings, depending on the sample material and on the glue used. © Anita Publications. All rights reserved.

References

1. Meltz G, Morey WH, Glenn WH, Opt Lett, 14 (1989) 823.

2. Hill KO, J Lightwave Technol, 15 (1997) 1263.

3. Kersey AD, Davis AD, Patrick HJ, LeBlanc M. Koo KP, Askins CG, Putnam MA, Friebele EJ, J Lightwave Technol, 15 (1997) 1442.

4. Falciai R, Fontana R, Schena A, Scheggi AM, Diffractive Optics and Optical Microsystems, Edited by Martellucci S and Chester A, (Plenum Press, New York),

1997, p. 293.

Asian Journal of Physics Vol 12, Nos 2&3 (2003) 251-256

An evanescent-wavelength optical fiber relative humidity sensor

Sunil K Khijwania, Rajeev Jindal and Jagdish P Singh

Diagnostic Instrumentation and Analysis Laboratory

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A novel optical fiber relative humidity sensor is proposed using a single U-bend plastic clad silica fiber. The sensor is fabricated using a thin film of PVA/CoCl₂ coated on the bare fiber core. A comprehensive study of the sensor was made in terms of performance optimization and practical uses. Sensor, comprising of fiber with a smaller core diameter is found to be more sensitive. The sensor exhibits a short response time, high repeatability and reversibility. ©Anita Publications. All rights reserved.

Total Refs: 7

1. Hesse H C, East German Patent, 106(1974)86.

2. Russell A P, Fletcher K S, Anal Chim Acta, 170(1985)209

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Asian Journal of Physics Vol 12, Nos 2&3 (2003) 257-262

Fiber-optic proximity sensor for mechatronic applications

Manish Ahuja, Amit Sadhu, M R Shenoy and S K Saha¹

Department of Mechanical Engineering, Indian Institute of Technology Delhi

¹Department of Physics, Indian Institute of Technology Delhi

Hauz Khas, New Delhi-110 016, India

mrshenoy@physics.iitd.ernet.in ( M R Shenoy)

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This paper describes the development of a fiber optic based proximity sensor to control the motion of objects moving on the conveyor belt of an assembly line. The sensor can detect the presence and absence of the object, with certain surface qualities, in the sensing zone and give a digital output.

Total Refs: 4

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Asian Journal of Physics Vol 12, Nos 2&3 (2003) 263-274

In-Fiber Gratings: Evolution, Optics and Applications in Sensing

Bishnu P Pal

Departmen of Physics

Indian Institute of Technology Delhi, Hauz Khas, New Deli-110 016, India

bppal@physics.iitd.ernet.in

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Optical fiber sensors have attracted a great deal of interest from the point of view of distributed measurements and due to their immunity from emi and also for-ultra-sensitive measurements in certain cases. Optical fiber gratings form an important platform for configuring a host of optical fiber sensors especially for distributed measurements of strain, temperature and refractive index. This paper is an attempt to focus on the evolution of this technology, its underlying optics, and some sample applications of these in sensing. © Anita Publications. All rights reserved.

Total Refs : 42

Cited : 2 Times

Asian Journal of Physics Vol 12, Nos 2&3 (2003) 275-282

Non-invasive, quantitative estimation of tissue physiological parameters with diffuse optical tomography (DOT)

Gargi Vishnoi

Biomedical Engineering Group, BJM Schoool of Biosciences and Bioengineering

Indian Institutue of Technology Bombay,powai, Mumbai-400 076, India

gargi@iitb.ac.in

Diffusing photons can be used as sensing mechanism to probe and characterize optically thick turbid medium such as human tissue. Here, Diffus Optical Tomography (DOT)

Total Refs : 10

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Asian Journal of Physics Vol 12, Nos 2&3 (2003) 283-291

Optical sensor system for non-invasive medical diagnostics

M Mukunda Rao, R Arul Ram and G V Srikrishnan

Biomedical Sciences Division

Sri Ramachandra Medical College & Research Institute (DU)

1,Ramachandra Nagar, Porur, Chennai-600 116, India

mukunda@vsnl.com

Total Refs : 9

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Asian Journal of Physics Vol 12, Nos 2&3 (2003) 293-297

Humidity sensing characteristics of potassium doped barium strontium titanate

(Ba_x Sr_1-x TiO₃) thin films prepared by sol-gel technique

Somnath C Roy, Uppireddi Kishore, G L Sharma and M C Bhatnagar

Thin Film Laboratory, Department of Physics

Indian Institute of Technology Delhi, Hauz Khas, New Delhi-110 016, India

Total Refs : 8

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Asian Journal of Physics Vol 12, Nos 2&3 (2003) 299-302

Electrical characterization of (Ba,Sr)TiO₃ thin films grown by sol-gel technique for humidity sensor applications

Seema Agarwal, M C Bhatnagar,and G L Sharma

Thin Film Laboratory, Department of Physics

Indian Institute of Technology Delhi, Hauz Khas, New Delhi-110 016, India

Glsharma6@hotmail.com

(Ba,Sr)TiO₃ (BST) thin films made by sol-gel technique are polycrystalline and porous in nature.

