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New Publications are available now online for this publication.
Please follow the links to view the publication.Networkable carbon monoxide control system for nomadic indoor cooking environment
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0597
In this paper we address the life-threatening problem of indoor CO air pollution generated by traditional indoor cooking practices in many local communities of sub-Sahara African countries. Using low cost smart wireless sensors we can provide an effective low cost life saving solution for many people and young lives today. Taking on a case study for using networkable wireless sensors we propose a new infrastructure to measure the amount of indoor carbon credit discharged during the cooking period with a view to establishing a new monitoring and control process of sending alerts through wireless channels to the fusing points. The work also reports a new networking design, practical issues and battery life management upon the measurements and simulation results. (5 pages)Online measurement solubility of CO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> in water based on membrane covered optical sensor
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.1075
This paper realized online measurement of CO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> solubility in water based on membrane covered optical sensors. This measurement method overcomed the disadvantages of the previous M value,the disadvantages mainly including measurement cycle is long and many influence factors,new method has increased dramatically in terms of accuracy and real-time. The method have a strong practical value in aquaculture and other occasions. (4 pages)The design for methane gas sensor based on MCU
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.1329
This paper proposed system design scheme, and introduced how to use a MCU to control every module. Then, we make the analysis and evaluation of the performance, have some summary and prospect for the key problems. (2 pages)Local adaptive sampling for an energy harvesting CO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> sensor
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.1084
For a sensor network, energy limitation is always a key factor to affect the continuous work of a sensor node. A good idea is harvesting energy from the environment to support the node to work continuously. However, energy from environment is varied with time, weather and season. So in order to use the varied environment energy, it is necessary to find a way to achieve real-time monitoring and adaptive working. In this paper, an algorithm called "Adaptive Sampling" was proposed to adapt the sample mode to the present energy condition. And solar energy is proposed as the energy source to power the system. Simulation proves that the algorithm can make the CO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> sensor flexibly achieve adaptive sampling under different energy condition with the least MSE 2.7767. This algorithm can be widely used in wireless sensor network power by energy harvesting for local adaptive sampling. (4 pages)Nanocrystaline ZnO-Si heterojunction methane sensor
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0458
ZnO gas sensors are widely used for environmental monitoring and industrial applications due to their advantages like small dimensions, low cost and convenient operation. On interaction with reducing gases, adsorbed oxygen concentration results in change of conductivity. The change in conductivity defines a measure of gas concentration. As the gas sensing mechanism is a surface reaction, use of nanostructured material improves gas sensing characteristics. Thus ZnO is greatly recognized for different commercial applications. In the present work a sol-gel derived Si-ZnO hetero junction with Au and AI gate pad is fabricated for the purpose of methane sensing. The characteristics of the device are studied by varying the temperature from 50°C to 250°C. The optimum temperature and voltage are calculated through the V-I characteristics with the presence of the reducing gas. The response magnitude of the device is found as -52%.Design and electro-thermal analysis of MEMS based micro-hotplate for gas sensor
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0444
Electro-thermal analysis of MEMS based Micro-hotplate design for gas sensor applications has been studied in this paper. Coventor-WareTM (A MEMS design and simulation software) has been used for electro-thermal analysis of 3D coupled field finite element model. In this simulation, temperature and power are evaluated with the variation of the thickness of the DilverPl heater layer. At the sensor temperature (typically 1500C-2000C), the power consumption is greatly reduced as the thickness decreases from 1 to 0.25 μm. The simulation results indicate that the design with 0.25μm DilverPI hot plate requires very low power consumption of 15.08mW, is suitable for gas sensor.A new saw device with tellurium sensing film for NO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> detection
http://dl-live.theiet.org/content/conferences/10.1049/cp.2010.0740
A new surface acoustic wave device is demonstrated using tellurium (Te) sensing film on ST-X quartz substrate to detect NO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> dynamically at room temperature. The real-time frequency shift as a function of NO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> gas concentration is collected by Universal Counter. Devices with three different Te thicknesses of 60, 120 and 180 nm have been compared. It is found that the device with 120 nm Te film has the largest frequency shift, the device with 180 nm Te film follows and the device with 60 nm Te film shows the smallest frequency shift.Multi-odor sources localization and tracking with wireless sensor network and mobile robots
http://dl-live.theiet.org/content/conferences/10.1049/cp.2010.1028
