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1.	Danielsson, B., et al. (författare) Recent investigations on calorimetric biosensors 1992 Ingår i: Sensors and Actuators B: Chemical. - 0925-4005. ; 6:1-3, s. 138-142 Tidskriftsartikel (refereegranskat)abstract New applications of a flow-calorimetric biosensor system, the enzyme thermistor (ET) are described. The ET measures the reaction heat in a small column containing immobilized biocatalyst as a temperature change of the effluent from the column. Since most biological reactions are exothermic, the ET has a very broad applicability and numerous assays of clinical as well as biotechnological interest have been studied. The procedure is well suited for monitoring and control of biotechnological processes due to its high operational stability. New results from this area are presented as well as developments on an automated thermometric immunoassay (TELISA). Miniaturized ET devices are suitable for portable monitoring of, for instance, blood glucose. Other recent work includes determinations in organic solvents, direct characterization of immobilized biocatalysts and monitoring of bioactivities in solution.
2.	Danielsson, Bengt, et al. (författare) Whole blood measurements with thermal micro-biosensors 1993 Ingår i: Sensors and Actuators B: Chemical. - : Elsevier BV. - 0925-4005. ; 14:1-3, s. 758-759 Tidskriftsartikel (refereegranskat)
3.	Svanberg, Sune (författare) Chemical sensing with laser spectroscopy 1996 Ingår i: Sensors and Actuators B: Chemical. - : Elsevier BV. - 0925-4005. ; 33:1-3, s. 1-4 Tidskriftsartikel (refereegranskat)abstract Laser spectroscopic techniques constitute powerful tools for chemical sensing. Atoms and molecules can be identified and quantified by their specific spectral signatures and the strength of the signals. A wide variety of methods for establishing spectroscopic contact with the species exist: absorption, emission, fluorescence, Raman scattering, acousto-optic, and opto-galvanic phenomena can be employed. Extreme sensitivity and specificity characterise the methods, which can be used for in situ monitoring and in some cases, for remote sensing. Through the special properties of laser radiation it is particularly simple to combine laser spectroscopy with fibre-optical techniques.
4.	Xie, Bin, et al. (författare) Development of a thermal micro-biosensor fabricated on a silicon chip 1992 Ingår i: Sensors and Actuators B: Chemical. - 0925-4005. ; 6:1-3, s. 127-130 Tidskriftsartikel (refereegranskat)abstract In order to develop a sensitive, versatile and inexpensive portable instrument, a calorimetric micro-biosensor was designed and fabricated by etching part of the flow system into a silicon wafer. The utility of the device was tested using the enzymes, catalase and penicillinase. This sensor showed good reproducibility and linearity up to 100 mM. The system also showed higher sensitivity than the conventional enzyme thermistor (ET) when identical sample volumes (20 μl) were applied. Finally, future prospects in this field are discussed.
5.	Xie, Bin, et al. (författare) Fast determination of whole blood glucose with a calorimetric micro-biosensor 1993 Ingår i: Sensors and Actuators B: Chemical. - 0925-4005. ; 15:1-3, s. 141-144 Tidskriftsartikel (refereegranskat)abstract Fast determination of whole blood glucose without any pretreatment was achieved using a calorimetric FIA micro-biosensor. Glucose oxidase was covalently immobilized, together with catalase, onto controlled pore glass beads and packed into a micro-column. By reducing the sample volume down to 1 μ1, a measurement period of about 40 s and an enlarged linear range of 0.5-20 mM glucose were obtained. The correlation coefficient was 0.98 when the micro-biosensor was compared to the Reflolux-S blood glucose analyser. The relative standard deviation for 100 blood samples was 3.7%.
6.	Xie, Bin, et al. (författare) Miniaturized thermal biosensors 1993 Ingår i: Sensors and Actuators B: Chemical. - 0925-4005. ; 16:1-3, s. 443-447 Tidskriftsartikel (refereegranskat)abstract Miniaturized thermal biosensors based on three different designs have been constructed. Properties relevant to decentralized bioanalysis have been investigated. A short measurement period (30 s per sample) and a broad linear range (0.5 mM to 100 mM for glucose and penicillin-V), using 1 μl sample volume, have been achieved.
7.	Jager, Edwin, 1973-, et al. (författare) On-chip microelectrodes for electrochemistry with moveable PPy bilayer actuators as working electrodes 1999 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 56:1-2, s. 73-78 Tidskriftsartikel (refereegranskat)abstract We present electrochemical microactuators which have all the electrodes necessary for the actuation—the working, counter, and reference electrodes—on-chip. This is a first step towards an all-polymer system, i.e., a system that does not require a liquid electrolyte. The microactuators' performance was as good as when standard, off-chip counter and reference electrodes were used. Specifically, the speed of actuation was the same. In addition, we obtained a good cyclic voltammogram, although the oxidation and reduction peaks were shifted and some noise was present. Apart from application in an all-polymer system, we will also use these microactuators for studies on the effect of mechanical stimulation of living cells.
8.	Abom, A.E., et al. (författare) Experimental evidence for a dissociation mechanism in NH3 detection with MIS field-effect devices 2003 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 89:1-2 Tidskriftsartikel (refereegranskat)abstract The gas response mechanism of ammonia detection with Pt-based metal-insulator-semiconductor (MIS) field-effect sensors was investigated. An experimental model system was designed which compares the responses of thick continuous Pt layers with controlled morphology and surface chemical composition, with the response of thin, discontinuous layers. The surface of a thick, continuous sputter-deposited Pt film is modified, either by (i) the deposition of a thin SiO2 overlayer, (ii) reactive sputter deposition of PtOx, or (iii) co-deposition of Pt with SiO2 in Ar + O2 atmospheres. We show that the ammonia response is caused by the formation of atomic hydrogen through the dissociation of NH3 at temperatures <200 °C. It is found that the modified surfaces exhibit increased ammonia selectivity compared to a pure Pt film. Results from this work indicate that the reason for the changed selectivity is the appearance of an oxidized PtOx phase or triple phase boundaries between Pt, SiO2 and the ambient gas, rather than for solely morphological reasons. © 2002 Elsevier Science B.V. All rights reserved.