Total Refs : 18

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Asian Journal of Physics Vol 12, No 2& 3 (2003) 339-344

Electrical conductivity, humidity sensing properties of SnWO₄ – SnO₂ composites synthesized by in situ method

R Sundaram, O M Sreedharan, C Mallika^a and K. S. Nagaraja*

*Department of Chemistry, Loyola Institute of frontier energy (LIFE ), Loyola College, Chennai -34,India

^aThermodynamics and Kinetic Division, IGCAR, Kalpakkam, India

Phone: +91-44-28175660 Fax: +91-44-28175566

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An intimate mixture of SnO and WO₃ in the mole ratio 4:1 was prepared by the high temperature route. as well as with 2mole % of LiOH. H2O and Mg(OH)2.H2O was sintered at 973K in air atmosphere in the form of cylindrical discs. The XRD of this sintered sample indicates the formation of SnWO₄ and SnO₂ phases only. DC. electrical conductivity measurements over the temperature range 310-510 K in air atmosphere form which the activation energies were determined. The current was found to increase linearly with the applied field indicating the Ohmic nature. The current increases exponentially against the temperature indicating the semiconductive nature of the sample. The activation energy for D.C. conductance was found to be 0.69 eV, The material was subjected to humidity sensin::, using d.c resistance measurements as a function of relative humidity in the range of 5-981X, RII, achieved by different water buffers thermostated at 298K. A plot of log R vs Relative humidity (RH) was made to compare the humidity sensing characteristics of the material. The sample was doped with 2mole % of Li* and Mg' to enhance the sensitivity towards moisture. It could he inferred that the drop in D.C. resistance for the Lit doped material is quite high when compared to that of undoped and Me* doped specimens. The sensitivity factor, S, (Rs.A/RomiA) for SWSO.1S, and Me doped samples are found to be 104, 21053 and 20, respectively. It is evident that the in situ generated composite of SnW04-SnO2 shows higher sensitivity (21053) than the same non-in situ generated composite sensitivity (6364 The response and recovery characteristics of this compound were assessed. 0 Anita Publications. All rights reserved

Total Refs : 12

1 Introduction

The measurement and control of humidity is important in many areas including meteorology, medicine, food production, agriculture and domestic environment. The measurement of relative humidity' seems to be very convenient. Of the various materials utilized for humidity detection, the metal oxides, which are physically and chemically stable, have been widely investigated at both elevated and room iemperatures²⁴. Investigations on materials based on electrolytic manganese oxide have proved to be highly promising and being operative at room temperature". However, our earlier investigations indicate that materials that possess metastable coexistence can have excellent sensitivity towards moisture". The main problem in handling tin oxides based humidity sensors is their thermal stability as their stoichiometry varies with sintering temperature though they are capable of operating in the D.C. mode unlike the conventional ceramic materials which require an A.C. mode. Hence, the present investigation aims at the development of humidity sensors operating in the D.C. mode based on tin oxide - tin tungstate composites obtained by in situ method.

2 Experimental

2. I Preparation of SnW0₄-SnO₂compo.sites

Since the mechanical mixtures of SnW0₄-SnO₂ composites showed high sensitivity towards moisture, a novel in situ method of synthesizing these composite was resorted for further improvement in the sensitivity. This type of in situ generation provides grain boundaries and hence enhances better efficiency. Intimate mixtures of undoped and Li` or Mg,^21. (2 mole %) doped SnO₂ and W0₁ in 4:1 mole

Asian Journal of Physics Vol 12, Nos 2&3 (2003) 345-354.

TCNQ- functionalized ormosil based electrochemical biosensors

P C Pandey, S Upadhyay, N K Shukla and S Sharma

Department of Chemistry, Banaras Hindu University, Varanasi-221 005

pcpandey@banaras.ernet.in;p_c_pandey@satyam.net.in, pcpandey.apc@itbhu.ac.in (P C Pandey)

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The electrochemical biosensors based on tetracyanoquinodimethane (TCNQ) encapsulated within palladium-linked organically modified sol-gel glass (ORMOSIL) and redox enzyme modified graphite paste electrodes are reported. The new ormosil is made using Pd_linked silane precursor containing, trimethoxysilane, HCl and TCQN powder at 25 ˚C. Two electrochemical biosensors, the first one for glucose and second one for peroxide are reported using TCNQ-functionalised ormosil and redox enzyme glucose oxidase/Horseradish peroxidase (HRP)] incorporated within graphite paste electrode. The performance of glucose biosensor and peroxide biosensor is examined based on cyclic voltammetry and amperometric measurements. The sensing of glucose is based on the measurement of anodic current at 0.25 vs Ag/AgCl as a function electrocatalytic oxidation of glucose oxidase on TCNQ-functionalized ormosil-modified electrode whereas the same for peroxide involves the measurement of cathodic current at 0 mV vs Ag/AgCl as a function of electrocatalytic reduction of Horseradish peroxidase on similar modified electrode system. Anodic oxidation of peroxidase has also been examined using four types of graphite paste modified electrodes. The Electrode-1 is made in absence of functionalized ormosil and HRP, Electrode-2 is made in the presence of HRP only, Electrode-3 is made in the presence of HRP and functionalized ormosil whereas Electrode-4 is made in the presence of functionalized ormosil only.The results suggest that peroxide undergoes both direct and electrocatalytic oxidation at anodic potential on functionalized ormosil-modified electrode.© Anita Publications. All rights reserved.

Total Refs:14

ASIAN JOURNAL OF PHYSICS