Localizing and tracking multiple static/moving odors in a real-time manner is a very difficult problem in the field of security. In this paper a solution has been proposed for the problem by using the integration of mobile robots and a static wireless sensor network. A multi-odor recognition algorithm is designed to identify and separate various sources. The static odor localization and moving odor tracking approach is provided, and the interaction method among the robot team and sensor network is analyzed. This solution is capable of separating individual odor sources and estimating the positions and speeds of multi-odor sources. The traditional GPSR routing protocol is modified to improve the network transmission performance. Simulation results show that the solution has good localization and tracking ability, and can be applied to industry and military fields.Study of eliminating noise of signal in fiber-optic Sensor System
http://dl-live.theiet.org/content/conferences/10.1049/cp.2010.1150
The measured gas concentration signal in the optical fiber gas sensor system is very weak, now extracting effective information from the weak signal still has some difficulties. In order to solve this problem, we choose the method which combine the discrete wavelet transform and the correlation function to process the optical fiber gas sensor system to eliminate noise. In the experiment, take the fiber methane for example, by detecting the standard concentration of methane gas, and processing the signal with the concentration of methane to verify the effect of noise elimination. The experiment shows that the effect of noise elimination which use the combination of discrete wavelet transform and the cross-correlation function is very good.Comparison between PPY and PPY/TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> as SAW sensitive films
http://dl-live.theiet.org/content/conferences/10.1049/cp.2010.1087
We present for the first time, to the best of authors' knowledge, a comparison investigation between the performance of polypyrrole (PPy) and PPy/TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> as surface acoustic wave (SAW) sensitive films employed in situ polymerization and self-assembly method onto ST-X cut quartz substrates for testing TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> dynamically at room temperature. Both sensitive films are characterized with scanning electron microscopy (SEM) and Fourier transform infrared spectroscopic (FT-IR) techniques. The performance of the device is analyzed in terms of frequency shift, which is real time collected by Universal Counter, as a function of the gas concentrations. For the sensitivity of both films, approximately negative frequency shifts of 30 Hz are measured for PPy to 15 ppm of NO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> but the nearly same amount of positive frequency shifts for PPy/ TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> to lOppm of NO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub>. And for the selectivity of both films, about negative 90 Hz and 50 Hz frequency shifts for PPy, but positive 110 Hz and 5 Hz frequency shifts for PPy/TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> are observed towards 100 ppm of NO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> and 100 ppm of H<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub>S, respectively.Application of quartz tuning forks in multiple-breath-helium washout measurement
http://dl-live.theiet.org/content/conferences/10.1049/cp_20080463
Multiple-breath-washout (MBW) measurements are regarded as a sensitive technique for lung function studies which can reflect the ventilation inhomogeneity of our respiratory airways [7,8,9]. Typically nitrogen is used as the tracer gas and is washed out by pure oxygen in multi-breath-nitrogen (MBNW) washout tests. In this work, instead of using nitrogen, 4He is used as the tracer gas. A commercial quartz tuning fork with a resonance frequency of f-32 kHz has been used for detecting the concentration of 4He gas at room temperature. This low-cost sensor has been used previously for detecting the gas density [11]. The resonance frequency of the tuning fork decreases linearly with increasing density of the surrounding gas and we use this effect to determine the helium concentration. The resulting washout curve from an asthmatic volunteer has smaller curve linearity compared to a normal healthy person which reflects the higher ventilation inhomogeneity of the respiratory airways. (4 pages)Optical fiber gas sensing system based on laser diode absorption spectroscopy
http://dl-live.theiet.org/content/conferences/10.1049/cp_20070759
Diode laser absorption spectroscopy (DLAS) has become an important gas analysis technology, and optical fiber sensing is a novel sensing technology. Combining laser diode absorption spectroscopy and optical fiber sensing technology, the optical fiber gas sensing system based on DLAS is designed and developed. The principle of DLAS is firstly introduced, then construction and characteristics of optical fiber gas sensing system based on DLAS are indicated. Field application shows that the gas sensing system can meet requirements of measurement, and has a promising application prospect.Ultra low power wireless communication for biomedical monitoring: trade-offs and design challenges
http://dl-live.theiet.org/content/conferences/10.1049/ic_20060298
This papers presents a solution to the shortcomings of current implantable and wearable sensors - the Sensium. This Toumaz solution is a low cost disposable integrated sensor chip that uses ultra low power. It is a tiny, non-intrusive module, a generic wireless sensor, and locally intelligent. Sensium-enabled `digital plaster' is a non-intrusive monitoring for chronic disease management and does not require battery change. Sensor input types supported include, ECG, 3-axis accelerometers, pressure, temperature, amperometric-N, amperometric-P, potentiometric, auxiliary voltage input and direct digital input.Towards a truly biomimetic olfactory microsystem: an artificial olfactory mucosa
http://dl-live.theiet.org/content/conferences/10.1049/ic_20060452
