Diana Pinho

University of Minho · Center for MicroElectromechanical Systems (CMEMS-UMinho)

Metallic nanoparticles are a type of nanomaterial synthesized from metallic precursors. Due to their unique physiochemical, electrical, and optical properties, metallic nanoparticles are widely studied and applied in various areas such as medicine, electronics, and heat transfer systems. However, conventional synthesis methods to produce metallic n...

Organ-on-a-Chip (OoC) technology is an ever-evolving field that combines engineering and biological sciences. These offer advantages such as reduced sample consumption, faster and cheaper analysis, and improved microenvironment control. For these reasons, researchers have increasingly used OoCs platforms to deepen the understanding of disease mecha...

Lab-on-a-chip (LOC) devices have been explored since the development of the first micro-total analysis system (μTAS) in the 1990s. During the last 30 years, significant developments have been achieved in the areas of microfabrication, microfluidics, biosensing, bioprinting, as well as in the integration of optical, acoustic, magnetic, thermal and e...

The evolution in the biomedical engineering field boosts innovative technologies, with microfluidic systems standing out as transformative tools in disease diagnosis, treatment, and monitoring. Numerical simulation has emerged as a tool of increasing importance for better understanding and predicting fluid-flow behavior in microscale devices. This...

Over the last decade, researchers have developed a variety of new analytical and clinical diagnostic devices. These devices are predominantly based on microfluidic technologies, where biological samples can be processed and manipulated for the collection and detection of important biomolecules. Polydimethylsiloxane (PDMS) is the most commonly used...

The issue of thermal control for space missions has been critical since the early space missions in the late 1950s. The demands in such environments are heightened, characterized by significant temperature variations and the need to manage substantial densities of heat. The current work offers a comprehensive survey of the innovative materials and...

The 3D printing technology is innovative, allowing the creation of customized objects. Due to the possible reduction of manufacturing costs, 3D objects printing becomes increasingly attractive to several industrial areas. High levels of customization are achieved at low cost on a wide variety of materials. Despite of high levels of reliability and...

Polydimethylsiloxane (PDMS) is one of the most used materials for the manufacture of microfluidic devices. Recent studies have combined microfluidic devices and cell cultures to originate a new group of devices, the organs-on-achip (OoC). These devices replicate the microphysiological features that can be found in the human body so that healthy and...

Three-dimensional (3D) printing, also known as additive manufacturing (AM), has emerged in the last decades as an innovative technology to build complex structures. It enables increasing design complexity and low-cost customization with a vast range of materials. AM capabilities contributed to a widespread acceptance of 3D printing in different ind...

The efficient separation of blood components using microfluidic systems can help to improve the detection and diagnosis of several diseases, such as malaria and diabetes. Therefore, a novel multi-step microfluidic device, based on passive crossflow filters was developed. Three different designs were proposed, fabricated and tested in order to evalu...

The increasing interest to establish significant correlations between blood cell mechanical measurements and blood diseases, has led to the promotion of microfluidic devices as attractive clinical tools for potential use in diagnosis. In this paper, it is presented a multi-step microfluidic device able to separate red and white blood cells (RBCs an...

The development of cancer models that rectify the simplicity of monolayer or static cell cultures physiologic microenvironment and, at the same time, replicate the human system more accurately than animal models has been a challenge in biomedical research. Organ-on-a-chip (OoC) devices are a solution that has been explored over the last decade. The...

Since microorganisms are evolving rapidly, there is a growing need for a new, fast, and precise technique to analyse blood samples and distinguish healthy from pathological samples. Fourier Transform Infrared (FTIR) spectroscopy can provide information related to the biochemical composition and how it changes when a pathological state arises. FTIR...

The Special Issue on "Microfluidic Tools for Noninvasive Biomedical Applications" in the journal Biology is being edited by Dr. Diana Pinho and Dr. Sandra Caravalho from INL—International Iberian Nanotechnology Laboratory, Portugal, is now open to receive submissions for peer-review and possible publication. Based on your scientific skills and inte...

Colorectal cancer is the second leading cause of cancer death worldwide. Significant advances in the molecular mechanisms underlying colorectal cancer have been made; however, the clinical approval of new drugs faces many challenges. Drug discovery is a lengthy process causing a rapid increase in global health care costs. Patient-derived tumour org...

In blood flow studies, image analysis plays an extremely important role to examine raw data obtained by high-speed video microscopy systems. This work shows different ways to process the images which contain various blood phenomena happening in microfluidic devices and in microcirculation. For this purpose, the current methods used for tracking red...

