Rui A. Lima

University of Minho · Departamento de Engenharia Mecânica (DEM)

Numerical simulation of carotid artery bifurcation is essential for understanding blood flow dynamics in this complex region, aiding in identifying patterns associated with stress points and atherosclerosis risk. This information is valuable for developing preventive and therapeutic strategies for vascular diseases, as well as optimizing medical de...

This study investigates the impact of hemodynamics on real intracranial aneurysms (IAs) using experiments and computational fluid dynamics (CFD) simulations. A particle tracking velocimetry (PTV) approach was used to study the vortical structures inside a real aneurysm and validate numerical simulations performed at a steady regime for different fl...

One of the most complex human physiological processes to study is pregnancy. Standard animal models, as well as two-dimensional models, lack the complexity and biological relevance required to accurately study such a physiological process. Recent studies have focused on the development of three-dimensional models based on microfluidic systems, desi...

Conventional methods for synthesizing metallic nanoparticles face challenges such as instability and environmental concerns. Therefore, new, simpler, and more eco-friendly methods are being explored. In this context, the study reports a green synthesis process to produce magnetic iron oxide nanoparticles using an aqueous extract of the alga Chlorel...

Researchers have placed engineered or natural tissues within microfluidic chips originating the so-called organ-on-a-chip (OoC) devices. With this technology, organ models can be subjected to phenomena that replicate the complex in vivo biological environment. Furthermore, the OoC devices constitute a more valuable, cost-effective and ethical optio...

Polydimethylsiloxane (PDMS) is an elastomer that has received primary attention from researchers due to its excellent physical, chemical, and thermal properties, together with biocompatibility and high flexibility properties. Another material that has been receiving attention is beeswax because it is a natural raw material, extremely ductile, and b...

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...

This review attempts to provide a comprehensive assessment of recent methodologies, structures, and devices for pool boiling heat transfer enhancement. Several enhancement approaches relating to the underlying fluid route and the capability to eliminate incipient boiling hysteresis, augment the nucleate boiling heat transfer coefficient, and improv...

The organ-on-a-Chip (OOC) concept appeared intending to increase the efficiency and effectiveness of R&D activities, and open doors to precision and personalized medicine. However, for such devices to provide adequate results, they must mimic a specific human microenvironment with great accuracy. In the present work, a computational model of an org...

The combination of microfluidic devices with cell culture methods has risen over the years due to their ability to replicate several diseases and test different therapeutic techniques. Unlike in vivo models, in vitro systems avoid ethical issues and allow researchers to control several physiological variables and mimic the physiological microenviro...

The aim of this study was to investigate the flow within intracranial aneurysms, which are localized dilations of cerebral arteries that pose a risk of rupture and strokes. Experimental analyses were conducted on scaled- down biomodels of a cerebral aneurysm to better understand its flow patterns. To carry out the experimental phase, the biomodels...

The examination of hyperelastic materials’ behavior, such as polydimethylsiloxane (PDMS), is crucial for applications in areas as biomedicine and electronics. However, the limitations of hyperelastic models for specific stress scenarios, with stress concentration, are not well explored on the literature. To address this, firstly, three constitutive...

A computational fluid dynamics (CFD) model of blood flow through hyperbolic contraction with a discrete phase model (DPM) was experimentally validated. For this purpose, the positions and velocities of red blood cells (RBCs) flowing in a microchannel with hyperbolic contraction were experimentally assessed using image analysis techniques, and were...

This study investigates the impact of hemodynamics on real intracranial aneurysms (IAs) using experiments and computational fluid dynamics (CFD) simulations. A particle tracking velocimetry (PTV) approach was used to study the vortical structures inside a real aneurysm and validate numerical simulations performed at a steady regime for different fl...

This work aims to present the development stages of a serpentine heat exchanger, composed uniquely of a thin layer of a silicon-based organic elastomeric polymer, polydimethylsiloxane (PDMS). The novelty of this heat exchanger is that it allows the flowing liquid to wet the surface to be cooled directly, an innovation in relation to traditional exc...

The traditional methods to measure the thermal conductivity of nanofluids (NFs) do not allow the investigation of critical features that affect the NF's heat transfer performance. For instance, during the thermal conductivity measurements, the NF's thermal properties may be subject to several critical features such as sedimentation, aggregation and...

The effect of nanoparticles on the mechanical behavior of red blood cells (RBCs) under an extensional flow has not been extensively studied. In this work, by using a microfluidic hyperbolic contraction, it is assessed the deformability of healthy RBCs in contact with ~20 nm nanoparticles of magnetic iron and non-magnetic cerium. The results showed...

Vegetable oils have been used as metalworking fluids (MWFs) for many years, particularly in small-scale metalworking operations and in industries where environmental regulations are strict. Before the development of modern MWFs, vegetable oils were one of the most common lubricants used for metalworking tools. The use of vegetable oils can be trace...

Late diagnosis and systemic toxicity associated with conventional treatments make oncological therapy significantly difficult. In this context, nanomedicine emerges as a new approach in the prevention, diagnosis and treatment of cancer. In this work, pH-sensitive solid magnetoliposomes (SMLs) were developed for controlled release of the chemotherap...