Today, the capability of the human olfactory system is still, in many ways, superior to that of artificial detection or the so- called electronic nose. Although electronic noses are often compared to their biological counterpart, they neither mimic its complex neural architecture nor achieve its performance in discriminating between complex odours. Recent developments in our understanding of the human olfactory system suggest that the olfactory mucosa (the lining of the nasal cavity comprising of a mucous layer and the olfactory epithelium) behaves like a gas chromatograph. Thus receptor cells distributed beneath the mucous layer (within the olfactory epithelium) provide both spatial and temporal chemosensory information. Here we report on the development of an artificial olfactory microsystem that replicates the basic structure of the olfactory mucosa. Our system employs an 80 element chemoresistive microsensor array fabricated on a 10 mm × 10 mm silicon die. The microsensors possess carbon black/polymer nanocomposite films as the odour-sensitive elements. In addition, a micro-fluidic package has been fabricated by micro- stereolithography, with an integrated channel to act as the nasal cavity (channel dimensions 500 μm × 500 μm × 2.4 m). This channel has been coated with Parylene C, as the retentive layer, in order to mimic the partitioning mucous layer of the olfactory mucosa. The fluidic package has been placed directly on top of the sensor array and has evenly spaced openings along the channel that encompass blocks of 5 sensing elements. Results show that this biomimetic system yields both spatial and temporal odorant signals, with a temporal chemical retention period of up to 110 seconds. Data analysis has revealed improvements in its ability to discriminate between two simple odours and a set of complex odours (i.e. essential oils). We conclude that closer emulation of the olfactory mucosa and nasal cavity could yield better odour discrimination and hence be superior to existing electronic nose technologies.Low power processing electronics for diabetes
http://dl-live.theiet.org/content/conferences/10.1049/ic_20060299
This paper presents an implementation of a silicon beta cell for the monitoring and treatment of patients with diabetes. The cell senses glucose and releases insulin. The biphasic insulin release is by exocytosis. Electrically excitable, the cell induces slow wave bursts with superimposed action potentials. A CMOS ISFET implementation is presented. The silicon beta cell presents low power ion sensing and intelligent processing.Electronic tongues
http://dl-live.theiet.org/content/conferences/10.1049/ic_20050119
The concept of a novel analytical sensing microsystem referred to here as an "electronic tongue" is presented; it is based upon a dual shear horizontal (SH) surface acoustic wave sensing device (SAW) that can discriminate between liquids of different basic tastes. 60 MHz SH-SAW dual delay-line sensors were micro-fabricated on 36° rotated Y-cut X-propagating LiTaO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">3</sub> and placed below a miniature housing containing the liquid under test. In this SAW sensor configuration, one delay-line is electrically shorted and the other is free. Theory relating to the electro-acoustic properties represented by the relative permittivity and conductivity of the sample liquid is presented and related to experimental results. Dilution tests have also been performed in order to determine the detection limit of this physical taste sensor and hence its potential application. Synthetic samples were analyzed with the four basic tastes of sour, salt, bitter, and sweet. The electronic tongue classified correctly all of the different basic tastes without a selective biological or chemical coating. The electronic tongue has also been employed to analysis the bacterial load in cow's milk. Finally, recent developments of high frequency, semi-wireless 433 MHz SAW sensors and associated fluidic micro-traps are given. (26 pages)The quantification of gas concentrations in mixtures of known gases using an array of tin oxide sensors
http://dl-live.theiet.org/content/conferences/10.1049/ic_20010112
There are many applications in which it is desirable to be able to predict the concentrations of gases in a gas mixture using simple and relatively cheap non-selective sensors. The outputs of the sensors are functions of the concentrations both of the gases and of the different gas mixtures. It is not possible to uniquely determine the concentrations of the gases in a mixture from the output of a single sensor. However this might be achieved if a sufficient number of different and suitably chosen sensors were used and the outputs from this array of sensors could be analysed. The purpose of the work described was to find the means of determining the concentrations of the gases in a mixture of known gases given the outputs from an array of different tin oxide sensors placed in the mixture, and further to furnish, for each individual mixture of gases, estimates for the errors in the predicted concentrations. Committees of multilayer perceptron artificial neural networks were trained using artificial data to predict the gas concentrations and the errors in these predictions. In a second procedure the sensor outputs were modelled mathematically in terms of the gas concentrations, based upon some simple physical assumptions. The unknown coefficients of the model were determined mathematically using the experimental data. (6 pages)Selected Topics in Advanced Solid State and Fibre Optic Sensors
http://dl-live.theiet.org/content/books/cs/pbcs011e
<p xmlns="http://pub2web.metastore.ingenta.com/ns/">The authors provide descriptions of the operation, characteristics and applications of the sensors on which they work, together with recent advances and prospects for the future.</p>Micromoulded spectrometers produced by the LIGA process
http://dl-live.theiet.org/content/conferences/10.1049/ic_19990869
MicroParts GmbH have produced a number of miniature spectrometers covering visible, near IR and mid IR wavelengths using microengineering techniques. This paper will explain the LIGA technique for the production of three dimensional microstructures. It will then explain the construction of the first micromoulded spectrometer for visible wavelengths, the subsequent development of a range of such devices for the near infra red and a modified spectrometer for gas detection in the mid infra red wavelength range. (10 pages)Flammable gas sensors based on sol-gel materials
http://dl-live.theiet.org/content/conferences/10.1049/ic_19980581