Atherosclerosis is one of the main causes of cardiovascular events, namely, myocardium infarction and cerebral stroke, responsible for a great number of deaths every year worldwide. This pathology is caused by the progressive accumulation of low-density lipoproteins, cholesterol, and other substances on the arterial wall, narrowing its lumen. To da...

Hemorheological alterations in the majority of metabolic diseases are always connected with blood rheology disturbances, such as the increase of blood and plasma viscosity, cell aggregation enhancement, and reduction of the red blood cells (RBCs) deformability. Thus, the visualizations and measurements of blood cells deformability flowing in microf...

During the last two decades, several kinds of particulate blood analogue fluids have been proposed, but none of those were able to mimic the multiphase effects of real blood. Hence, it is clear that it is crucial to develop a simple multiphase blood analogue to be used for in vitro experiments at both macro- and microscale level. To the best of our...

There is a continuous search for better and more complete in vitro models with mechanical properties closer to in vivo conditions. In this work a manufacturing process, based on a lost core casting technique, is herein reported to produce aneurysm biomodels to perform experimental hemodynamic studies. By using real artery images combined with a los...

A critical issue in additive manufacturing (AM) is the control of the printer actuators such that the deposition of material (or a few different materials) takes place in an organized way. Typically, the actuators are connected with a low-level controller that can receive computer numerical control (CNC) instruction. A 3D printer controller is, usu...

The Colebrook [1] equation is considered the standard for the calculation of friction factor for turbulent flow in commercial pipes, but it is implicit, and therefore it must be computed by iterative methods. Although such iterative computation quickly converges, the computational time in large pipe system simulations can be reduced using an accura...

The Colebrook [1] equation is considered the standard for the calculation of friction factor for turbulent flow in commercial pipes, but it is implicit, and therefore it must be computed by iterative methods. Although such iterative computation quickly converges, the computational time in large pipe system simulations can be reduced using an accura...

Biomedical microfluidic devices are fabricated using different fabrication technologies. The most popular method is the soft-lithography manly due their main attraction, its high resolution capabilities and low material cost. However, usually, the fabrication of the moulds to produce microfluidic devices, is performed in a cleanroom environment and...

The loss of the red blood cells (RBCs) deformability is related with many human diseases, such as malaria, hereditary spherocytosis, sickle cell disease, or renal diseases. Hence, during the last years, a variety of technologies have been proposed to gain insights into the factors affecting the RBCs deformability and their possible direct associati...

Since the first microfluidic device was developed more than three decades ago, microfluidics is seen as a technology that exhibits unique features to provide a significant change in the way that modern biology is performed. Blood and blood cells are recognized as important biomarkers of many diseases. Taken advantage of microfluidics assets, change...

Polydimethylsiloxane (PDMS) has a wide variety of commercial and industrial applications due to its mechanical and rheological properties in a range similar to the living tissues. In this study, we demonstrate that PDMS can be used to produce deformable microparticles to be integrated in the development of particulate blood analogue fluids. The dif...

Um parâmetro fundamental no projeto de sistemas de condutas de fluidos é a perda de energia causada pelo atrito viscoso, a qual é quantificada pelo fator de atrito. Em escoamentos turbulentos a expressão padrão utilizada para quantificar essa perda de energia é a correlação empírica introduzida por Colebrook (1939), que deve ser calculada iterativa...

Purpose The aim of this paper is to characterize the rheological properties of the flux media exposed to different levels of solicitation and to determine its influence on the rheology of the solder paste. The data obtained experimentally are fundamental for the development of numerical models that allow the simulation of the printing process of p...

Microfluidic devices have been widely used as a valuable research tool for diagnostic applications. Particularly, they have been related to the successful detection of different diseases and conditions by assessing the mechanical properties of red blood cells (RBCs). Detecting deformability changes in the cells and being able to separate those cell...

Blood analogues have long been a topic of interest in biofluid mechanics due to the safety and ethical issues involved in the collection and handling of blood samples. Although the current blood analogue fluids can adequately mimic the rheological properties of blood from a macroscopic point of view, at the microscopic level blood analogues need fu...

Presently 3D printers are gaining widespread attention by both biomedical research and industrial community. 3D printing is a process based on 3D additive manufacturing technology, in which a three-dimensional object is created by gradually adding successive layers of a material under computer control. This paper shows the ability of the desktop 3D...

Techniques, such as micropipette aspiration and optical tweezers, are widely used to measure cell mechanical properties, but are generally labor-intensive and time-consuming, typically involving a difficult process of manipulation. In the past two decades, a large number of microfluidic devices have been developed due to the advantages they offer o...