Microneedles (MNs) have been widely used in biomedical applications for drug delivery and biomarker detection purposes. Furthermore, MNs can also be used as a stand-alone tool to be combined with microfluidic devices. For that purpose, lab- or organ-on-a-chip are being developed. This systematic review aims to summarize the most recent progress in...

The ocean has a huge impact on our way of life; therefore, there is a need to monitor and protect its biodiversity [...]

Cancer continues to be one of the diseases that most affect the population around the world and different lines of research have been conducted to develop new therapies. However, a critical problem in this process is the lack of suitable in vitro preclinical platforms to assess the drug targets, toxicity, and efficacy. In order to surpass these iss...

Organs-on-a-chip, OoC, have been extremely important to reduce the use of animal models allowing researchers to conduct accurate in vitro experiments with high throughput. Year after year, increasingly complex OoC platforms have been developed to better recapitulate the in vivo environment, and numerical simulations have played a fundamental role i...

Although polylactic acid (PLA) is one of the most used materials in additive manufacturing, its mechanical properties are quite limiting for its practical application, therefore, to improve these properties it is frequent to add fibers and, in this way, create a more resistant composite material. In this paper, the authors developed PLA composites...

Cerebral aneurysm is an abnormal dilatation of the blood vessel which affects a high percentage of the worldwide population. One way to investigate this pathology is using in vivo techniques, but these types of experiments have a high cost and low reproducibility. Thus, to understand the local hemodynamics of brain aneurysms, it is imperative to ma...

The separation of red blood cells (RBCs) from blood plasma and the analysis of individual RBCs are of great importance, as they provide valuable information regarding the health of their donor. Recent developments in microfluidics and microfabrication have contributed to the fabrication of microsystems with complex features to promote the separatio...

Cardiovascular diseases are amongst the main causes of death worldwide, and the main underlying pathological process is atherosclerosis. Over the years, fatty materials are accumulated in the arterial which consequently hinders the blood flow. Due to the great mortality rate of this disease, hemodynamic studies within stenotic arteries have been of...

Additive manufacturing technologies are playing a decisive role in the laboratory environment, making a significant difference in STEAM education. Students use additive manufacturing to create physical models, topographic maps, biology artifacts, artwork, all types of engineering prototypes and solving mathematics challenges. By bringing additive m...

Background and objective: In recent years, progress in microfabrication technologies has attracted the attention of researchers across disciplines. Microfluidic devices have the potential to be developed into powerful tools that can elucidate the biophysical behavior of blood flow in microvessels. Such devices can also be used to separate the susp...

At the end of 2019, the coronavirus appeared and spread extremely rapidly, causing millions of infections and deaths worldwide, and becoming a global pandemic. For this reason, it became urgent and essential to find adequate tests for an accurate and fast diagnosis of this disease. In the present study, a systematic review was performed in order to...

In this work, we carried out a comparison between the dry machining of an aluminum block with conventional cutting oil and a block with vegetable oil. The two oils had different flow rates. Using the Taguchi method, it was possible to determine the matrices for optimizing the best parameters for each group of tests. Then, we studied the utility of...

Fluids containing colloidal suspensions of nanometer-sized particles (nanofluids) have been extensively investigated in recent decades with promising results. Driven by the increase in the thermal conductivity of these new thermofluids, this topic has been growing in order to improve the thermal capacity of a series of applications in the thermal a...

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...

Every year, cancer causes millions of deaths around the globe, and researchers have been engaged to provide novel therapies for this threatening disease. However, this process is commonly hampered by failures in clinical trials. For this reason, efforts have been made to develop in vitro models capable of modelling the complex and heterogeneous tum...

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...

Intracranial aneurysms (IA) are dilations of the cerebral arteries and, in most cases, have no symptoms. However, it is a very serious pathology, with a high mortality rate after rupture. Several studies have been focused only on the hemodynamics of the flow within the IA. However, besides the effect of the flow, the development and rupture of the...

Organ-on-chip (OoC) platforms are a new class of advanced microfluidic devices that have been attracting significant attention for drug development since they can allow a faster and more patient specific evaluation of the effects of drugs due to the mimicking of organ human models. As most microfluidic devices, the great majority of the OoC is made...

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...

A linear electromagnetic energy harvesting device for underwater applications, fabricated with a simple manufacturing process, was developed to operate with movement frequencies from 0.1 to 0.4 Hz. The generator has two coils, and the effect of the combination of the two coils was investigated. The experimental study has shown that the energy captu...

The development of micro- and nanodevices for blood analysis continues to be agrowing interdisciplinary subject that demands the careful integration of different research fields [...]

Polydimethylsiloxane (PDMS) is one of the best known elastomers and has been used in several areas of activity, due to its excellent characteristics and properties, such as biocompatibility, flexibility, optical transparency and chemical stability. Furthermore, PDMS modified with other materials promotes the desired changes to broaden its range of...