The sol-gel route to the fabrication of metal oxide thin film gas sensors offers promising advantages over traditional manufacturing technologies. In particular, the low temperature fabrication process and reliable doping procedure allows the production of high surface area, high porosity materials. Metal alkoxide and metal chloride precursors have been used to prepare high surface area SnO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> materials; Pt and Pd catalysts were added to the surface by evaporation of the appropriate metal salt. X-ray Powder Diffraction (XRPD) studies have shown these materials to be nanocrystalline with an average particle size of 2-3 nm. The use of polyacrylic acid as an organic template has been explored to improve the porosity of the materials. In this paper we present the preliminary results of a study into the detection of mixtures of low ppm concentrations of flammable gases and vapours. Initial studies of the response of unmodified SnO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> to simple binary mixtures of vapours and gases have shown that the response is not easily interpreted in terms of the individual gas responses and there is some evidence of interference effects. The response of Pt or Pd modified SnO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> materials to gas mixtures does however show additive effects. This can be attributed to the complete oxidation of the gases and hence the removal of interfering reaction intermediates. However, reductions in response are observed due to the increased competition for active catalytic sites on the surface. The materials are capable of selectively detecting carbon monoxide in the presence of high concentrations of methane at very low temperatures (less than 100°C) making them suitable for use as inexpensive domestic CO sensors. (6 pages)Migration of explosives in the environment and testing of detection methods for humanitarian demining
http://dl-live.theiet.org/content/conferences/10.1049/cp_19980712
The research at FOA considering the mine problem is focused on developing new methods for military mine clearance and humanitarian demining. This study reports on work aimed at determining parameters that influence the migration of explosives in the soil and the atmosphere. The preliminary investigation of the uptake of nitrogen from explosives by pansy plants produced a few interesting results. We found differences in the ability of the plants to utilise the nitrogen from the different explosives. The group of plants watered with the ADN-solution appeared to be rather unhealthy, probably, due to poisoning effects by the ADN substance or a degradation product, which influences the root system. We also found that the plants watered with the NTO-solution showed up with leaves with a yellow-white colour.Multisensor technology for buried land mines detection
http://dl-live.theiet.org/content/conferences/10.1049/cp_19980708
The main problems in practical realization of mass scale demining consist in the presence of two opposite tendencies: (1) express methods of mines detection have unacceptable number of false alarm and/or mine omissions in real field conditions and in presence of different natural and man made items, (2) reliable methods of hidden explosive and buried mine identification have unacceptable low speed of detection. To overcome this difficulty, we have implemented multisensor technology that combines a fast method of mine detection and a slow but very reliable method of explosive identification in suspicious places. We have used the neutron-neutron (n,n) method for fast detection of buried land mines because it has much lower omission rate as compared to other methods. The (n,n) method is based on the difference of neutron moderation capability of the explosive substance and that of the surrounding media. To identify explosives the neutron-gamma (n,γ) method is used. The (n,γ)-technology is based on irradiation of an object by neutron flux, registration and comparative analysis of the characteristic features of the secondary gamma-rays generated by nuclei of the substance. In other words, we provide real time in situ qualitative and quantitative analysis of the object (soil) and different inclusions (items) via registration of features of the prompt secondary gamma-rays (intensity, angular, energy, and spatial distributions) which are specific for every nucleus.Chemical sensor analysis
http://dl-live.theiet.org/content/conferences/10.1049/ic_19970828
Chemical sensors are devices which incorporate a chemical recognition element which is in intimate contact with a transducer, the aim of which is usually to provide a digital electronic signal. Such devices are usually operated continuously, to provide a real time analysis of a specific chemical, or group of chemicals. It is also possible to use these devices to make one-shot, spot checks, or to incorporate them into instrumentation such as flow-injection analysers, or automated multi-analysers. The recognition element is the key feature of chemical sensors and may be an inorganic or organic compound or of biological origin. In the latter case, the devices are termed biosensors. The use of biological components has created considerable interest due to the often very high selectivities of these materials for their target analytes. Examples of these recognition components are discussed as well as some sensor types: ion selective electrodes, ISFETs, amperometric sensors, optical chemical sensors. (3 pages)The lab on a chip
http://dl-live.theiet.org/content/conferences/10.1049/ic_19971060
Using the example of open-tubular liquid chromatography, the authors demonstrate improved performance, cheap and simple production and miniaturisation through microengineering. Improved performance can result from efficient heat transfer (capillary electrophoresis and PCR), reduced diffusion path lengths (chromatography and coupled chemical reactions) and from the ability to produce devices with optimised geometry. Microengineering can also allow method integration, leading to the concept of an entire analytical facility on a single chip. Given the early promise, it is likely that these devices, or less complex microengineered structures which couple chemical or biochemical sensors with suitable sample processing packages, will become important tools in industrial, environmental and clinical measurement. (3 pages)Minimally invasive glucose and lactate sensors
http://dl-live.theiet.org/content/conferences/10.1049/ic_19971059