9.	Abom, A.E., et al. (författare) Thin oxide films as surface modifiers of MIS field effect gas sensors 2002 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 85:1-2, s. 109-119 Tidskriftsartikel (refereegranskat)abstract The catalytic activity at the surface of Pt based MIS field effect gas sensors is modified by the deposition of thin films of SnO2, Al2O3 and SiO2, grown by reactive sputtering. It is found that a very thin layer (<10 nm) of SiO2 and SnO2 changes the catalytic activity towards higher NH3 selectivity, but with thicker films the sensor response vanishes. Since the response mechanism for these sensors is dependent on dissociation of molecules, it is likely that at low temperatures (140 °C), neither dissociation on nor transport/diffusion through the thicker films takes place. However, with Pt in conjunction with SiO2 or SnO2, the surface reactions will be altered, with enhanced NH3 selectivity as a result. A thin film of Al2O3, on the other hand, has a much smaller influence on the gas response to the test gases used in this work. Furthermore the sputtering process is found to strongly influence the sensor responses, and specifically reduce the sensitivity of the sensor. A thin intermediate layer of evaporated Pt does not completely protect the underlying structure from sputter induced damage. © 2002 Elsevier Science B.V. All rights reserved.
10.	Andersson, Helene, et al. (författare) A valve-less diffuser micropump for microfluidic analytical systems 2001 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 72:3, s. 259-265 Tidskriftsartikel (refereegranskat)abstract The suitability of valve-less micropumps in biochemistry has been shown. Fluids encountered in various biochemical methods that are problematic for other micropumps have been pumped with good performance. The pump is fabricated as a silicon-glass stack with a new process involving three subsequent deep reactive ion etching steps. Some of the main advantages of the valve-less diffuser pump are the absence of moving parts (excluding the pump diaphragm), the uncomplicated planar design, and high pump performance in terms of pressure head and flow rare. In addition, the micropump is self-priming and insensitive to particles and bubbles present in the pumped media. The results show that the valve-less micropump successfully pumps fluids within the viscosity range of 0.001-0.9 N s/m(2). The micropump is not sensitive to the density, ionic strength, or pH of the pumped media. Effective pumping of solutions containing beads of different sizes was also demonstrated. Living cells were pumped without inducing cell damage and no cell adhesion within the pump chamber was found. No valve-less micropump has previously been reported to pump such a wide variety of fluids.
11.	Andersson, Helene, et al. (författare) Consecutive microcontact printing - ligands for asymmetric catalysis in silicon channels 2001 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 79:1, s. 78-84 Tidskriftsartikel (refereegranskat)abstract Consecutive microcontact printing ( mu CP) has been developed to enable multiple functionalization of silicon surfaces, such as the immobilization of chiral ligands. The technique involves two subsequent printing steps using unstructured poly(methylsiloxane) stamps. The pattern is already defined on the substrate, consisting of etched channels. Hence, no precise alignment is needed between the two printing steps. A carboxylic acid group containing reagent was initially printed onto the silicon oxide surface and transformed to an anhydride. hi the second printing step an ester bond was formed with the hydroxy-functionalized ligand. The formed molecular layers were evaluated by contact angle measurements, scanning electron microscopy (SEM) and electron spectroscopy for chemical analysis (ESCA), indicating that the consecutive mu CP was successful. Initially, printing was performed on planar silicon surfaces but to realize a flow-through microfluidic device for high throughput screening a mu CP technique was developed for etched channels. To verify the technique, hydrophobic valves consisting of octadecyltrichlorosilane were formed using mu CP in deep reactive ion etched channels (50 mum wide and 50 mum deep). The printed hydrophobic patches were visualized by SEM and functioned well. Finally, the consecutive mu CP technique was applied to immobilize the ligand in the channels. The channels were then sealed with a low-temperature bonding technique using an adhesive PDMS film, which does not destroy the printed ligand. In this study mu CP is used in a novel manner. It enables a convenient method for performing complex surface modification of etched structures, which is a frequently appearing problem in biochemical microfluidic systems.
12.	Andersson, Helene, et al. (författare) Expandable microspheres - surface immobilization techniques 2002 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 84:2-3, s. 290-295 Tidskriftsartikel (refereegranskat)abstract In this study, a novel component for microfluidics is introduced. Expandable microspheres have been studied for their application in microfluidics. Two methods for selective immobilization of expandable microspheres without the use of mechanical barriers on silicon, including patterning by photolithography and self-assembly based on surface chemistry have been shown. After the immobilization step the microspheres were expanded thermally. The expansion is irreversible and the volume of the microspheres increases more than 60 times. Patterns of microspheres with features as small as 15 pm have successfully been generated by photolithography. By using self-assembly the microspheres can conveniently be immobilized in monolayers. Future applications of the expandable microspheres can be as fluidic components, such as one-shot valves or micropumps, positioning other microcomponents or to enlarge the surface area.
13.	Andersson, Helene, et al. (författare) Hydrophobic valves of plasma deposited octafluorocyclobutane in DRIE channels 2001 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 75:1-2, s. 136-141 Tidskriftsartikel (refereegranskat)abstract The suitability of using octafluorocyclobutane (C4F8) patches as hydrophobic valves in microfluidic biochemical applications has been shown. A technique has been developed to generate lithographically defined C4F8 hydrophobic patches in deep reactive ion-etched silicon channels. Some of the advantages of this process are that no specific cleaning of the substrate is required, C4F8 is deposited on the sidewalls and the bottom of the channels, a standard photoresist mask can be used to define the patches, and that it is a fast and convenient dry chemical process performed by a standard inductively coupled plasma etcher using the Bosch process. Different patch lengths (200-1000 mum) of C4F8 were deposited in 50 mum wide channels to evaluate which size is most suitable for microfluidic biochemical applications. The valve function of the hydrophobic patches was tested for the following liquids: DD water, acetone, propanol, bead solution and a mixture used for pyrosequencing of DNA. Patch lengths of 200 mum of C4F8 successfully stopped each solution for at least 20 consecutive times. The C4F8 film resists water for at least 5 h. The hydrophobic valve also resists very high concentrations (25%) of surfactants (Tween 80). C4F8 shows a much higher resistance towards water and surface active solutions than previous hydrophobic patches. However, 50% Tween 80 was not stopped at all by the hydrophobic patch. An applied pressure of 760 Pa at the inlet was needed for water to over-run the hydrophobic patch.
