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Biblioteca Digital do IPB (53.442 recursos)

A Biblioteca Digital do IPB, tem por objectivo divulgar e permitir o livre acesso à produção científica produzida pela comunidade académica, promovendo a integração, partilha e a visibilidade da informação científica e garantindo a preservação da memória intelectual do Instituto Politécnico de Bragança.

DTM - Livros e Capítulos de Livros

Mostrando recursos 1 - 8 de 8

  1. Visualization of the cell-free layer (CFL) in a PDMS microchannel with a micro-stenosis

    Pinho, Diana; Yaginuma, Tomoko; Faustino, V.; Pinto, Elmano; Rodrigues, Raquel Oliveira; Cidre, Diana; Pereira, Ana I.; Lima, R.
    Red blood cells (RBCs) have a tendency to undergo axial migration due to the parabolic velocity profile which results in a high shear stress around wall that forces the RBC to move towards the center induced by the tank treading motion of the RBC membrane. As a result there is a formation of cell-free layer (CFL) with extremely low concentration of cells. Based on this phenomenon several works have proposed microfluidic designs to separate the suspending physiological fluid from whole in vitro blood. However, most of these studies have the aim of the complete extraction of cells from plasma which...

  2. Separation and deformation of red blood cells in PDMS microchannels

    Rodrigues, Raquel Oliveira; Faustino, V.; Pinho, Diana; Pinto, Elmano; Cidre, Diana; Yaginuma, Tomoko; Taboada, B.; Bento, David; Lima, R.
    Over the years, several experimental techniques were performed in in vitro environments, in an attempt to understand the flow behaviour of blood in microcirculation. Several of these studies were performed in glass capillaries, and have produced significant results with respect to rheological properties of blood [1, 2]. Another way to perform in vitro blood studies is to use microchannels fabricated by soft- lithography [3, 4] and xurography [5]. With these techniques several studies have focused in the formation of the cell-free layer (CFL) that is caused by the tendency of red blood cells (RBCs) to migrate toward the centre of...

  3. Flow of red blood cells in microchannel networks: in vitro studies

    Cidre, Diana; Rodrigues, Raquel Oliveira; Faustino, V.; Pinto, Elmano; Pinho, Diana; Bento, David; Fernandes, Carla S.; Dias, Ricardo P.; Lima, R.
    Human blood is a multiphase biofluid primarily composed by the deformable red blood cells (RBCs) suspended in plasma. Because the complex structure of RBCs, blood exhibits unique flow characteristics on micro-scale level, due to their complex biochemical mechanisms and their response to both shear and extensional flow, which influence the rheological properties and flow behaviour of blood [1,2]. In the past years in vitro blood studies have been extensively performed and some important physiological phenomena, such as Fahraeus and Fahraeus-Lindqvist effect, were revealed [1,3]. This pioneer studies performed by Fahraeus and Fahraeus-Lindqvist in straight glass microchannels [4] revealed that for narrow...

  4. Blood flow in microchannels manufactured by a low cost technique: xurography

    Pinto, Elmano; Taboada, B.; Faustino, V.; Cidre, Diana; Rodrigues, Raquel Oliveira; Miranda, João Mário; Garcia, Valdemar; Dias, Ricardo P.; Lima, R.
    The xurography is a technique that has been used to make molds to produce microchannels. In contrast to soft lithography [1, 2], xurography uses equipments and materials commonly used in the printing industry, such as cutting plotters, vinyl and other materials. The main advantage of this technique is to fabricate microchannels at a reduced cost [3, 4]. The Fahraeus-Lindqvist effect is a well know phenomenon that happens in microcirculation, where red blood cells (RBCs) have tendency to migrate toward the centre of the microtube resulting in a marginal cell-free layer (CFL) at regions adjacent to the wall [5]. Recently several...

  5. Micro-flow visualization of magnetic nanoparticles for biomedical applications

    Lima, R.; Joseyphus, R. J.; Ishikawa, Takuji; Imai, Yohsuke; Yamaguchi, Takami
    An investigation to measure the flow behavior of magnetic nanoparticles through a 100mm microchannel is conducted. The magnetic field is applied externally by a permanent magnet and by using a micro-PTV system it was possible to measure the flow behavior of magnetic nanoparticles at different flow rates and magnetic fields through a 100mm glass capillary. A strong dependence on both magnetic and hydrodynamic force is observed on the nanoparticles fluidic paths. Based on these in vitro studies, important parameters and issues that require further understanding and investigation are point out.

  6. Blood flow behavior in microchannels: past, current and future trends

    Lima, R.; Ishikawa, Takuji; Imai, Yohsuke; Yamaguchi, Takami
    Over the years, various experimental methods have been applied in an effort to understand the blood flow behavior in microcirculation. Most of our current knowledge in microcirculation is based on macroscopic flow phenomena such as Fahraeus effect and Fahraeus-Linqvist effect. The development of optical experimental techniques has contributed to obtain possible explanations on the way the blood flows through microvessels. Although the past results have been encouraging, detailed studies on blood flow behavior at a microscopic level have been limited by several factors such as poor spatial resolution, difficulty to obtain accurate measurements at such small scales, optical errors arisen from walls of the microvessels, high concentration...

  7. Velocity fields of blood flow in microchannels using a confocal micro-PIV system

    Lima, R.; Ishikawa, Takuji; Tanaka, S.; Takeda, Motohiro; Tsubota, Ken-ichi; Wada, Shigeo; Yamaguchi, Takami
    The in vitro experimental investigations provide an excellent approach to understand complex blood flow phenomena involved at a microscopic level. This paper emphasizes an emerging experimental technique capable to quantify the flow patterns inside microchannels with high spatial and temporal resolution. This technique, known as confocal micro-PIV, consists of a spinning disk confocal microscope, high speed camera and a diode-pumped solid state (DPSS) laser. Velocity profiles of pure water (PW), physiological saline (PS) and in vitro blood were measured in a 100mm glass square and rectangular polydimethysiloxane (PDMS) microchannel. The good agreement obtained between measured and estimated results suggests that this system is a very promising technique to obtain...

  8. Microscale flow dynamics of red blood cells in microchannels: an experimental and numerical analysis

    Lima, R.; Nakamura, M.; Omori, T.; Ishikawa, Takuji; Wada, Shigeo; Yamaguchi, Takami
    Approximately, the half volume of the blood is composed of red blood cells (RBCs) which is believed to strongly influence its flow properties. Blood flow in microvessels depends strongly on the motion, deformation and interaction of RBCs. Several experimental studies on both individual and concentrated RBCs have already been performed in the past (Goldsmith 1971, Goldsmith and Marlow 1979, Chien et al. 1984, Goldsmith and Turitto 1986). However, all studies used conventional microscopes and also ghost cells to obtain visible trace RBCs through the microchannel. Recently, considerable progress in the development of confocal microscopy and consequent advantages of this microscope over the conventional microscopes have led to a new technique...

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