We have further developed an in vivo technique which appears to overcome most problems of existing glucose and lactate sensors: the open microflow. This exploits the small negative hydrostatic pressure of subcutaneous tissue to enable continuous flow of buffer solution around the electrode tip. This pumpless fluid flow hydrates local tissue, yet remains under physiological control as part of the balance of transcapillary fluid exchange, as determined by osmotic and hydrostatic pressure balance (Starling's forces). The functional outcome of the needle-microflow combination in the case of glucose, is rapid in vivo stabilisation, identity of blood to tissue levels, a tissue lag time of under one minute and maintained stability. (2 pages)Interface electronics for resistive and piezoelectric polymer gas sensors
http://dl-live.theiet.org/content/conferences/10.1049/ic_19961296
An electronic interface has been designed and built which allows changes in the properties of hybrid conducting polymer sensors to be measured by a host computer. It has analogue circuitry which is used to measure polymer resistance, and digital circuitry which provides a measure of the period of oscillation of piezoelectric element (PZE) with a polymer deposit. Initial tests were made with physically separate sensor types but the design is intended for a hybrid sensor with a single polymer deposit on a PZE. A Field Programmable Gate Array (FPGA) has been configured to act as a period meter, which achieves a resolution of better than 1 part in 2 million. An embedded single-chip microcontroller accepts simple commands from a host computer and coordinates the activity of analogue multiplexers, a precision ADC, and the FPGA to give 1 reading per second from and array of 6 hybrid sensors. Other features have been included which allow for temperature measurement and control, numerical pre-processing as well as programmable gain and offset. The result is a superior instrument which aims to meet the emerging needs of industrial and research applications. (4 pages)Application of conducting polymer odour sensing arrays to malodour monitoring
http://dl-live.theiet.org/content/conferences/10.1049/ic_19961293
Conducting polymer sensor arrays are becoming very powerful tools in a wide variety of odour measurement applications. We have developed an analytical odour sensing device that is capable of sensing some of the malodorous compounds with low olfactory thresholds to the human nose. In testing against chemical components present in pig slurry, we found that the response to individual components was proportional to concentration, though the relationship was nonlinear. Many of the individual components are discriminated from each other, when presented singly to the sensor array. The sensors are not poisoned by the chemicals and give reproducible responses over a long period. The system was used to measure the odour emitted from fresh pig slurry, and a correlation was done with a human panel for assessment of odour intensity. (4 pages)The influence of PcCu layer crystalline structure on the parameters of SAW gas sensors
http://dl-live.theiet.org/content/conferences/10.1049/cp_19960077
This paper presents some problems concerned with SAW NO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> sensors employing copper phthalocyanine (PcCu) as the chemical interface. We have investigated the influence of crystalline structure of PcCu coating on the sensor sensitivity of generated frequency. The experiments were carried out for SAW delay lines on STX quartz and 128° YX lithium niobate. It was found that for the investigated range of parameters the β-PcCu layer provides several times better sensor sensitivity and temperature stability of SAW delay line generation frequency than α-PcCu layer of the same mass. This is valid for both substrates used.Flow and microflow - applications in biomedical sensing devices
http://dl-live.theiet.org/content/conferences/10.1049/ic_19961016
Fluid microflow using porous filters and capillaries offers a valuable means of transferring small volumes of fluid sample and reagents located within one element of a sensor complex to another, viz. the detector surface. Alternatively, fluid microflow directed over a sensor surface can provide a mobile self-cleaning barrier protecting the sensor interface. Useful advances in the application of microflow technology for biomedical sensing devices have been achieved at the University of Manchester using both these strategies. This presentation concerns the role respectively of microflow at electrochemical sensors for in-vivo needles to measure glucose and in-vitro planar sensors for immunomediated hormone analysis. (3 pages)Temperature dependence of SH-APM delay-lines on quartz: design rules for (bio)chemical sensors
http://dl-live.theiet.org/content/conferences/10.1049/cp_19960035
In this paper, we propose new results in the case of SH-APM delay-lines on quartz substrate. These modes propagate at discrete frequencies that are defined in the case of free surfaces. We describe in detail the SH-APM, its propagation characteristics and its responses to temperature variations in order to design biochemical sensors; theoretical studies of temperature dependence are examined and experimental results with various frequency modes for different plate geometries are presented. They show the frequency-temperature sensitivities.Sub-micrometre fibre optic chemical sensor
http://dl-live.theiet.org/content/conferences/10.1049/ic_19951221
The near-field interaction between an optical aperture of sub-micrometre diameter and a sample surface can be exploited to spectroscopically probe a biological medium with a resolution unattainable with traditional far-field techniques. A simple, low-cost technique is described for producing a chemical sensor which is based on the principles of near-field optics, and preliminary results obtained using this device to measure pH within individual mammalian cells is reported. (6 pages)Surface plasmon resonance technique for pollution monitoring
http://dl-live.theiet.org/content/conferences/10.1049/ic_19951506
The surface plasmon resonance (SPR) response of metal free phthalocyanine to the exposure NO gases is shown. A shift in resonance leads to the study of the changes of the effective relative permittivity of the overlayer. The SPR response of calix[4]resorcinarene LB films is also shown. Fast and reversible response was obtained by this method. Individual interaction mechanisms were also discussed. (5 pages)Silicon-on-insulator integrated optical biosensors for environmental monitoring
http://dl-live.theiet.org/content/conferences/10.1049/ic_19951117