14.	Andersson, Helene, et al. (författare) Microfluidic devices for cellomics : a review 2003 Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 92:3, s. 315-325 Forskningsöversikt (refereegranskat)abstract A review of microfluidic devices for cellomics is presented. After a brief description of the historical background of Lab-on-Chip (LOC) devices, different areas are reviewed. Devices for cell sampling are presented, followed by cell trapping and cell sorting devices based upon mechanical and electrical principles. Subsequently, a popular type of cell sorters, flow cytometers, is considered, followed by a chapter describing devices for cell treatment: cell lysis, poration/gene transfection and cell fusion devices. Finally a number of microfluidic devices for cellular studies are reviewed. The large amount of very recent publications treated in this review indicates the rapidly growing interest in this exciting application area of LOC.
15.	Andersson, Helene, et al. (författare) Micromachined flow-through filter-chamber for chemical reactions on beads 2000 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 67:1-2, s. 203-208 Tidskriftsartikel (refereegranskat)abstract A new flow-through micromachined device for chemical reactions on beads has been designed, manufactured, and characterized. The device has an uncomplicated planar design and microfabrication process. Both nonmagnetic and magnetic beads can be collected in the reaction chamber without the use of external magnets. The sample flow-through volume of liquid or gas is adjustable and unlimited. The device is sealed with Pyrex to allow real time optical detection of the chemical reactions. At a constant pressure of 3 kPa at the inlet the flow rate for water is about 3.5 mu l/min without beads in the filter chamber, for all the designs. The smallest reaction chamber has a volume of 0.5 nl and can collect approximately 50 beads with a diameter of 5.50 mu m. At a constant pressure of 3 kPa at the inlet, the flow rate for water is about 2.0 mu l/min when the reaction chamber is completely packed with beads. Hence, the flow rate decreases with about 40% when the reaction chamber is packed with beads. The flow-through microfluidic device is not sensitive to gas bubbles, and clogging of the filter is rare and reversible. The beads are easy to remove from the reaction chamber making the micromachined flow-through device reusable. A new and simple technique for fluid interconnection is developed.
16.	Andersson, Mike, et al. (författare) Development of a ChemFET sensor with molecular films of porphyrins as sensitive layer 2001 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 77:1-2, s. 567-571 Tidskriftsartikel (refereegranskat)abstract The interaction of chemical species with molecular films of porphyrins causes variations of the work function of the film itself, as it has been recently demonstrated by using the Kelvin probe technique. This characteristic makes porphyrins films suitable to be used as sensitive layers in ChemFET sensors. In this paper, we present a preliminary report about the fabrication and testing of such gas sensitive devices. The technological solutions towards an optimised device are also illustrated and discussed. © 2001 Elsevier Science B.V.
17.	Arbab, A., et al. (författare) Evaluation of gas mixtures with high-temperature gas sensors based on silicon carbide 1994 Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 19:1-3, s. 562-565 Tidskriftsartikel (refereegranskat)abstract Field-effect devices with a catalytic metal gate are operated as gas sensors over a large temperature range by the use of 6H-silicon carbide (bandgap 2.9 eV) instead of silicon (1.1 eV) as the semiconducting material. We have produced metal-silicon dioxide-silicon carbide (MOSiC) capacitors with platinum as the gate metal that can be operated above 800-degrees-C. The sensitivity of the Pt-MOSiC devices to hydrogen and hydrocarbons was tested in various oxygen atmospheres. The response to mixtures of hydrogen and saturated hydrocarbons indicated the existence of two different sensing mechanisms.
18.	Arbab, A., et al. (författare) Gas sensors for high temperature operation based on metal oxide silicon carbide (MOSiC) devices 1993 Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 15:1-3, s. 19-23 Tidskriftsartikel (refereegranskat)abstract Catalytic metal gate-silicon dioxide-silicon carbide (MOSiC) capacitors operating to about 800-degrees-C are used as high temperature gas sensor devices. Hydrogen or hydrogen containing molecules, which are dissociated on the catalytic metal surface, create a decrease of the flat band voltage of the MOS capacitor. The MOSiC devices with a platinum gate respond to saturated hydrocarbons in air at concentrations well below the explosion limits.
19.	Artursson, Tom, et al. (författare) Wavelet transform of electronic tongue data 2002 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 87:2, s. 379-391 Tidskriftsartikel (refereegranskat)abstract A measurement in a multi-sensor system is characterized by a large array of numbers (a vector or a matrix), sometimes several thousands. In order to increase the interpretability of the measurements, decrease the calculation demand on the computer, and/or to reduce noise, an alternative, more compact, representation of the measurement can be made which describes the important features of the measurement well but with a much smaller vector. The purpose of this paper is to show that for a particular wet-chemical sensor system (pulsed voltammetry, also called an electronic tongue) the data compression can be made using a wavelet transform together with different wavelet selection algorithms for different purposes. The resulting compressed data can also be used for easy interpretation of the measurements and to give hints for improvements or simplifications of the measurement procedure. Two different criteria for selection of wavelet coefficients have been used, variance and discriminance, in two different cases. The variance criterion was used when variations of any kind in the raw data was studied during monitoring of water in drinking water production plant. In this case, the number of variables was reduced with a factor of 18, without loosing relevant information. In the other case, the focus was to separate different microorganisms, therefore, the discriminance selection criterion was successfully used. The number of variables was reduced by a factor of 144, this smaller data set captured the important information for separating the microorganisms, which led to better classification of the test set. © 2002 Published by Elsevier Science B.V.
