Encontrados 14 documentos, a visualizar página 1 de 2
Fluorescence and diffuse reflectance spectroscopy for early cancer detection us...
Ferreira, D. S.; Coutinho, Paulo J. G.; Castanheira, Elisabete M. S.; Correia, J. H.; Minas, GraçaThis paper describes the design of a miniature, cost-effective spectroscopy system for assessing tissue biochemical and morphological information using a few wavelengths. This instrument will integrate thin-film optical filters and silicon photodiodes, avoiding the use of a spectrograph and optical fibers. The components in the set-up design are described. The feasibility of using only 16 wavelengths to accurat...
Numerical study of micromixing combining alternate flow and obstacles
Miranda, J. M.; Oliveira, Hugo; Teixeira, J. A.; Vicente, A. A.; Correia, J. H.; Minas, GraçaMixing in microsystems, combining alternate flow with obstacles, is studied by numerical methods. Simulations show that the layers of high and low solute concentrations, created by the alternate flow, are split into smaller chunks of fluid by obstacles inserted in the mixing channel, decreasing the critical mixing length. Reverse flow is necessary to guarantee symmetry and good mixing. Mixing increases with the...
Autofluorescence spectroscopy of a human gastrointestinal carcinoma cell line -...
Ferreira, D. S.; Henriques, Mariana; Oliveira, Rosário; Correia, J. H.; Minas, GraçaHuman tissues show autofluorescence (AF) emission spectra when excited by ultraviolet or shortwavelength visible light. The intensity and shape of these spectra are dependent on the tissues pathological state and, therefore, its measurement gives information about the degree of malignant transformations that could lead to cancer. In this article, it is characterized the AF spectra of one human gastrointestinal ...
Lab-on-a-chip for biological fluids analysis by spetrophotometry
Minas, Graça; Wolffenbuttel, R. F.; Correia, J. H.The healthcare sector is nowadays one of the most dynamic and where the novelty is a strategic and operational imperative. The possibility of increase the quantity and quality of clinical analysis, performed with instantaneous results and outside the clinical laboratories, contributes to a better quality in the health care services and also a better efficiency in the clinical and administrative processes [1]. T...
Design of a lab-on-a-chip for clinical tests of human physiological fluids
Miranda, J. M.; Minas, Graça; Vicente, A. A.; Teixeira, J. A.Labs-on-a-chip are useful to perform in situ clinical tests with instantaneous results. In this work, the design phase of the development of a lab-on-a-chip is presented. The device will be used to perform tests on physiological fluids. It will be able to test 8 components: calcium, chloride, creatinine, glucose, magnesium, total protein, urea and uric acid. A sample of the physiological fluid reacts with sever...
Scintillating microcavities for X-ray imaging sensors
Rocha, J. G.; Minas, Graça; Gonçalves, L. M.; Lanceros-Méndez, S.Over the last years several prototypes of detectors for digital radiography, based on different approaches, have been developed. One those approaches is based on scintillating crystals, which convert the x-ray energy into visible light that will be detected by photodetectors. The biggest difficulty of this kind of detectors is the fact that the produced visible light must be guided to the photodetectors. This c...
A tunable Fabry-Perot optical filter for application in biochemical analysis of...
Gonçalves, L. M.; Minas, Graça; Pinheiro, C.; Lanceros-Méndez, S.; Rocha, J. G.This paper reports a Fabry-Perot tunable optical filter for application in clinical analysis, especially to measure the concentration of biochemical substances in biological fluids. Its tunable characteristics enable the measurement of different biochemical substances with the same device. It is composed of two parallel thin silver mirrors with a β-PVDF (Poly(Vinylidene Fluoride) in its β phase) film in-between...
Oscillatory and alternate flows in a microfluidic device
Oliveira, Hugo Carneiro; Miranda, J. M.; Teixeira, J. A.; Vicente, A. A.; Correia, J. H.; Minas, GraçaThe mixing properties of systems with oscillatory or alternate flows are studied by numerical methods. Preliminary results show that, for alternate flows, the contact area between high and low concentration regions increases and mixing is achieved from the combination of transversal diffusion and axial advection. The improvement in the mixing process shows that this method is very useful for designing mixers in...
Micro-laboratório num chip para análise de fluidos biológicos
Minas, Graça; Correia, J. H.O sector da Saúde é hoje um dos mais dinâmicos e onde a capacidade de inovação é um imperativo estratégico e operacional. Neste artigo apresenta-se um micro-laboratório num chip para análise espectrofotométrica de fluidos biológicos. Permite, especificamente, a determinação selectiva da concentração de várias biomoléculas nesses fluidos, em tempo real, no próprio local, com baixas concentrações, com pequenos vo...
Microssistema laboratorial para análise de fluidos biológicos
Minas, GraçaOs médicos prescrevem análises a fluidos biológicos que são realizadas em laboratórios de análises clínicas. Todo este processo é moroso em termos de tempo, não permitindo ao médico um diagnóstico fidedigno na hora da consulta. Para além da demora, existem ainda problemas de possíveis enganos logísticos, tais como a etiquetagem errada ou a perda de amostras, o que pode atrasar significativamente o diagnóstico. ...
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