It is shown that the fabrication of a family of silicon based evanescent optical field sensors can be produced using well established silicon microelectronics processes. Such devices offer advantages of low cost and high sensitivity compared with conventional technologies. A further cost advantage arises from the generic nature of the technology. This is largely due to the active features of silicon circuits. New sensors will only require the development of appropriate receptor layers. Ink-jet printing provides the means to produce highly controlled droplets of very low volume. These can be printed at high speed and are controlled by a microprocessor. It is therefore possible to produce small receptor film regions. (6 pages)Dielectrophoretic sensors for microbiological applications
http://dl-live.theiet.org/content/conferences/10.1049/ic_19951512
Novel microbiological sensors based on the dielectrophoretic (DE) effect have been demonstrated. Co-planar electrode sensors have been shown to have excellent selectivity and collection efficiency for ozone treated and untreated Cryptosporidium parvum oocysts, demonstrating the potential of DE as a basis for rapid sensing of microbiological species of interest to public health. The principle of grid electrode sensors for high flow (i.e. on-line monitoring) applications has been demonstrated; although quantitative different DE collection efficiencies of ozone treated and untreated Cryptosporidium parvum oocysts were observed compared with the co-planar electrodes sensors. However, sufficient discrimination was retained for viable sensing. Finally, on-going and future work on fully micromachined grid electrodes is well advanced and is showing promising progress. (2 pages)Multiplexed optical fibre sensor for in-process liquid sensing applications
http://dl-live.theiet.org/content/conferences/10.1049/ic_19951116
Optical fibre sensors are attractive for sensing applications in hazardous and in hostile environments. An investigation into a frequency domain, multiplexed optical fibre sensor for in-process and simultaneous measurement of multiple properties of liquids is reported. (3 pages)Fabrication methods for integrated biosensors
http://dl-live.theiet.org/content/conferences/10.1049/ic_19951514
The use of sensors in medical and environmental applications is increasing rapidly. Biosensors make up a proportion of this market. By modifying fabrication techniques from the well established electronics industry the manufacture of cheap and reliable biosensors could be realised alongside the development of integrated biosensors. By incorporating the necessary electronics on the same substrate as the sensor, noise and cost could be reduced. All steps for the fabrication of the sensor part of an integrated glucose sensor have been developed, along with a useful technique for the deposition of polymer membranes. The set polymer must not be soluble in acetone for this technique to work. (5 pages)A portable pulsed photoacoustic sensor for the monitoring of hydrocarbons in process water
http://dl-live.theiet.org/content/conferences/10.1049/ic_19951115
During the operation of offshore production platforms, marine contamination can occur from leakage, spillage and from the overboard discharge of process water. For every 100 tonnes of oil extracted from North Sea reservoirs, 130 tonnes of contaminated process water are generated (1990 figures) and when discharged overboard, the current protocol limits the oil content of discharged water to 40 parts per million (ppm) averaged over a calendar month Thus with North Sea production approaching 100,000,000 tonnes per annum, an annual contamination of some 4,000 tonnes of oil could be discharged overboard from production platforms. This situation is replicated in most offshore facilities world-wide and represents a global threat to sensitive marine environments. The present methods for the detection of oil in discharge water are based either on chemical analysis of intermittent samples or bypass pipelines with instrumentation to detect either dissolved or dispersed hydrocarbons by a variety of optical techniques including absorption, scattering and fluorescence. Tests have shown that no single instrument entirely meets either the present needs or satisfies the requirements of the more stringent future legislation which may limit total hydrocarbon content to 30 ppm or less. To meet this need and to develop a new generation of systems for environmental monitoring, a completely novel type of in-line instrumentation is being developed based on the photoacoustic technique. The instrument has been designed primarily for the monitoring of oil in process water but may also find application in the oil detection in the open sea and in the detection of oil and other pollutants in rivers, estuaries, lochs and sewage. (3 pages)Novel technique to improve optical fibre sensor's response for industrial applications
http://dl-live.theiet.org/content/conferences/10.1049/ic_19951515
A general major disadvantage of optical fibre sensors (OFS) is a non-linear (sigmoidal) response which produces a limited useable linear region. This work presents a novel method of overcoming this problem by the use digital instrumentation and signal processing. Previously we have shown that by appropriate selection of eight wave ordinates from the spectral response of an optical fibre pH sensor as inputs to a trained multilayer artificial neural network, the response range of the sensor can be extended from the normal pH 5.0-7.25 range to the full sensitivity of the sensor, i.e. pH 2.51-9.76 range with a worst error of only 0.08 pH. Application of this method is illustrated. The method is currently adopted to a new, simple and portable instrument based on the use of three LEDs as light sources. In this preliminary study, the sensor just simply measures colour changes of thymol blue indicator in an acid-base pH titration. The application of the neural network to process the colour changes of thymol blue indicator in the acid-base titration is illustrated. (6 pages)Hydrogel based distributed fibre optic sensor for measuring soil salinity and soil water potentials
http://dl-live.theiet.org/content/conferences/10.1049/ic_19951217