20.	Assadi, A., et al. (författare) Interaction of planar polymer Schottky barrier diodes with gaseous substances 1994 Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 20:1, s. 71-77 Tidskriftsartikel (refereegranskat)abstract Conducting polymers appear very attractive as sensor materials either as the gas-sensitive component or as a matrix for easy immobilization of a specific substrate. The planar Schottky barrier diode with poly(3-octylthiophene), P3OT, as the semiconductor is used as a sensor for the detection of different gas species. The shifts in the current-voltage (C-V) characteristics as well as the C-V characteristics of the diodes due to water and ethanol vapour, ammonia gas and nitric oxide gases are studied. Nitric oxide and ammonia give the largest and most specific changes of the C-V characteristics. Nitric oxide has a doping effect, which increases the reverse current, while ammonia is the only gas that causes a negative change in the forward bias current of the I-V curve. The planar configuration of the Schottky barrier diode facilitates the absorption of gaseous species in the environment, and provides a simple method for production of gas sensors.
21.	Baranzahi, Amir, et al. (författare) Gas sensitive field effect devices for high temperature 1995 Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 26:1-3, s. 165-169 Tidskriftsartikel (refereegranskat)abstract Field effect sensors based on metal-oxide-silicon carbide (MOSiC) devices are used as high temperature gas sensors. They are sensitive to, for example, saturated hydrocarbons and hydrogen and can be operated up to at least 800 degrees C, which make them suitable for several types of combustion control. A metal gate with two layer platinum and a buffer layer of tantalum silicide in between gave a large increase in the long term stability of the sensors. At temperatures below 600 degrees C, the response to ethane in oxygen was shown to have a threshold at a ratio of about 0.38 for the ethane-to-oxygen concentrations. Below this ratio, the surface can be considered as mainly oxygen covered and the response is small. Above this ratio the metal surface is probably mainly hydrogen covered and the response is considerably larger.
22.	Baranzahi, Amir, et al. (författare) Response of metal-oxide-silicon carbide sensors to simulated and real exhaust gases 1997 Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 43:1-3, s. 52-59 Tidskriftsartikel (refereegranskat)abstract Field effect devices based on catalytic metal-oxide-silicon carbide (MOSiC) structures can be used as high temperature gas sensors. The devices are sensitive to hydrocarbons and hydrogen and can be operated up to at least 900 degrees C, which make them suitable for several combustion applications, Simulated and real exhaust gases from a car engine have been studied at sensor temperatures from 200 to 650 degrees C, and it was round that the sensor signal is high for excess hydrocarbon and low for excess oxygen. The response time is less than 100 ms and only a small degradation of the devices was observed after several days of operation. The devices also react to changes of the gas composition In the fuel-rich and fuel-lean region. The devices show an interesting temperature dependence in the fuel rich region.
23.	Briand, D., et al. (författare) Modulated operating temperature for MOSFET gas sensors : Hydrogen recovery time reduction and gas discrimination 2003 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 93:1-3, s. 276-285 Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract This communication presents a modulated mode of operation for MOSFET gas sensors. A low-power micromachined device allows pulsing the temperature of MOSFET gas sensors with a time constant less than 100ms. Modulating the temperature during the gas exposure modifies the kinetics of the gas reactions with the sensing film. The way the sensor response is modified by the temperature modulation depends on the sensor "history", on the nature of the surrounding gaseous atmosphere, and on the type of materials used as catalytic sensing film. Pulsing the temperature up just after the gas exposure can reduce the recovery time for specific applications, such as for hydrogen detection. Cycling the temperature can allow the discrimination between different gas mixtures. Discrimination was shown for gaseous mixtures of hydrogen and ammonia in air. The results obtained indicate that a "smart" combination of sample and temperature profile could be used to expand the information content in the sensor response. © 2003 Elsevier Science B.V. All rights reserved.
24.	Eriksson, Mats, 1963-, et al. (författare) The influence of CO on the response of hydrogen sensitive Pd-MOS devices 1997 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 42:3, s. 217-223 Tidskriftsartikel (refereegranskat)abstract In order to understand and correctly interpret the response of chemical sensors under measurement conditions, detailed studies of molecule—sensor interactions under well-controlled conditions are needed. In this work, the influence of CO on the response of a hydrogen sensitive Pd—metal-oxide-semiconductor (Pd—MOS) device with a dense Pd film is studied in ultrahigh vacuum (UHV). The results show that although CO by itself does not induce any response of the device, CO may have a significant influence on the hydrogen response, especially so in the presence of oxygen. It is also shown that high CO coverages on the Pd surface increases the time needed to obtain equilibrium between the gas phase hydrogen pressure and the response of the Pd—MOS device. This is due to a CO induced increase of the activation energies of the dissociation and association processes for hydrogen. The effect on the hydrogen response is small for CO coverages below 0.2 monolayers and increases dramatically above this coverage.
25.	Filippini, Daniel, et al. (författare) Distinctive photocurrent chemical images on bare SiO2 between continuous metal gates 2003 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 95:1-3, s. 116-122 Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract Distinctive two-dimensional chemical images of hydrogen, ammonia and nitrogen dioxide have been obtained using a scanning light pulse technique (SLPT) on a metal-oxide-semiconductor (MOS) device. The sensor consists of an MOS capacitor with two continuous metal gates of Pd (40nm) and Au (50nm) arranged in a concurrent geometry, leaving a bare silicon dioxide region in between the biased gates. The present arrangement provides a new robust alternative to the existing strategies used to induce spatially distributed chemical responses, required for SLPT and allows to measure the response in a different place than where the biasing electrodes operate. Accordingly, the splitting of biasing and detection coordinates enables to optimize electrical and chemical functions separately providing a higher versatility in the choice of functional sensing materials or stable biasing electrodes. © 2003 Elsevier B.V. All rights reserved.