Polydimethylsiloxane (PDMS), due to its remarkable properties, is a suitable polymer for the production of microparticles with industrial and medical applications. The micro-sized PDMS liquid droplets suffer a pronounced shrinkage while curing to turn into solid particles. In this article, we report the calibration of the shrinkage phenomenon in th...

Bifurcating networks are commonly found in nature. One example is the microvascular system, composed of blood vessels consecutively branching into daughter vessels, driving the blood into the capillaries, where the red blood cells (RBCs) are responsible for delivering O2 and up taking cell waste and CO2. In this preliminary study, we explore a micr...

Red blood cells (RBCs) deformability is a high relevant mechanical property, whose variations are associated with some diseases, such as diabetes and malaria. Therefore, the present study aims to compare different image processing methods for assessing the RBCs deformability in a continuous flow, measured in a polydimethylsiloxane (PDMS) microchann...

Reflow soldering process is widely implemented in the electronics industry. This method allows the attachment of electronic components to a printed circuit board (PCB) through the melting of solder paste, which makes the interconnection between them. The reflow soldering process must ensures the correctly melting of the solder paste and heating of...

Suspensions of healthy and pathological red blood cells (RBC) flowing in microfluidic devices are frequently used to perform in vitro blood experiments for a better understanding of human microcirculation hemodynamic phenomena. This work reports the development of particulate viscoelastic analogue fluids able to mimic the rheological and hemorheolo...

Intracranial aneurysm is a local dilatation of an intracranial artery with high risk of rupture and death. Although it is generally accepted that the weakening of the arterial wall is the main cause for the rupture of an aneurysm, it still no consensus about the reasons for its creation, expansion and rupture. In particular, what is the role played...

Polydimethylsiloxane (PDMS), due to its remarkable properties, is one of the most widely used polymers in many industrial and medical applications. In this work, a technique based on a flow focusing technique is used to produce PDMS spherical particles with sizes of a few microns. PDMS precursor is injected through a hypodermic needle to form a fil...

The most common and used technique to produce microfluidic devices for biomedical applications is the soft-lithography. However, this is a high cost and time-consuming technique. Recently, manufacturers were able to produce milling tools smaller than 100 μm and consequently have promoted the ability of the micromilling machines to fabricate microfl...

The cell-free layer (CFL) is a hemodynamic phenomenon that has an important contribution to the rheological properties of blood flowing in microvessels. The present work aims to find the closest function describing RBCs flowing around the cell depleted layer in a polydimethysiloxane (PDMS) microchannel with a diverging and a converging bifurcation....

The interest in the development of blood analogues has been increasing recently as a consequence of the increment in the number of experimental hemodynamic studies and the difficulties associated with the manipulation of real blood in vitro because of ethical, economical or hazardous issues. Although one-phase Newtonian and non-Newtonian blood anal...

Red blood cells (RBCs) in microchannels has 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 centre induced by the tank treading motion of the RBC membrane. As a result there is a formation of a cell free layer (CFL) with extremely low...

The behavior of suspensions of individual blood cells, such as red blood cells (RBCs), flowing through microvessels and microfluidic systems depend strongly on the hematocrit (Hct), microvessel topology and cell properties. Although it is well known that blood rheological properties are temperature dependent, to the best of our knowledge no work ha...

Blood flow presents several interesting phenomena in microcirculation that can be used to develop microfluidic devices capable to promote blood cells separation and analysis in continuous flow. In the last decade there have been numerous microfluidic studies focused on the deformation of red blood cells (RBCs) flowing through geometries mimicking m...

Trajectories of both RBC and PBMC flowing around the cross-flow pillars. RBCs deform and pass through the pillars into the branch channel whereas a PBMC rolls along the pillars in the direction of the primary flow.

The study of the blood flow behaviour through microchannels is crucial to improve our understanding about blood flow phenomena happening in the human microcirculatory system. However, the difficulties associated with the use of in vitro blood, such as coagulation and sample storage, have promoted the increasing interest to develop fluids with rheol...

Axial migration of individual red blood cells (RBCs) is a well known effect that happens in microchannels with dimensions below 300 μm. This effect is known as the Fåhræus-Lindqvist effect gives place to a cell free layer (CFL) of plasma located around the walls of the microchannel [1]. Several flow studies regarding the CFL measurement exist in in...

Several studies have already demonstrated that it is possible to perform blood flow studies in microfluidic systems fabricated by using low-cost techniques. However, most of these techniques do not produce microchannels smaller than 100 microns and as a result they have several limitations related to blood cell separation. Recently, manufacturers h...