The ability of a distributed fibre-optic chemical sensor to discriminate between different water potentials is assessed. The sensor utilises the swelling of a poly(ethylene oxide) based hydrogel coating on a GFRP support cable and a kevlar thread, to modulate the Rayleigh backscattering signal through quasi-sinusoidal distortions of fixed periodicity, on a multimode graded index optical fibre attached to it. The performance of xerogel poly(ethylene oxide) pieces was initially measured through equilibrium water uptake (EWU) studies using different NaCl solutions as an osmotic medium. The results were then compared with in situ OTDR studies of the sensor's behaviour. It was shown that the sensor was able to discriminate between a range of water potentials, and different concentrations of NaCl solutions at a resolution of 0.05 mol It<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">-1</sup>. The distributed nature of the sensor makes it particularly useful for a wide range of applications such as to monitor salinity and water quality in coastal areas. Alternatively, when the sensor is immersed in aqueous solutions containing mixtures of unknown species, it can provide distributed `surrogate' measurements which may be useful to the sample collection procedure usually linked with further analysis in a chemical laboratory. Preliminary observations from experiments with soils, have shown that it is possible to measure changes in soil water potential in the region of approximately -45 kPa. (6 pages)Single mode optical fibre surface plasma wave chemical sensor
http://dl-live.theiet.org/content/conferences/10.1049/ic_19951212
We have demonstrated a new type of single mode optical fibre plasma wave sensor with a very broad spectral response ranging over 400 nm. This is achieved by a distributed phase matching between the fibre and plasma modes, resulting from the tapering of the fibre. The optimum response of this device is around 750 nm, and can detect changes in refractive index as low as 5×10<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">-4</sup>. (5 pages)BIOPTICAS: optical biosensing techniques for monitoring organic pollutants in the aquatic environment
http://dl-live.theiet.org/content/conferences/10.1049/ic_19951119
The aim of the BIOPTICAS project is to develop optically-based analytical techniques for the detection and measurement of low concentrations of organic pollutants in the aquatic environment. A number of sensors and biochemical methods are being investigated, enabling the potential development of highly sensitive biosensing instruments for the measurement of pesticides and herbicides in surface, ground and drinking waters. (4 pages)The gas sensing properties of chloro-aluminium phthalocyanine thin films
http://dl-live.theiet.org/content/conferences/10.1049/ic_19951513
The behaviour of ClAlPc thin film gas sensors is studied in the presence of NO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> and O<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub>. The change in the dark conductivity of ClAlPc thin films on exposure to NO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> at several different temperatures is investigated. In particular, the temperature of maximum sensitivity (T<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">max</sub>) and the minimum temperature for good reversibility (T<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">min</sub>) of ClAlPc thin films has been determined and related to gas sensor applications. Sensitivity (s) of ClAlPc to NO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> is also measured at several different temperatures. It is found that by increasing temperature the sensitivity decreases, but reversibility is greatly enhanced. (18 pages)Integrated optical surface plasmon resonance biosensor for pesticide analysis
http://dl-live.theiet.org/content/conferences/10.1049/ic_19951120
We report the design, fabrication and performance of gold coated waveguide surface plasmon resonance biosensors for the detection of the pesticide simazine in aqueous solution. The operation of the sensor was verified against the biotin-avidin biochemical model. The output power of the sensor showed a decrease of 32% on binding a dual layer of biotin-avidin. Calibration of the sensor against standard simazine solutions using a competitive test format was performed and the system was determined to have a detection limit of 0.22 μg/l. (6 pages)Improved chemical sensing characteristics of conducting polymers interrogated at high frequencies
http://dl-live.theiet.org/content/conferences/10.1049/ic_19951505
Research efforts have been under way for almost twenty years aimed at the use of conducting polymers to monitor volatile chemicals. In some cases, this work has led to commercial exploitation. The mechanisms by which interaction between the polymer surface and the volatile chemicals cause electrical changes in the polymer are not fully understood and this paper will begin by briefly reviewing this important area. It will go on to show that major advantages accrue from interrogating conducting polymers using high frequency techniques rather than the dc methods used by most researchers. These advantages will be quantified by reference to simple models that have been built for a sensor configuration in use by the present authors. In addition, comparisons between the dielectric properties of the sensors predicted by the model and from measurements will be compared. The paper will conclude with a few examples of measurements made using a device for conducting polymer gas sensors operating at less than 1 MHz. (5 pages)Distributed sensing of physical and chemical parameters for structural monitoring
http://dl-live.theiet.org/content/conferences/10.1049/ic_19950593
Simultaneous recovery of temperature and strain over a single sensor length has been demonstrated using the information recovered from polarimetric measurements on the LP<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">01</sub> and LP<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">11</sub> modes of polarisation maintaining fibre. Temperature information was recovered to within 2°C and strain recovery was better than 10 μɛ. The measurement method is entirely compatible with distributed measurement methods. A novel generic form of sensor capable of performing distributed measurements on a chemical species has been designed. This sensor has been shown to be an efficient means of detecting water ingress. With the use of suitable OTDR instrumentation, wetted sensor lengths of less than one metre, can be detected and located. The sensor has given meaningful information on the location of voided regions during a cement grouting process. (6 pages)Synthesis and enhanced gas-sensing properties of mesoporous hierarchical α-Fe<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub>O<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">3</sub> architectures from an eggshell membrane