26.	Filippini, D., et al. (författare) New NO2 sensor based on Au gate field effect devices 2001 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 78:1-3, s. 195-201 Tidskriftsartikel (refereegranskat)abstract A new NO2 field effect gas sensor based on Au gates is demonstrated and the influence of gate morphology on sensor response is evaluated. A sensitization mechanism, for non-catalytic continuous gates, based on grain boundary diffusion is proposed. The sensors are fabricated as MOS (metal-oxide-semiconductor) capacitors with sputtered or thermal evaporated Au gates (at different substrate temperatures) with thickness between 75 and 960 nm. The devices' sensitivity, in the range of 15-200 ppm of NO2 in dry air, depends strongly on gate morphology, shorter response times and larger voltage shifts are correlated with smaller grain sizes. Scanning-electron-microscope (SEM) images show that the microstructure is very stable after 5 months of gas exposure at temperatures up to 200°C. The sensors are selective to NO2 (with NO, H2 and CO as interfering gases) and selectivity depends also on gate structure. © 2001 Elsevier Science B.V. All rights reserved.
27.	Filippini, D., et al. (författare) Thick film Au-gate field-effect devices sensitive to NO2 2002 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 81:2-3, s. 296-300 Tidskriftsartikel (refereegranskat)abstract Screen printed thick film gold gate MOS capacitors are selectively sensitive to the presence of NO2 in air. Metallo-organic gold inks produce open gate structures, with positive flat-band-voltage shifts of 2.72mV/ppm at 140ppm of NO2 in air, comparable to PVD deposited thin film devices. Standard gold pastes are denser, coarser grained thick films of alloyed composition, which reverse the polarity of the flat-band-voltage shift. No cross sensitivity to H2 or NO is apparent. © 2002 Elsevier Science B.V. All rights reserved.
28.	Granstedt, Fredrik, et al. (författare) Gas sensor with electroacoustically coupled resonator 2001 Ingår i: Sensors and Actuators. - 0925-4005. ; 78, s. 161-165 Tidskriftsartikel (refereegranskat)abstract A new configuration for a gas sensor is demonstrated. The configuration consists of an electroacoustic element coupled to an acoustic resonator, such as Kundt's tube, exhibiting a resonance frequency that is related to the velocity of sound, which, in turn is a function of the molecular mass of the gas within the resonator. Electrical impedance measurements were performed, whereby a resonance peak attributable to the resonator was identified. Contributing effects to the quality factor, Q, of the resonance, was analyzed. Predictable shifts of the resonance frequency were observed when adding CO2 and He to air, and when varying the resonator length. Linearity within the experimental accuracy was confirmed. The new sensor configuration offers the potential advantages of smaller size, improved dynamic response, and lower cost. © 2001 Elsevier Science B.V. All rights reserved.
29.	Hedborg, Eva, et al. (författare) Polymer membranes for modification of the selectivity of field-effect gas sensors 1992 Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 7:1-3, s. 661-664 Tidskriftsartikel (refereegranskat)abstract Polymer membranes are used to increase the selectivity to certain gases of metal silicon dioxide-semiconductor (MOS) structures. Other parameters which influence the selectivity of MOS structures are the type of gate metal, its microstructure (dense or porous) and the operating temperature of the device. Photoresists as membranes can be patterned by photolithographic methods. Membranes, 1-2-mu-m thick, of positive and negative photoresist are applied on MOS capacitors with 6 nm iridium as the gate metal, operated at 150-degrees-C. The influence of the membranes on the response to three gases, hydrogen, ammonia and ethanol, has been investigated. The hydrogen response decreases bv about half with the use of a photoresist membrane. The ammonia response shows a characteristic change in the kinetics, while the ethanol response almost disappears. Positive and negative resist influence the gas response in similar ways, in spite of their different molecular structures.
30.	Heideman, René, et al. (författare) Fabrication and packaging of integrated chemo-optical sensors 1996 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 35:1-3, s. 234-240 Tidskriftsartikel (refereegranskat)abstract This paper describes the design and fabrication of a sensitive integrated chemo-optical sensor supplied with on-chip fiber-to-waveguide connectors. The sensor is designed for TE-polarized light with wavelength of 633 nm. The fiber-to-chip connectors are based on easily fabricated silicon V-grooves combined with a smooth sawcut. The sawcut is defining the channel waveguide endface. The sensor is based on a phase modulated Mach-Zehnder interferometer, using the electro-optic effect of the waveguiding material zinc oxide (ZnO). The fiber-to-chip connector units have a typical coupling efficiency of 0.1–1%. The electro-optical voltage × length product Vπ is 15 ± 4 V cm at frequencies above 100 Hz. Preliminary experiments on the general (passive) sensor response showing its expected high sensitivity are discussed.
31.	Holmin, Susanne, et al. (författare) Compression of electronic tongue data based on voltammetry - A comparative study 2001 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 76:1-3, s. 455-464 Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract In this paper, three data compression methods are investigated to determine their ability to reduce large data sets obtained by a voltammetric electronic tongue without loss of information, since compressed data sets will save data storage and computational time. The electronic tongue is based on a combination of non-specific sensors and pattern recognition tools, such as principal component analysis (PCA). A series of potential pulses of decreasing amplitude are applied to one working electrode at a time and resulting current transients are collected at each potential step. Voltammograms containing up to 8000 variables are subsequently obtained. The methods investigated are wavelet transformation (WT) and hierarchical principal component analysis (HPCA). Also, a new chemical/physical model based on voltammetric theory is developed in order to extract interesting features of the current transients, revealing different information about species in solutions. Two model experiments are performed, one containing solutions of different electroactive compounds and the other containing complex samples, such as juices from fruits and tomatoes. It is shown that WT and HPCA compress the data sets without loss of information, and the chemical/physical model improves the separations slightly. HPCA is able to compress the two data sets to the largest extent, from 8000 to 16 variables. When data sets are scaled to unit variance, the separation ability improves even further for HPCA and the chemical/physical model. © 2001 Elsevier Science B.V.
