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Rheological Characterization of Healthy and non-Healthy Blood using Electronic Detection of the Fluid Front

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Universitat de Barcelona. Facultat de Física

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[eng] In this research, we developed a technique and experimental setup that is the basis of a device, for the characterization of blood rheology and its connection to the rigidity of red blood cell (RBC). Our experimental device consisted of a microfluidic channel, a pump, and electronic pins for the detection of fluid front advancement. These microfluidic channels were fabricated using photolithography techniques, constructed from polydimethylsiloxane (PDMS), and embedded with gold electrodes to ensure accurate measurements.
The first part of the work consists of the design of a microrheometer, intended to characterize blood and plasma samples by electronically monitoring fluid advancement inside the microfluidic channels. Using this, we have been able to obtain the viscosity values for fluids including water, blood, and plasma samples from healthy donors. Our setup included a pump for generating pressure, detection pins, an acquisition card, a computer, and PDMS microfluidic channels with gold electrodes. The ability to replicate these channels proved to be useful, allowing for cost-effective and highly precise experiments.
Our research expanded to investigate the rheological properties of blood, particularly their impact on RBCs, within the context of various hematological diseases. We compared pathological and healthy samples, aiming to develop a diagnostic tool based on the unique rheological patterns exhibited by normal blood. To account for hematocrit levels, we employed a mathematical model to standardize blood viscosity. We analyzed samples from patients with beta-thalassemia trait (βTT) and iron deficiency anemia (IDA), comparing our results to the Laser Optical Rotational Red Cell Analyzer (LORRCA). Furthermore, we explored the effects of changes in tonicity by introducing deionized water (DIW) and sodium chloride (NaCl) into blood samples from healthy donors. A
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novel PDMS channel geometry allowed us to obtain a normalized viscosity curve at various shear rates within a single experiment. DIW induced non-Newtonian behavior, while NaCl resulted in more Newtonian behavior. Visual evidence illustrated the creation and rupture of RBCs as tonicity levels changed.
Our research also extended to the study of malaria-infected blood samples. We adopted a lab-on-a-chip approach, constructing microfluidic channels with micro slits to simulate the spleen's pitting process during malaria infection. This led to altered RBC deformability and increased cell wall rigidity. We characterized plasmodium falciparum-infected RBCs, assessing hemolysis and the presence of once-infected RBCs. These findings shed light on the spleen's role in malaria pathophysiology.
This thesis has been carried out under the Industrial Doctorate program (DI 068 2018). For this reason, the research herein presented has been aimed at the construction of a prototype for point-of care device that could perform viscosity measures on blood samples automatically, using a simple interface, and calculating the results in a few seconds.
In addition to our published work, we explored industrial applications, conducting rheology experiments to obtain viscosity data for different dilutions of hyaluronic acid (HA) and sodium alginate (SA) in deionized water (DIW). Our findings demonstrated shear-thinning behavior with increasing concentration. Additionally, we developed a method to change the wettability of PDMS surfaces, transforming them from hydrophobic to hydrophilic using plasma treatment in a clean room, which holds promise for various applications.
In summary, our research journey has unveiled valuable insights into blood rheology and its intricate relationship with RBCs. Our innovative techniques and findings offer potential applications in both the medical and industrial fields, demonstrating the far-reaching impact of our extensive research.

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[spa] En este trabajo, desarrollamos un microreómetro para caracterización reológica de la sangre en relación con la rigidez de la pared celular de los glóbulos rojos a través de la detección del avance del frente de fluido usando un micro canal de polydimetilsiloxano con electrodos de oro. El montaje experimental incluye una bomba y una tarjeta de adquisición junto con hardware para conexión a un ordenador. Estos son la base para el desarrollo de un dispositivo point-of-care para el diagnóstico de enfermedades que afectan los glóbulos rojos.
La primera parte del trabajo consiste en caracterizar muestras de sangre y plasma, obteniendo valores de viscosidad. Luego, estudiamos la viscosidad de muestras de sangre de pacientes con betatalasemia y anemia por deficiencia de hierro, aplicando un modelo matemático para normalizar los valores de viscosidad con independencia del hematocrito de la muestra. Luego, analizamos los cambios en la viscosidad de muestras luego de agregar agua desionizada y cloruro de sodio, observando cambios en el comportamiento de los glóbulos rojos. El agua desionizada causó comportamiento no newtoniano, mientras que el NaCl causó uno más newtoniano. Visualmente confirmamos crenación y ruptura de los glóbulos. También experimentamos en muestras de sangre infectadas por la malaria, simulando el proceso de pitting del bazo. Además de los artículos publicados, realizamos experimentos de reología para en soluciones de ácido hialurónico, alginato de sodio y L-arginina en agua desionizada.

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Rheological Characterization of Healthy and non-Healthy Blood using Electronic Detection of the Fluid Front