In this review work, the recent progress made in the use of nanofluids (NFs) applied in three specific areas will be presented: machining, solar energy, and biomedical engineering. Within this context, the discussions will be guided by emphasizing the thermal and stability properties of these fluids. In machining, NFs play a prominent role in the p...

Atherosclerosis is one of the leading causes of death worldwide. It is a chronic inflammatory disease of the arterial wall that progressively reduces the lumen size because of plaque formation. To understand this pathological process, several hemodynamic studies have been carried out, either experimentally or numerically. However, experimental stud...

Engineering education is a challenging topic that has been deeply explored in order to provide better educational experiences to engineering students, and the learning by doing approach has been appraised. Amidst a global pandemic, an engineering summer program denominated i9Masks emerged and aimed to create transparent facial masks for preventing...

Organ-on-a-chip (OoC) platforms have revolutionized the drug development process by offering an effective alternative to animal models. These advanced microfluidic platforms mimic the organ functions at a microscale, and they can be produced at a large scale and at a lower price. Despite the variety of OoC models developed up to now, the combinatio...

Polydimethylsiloxane (PDMS) is an elastomer with excellent optical, electrical and mechanical properties, which makes it well-suited for several engineering applications. Due to its biocompatibility, PDMS is widely used for biomedical purposes. This widespread use has also led to the massification of the soft-lithography technique, introduced for f...

Polydimethylsiloxane (PDMS) is one of the most promising elastomers due its remarkable proprieties such as good thermal stability, biocompatibility, corrosion resistance, flexibility, low cost, ease of use, chemically inertia, hyperplastic characteristics, and gas permeability. Thus, it can be used in areas such as microfluidic systems, biomedical...

Polydimethylsiloxane (PDMS) has been a promising material for microfluidic, particularly in lab-on-chip. Due to the panoply of good physical, mechanical and chemical properties, namely, viscosity, modulus of elasticity, colour, thermal conductivity, thermal coefficient of expansion, its application has been increasingly requested in quite different...

The nanofluids (NFs) are known as a colloidal suspension where nanoparticles (NPs) are dispersed in conventional base fluids (BFs). This suspension has been frequently used to augment the heat transfer (HT) capacity of a fluid by studying their thermophysical properties. This review outlines the most recent advances on the NFs thermal properties an...

This study addresses the combination of customized surface modification with the use of nanofluids, to infer on its potential to enhance pool boiling heat transfer. Hydrophilic surfaces patterned with superhydrophobic regions are prepared and used to act as surface interfaces with nanofluids (water with gold, silver and alumina nanoparticles) and i...

This study presents a research experience with engineering students at undergraduate and graduate levels, during the summer of 2020 at the School of Engineering, University of Minho, Portugal. Following the first pandemic event in Portugal, from March to May 2020, the Foundation for promoting Science and Technology (FCT) has opened a call for resea...

Intracranial aneurysm (IA) is a pathology that in most cases does not present symptoms in the patient and is still not well understood in relation to the interaction of factors that develop it. Therefore, determining methods to assess risk factors and assist in medical diagnosis is of great importance. With that, the objective of this work was to c...

Numerical simulations have revolutionized research in several engineering areas by contributing to the understanding and improvement of several processes, being biomedical engineering one of them. Due to their potential, computational tools have gained visibility and have been increasingly used by several research groups as a supporting tool for th...

The analysis of the thermal conductivity of nanofluids (NFs) is extremely important to better understand the heat transfer mechanisms involved in the performance and efficiency of several thermal devices. In this work, two different NFs were tested using distilled water (DI-Water) as the base fluid. The first was a traditional NF formed by Al2O3 na...

This experimental and phenomenological study investigated fluctuations and characteristic frequencies of pressure drop and flow pattern during flow boiling of isobutane in a horizontal mini-channel 1.0 mm in diameter. The fluid was investigated at a saturation condition of 27°C, heat flux ranging between 1 and 80 kW/m² and mass flux ranging from 38...

This paper presents a qualitative and quantitative comparison between the finite element and the finite volume methods for the fluid-structure interaction simulation of blood flow through a real stenosed artery. The artery geometry corresponds to a severely stenosed (around 75 % lumen reduction) portion of the brachiocephalic trunk, located immedia...

Three-dimensional (3D) in vitro models, such as organ-on-a-chip platforms, are an emerging and effective technology that allows the replication of the function of tissues and organs, bridging the gap amid the conventional models based on planar cell cultures or animals and the complex human system. Hence, they have been increasingly used for biomed...

Microfluidics has proven to be an extraordinary working platform to mimic and study blood flow phenomena and the dynamics of components of the human microcirculatory system. However, the use of real blood increases the complexity to perform these kinds of in vitro blood experiments due to diverse problems such as coagulation, sample storage, and ha...

Polydimethylsiloxane (PDMS) is a polymer that has attracted the attention of researchers due to its unique properties such as transparency, biocompatibility, high flexibility, and physical and chemical stability. In addition, PDMS modification and combination with other materials can expand its range of applications. For instance, the ability to pe...