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- Flow of physiological fluids in microchannels: the sedimentation effectPublication . Garcia, Valdemar; Correia, Teresa Montenegro; Dias, Ricardo P.; Lima, Rui A.Microfluidic devices are becoming one of the most promising new tools for diagnostic applications and treatment of several chronic diseases. Hence, it is increasingly important to investigate the rheological behaviour of physiological fluids in microchannels. The main purpose of the present experimental work is to investigate the flow of two different physiological fluids frequently used in microfluidic devices. The working fluids were physiological saline (PS) and dextran 40 (Dx40) containing about 6% of sheep red blood cells (RBCs), respectively. The capillaries were placed horizontally on a slide glass and the flow rate of the working fluids was kept constant by using a syringe pump. By means of a camera the images were taken and transferred to the computer to be analysed. Generally, the results show that PS and Dx40 have different flow behaviour due to the sedimentation of the RBCs.
- Fabricação de microcanais utilizando o método de xurografia: visualização da camada livre de célulasPublication . Pinto, Elmano; Pinho, Diana; Bento, David; Correia, Teresa Montenegro; Garcia, Valdemar; Dias, Ricardo P.; Miranda, João MárioNo presente estudo, pretendeu-se desenvolver/melhorar uma metodologia de microfabricação de baixo custo, conhecida por xurografia e efectuar a visualização e quantificação da camada livre de células para diferentes escoamentos sanguíneos em microcanais.
- Dynamic sedimentation measurements of physiological fluids in biomedical devicesPublication . Garcia, Valdemar; Correia, Teresa Montenegro; Dias, Ricardo P.; Lima, Rui A.Currently, biomedical microdevices are becoming one of the most promising tools for the diagnostic and treatment of several diseases, such as diabetes, malaria and cancer. Hence, it is increasingly important to investigate the rheological behaviour of physiological fluids in microchannels in order to make use on the physics of microfluidics to either develop new lab-on-chip devices and to optimize the design of existent biomicrofluidics chips. The main objective of this study is to investigate the flow behaviour of two different physiological fluids frequently used in biomedical microdevices. The working fluids used in this study were physiological saline (PS) and dextran 40 (Dx40) containing about 6% of sheep red blood cells (RBCs), respectively. By using a syringe pump and a camera it was possible to measure qualitatively the flow behaviour within a horizontal capillary.
- Flow of physiological fluids in microchannels: the sedimentation effectPublication . Garcia, Valdemar; Dias, Ricardo P.; Correia, Teresa Montenegro; Lima, Rui A.Microfluidic devices are becoming one of the most promising new tools for diagnostic applications and treatment of several chronic diseases. Hence, it is increasingly importante to investigate the rheological behaviour of physiological fluids in microchannels.The main purpose of the presente experimental work is to investigate the flow of two different physiological fluids frequently used in microfluidic devices. The working fluids were physiological saline (PS) and dextran 40 (Dx40) containing about of 6% of sheep red blood cells (RBCs), respectively. The cappilaries were placed horizontally on slide glass and the flow rate of the working fluids was kept constant by using a syringe pump. By means of a camera the images were taken and transferred to the computer to be analysed. Generally, the results show that PS and Dx40 have different flow behaviour due to the sedimentation of RBCs.
- In vitro blood flow in circular PDMS microchannels: effect of the flow rate and hematocritPublication . Garcia, Valdemar; Dias, Ricardo P.; Correia, Teresa Montenegro; Lima, Rui A.; Pinheiro, Elisa; Pinho, Diana; Rodrigues, Pedro JoãoRecently, Lima et al. (1) has performed confocal micro-PIV measurements on the blood flow through straight PDMS microchannel. In the study they have observed that the formation of the cell free layer is enhanced as the cross section ratio increases. However, the cross section ratio is not the only parameter that contributes for the creation of the cell-free layer. Hence, several other physical and hemorheological factors (such as flow rate, hematocrit, viscosity and cell deformability) need to be investigated in order to make use on the physics of microfluidics to either develop new lab-on-chip devices or to optimize the design of the existent microfluidic chips. The main aim of the present study is to show the effect of both flow rate and hematocrit on the blood flow and cell behavior. The circular polydimethylsiloxane (PDMS) microchannels were fabricated by using wire casting technique and the experiments were carried out by using dextran 40 containing different fractions of red blood cells (RBCs). The in vitro blood flow was measured by means of video microscopy and image analysis. Additionally, the pressure drop was also measured.
- Flow of physiological fluids in microchannels: the sedimentation effectPublication . Garcia, Valdemar; Correia, Teresa Montenegro; Dias, Ricardo P.; Lima, Rui A.
- Fabricação de microcanais utilizando o método de xurografia: visualização da camada livre de célulasPublication . Pinto, Elmano; Pinho, Diana; Bento, David; Correia, Teresa Montenegro; Garcia, Valdemar; Dias, Ricardo P.; Miranda, João Mário; Lima, Rui A.No presente estudo, pretendeu-se desenvolver/melhorar uma metodologia de microfabricação de baixo custo, conhecida por xurografia e efectuar a visualização e quantificação da camada livre de células (CLC) junto às paredes para diferentes escoamentos sanguíneos em microcanais.
- Dynamic sedimentation measurements of physiological fluids in biomedical devicesPublication . Garcia, Valdemar; Correia, Teresa Montenegro; Dias, Ricardo P.; Lima, Rui A.In this experimental work we investigate the flow of two different physiological fluids frequently used in microfluidic devices: physiological saline (PS) and dextran 40 (Dx40) containing about 6% of sheep red blood cells (RBCs), respectively. The capillaries were placed horizontally on a slide glass and the flow rate of the working fluids was kept constant. Images were obtained and analysed. Generally, the results show that PS and Dx40 have different flow behaviour due to the sedimentation of the RBCs.
- In vitro blood flow in circular PDMS microchannels: effect of the flow rate and hematocritPublication . Garcia, Valdemar; Dias, Ricardo P.; Correia, Teresa Montenegro; Pinheiro, Elisa; Pinho, Diana; Lima, Rui A.; Rodrigues, Pedro JoãoSeveral studies have shown that information obtained on the rheological properties of blood from glass capillaries differs from the situation in vivo [1]. It is therefore important to investigate in vitro blood fluids which have a behavior as close as possible of the in vivo environment.