Biofluids
Coronary Artery Disease
This study, initiated in 2008 in collaboration with the cardiology team at Vila Nova de Gaia Hospital, focuses on the left coronary artery and examines the effects of geometry, blood rheology, and pulsatile flow. Experimental techniques employing particle image velocimetry (PIV) were developed to analyze the flow field, complemented by the development and validation of numerical models. The research extended to studying arteries with stenoses, analyzing changes in the flow field and their effects on wall shear stresses through both experimental and numerical methods. Subsequently, coronary artery images from patients at Vila Nova de Gaia Hospital were analyzed. This analysis led to the creation of a predictive tool aimed at forecasting stenosis evolution, based on the hypothesis that wall shear stress distribution significantly influences arteriosclerosis development.
Coronary artery disease (CAD) ranks among the leading global causes of death, and Portugal is no exception. The SimulCAD project represents a pioneering effort to develop an AI-driven Decision Support System (DSS) for predicting CAD progression. Operating within a multidisciplinary consortium, including collaboration with Braga’s Catheterization laboratory (CCAB) since 2019, this initiative leverages a comprehensive database of over 20,000 diagnostic coronary angiography records. By integrating clinical data, 3D imaging analysis, computational fluid dynamics (CFD), and machine learning (ML), the purpose is to discover morphological and hemodynamic patterns directly correlated with the progression of atherosclerosis and transform CAD management by providing precise prognostic tools that enhance clinical decision-making and improve patient outcomes.
Rheology and magnetorheology of human biofluids
Since 2012, studies on the rheological characterisation of biopolymers and biofluids have been developed. Passive microrheology was used to measure the shear response of human blood preserved with EDTA. The results showed the elastic nature of blood. In addition, four different polymer solutions with different refractive indices (1.39 and 1.41) were proposed as viscoelastic blood analogues capable of mimicking human blood’s shear and extensional rheology. The scientific community has used these blood analogues since then.
A recent study was conducted to analyse the complex rheology of human blood plasma. This research was extended to the microrheological characterisation of Cyanoflan in human blood plasma. The application of microrheological techniques was fundamental, allowing for a detailed examination of the behaviour of Cyanoflan particles within the complex fluid dynamics of human blood plasma. Passive microrheology techniques have offered a unique perspective in understanding how Cyanoflan interacts with blood plasma constituents.
The research team is currently investigating the impact of magnetic fields on the viscoelastic properties of human blood. The primary objective of this project is to establish a pioneering framework for predicting how blood viscoelasticity is influenced by magnetic fields during shear and uniaxial extensional flows. This research addresses questions concerning the correlation between blood rheology and the intensity and orientation of the magnetic field, the alterations in blood microstructure under these external forces, and their manifestation in its intrinsic characteristics. Ultimately, this research will significantly contribute to the field of hemorheology for biomedical applications.
Biofilms in medical devices
Biofilms are agglomerations of microorganisms embedded in a matrix of EPS. This structure provides to the microorganisms a higher resistance against chemical and mechanical removal processes, increasing their antibiotic resistance. Cleaning of catheters/micro channels is a crucial operation. We seek new solutions to prevent cell adhesion and biofilms development, and infection risk reduction techniques. Devices to study biofilms, organs-on-a-chip and cell communities are also under development.
Food rheology
International collaborations (Randy Ewoldt from the University of Illinois at Urbana-Champaign and Clara A. Tovar from the University of Vigo) led to the publishing of some exciting works related to characterising the viscoelastic response of two distinct varieties of the Spanish cheese, Afuega’l Pitu, the atroncau blancu and roxu varieties, both holding the prestigious PDO (Protected Designation of Origin) designation under varying stress conditions, providing valuable insights into their mechanical behaviour. The LAOStress analysis was a powerful tool to unveil the dynamic interplay of forces within the cheese matrix, offering a unique perspective on these cheeses’ structural and textural attributes.
Complex fluid dynamics around microbots prototypes
Studies on 3D fluid flow around microscale vehicles (microbots) moving through blood vessel analogues to characterize their hydrodynamics and provide guidelines for use in human circulatory system are foreseen. This project opened collaborations with companies manufacturing 3D printed microdevices favoring the international networking and participation in H2020 projects. Two research projects relating with this topic have already been founded since 2014.