| 1. |
- Anderson, Henrik, et al.
(författare)
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Quartz crystal microbalance sensor design : I. Experimental study of sensor response and performance
- 2007
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 123:1, s. 27-34
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates a novel quartz crystal microbalance (QCM) biosensor with a small and rectangular flow cell along with a correspondingly shaped crystal electrode. The sensor was evaluated with impedance analysis and compared to standard circular sensor crystals and sensor crystals with small circular electrodes. Comparative QCM measurements on an antibody–antigen interaction system were carried out on the rectangular and standard circular sensor systems. Impedance analysis and subsequent data extraction of the three different sensor crystals showed that the smaller sensors had significantly higher Q-values in air, but that liquid load on the electrodes lowered the Q-values radically for all crystals. Under liquid load, Q-values for the standard circular and the rectangular sensors were similar whereas the Q-value for the small circular sensor was 50% higher. QCM experiments showed that the QCM system with rectangular crystal electrodes was fully functional in a liquid environment. The rectangular system showed higher and more rapid responses for series of antibody injections, albeit at a higher noise level than the standard system. The study elucidates a significant potential for improvement of sensor performance by optimising the sensor electrode size and shape together with the flow cell geometry.
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| 2. |
- Andersson, Olof, et al.
(författare)
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Imaging SPR for detection of local electrochemical processes on patterned surfaces
- 2008
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 134:2, s. 545-550
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Tidskriftsartikel (refereegranskat)abstract
- Imaging surface plasmon resonance (iSPR) was used in conjunction with voltammetry to investigate the possibility of detecting local electrochemical processes in situ on chemically modified electrodes. More specifically, a pattern of self-assembled monolayers (SAMs) of thiocholesterol and 1-hexadecanethiol was microcontact printed on gold substrates, and the blocking characteristics on different parts of the pattern were investigated. The SPR images reflected the changes in the refractive index over the working electrode due to electrochemical processes, which in the present case showed the ability of the SAMs to impede faradaic reactions. The results show that differences in packing densities or porosity of SAMs in different regions of a patterned surface can be visualized as electrochemical images using iSPR. The strength of utilizing an optical detection method for electrochemical characterization lies in the ability to achieve lateral resolution in real-time. Electrochemical reactions can also be used to enhance the contrast in SPR images of thin layers of components with similar thicknesses and refractive indices.
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| 3. |
- Bakker, Jimmy W. P., et al.
(författare)
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Enhancing classification capabilities of computer screen photo-assisted fluorescence fingerprinting
- 2005
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Ingår i: Sensors and Actuators B: Chemical. - : Elsevier BV. - 0925-4005. ; 110:2, s. 190-194
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Tidskriftsartikel (refereegranskat)abstract
- The separation of emission from transmitted light for the fingerprinting of fluorescent substances using a computer screen photo-assisted technique (CSPT) is demonstrated. CSPT is a technique for optical evaluation using a simple cell with just a standard computer set and a web camera as instrumentation. It has been demonstrated to be a versatile system for colorimetric and fluorescent fingerprinting. Here the omnidirectional property of fluorescent emission is utilized to separate it from the background, using a simple optical arrangement compatible with CSPT purposes. This enhances the classification capabilities and makes classification at sub-μM concentrations possible.
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| 4. |
- Barkå, Jonas, et al.
(författare)
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Background compensation in computer screen photo-assisted reflectance fingerprinting
- 2006
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 120:1, s. 79-85
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Tidskriftsartikel (refereegranskat)abstract
- The computer screen photo-assisted technique (CSPT) is a method for the classification of colorimetric assays utilizing ordinary computer sets and web cameras as instrumentation. In CSPT measurements the web camera captures the image of the assay under the screen illumination, and typically a spurious spatial distribution of intensities is overlapped on the image. This issue is examined here, focusing on the effect of the sample and illuminating colors on the spatial modulation of intensity. A method for the selection of colors composing an illuminating sequence that minimizes the spatial variability is proposed. The approach is tested for the classification of different color substances showing improvements up to 53% of the intra/inter cluster distance ratio measured in a PCA space, when compared to randomly chosen colors. © 2006 Elsevier B.V. All rights reserved.
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| 5. |
- Belmonte, J.C., et al.
(författare)
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Micromachined twin gas sensor for CO and O2 quantification based on catalytically modified nano-SnO2
- 2006
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 114:2, s. 881-892
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Tidskriftsartikel (refereegranskat)abstract
- In this work we present a micromachined twin sensor that can distinguish between carbon monoxide (CO) and O2 gas taking advantage of the high sensitivity of SnO2 to these gases. The SnO2 nanoparticles of both sensors are catalytically modified with different Pd loadings that act as active filters. In this way, one sensor response is turned to present a higher sensitivity to CO than to O2, whereas the other sensor is mainly turned for detecting O2 variations. The twin sensor has two membranes in the same die of micromachined silicon. Each membrane works independently from the other without any cross talk of temperature. The resistance data obtained from this twin sensor as a function of CO and O 2 concentrations is parametrized. Then, two functions are calculated for the quantification of CO/O2 gas mixtures. A comparison with commercial gas sensors is shown. © 2005 Elsevier B.V. All rights reserved.
