Assessment of the Deformability and Velocity of Healthy and Artificially Impaired Red Blood Cells in Narrow Polydimethylsiloxane (PDMS) Microchannels

Boas, Liliana Vilas; Faustino, Vera; Lima, Rui; Miranda, J. M.; Minas, Graça; Fernandes, Carla S.; Catarino, Susana Oliveira

doi:10.3390/mi9080384

Cited by 40 publications

(32 citation statements)

References 30 publications

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“…As shown in Figure 1a, a multi-layer mold was designed to improve precision and repeatability. The stainless steel template had high stiffness and ccould be reused without wear, compared with conventional PDMS or SU-8 soft-lithography [29,30]. Chemical etching is a common method to pattern stainless steel with high-resolution, which determines the shape and height of micromachines [31].…”

Section: Methodsmentioning

confidence: 99%

Magnetic Micromachine Using Nickel Nanoparticles for Propelling and Releasing in Indirect Assembly of Cell-Laden Micromodules

Wang

Cui

et al. 2019

Micromachines

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Magnetic micromachines as wireless end-effectors have been widely applied for drug discovery and regenerative medicine. Yet, the magnetic assembly of arbitrarily shaped cellular microstructures with high efficiency and flexibility still remains a big challenge. Here, a novel clamp-shape micromachine using magnetic nanoparticles was developed for the indirect untethered bioassembly. With a multi-layer template, the nickel nanoparticles were mixed with polydimethylsiloxane (PDMS) for mold replication of the micromachine with a high-resolution and permeability. To actuate the micromachine with a high flexibility and large scalable operation range, a multi-pole electromagnetic system was set up to generate a three-dimensional magnetic field in a large workspace. Through designing a series of flexible translations and rotations with a velocity of 15mm/s and 3 Hz, the micromachine realized the propel-and-throw strategy to overcome the inevitable adhesion during bioassembly. The hydrogel microstructures loaded with different types of cells or the bioactive materials were effectively assembled into microtissues with reconfigurable shape and composition. The results indicate that indirect magnetic manipulation can perform an efficient and versatile bioassembly of cellular micromodules, which is promising for drug trials and modular tissue engineering.

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Section: Methodsmentioning

confidence: 99%

Magnetic Micromachine Using Nickel Nanoparticles for Propelling and Releasing in Indirect Assembly of Cell-Laden Micromodules

Wang

Cui

et al. 2019

Micromachines

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“…In previous studies, the deformability of single RBC was quantified with several quantifiers such as the deformability index (DI), cell margination, transit time, individual RBC velocity, and cell lysis. By referring to the recent work conducted by Catarino et al [ 37 ], the deformability index (DI) was found to be proportional to the RBC velocity for various degrees of RBCs, by measuring the RBC velocity and the deformed shape of RBCs. From this result, RBC velocity travelled in the microfluidic channel varied depending on the RBC deformability.…”

Section: Methodsmentioning

confidence: 99%

A Disposable Blood-on-a-Chip for Simultaneous Measurement of Multiple Biophysical Properties

Kang

2018

Micromachines

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Biophysical properties are widely used to detect pathophysiological processes of vascular diseases or clinical states. For early detection of cardiovascular diseases, it is necessary to simultaneously measure multiple biophysical properties in a microfluidic environment. However, a microfluidic-based technique for measuring multiple biophysical properties has not been demonstrated. In this study, a simple measurement method was suggested to quantify three biophysical properties of blood, including red blood cell (RBC) deformability, RBC aggregation, and hematocrit. To demonstrate the suggested method, a microfluidic device was constructed, being composed of a big-sized channel (BC), a parallel micropillar (MP), a main channel, a branch channel, inlet, and outlets. By operating a single syringe pump, blood was supplied into the inlet of the microfluidic device, at a periodic on-off profile (i.e., period = 240 s). The RBC deformability index (DI) was obtained by analyzing the averaged blood velocity in the branch channel. Additionally, the RBC aggregation index (AIN) and the hematocrit index (HiBC) were measured by analyzing the image intensity of blood flows in the MP and the BC, respectively. The corresponding contributions of three influencing factors, including the turn-on time (Ton), the amplitude of blood flow rate (Q0), and the hematocrit (Hct) on the biophysical indices (DI, AIN, and HiBC) were evaluated quantitatively. As the three biophysical indices varied significantly with respect to the three factors, the following conditions (i.e., Ton = 210 s, Q0 = 1 mL/h, and Hct = 50%) were maintained for consistent measurement of biophysical properties. The proposed method was employed to detect variations of biophysical properties depending on the concentrations of autologous plasma, homogeneous hardened RBCs, and heterogeneous hardened RBCs. Based on the observations, the proposed method exhibited significant differences in biophysical properties depending on base solutions, homogeneous hardened RBCs (i.e., all RBCs fixed with the same concentration of glutaraldehyde solution), and heterogeneous hardened RBCs (i.e., partially mixed with normal RBCs and homogeneous hardened RBCs). Additionally, the suggested indices (i.e., DI, AIN, and HiBC) were effectively employed to quantify three biophysical properties, including RBC deformability, RBC aggregation, and hematocrit.