http://dl-live.theiet.org/content/journals/10.1049/mnl.2012.0631
Mesoporous hierarchical α-Fe<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub>O<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">3</sub> was prepared by a simple soakage process and followed by calcination, using eggshell membrane (ESM) as a biotemplate. The hierarchical architectures composed of interconnected hollow nanotubes replicated from ESM and showed a large surface area (45.57 m<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sup> g<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">−1</sup>). A possible formation mechanism of the hierarchical α-Fe<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub>O<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">3</sub> was proposed. Benefiting from the mesoporous hierarchical structures and high surface area, the ESM-morphic α-Fe<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub>O<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">3</sub> sensor exhibits enhanced gas-sensing performance. The results demonstrated that the sensor showed the highest selectivity and sensitivity to acetic acid among the tested gases, and rapid response and recovery times (18 and 4 s to 50 ppm of acetic acid).Microelectrode sensor utilising nitro-sensitive polymers for application in explosives detection
http://dl-live.theiet.org/content/journals/10.1049/mnl.2012.0459
This Letter describes a fabrication of a microsensor incorporating a novel customised nitro-sensitive polymer derived from the propylenedioxythiophene family. Electrochemical polymerisation was used to selectively grow different types of localised polymer films on interdigitated electrode arrays, thereby fabricating miniature sensors that exhibited a highly selective and reversible response to chemical vapours containing ‘nitro’ (NO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub>) groups. Such nitro-bearing vapours are also present in trace quantities in the atmosphere in the presence of explosives. Vapours of nitropropane and nitrobenzene, serving as model analytes for explosives, were used for sensor testing. The sensors were demonstrated to have up to three orders of magnitude higher signal response to vapours from nitro compounds compared to other vapours commonly found in the atmosphere. The authors believe this is the highest selectivity to nitro compounds reported from a polymer-based chemicapacitor sensor.Robust feature extraction from impedimetric signals using wavelet packet decomposition with application to cytotoxicity testing
http://dl-live.theiet.org/content/journals/10.1049/iet-smt.2012.0009
Impedance-based cytotoxicity testing provides a simple, real-time and non-invasive assay technique that interferes minimally with cell morphology and function. In this study, impedimetric measurements of ECV304 cells with increasing concentrations of hydrogen peroxide were performed over 3 h, using D sensor connected to a lock-in amplifier at frequencies between 200 and 830 kHz. The output signals were analysed and decomposed using a two-level wavelet packet decomposition to obtain low- and higher-frequency coefficients of each signal. Subsequently, the sum of the negative and positive values and the difference values of each sub-band were calculated to acquire features of the signal coefficients. The patterns of features were compared with the microscopy images showing morphological changes of the cells for the four hydrogen peroxide concentrations and correlations between the extracted features and the morphological changes were identified. This demonstrated that wavelet packet decomposition was an effective feature extraction technique, which could provide a robust input vector for toxin clustering and classification purposes.Alter the sheet resistance of carbon nanotube-coated cellulose fabric with argon plasma pretreatment
http://dl-live.theiet.org/content/journals/10.1049/mnl.2012.0431
Cellulose fabrics were coated with single-walled carbon nanotubes (SWCNTs) by a dip-drying process. Scanning electron microscopy (SEM) and Raman spectroscopy analyses indicate the attachment of SWCNTs. The sheet resistance of SWCNT-coated fabrics can be altered by modifying the raw cellulose fabrics with low-pressure argon plasma. An initial plasma ablation of up to 3 min results in the decrease of sheet resistance, which can be ascribed to the increase of fibre surface roughness, evidenced by SEM analyses. A further increase in the extent of plasma ablation brings about the increase in sheet resistance, which is associated with the incorporation of oxygen functionalities, supported by the data obtained on colour strength measurements.Mimicking the biological olfactory system: a Portable electronic Mucosa
http://dl-live.theiet.org/content/journals/10.1049/iet-nbt.2010.0032
In this study the authors report on the development of a new type of electronic nose (e-nose) instrument, which the authors refer to as the Portable electronic Mucosa (PeM) as a continuation of previous research. It is designed to mimic the human nose by taking significant biological features and replicating them electronically. The term electronic mucosa or simply e-mucosa was used because our e-nose emulates the nasal chromatographic effect discovered in the olfactory epithelium, located within the upper turbinate. The e-mucosa generates spatio-temporal information that the authors believe could lead to improved odour discrimination. The PeM comprises three large sensor arrays each containing a total of 576 sensors, with 24 different coatings, to increase the odour selectivity. The nasal chromatographic effect provides temporal information in the human olfactory system, and is mimicked here using two-coated retentive channels. These channels are coated with polar and non-polar compounds to enhance the selectivity of the instrument. Thus, for an unknown sample, the authors have both the spatial information (as with a traditional e-nose) and the temporal information. The authors believe that this PeM may offer a way forward in developing a new range of low-cost e-noses with superior odour specificity.