| 1. |
- Filippini, Daniel, et al.
(författare)
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Chemical image generation with a grid-gate device
- 2004
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 96:12, s. 7583-7590
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Tidskriftsartikel (refereegranskat)abstract
- Scanning light pulse technique generating distinctive chemical images of diverse gases is demonstrated using a sensing arrangement that allows unrestricted choice of sensing materials, disregarding its conductivity or morphology. The present device, a metal oxide semiconductor structure, disentangles biasing from chemical functions by providing an inert grid as a gate that supplies the proper biasing, while functional materials even in the form of disconnected clusters can be used for sensing. The reading of conductimetric chemical responses of clustered materials, in nominal operating conditions, is demonstrated by the generation of chemical images acquired for inversion biasing conditions. © 2004 American Institute of Physics.
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| 2. |
- Filippini, Daniel, et al.
(författare)
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Chemical images generated by large area homogeneous illumination of metal-insulator-semiconductor structures
- 2003
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 82:21, s. 3791-3793
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Tidskriftsartikel (refereegranskat)abstract
- The induction of distinctive chemical images in the field-effect devices upon gas exposure by the use of a controlled large area illumination provided by a computer screen was reported. To generate two-dimensional photocurrent images, the concurrent optical and chemical modulation of the semiconductor surface potential of a single metal-oxide-semiconductor capacitor was used. It was concluded that the use of a computer screen as a programmable light source simplifies a normally complex setup.
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| 3. |
- Filippini, Daniel, et al.
(författare)
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Chemical imaging by a computer screen aided scanning light pulse technique
- 2002
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 81:20, s. 3891-3893
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Tidskriftsartikel (refereegranskat)abstract
- The demonstration of a scanning light pulse technique (SLPT) for the generation of selective chemical images was done. The programmable light source provided by a standard cathode-rays tube computer screen was used for this purpose. The testing of the concept was done with a metal-oxide-semiconductor capacitor with catalytic gates of platinum and palladium spatially distributed in transversal directions.
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| 4. |
- Filippini, Daniel, et al.
(författare)
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Computer screen photo-assisted spectral fingerprinting of luminescent polythiophene pH reporter
- 2004
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Ingår i: IEEE Sensors. Proceedings. - : IEEE. - 1930-0395 .- 2168-9229. ; 3, s. 1377-1380
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Tidskriftsartikel (refereegranskat)abstract
- The capability of the computer screen photo-assisted technique (CSPT)for the spectral fingerprinting of a photoactive polythiophene derivative (POWT) used as pH reporter is demonstrated. POWT is part of a family of industrial scalable materials, well established for organic electronics and biomedical applications, which is used here to demonstrate the capability of CSPT for tracing key spectral features. The ability of CSPTfor substance classification, corroborated by principal component analysis (PCA), successfully compares to standard spectroscopy, especially considering the involved equipments: CSPT is only a computer set and a web camera.
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| 5. |
- Filippini, Daniel, et al.
(författare)
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Distinctive photocurrent chemical images on bare SiO2 between continuous metal gates
- 2003
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Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 95:1-3, s. 116-122
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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.
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| 6. |
- Filippini, Daniel, et al.
(författare)
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Gap-gate field effect gas sensing device for chemical image generation
- 2004
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 84:15, s. 2946-2948
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Tidskriftsartikel (refereegranskat)abstract
- A field effect chemically sensing device, suited for the generation of scanning light pulse technique (SLPT) chemical images, was proposed. The device was a MOS capacitor made on p-Si (10 ?), thermally oxidized to 120 nm and metallized on its underside with 200 nm of Al. The biasing electrodes were two parallel Al tracks 100 nm thick spaced 1 mm from each other. The results demonstrate the complete separation between biasing and sensing functions in devices designed for SLPT chemical image generation.
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| 7. |
- Filippini, Daniel, et al.
(författare)
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Hydrogen detection on bare SiO2 between metal gates
- 2002
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 91:6, s. 3896-3903
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Tidskriftsartikel (refereegranskat)abstract
- Metal-oxide-semiconductor capacitors with gates of Pd and Au forming a wedge of bare SiO2 between them are described. It is observed that the sensitivity to H2 in the wedge is larger than on the outside of the metal gates due to the different distribution of potential determined by the geometrical constraints. The local response of the surface is obtained through the use of a scanning light pulse technique (SLPT), showing photocurrent versus voltage curves shifted to more negative voltages upon exposure to hydrogen. Within the wedge there is a two-dimensional photocurrent pattern composed of two splitting photocurrent peaks, whose separation depends on the distance between Au and Pd contacts, and on the composition of the ambient. The transient response in the wedge is comparable to that of Pd gates and the possibility of detecting hydrogen (or other molecules) by measuring on the bare insulator surface provides new possibilities for the use of field-effect structures for gas sensing. A semiempirical model describing the SLPT response for this particular geometry, conforms to experimental features, and highlights the sensitivity of the distribution of potential in the wedge to the density of charges induced on the semiconductor surface. © 2002 American Institute of Physics.