Microfluidic devices are electrical/mechanical systems that offer the ability to work with minimal sample volumes, short reactions times, and have the possibility to perform massive parallel operations. An important application of microfluidics is blood rheology in microdevices, which has played a key role in recent developments of lab-on-chip devi...

One of the most interesting hemodynamic phenomenon observed in microchannels is the existence of a marginal cell-free layer (CFL) at regions adjacent to the wall. This is a well known phenomenon that occurs in simple glass capillaries and in vivo microvessels, but has never been investigated in detail in biomedical microdevices containing complex g...

In this chapter we discuss the cell-free layer (CFL) developed adjacent to the wall of microgeometries containing complex features representative of the microcirculation, such as contractions, expansions, bifurcations and confluences. The microchannels with the different geometries were made of polydimethylsiloxane (PDMS) and we use optical techniq...

Studies of in vitro blood flow behaviour in stenosis are essential not only as an attempt to understand this phenomenon, but also to develop microfluidic devices, as an alternative clinical methodology to detect blood diseases. Regarding a better understanding of the role that rigid Red Blood Cells (rRBCs) play in the blood flow behaviour, we have...

Red blood cell (RBC) deformability has become one of the important factors to assess blood and cardiovascular diseases. The interest on blood studies have promoted a development of various microfluidic devices that treat and analyse blood cells. Recent years, besides the RBC deformability assessment, these devices are often applied to cancer cell d...

The purpose of this paper is to develop a system able to study experimentally the displacement field of an in vitro intracranial aneurysm. Origin and growth of aneurysms is the result of a complex interaction between biological processes in the arterial wall and the involved hemodynamic phenomena’s. Once the aneurysm forms, the repetitive pressure...

The present study uses a hyperbolic microchannel with a low aspect ratio (AR) to investigate how the red blood cells (RBCs) deform under conditions of both extensional and shear induced flows. The deformability is presented by the degree of the deformation index (DI) of the flowing RBCs throughout the microchannel at its centerline. A suitable imag...

Blood flow in microcirculation shows several interesting phenomena that can be used to develop microfluidic devices for blood separation and analysis in continuous flow. In this study we present a novel continuous microfluidic device for partial extraction of red blood cells (RBCs) and subsequent measurement of RBC deformability. For this purpose,...

In recent years, the population algorithms are becoming increasingly robust and easy to use, based on Darwin's Theory of Evolution, perform a search for the best solution around a population that will progress according to several generations. This paper present variants of hybrid genetic algorithm - Genetic Algorithm and a bio-inspired hybrid algo...

The current study proposes an automatic method for the segmentation and tracking of red blood cells flowing through a 100- μm glass capillary. The original images were obtained by means of a confocal system and then processed in MATLAB using the Image Processing Toolbox. The measurements obtained with the proposed automatic method were compared wit...

A separação e a identificação de células são essenciais em várias aplicações biomédicas, incluindo a biologia celular e os métodos de diagnóstico e terapêuticos. O sangue é um fluido não-Newtoniano contendo inúmeras informações preciosas sobre o estado fisiológico e patológico do corpo humano. No entanto, devido à sua complexidade, existem actualme...

Image analysis is extremely important to obtain crucial information about the blood phenomena in microcirculation. The current study proposes an automatic method for segmentation and tracking red blood cells (RBCs) flowing through a 100 μm glass capillary. The original images were obtained by means of a confocal system and then processed in MatLab...

In this study, in vitro blood flowing through a 100 μm glass capillary was studied. The images were captured using a confocal system and post-processed using Image J and MatLab. The aim of the present work, was to measure the trajectories of the cell-free layer (CFL) by using two different methods, i. e., a manual method (MM) and an automatic metho...

The current study proposes an automatic method for the segmentation and tracking of red blood cells (RBCs) flowing through a 100 mum glass capillary. The measurements obtained with the proposed automatic method are compared with a manual tracking method using nonlinear optimization techniques.

The motion of the red blood cells (RBCs) flowing in microvessels and microchannels depend on several effects, such as hematocrit (Hct), geometry, and temperature. According to our knowledge, the effect of the temperature on RBC motion was never investigated at a microscale level. Hence, the aim of the present work is to determine the effect of the...

The rheological behaviour of the red blood cells (RBCs) flowing in microvessels and microchannels depend on several effects, such as hematocrit (Hct), geometry, and temperature. Previous in vitro studies have measured the Hct effect on the radial dispersion (Dyy) at both diluted and concentrated suspensions of RBCs. However, according to our knowle...