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| 6. |
- Bianchi, S., et al.
(författare)
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Indium oxide quasi-monodimensional low temperature gas sensor
- 2006
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 118:1-2, s. 204-207
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the sensing properties of indium oxide nanostructures and tailored the deposition conditions in order to obtain nano-wires of indium oxide. We have comparatively tested the gas sensing properties of nano-wires with micrometric or even nanometric size. The micro-wires feature interesting gas sensitivity at room temperature, particularly in the case of nitrogen dioxide detection. The sensing performance is improved as the lateral dimension of the wire decreases. © 2006 Elsevier B.V. All rights reserved.
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| 7. |
- Bjorklund, Robert, et al.
(författare)
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Automatic optimization of experimental conditions for fast evaluation of diagnostic tests using ubiquitous instrumentation
- 2008
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 134:1, s. 199-205
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Tidskriftsartikel (refereegranskat)abstract
- Rapid quantitative determinations of creatinine, potassium and glucose, all important parameters in routine medical diagnostics, are demonstrated using a computer screen photo-assisted technique (CSPT). CSPT uses regular computer screens as light sources and web cameras as imaging detectors for supporting optical evaluations of diverse character. The ubiquity and versatility of the setup, makes CSPT an attractive candidate for point of care determinations. A robust procedure for the automatic selection of experimental conditions in CSPT evaluation, including camera channels and illuminating colors that minimize the measuring time up to 5 times is described. The method utilizes the correlation between experimental conditions and classification scores, obtained under a generic 50 color training session, to extract measuring sequences as short as 9 s. The extracted measuring conditions automatically adapted to the different tests provided a general, practical and fast approach for CSPT optimization in real scenarios. © 2008 Elsevier B.V. All rights reserved.
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| 8. |
- Bolin, Maria, et al.
(författare)
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Nano-fiber scaffold electrodes based on PEDOT for cell stimulation
- 2009
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Ingår i: SENSORS AND ACTUATORS B-CHEMICAL. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 142:2, s. 451-456
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Tidskriftsartikel (refereegranskat)abstract
- Electronically conductive and electrochemically active 3D-scaffolds based on electrospun poly(ethylene terephthalate) (PET) nano-fibers are reported. Vapour phase polymerization was employed to achieve an uniform and conformal coating of poly(3,4-ethylenedioxythiophene) doped with tosylate (PEDOT:tosylate) on the nano-fibers. The PEDOT coatings had a large impact on the wettability, turning the hydrophobic PET fibers super-hydrophilic. SH-SY5Y neuroblastoma cells were grown on the PEDOT coated fibers. The SH-SY5Y cells adhered well and showed healthy morphology. These electrically active scaffolds were used to induce Ca2+ signalling in SH-SY5Y neuroblastoma cells. PEDOT:tosylate coated nano-fibers represent a class of 3D host environments that combines excellent adhesion and proliferation for neuronal cells with the possibility to regulate their signalling.
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| 9. |
- Comini, Elisabetta, et al.
(författare)
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Effects of Ta/Nb-doping on titania-based thin films for gas-sensing
- 2005
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 108:1-2 SPEC. ISS., s. 21-28
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Tidskriftsartikel (refereegranskat)abstract
- Thin films of titania with the addition of niobium and tantalum have been achieved by reactive sputtering process. Structural and morphological studies have been carried out by means of XRD, RBS, TEM and AFM in order to correlate the microstructural features to the sensing performance of the layers. The films proved sensitive to ethanol and carbon monoxide and ammonia. In the case of niobium addition, it was shown that annealing temperature and niobium content strongly influence the gas response of the films converting a n-type response, which is typical of pure TiO2 and of most of metal-oxide sensors, to a p-type response; this peculiarity is crucial for the discrimination of different gases. In the case of tantalum addition, the annealing treatment at 800 °C led only to a phase transformation that reduced the sensing performance of the layer. High sensitivity to CO is achieved with anatase or mixed anatase and rutile phases, while the rutile phase only exhibit a low gas sensitivity. © 2005 Elsevier B.V. All rights reserved.
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| 10. |
- Comini, E., et al.
(författare)
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Influence of iron addition on ethanol and CO sensing properties of tin oxide prepared with the RGTO technique
- 2006
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 115:2, s. 561-566
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Tidskriftsartikel (refereegranskat)abstract
- Effects of iron introduction in RGTO prepared tin oxide gas sensors are presented. The films were deposited by sputtering from a tin target with the introduction of an adjustable number or iron inset. Iron content was varied in the range 0-7%. The thin films are investigated by the volt-amperometric technique for electrical and gas-sensing properties. The layers are capable of sensing CO and ethanol, no evidence of surface poisoning is detected, and recovery of the resistance is complete. The response of the sensors is stable and reproducible at all operating temperatures tested (200-500 °C) during 3 months of operation. © 2005 Elsevier B.V. All rights reserved.
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