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| 8. |
- Filippini, Daniel, et al.
(författare)
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LCD-aided computer screen photo-assisted technique for colorimetric assays evaluation
- 2004
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 103:01-Feb, s. 158-164
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Tidskriftsartikel (refereegranskat)abstract
- The ability of the computer screen photo-assisted technique (CSPT) to evaluate color samples through its light transmittance profiles is demonstrated by using liquid crystal displays (LCD) as light sources. Transmittance profiles are more drastically affected by angular dependencies than those obtained with CRT illumination. A local light reference computation is introduced to counteract this effect yielding equivalent profiles for both kinds of displays thus allowing for a broader universe of platforms to perform CSPT experiments, including mobile devices. (C) 2004 Elsevier B.V. All rights reserved.
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| 9. |
- Filippini, Daniel, et al.
(författare)
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Microplate based biosensing with a computer screen aided technique
- 2003
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Ingår i: Biosensors & bioelectronics. - 0956-5663 .- 1873-4235. ; 19:1, s. 35-41
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Tidskriftsartikel (refereegranskat)abstract
- Melanophores, dark pigment cells from the frog Xenopus laevis, have the ability to change light absorbance upon stimulation by different biological agents. Hormone exposure (e.g. melatonin or α-melanocyte stimulating hormone) has been used here as a reversible stimulus to test a new compact microplate reading platform. As an application, the detection of the asthma drug formoterol in blood plasma samples is demonstrated. The present system utilizes a computer screen as a (programmable) large area light source, and a standard web camera as recording media enabling even kinetic microplate reading with a versatile and broadly available platform, which suffices to evaluate numerous bioassays. Especially in the context of point of care testing or self testing applications these possibilities become advantageous compared with highly dedicated comparatively expensive commercial systems.
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| 10. |
- Filippini, Daniel, et al.
(författare)
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Spectroscopic information retained in screen photo-assisted techniques
- 2004
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Ingår i: Analytica Chimica Acta. - : Elsevier BV. - 0003-2670 .- 1873-4324. ; 521:2, s. 237-244
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Tidskriftsartikel (refereegranskat)abstract
- The computer screen photo-assisted technique (CSPT), a recently reported method for characterization of colorimetric assays, has been modeled and the ability of the technique to retain key spectral features has been determined. The robustness of CSPT to operate with different kind of screens is demonstrated and a physical explanation of the result is provided. Simulated CSPT transmittances corroborate experimental results, and enable comparison with standard methods for qualitative and quantitative evaluation. © 2004 Elsevier B.V. All rights reserved.
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| 11. |
- Manzano, J., et al.
(författare)
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Computer screen illumination for the characterization of colorimetric assays
- 2003
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Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 96:1-2, s. 173-179
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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.
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| 12. |
- Manzano, J., et al.
(författare)
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Principal component analysis of sample response to RGB light
- 2004
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Ingår i: The Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654 .- 1364-5528. ; 129:2, s. 182-189
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Tidskriftsartikel (refereegranskat)abstract
- In this article we present a principal component analysis (PCA) for data generated by a web camera recording of a two dimensional array of samples illuminated with CRT and TFT screens. In order to create a robust cross-platform identification system useful in bio-analysis we investigate a "buoyant" approach to PCA. Using such approach we assess the relevance of keeping local reference samples to compensate for the spurious angle dependence introduced by TFT screens. We show how local references allow for the detection of such screen dependent angular anisotropy and the construction of a new coordinate space where this effect is considerably reduced. This new coordinate space is built using only the RGB coordinates provided by the camera without resorting to the screen RGB coordinates. Finally we investigate the sensitivity of sample tagging with respect to the number of illuminating colours. We show that 3 quasi-pure R, G and B colours are enough to obtain good separation of data and robust CRT/TFT cross platform tagging.
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| 13. |
- Uchida, H, et al.
(författare)
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Unsupervised scanning light pulse technique for chemical sensing
- 2004
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 103:01-Feb, s. 225-232
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Tidskriftsartikel (refereegranskat)abstract
- A scanning light pulse technique (SLPT) operating in a totally unsupervised way suitable for chemical sensing and the efficient screening of new sensing materials is demonstrated. The procedure automatically determines inflexion points (optimum biasing condition) and photocurrent amplitudes from locally acquired i-V characteristics of metal-insulator-semiconductor structures that enables optimum biased measurements properly re-scaled to avoid spurious amplifying effects. Additionally, the procedure allows composing flat-band voltage shift patterns within the same experiment, and avoiding feedback mode measurements. Optimum bias patterns when used to modulate subsequent measurements, allow a fast recording mode. (C) 2004 Elsevier B.V. All rights reserved.
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