32.	Lloyd-Spets, Anita, et al. (författare) High temperature catalytic metal field effect transistor for industrial applications 2000 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 70:1-3, s. 67-76 Tidskriftsartikel (refereegranskat)abstract Field effect chemical sensors, utilising silicon carbide as semiconductor, can be operated at high temperature and in rough environments. Gas sensitive field effect transistors, MISiCFET, are now developed (ACREO, Kista in Sweden). This will increase the number of possible applications for field effect gas sensors. The first batch of MISiCFET devices is possible to operate in intermittent pulses of hydrogen/oxygen up to 775°C. At temperature above 600°C, the gas response of the MISiC devices has very short time constants for a change between oxidising and reducing atmosphere and cylinder specific monitoring of a combustion engine has been demonstrated. Other industrial applications, like exhaust diagnosis and flue gas monitoring, have been demonstrated by the use of MISiC Schottky diodes at lower temperatures, 200°C-500°C.
33.	Lundström, Ingemar, et al. (författare) Catalytic metals and field-effect devices—a useful combination 1990 Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 1:1-6, s. 15-20 Tidskriftsartikel (refereegranskat)abstract The properties of gas-sensitive field-effect devices with catalytic metal gates are described. We demonstrate especially how the selectivity of these sensors depends on parameters such as the choice of catalytic metal, the structure of the catalytic metal film and the operation temperature of the device. The sensitivity towards molecules like hydrogen, ammonia, ethanol and ethylene is demonstrated. The selectivity pattern of devices with catalytic metal gates is discussed in relation to the fabrication of multisensor arrays and the development of 'artificial olfactory senses'.
34.	Lundström, Ingemar, et al. (författare) From hydrogen sensors to olfactory images — twenty years with catalytic field-effect devices 1993 Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 13:1-3, s. 16-23 Tidskriftsartikel (refereegranskat)abstract A personal description of the history of gas-sensitive field-effect devices is given. It is shown how the originally described palladium-gate metal-oxide-semiconductor field-effect transistor has developed into sensing surfaces enabling the production of response images to odours. Images obtained for the odour from different cheeses are presented as examples of such artificial olfactory images.
35.	Lundström, Ingemar, et al. (författare) Recent developments in field-effect gas sensors 1995 Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 23:2-3, s. 127-133 Tidskriftsartikel (refereegranskat)abstract Some of the ongoing studies at our laboratory of gas-sensitive field-effect devices with catalytic metal gates are reviewed. More particularly, we discuss the use of such devices in so-called electronic noses due to the possibility of changing the selectivity patterns of the devices by the choice of catalytic metal and operation temperature. Several examples of the application of electronic noses consisting of field-effect devices in combination with metal oxide-based sensors are given. Finally, a summary is given of some remaining scientific problems and studies related to the understanding and development of gas-sensitive field-effect devices.
36.	Löfdahl, Mikael, et al. (författare) Chemical images 2000 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 70:1-3, s. 77-82 Tidskriftsartikel (refereegranskat)abstract Chemical sensors can be used to generate a vast amount of information about the emissions from bio- and chemical processes, from food and bacteria and from a number of products. These emissions are either wanted or should be avoided. Wolfgang Gopel was one of those who recognized early the large potential of chemical sensor arrays and different modes of operation of a given sensor. We describe how large area field effect devices, with catalytic metal gates, can be used for the construction of a response image of a gaseous emission. More specifically, we discuss the new possibilities obtained through the use of catalytic metals with a gradient in thickness. Some basic features of such sensing surfaces are demonstrated and, finally, time-dependent response images from aging meat are used to demonstrate the potential of the method used. It is based on a scanning light pulse technique (SLPT) which measures local polarization or work function changes in two dimensions and, e.g. a sensing surface consisting of bands of different catalytic metals with a gradient in thickness.
37.	Löfdahl, Mikael, et al. (författare) Gas response dependence on gate metal morphology of field-effect devices 2001 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 80:3, s. 183-192 Tidskriftsartikel (refereegranskat)abstract The dependence of the gas response on the gate metal morphology of field-effect gas sensors has been investigated in a new systematic way by using a scanning light pulse technique (SLPT) together with fabrication of metal gates where the metal morphology is continuously varied over the gate area. With the SLPT the local gas response at different points of the gate area can be measured. Furthermore, a mass spectrometric local gas sampling technique has been applied in combination with the local gas response measurements, which gives complementary information about the surface chemistry and how it changes with the morphology of the metal gate. Three different gate metals, Pd, Pt and Ir, have been studied by analysing the morphology and the gas response to five different gases, H2, NH3, C2H5OH, C2H4 and CH3CHO. Morphological aspects such as crack coverage, concentration of cracks and the length of the crack boundary, have been calculated from acquired scanning electron microscopy (SEM) images. Different possible response mechanisms are discussed in order to explain the observed responses and to understand the role of the morphology and the choice of the catalytic metal. Only in the case of ammonia a direct correlation between the morphological aspects, e.g. crack coverage, and the response was found. For Pd large changes in the local water pressure close to the metal gate surface have been measured at different parts of the metal gate by using the local gas sampling technique and a correlation is observed with the simultaneously measured gas response. Of the response mechanisms discussed in this contribution only a dissociative mechanism, where hydrogen atoms trapped at the interface between the metal gate and the insulator gives the response of the device, is consistent with all obtained results. © 2001 Elsevier Science B.V. All rights reserved.
38.	Manzano, J., et al. (författare) Computer screen illumination for the characterization of colorimetric assays 2003 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 96:1-2, s. 173-179 Tidskriftsartikel (refereegranskat)abstract Colorimetric evaluation of samples sorted in a two-dimensional (2D) array is performed with a computer screen used as a controlled light source and a web camera as detector. The transmittance profiles are predicted with a 12 parameters model within errors of 5 or 10% for qualitative or semi-quantitative purposes, respectively. The use of random colour illumination additionally enables robust acquisition with only 50 snap-shots (in less than 1min) that contains the information of the whole array, independently of the number of samples. © 2003 Published by Elsevier B.V.
