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Projeto de investigação
Portable Microfluidic system for fast molecular diagnostics of Stroke
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A Review of Methods to Modify the PDMS Surface Wettability and Their Applications
Publication . Neves, Lucas Boniatti; Afonso, Inês Santos; Nobrega, Glauco; Barbosa, Luiz G.; Lima, Rui A.; Ribeiro, J.E.
Polydimethylsiloxane (PDMS) has attracted great attention in various fields due to its excellent properties, but its inherent hydrophobicity presents challenges in many applications that require controlled wettability. The purpose of this review is to provide a comprehensive overview of some key strategies for modifying the wettability of PDMS surfaces by providing the main traditional methods for this modification and the results of altering the contact angle and other characteristics associated with this property. Four main technologies are discussed, namely, oxygen plasma treatment, surfactant addition, UV-ozone treatment, and the incorporation of nanomaterials, as these traditional methods are commonly selected due to the greater availability of information, their lower complexity compared to the new techniques, and the lower cost associated with them. Oxygen plasma treatment is a widely used method for improving the hydrophilicity of PDMS surfaces by introducing polar functional groups through oxidation reactions. The addition of surfactants provides a versatile method for altering the wettability of PDMS, where the selection and concentration of the surfactant play an important role in achieving the desired surface properties. UV-ozone treatment is an effective method for increasing the surface energy of PDMS, inducing oxidation, and generating hydrophilic functional groups. Furthermore, the incorporation of nanomaterials into PDMS matrices represents a promising route for modifying wettability, providing adjustable surface properties through controlled dispersion and interfacial interactions. The synergistic effect of nanomaterials, such as nanoparticles and nanotubes, helps to improve wetting behaviour and surface energy. The present review discusses recent advances of each technique and highlights their underlying mechanisms, advantages, and limitations. Additionally, promising trends and future prospects for surface modification of PDMS are discussed, and the importance of tailoring wettability for applications ranging from microfluidics to biomedical devices is highlighted. Traditional methods are often chosen to modify the wettability of the PDMS surface because they have more information available in the literature, are less complex than new techniques, and are also less expensive.
Recent Advances of PDMS In Vitro Biomodels for Flow Visualizations and Measurements: From Macro to Nanoscale Applications
Publication . Souza, Andrews; Nobrega, Glauco; Neves, Lucas Boniatti; Barbosa, Filipe; Ribeiro, J.E.; Ferrera, Conrado; Lima, Rui A.
Polydimethylsiloxane (PDMS) has become a popular material in microfluidic and macroscale in vitro models due to its elastomeric properties and versatility. PDMS-based biomodels are widely used in blood flow studies, offering a platform for improving flow models and validating numerical simulations. This review highlights recent advances in bioflow studies conducted using both PDMS microfluidic devices and macroscale biomodels, particularly in replicating physiological environments.
PDMS microchannels are used in studies of blood cell deformation under confined conditions, demonstrating the potential to distinguish between healthy and diseased cells. PDMS also plays a critical role in fabricating arterial models from real medical images, including pathological conditions such as aneurysms. Cutting-edge applications, such as nanofluid hemodynamic studies and nanoparticle drug delivery in organ-on-a-chip platforms, represent the latest developments in PDMS research. In addition to these applications, this review critically discusses PDMS properties, fabrication methods, and its expanding role in micro- and nanoscale flow studies.
Advances in Microfluidic Systems and Numerical Modeling in Biomedical Applications: A Review
Publication . Ferreira, Mariana; Carvalho, Violeta Meneses; Ribeiro, J.E.; Lima, Rui A.; Teixeira, Senhorinha F.C.F.; Pinho, Diana
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 review explores fabrication techniques
and common materials of microfluidic devices, focusing on soft lithography and additive manufacturing.
Microfluidic systems applications, including nucleic acid amplification and protein synthesis,
as well as point-of-care diagnostics, DNA analysis, cell cultures, and organ-on-a-chip models (e.g.,
lung-, brain-, liver-, and tumor-on-a-chip), are discussed. Recent studies have applied computational
tools such as ANSYS Fluent 2024 software to numerically simulate the flow behavior. Outside of
the study cases, this work reports fundamental aspects of microfluidic simulations, including fluid
flow, mass transport, mixing, and diffusion, and highlights the emergent field of organ-on-a-chip
simulations. Additionally, it takes into account the application of geometries to improve the mixing
of samples, as well as surface wettability modification. In conclusion, the present review summarizes
the most relevant contributions of microfluidic systems and their numerical modeling to
biomedical engineering.
Experimental Investigation of Green Nanofluids: Assessment of Wettability, Viscosity and Thermal Conductivity
Publication . Nobrega, Glauco; Cardoso, Beatriz D.; Barbosa, Filipe; Pinho, Diana; Abreu, Cristiano; Souza, Reinaldo Rodrigues de; Moita, Ana S.; Ribeiro, J.E.; Lima, Rui A.
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 nanoparticles face challenges such as instability and environmental concerns, prompting the exploration of greener synthesis methods. Green synthesis uses natural resources like plants and algae as reducing agents, offering a more environmentally friendly approach for the synthesis of metallic nanoparticles. These green-synthesized metallic nanoparticles can enhance heat transfer by becoming part of nanofluids (NFs), which are colloidal mixtures of NPs in a fluid base. NFs, employed for heat transfer.
As a result, it is essential to characterize the NFs regarding wettability, viscosity, and thermal conductivity. The results of the spectrophotometer confirmed the green synthesis of NPs, and it was observed that the increase in NP concentration impacted the contact angle, improving the ability to wet.
The thermal conductivity is also modified, with an improvement of 11.3% compared to distilled water, without a significant increase in fluid viscosity.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
Concurso de Projetos de I&D em Todos os Domínios Científicos - 2022
Número da atribuição
2022.02085.PTDC