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“…The concentration of RBCs in plasma and their deformability, in healthy conditions, plays an important role to define blood as a non-Newtonian fluid [1]. Some diseases, such as sickle-cell anemia, malaria, diabetes, polycythemia, cancer, heart disease are responsible to change the rheological and flow properties of the blood [2][3][4][5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

In vitro blood flow visualizations and cell-free layer (CFL) measurements in a microchannel network

Bento

Fernandes

Miranda

et al. 2019

Experimental Thermal and Fluid Science

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Microvascular networks are not simple straight microchannels but rather complex geometries composed by successive asymmetric divergent and convergent bifurcations. Despite the extensive research work in this field, still lack of knowledge about the blood flow behavior in microvascular networks. The current study applies the most current advanced visualization and microfabrication techniques to provide further insights into to the blood flow in network geometries. Hence, by using a high-speed video microscopy system, blood flow measurements and visualizations of the cell-free layer (CFL) were performed along a microchannel network composed by several divergent and convergent bifurcations. The inlet flow rate was kept constant whereas the hematocrit (Hct) and the depth of the geometry was changed in order to evaluate their effects into the CFL thickness. The results, show clearly that the Hct has a significant impact on the CFL thickness whereas the effect of reducing the depth did not contribute to a noticeable change on the CFL. In addition, the in vitro blood flow results reported here provide for the first time that in microfluidic devices having several asymmetric confluences it is likely to have the formation of several CFLs not only around the walls but also in middle of the main channels just downstream of the last confluence apex. Although, to best of our knowledge there is no evidence that this kind of flow phenomenon also happens in vivo, we believe that for microvascular networks with similar geometries and under similar flow conditions tested in this work, this kind of phenomenon may also happen in vivo. Furthermore, the results from this study could be extremely helpful to validate current numerical microvascular network models and to develop more realistic multiphase numerical models of blood flow in microcirculation.the vessel size dependent effective viscosity (known as Fahraeus-Lindqvist effect) [2,6]. By decreasing the tube diameter there is a decrease of the apparent viscosity, due to the migration of RBCs towards the core flow and consequent increase of the CFL thickness around the walls. These microscale hemodynamic phenomena play an important role in blood mass transport mechanisms [3,11]. The CFL thickness depends of several factors such as cell concentration, deformability, vessel diameter, cell aggregation, flow rate, presence of microbubbles and geometry of the microchannels [12][13][14][15][16][17][18][19][20]. For instance, by increasing the concentration of RBCs, i.e., increasing the hematocrit (Hct), there is a decrease of CFL thickness [17,21].The bifurcations are geometries extremely common in both microvessels and microfluidic devices and it is important to improve our current understanding regarding the influence of the bifurcations and confluences on the blood flow behavior at a microscale level. As a result, several numerical and in vitro blood flow studies have investigated the effect these complex https://doi.

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Assessment of the Deformability and Velocity of Healthy and Artificially Impaired Red Blood Cells in Narrow Polydimethylsiloxane (PDMS) Microchannels

Cited by 40 publications

References 30 publications

Magnetic Micromachine Using Nickel Nanoparticles for Propelling and Releasing in Indirect Assembly of Cell-Laden Micromodules

Magnetic Micromachine Using Nickel Nanoparticles for Propelling and Releasing in Indirect Assembly of Cell-Laden Micromodules

A Disposable Blood-on-a-Chip for Simultaneous Measurement of Multiple Biophysical Properties

In vitro blood flow visualizations and cell-free layer (CFL) measurements in a microchannel network

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