39.	Nakagomi, Shinji, et al. (författare) Influence of carbon monoxide, water and oxygen on high temperature catalytic metal-oxide-silicon carbide structures 1997 Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 45:3, s. 183-191 Tidskriftsartikel (refereegranskat)abstract High temperature sensors, Schottky diodes and capacitors, based on catalytic metal-oxide-silicon carbide devices are investigated. Reducing gases like hydrogen and other hydrogen containing gases, decrease the barrier height and the flat band voltage, respectively, which is used as the sensor signal. The sensitivity of the devices at 600 degrees C to mixtures of carbon monoxide and oxygen with and without water vapour is studied in this paper. A large binary response of the sensors to carbon monoxide similar to the sensor response to hydrogen gas is observed. Close to the stoichiometric ratio of carbon monoxide and oxygen, the signal changes from a high to a low value corresponding to an excess of carbon monoxide and an excess of oxygen, respectively. When hydrogen is added to a mixture of carbon monoxide and oxygen, the signal changes from a high to a low value at a higher oxygen concentration. Since the response of these devices to hydrogen and hydrogen containing gases is supposed to emanate from hydrogen atoms, the mechanism of the response to carbon monoxide is discussed. The signal to carbon monoxide as well as to hydrogen decreases in the presence of water vapour and the reason for this is discussed.
40.	Nilsson, David, et al. (författare) An all-organic sensor-transistor based on a novel electrochemical transducer concept printed electrochemical sensors on paper 2002 Ingår i: Sensors and Actuators B: Chemical. - 0925-4005. ; 86:2-3, s. 193-197 Tidskriftsartikel (refereegranskat)abstract A novel transducer concept based on an organic electrochemical transistor is described. Its function as an integral part of an air humidity sensor, in which the proton conductor Nafion acts as sensitivity layer has been realised. The resulting electrochemical sensor–transistor, based on the conducting polymer PEDOT:PSS, operates at low voltages, on the order of 1 V. The sensor response, measured as the drain–source current of the electrochemical transistor, versus air humidity, has a close to exponential behaviour. The sensor can be realised using exclusively printing and coating fabrication techniques. Here, we demonstrate devices realised on plastic foils and on ordinary coated fine paper substrates. This organic electrochemical transducer promise future applications such as all-integrated low-cost sensor tags for single-use chemical sensors.
41.	Pardo, M., et al. (författare) Data preprocessing enhances the classification of different brands of Espresso coffee with an electronic nose 2000 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 69:3, s. 397-403 Tidskriftsartikel (refereegranskat)abstract Two different ways of preprocessing chemical sensor data are presented as a means to improve the interpretation and the classification ability of an electronic nose (EN). The practical problem at hand is the distinction between four commercial coffee blends - containing up to 12 types of coffees - all of which are to be consumed as Espresso. Coffee was sampled in three successive preparation phases: a beans, ground (powder) or liquid (the actual Espresso). In the case of beans, stress is put on the improved clusters visualization after the preprocessing and before the actual classification is performed. Different catalysed sensors and successive extractions were used to differentiate the response pattern towards the various coffees. The features which permitted the best samples' classification as judged from Principal Component Analysis (PCA) score plots were selected. To this end, an empirical search strategy inside the feature space is presented. Scores from PCA were subsequently utilized as inputs for a feed forward multilayer perceptron (MLP) with cross-validation resulting in 100% correct classification with just two sensors. In the case of ground coffee, a (supervised) drift compensation algorithm was developed. It essentially consists of removing the first principal component (PC) for every cluster since this is seen to be given by the drift. An 87.5% classification performance was achieved. Liquid coffee, on the other hand, was not successfully classified, probably due to the difficulty in assuring reproducible sampling conditions.
42.	Poksinski, Michal, et al. (författare) In situ monitoring of metal surfaces exposed to milk using total internal reflection ellipsometry 2003 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 94:3, s. 247-252 Tidskriftsartikel (refereegranskat)abstract A technique combining ellipsometry with total internal reflection is presented. The method is called total internal reflection ellipsometry (TIRE) and is suitable for monitoring of internal surfaces which opens new possibilities for measuring adsorption on metal surfaces in opaque liquids. Results from measurements of adsorption of milk and subsequent cleaning with sodium hydroxide on metal surfaces are given. These include studies on gold, iron, and chromium surfaces. A schematic design of the instrument used in TIRE is included. The main advantages of the system are non-invasive probing, fast response, and high sensitivity. The method has potential for applications in monitoring of internal surfaces of pipelines in industrial processes.
43.	Rosental, Arnold, et al. (författare) Gas sensing properties of epitaxial SnO2 thin films prepared by atomic layer deposition 2003 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 93:1-3, s. 552-555 Tidskriftsartikel (refereegranskat)abstract Undoped SnO2 thin films are grown on α-Al2O3(0 1 2) (r-cut sapphire) substrates by gas phase atomic layer deposition (ALD). Two precursor pairs, SnI4–O2 and SnCl4–H2O2, both new for ALD, are used. The films have a cassiterite structure and are (1 0 1)[0 1 0]cassiterite\|\|(0 1 2)[1 0 0]sapphire oriented. A good epitaxial quality and the conductivity acceptable from the standpoint of semiconductor gas sensors are achieved for ultrathin films grown from SnI4–O2 at 600 °C. The sensitivity of these films to CO in air has a maximum at a thickness of about 10 nm. Response rise and decay times belonging to a several seconds interval are measured. The films are assumed to function as a single grain.
44.	Sandström, K. J. Mattias, et al. (författare) Amperometric biosensor for formic acid in air 2000 Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 70:1–3, s. 182-187 Tidskriftsartikel (refereegranskat)abstract The possibility of developing a simple, inexpensive and specific personal passive “real-time” air sampler incorporating a biosensor for formic acid was investigated. The sensor is based on the enzymatic reaction between formic acid and formate dehydrogenase (FDH) with nicotinamide adenine dinucleotide (NAD+) as a co-factor and Meldola's blue as mediator. An effective way to immobilise the enzyme, co-factor and Meldola's blue on screen-printed, disposable, electrodes was found to be in a mixture of glycerol and phosphate buffer covered with a gas-permeable membrane. Steady-state current was reached after 4–15 min and the limit of detection was calculated to be below 1 mg/m3. However, the response decreased by 50% after storage at −15°C for 1 day.
45.	Scharnagl, K., et al. (författare) Hydrogen detection at high concentrations with stabilised palladium 2001 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 78:1-3, s. 138-143 Tidskriftsartikel (refereegranskat)abstract In order to improve the stability to high hydrogen concentrations, of hybrid suspended gate field effect transistors (HSGFETs) with thin palladium films as sensitive layer, Pd-Ni and Pd-Ag alloys have been produced by co-evaporation techniques in UHV. In this paper, the preparation methods as well as hydrogen response measurements are presented. The observed results show that the Pd-Ni alloy is an appropriate material for hydrogen sensing at concentrations up to 2% H2, even at room temperature. The response to 2% H2 is around 500 mV at dry conditions. It is reduced to less than half of this value with moistened carrier gas, but at the same time, the desorption time is lowered. In contrast, the Pd-Ag alloy was not stable. A large drift of the sensor signal was observed and the morphology as well as the composition had changed after the test gas exposures. © 2001 Published by Elsevier Science B.V.
46.	Solis, J. L., et al. (författare) Identifying natural and artificial odours through noise analysis with a sampling-and-hold electronic nose 2001 Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 77:1-2, s. 312-315 Tidskriftsartikel (refereegranskat)abstract A sampling-and-hold type electronic nose was used to investigate "frozen" sensor dynamics. The sensor was heated to the sensing temperature and exposed to a chemical environment for a short time. Then, while keeping the sensor in the chemical environment, the heating was switched off so that the sensor cooled down to room temperature. Chemicals species become trapped in the sensor film, and therefore, the current transport in the film is changed. The trapped chemicals are usually located at grain boundaries, and they influence the charge transport in the grains and between the grains. This gives random fluctuations to the local conductivity. Resistance noise was employed to extract chemical information from the sensor in the cold state.
47.	Svenningstorp, H., et al. (författare) Detection of HC in exhaust gases by an array of MISiC sensors 2001 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 77:1-2, s. 177-185 Tidskriftsartikel (refereegranskat)abstract Future legislations for car emissions make direct measurements in exhaust gases of hydrocarbon (HC) as well as CO and NOx interesting. Robust sensors that can stand the high temperature and rough environment in the exhaust gases are needed. Silicon carbide has the advantage of being a chemically very inert material, which, due to its high band gap, is a semiconductor even at temperatures around 800°C. Catalytic metal insulator silicon carbide Schottky diode sensors respond to gases like H2, HC, NOx in exhaust gases. The choice of catalytic metal, structure of the metal, and the operation temperature determines the response pattern to different gases. Here we will demonstrate that an array of different MISiC sensors to some extent predicts the HC concentration in gasoline exhaust gases. Chemometric methods are used for the evaluation of the signals. © 2001 Elsevier Science B.V.
48.	Svenningstorp, Henrik, et al. (författare) Influence of catalytic reactivity on the response of metal-oxide-silicon carbide sensor to exhaust gases 1999 Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 57:1-3, s. 159-165 Tidskriftsartikel (refereegranskat)abstract Catalytic metal insulator silicon carbide, MISiC, Schottky diodes are promising devices for on board exhaust diagnosis in cars. These sensors show a direct or indirect sensitivity to gases like H-2, CO, HC (hydrocarbons) and O-2. The catalytic reactivity of the sensor will effect the gas sensing conditions. In some situations knowledge about the reactivity of the catalytic surface may give more information about the exhaust gas composition. For instance, the sensor signal normally moves to a lower voltage in an ambient containing H-2 and HC, however, under certain conditions when exposed to rich gas mixtures, the HC response is opposite the one for H-2. Measurements performed by the MISiC sensors on simulated exhaust gas mixtures, either rich or lean, are shown here. Some fundamental studies of the HC response have been performed. Reaction limitation conditions are suggested as an explanation for the response of HC opposite the one of H-2.
49.	Söderström, Charlotte, et al. (författare) Recognition of six microbial species with an electronic tongue 2003 Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 89:3, s. 248-255 Tidskriftsartikel (refereegranskat)abstract An electronic tongue based on pulsed voltammetry over an array of electrodes with different selectivity and sensitivity patterns was used to recognize six different microorganisms: one yeast, two bacteria, and three molds. Measurements were performed during the whole growth period, from the lag phase to the stationary phase. The electrode array was dipped into the malt extract growth medium and voltage was applied over the electrodes in pulses of different amplitude and the resulting current data was sampled and collected in a matrix. Evaluation of the electronic tongue data was made with principal component analysis (PCA) and soft independent modeling of class analogy (SIMCA). PCA was performed on data from the lag, the logarithmic, and also the stationary growth phase. In the lag growth phase no recognition of species was visible in the PCA score plots. After further growth however all the included microbial species could be recognized from each other. The ability to predict membership of new replicates of the species to the right classes was verified with SIMCA. © 2003 Elsevier Science B.V. All rights reserved.
50.	Tobias, Peter, et al. (författare) Moving gas outlets for the evaluation of fast gas sensors 1999 Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 58:1-3, s. 389-393 Tidskriftsartikel (refereegranskat)abstract A new method for the evaluation of fast gas sensors is described. By using moving gas outlets, we can quickly change the ambient around a sensor. Different platinum-insulator-silicon carbide (MISiC) structures are investigated. Their sensor response contains fast components, which respond within milliseconds to a change in the ambient from a reducing gas to an oxidising gas and vice versa. Cylinder specific monitoring of car engines with the MISiC structures is discussed.

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