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Projeto de investigação
All-Fibre Integrated Photovoltaic Storage Device for e-Textiles
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Publicações
Drug Delivery from PCL/Chitosan Multilayer Coatings for Metallic Implants
Publication . Soares, I.; Faria, Jaime Moreira Machado; Marques, A. C.; Ribeiro, Isabel A. C.; Baleizão, Carlos; Bettencourt, Ana F.; Ferreira, Isabel; Baptista, Ana Catarina; DCM - Departamento de Ciência dos Materiais; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); ACS - American Chemical Society
Implant-related infections, mainly caused by Staphylococcus aureus, are a major health concern. Treatment is challenging due to multi-resistant strains and the ability of S. aureus to adhere and form biofilms on bone and implant surfaces. The present work involved the preparation and evaluation of a novel dual polymeric film coating on stainless steel. Chitosan and polycaprolactone (PCL) multilayers, loaded with poly(methyl methacrylate) (PMMA) microspheres encapsulating vancomycin or daptomycin, produced by the dip-coating technique, allowed local antibiotic-controlled delivery for the treatment of implant-related infections. Enhanced adhesion of the film to the metal substrate surface was achieved by mechanical abrasion of its surface. Studies have shown that for both drugs the release occurs by diffusion, but the release profile depends on the type of drug (daptomycin or vancomycin), the pH of the solution, and whether the drug is freestanding (directly incorporated into the films) or encapsulated in PMMA microspheres. Daptomycin freestanding films reached 90% release after 1 day at pH 7.4 and 4 days at pH 5.5. In comparison, films with daptomycin encapsulated microspheres reached 90% release after 2 h at pH 5.5 and 2 days at pH 7.4. Vancomycin encapsulated and freestanding films showed a similar behavior reaching 90% release after 20 h of release at pH 5.5 and 2 and 3 days, respectively, at pH 7.4. Furthermore, daptomycin-loaded films showed activity (assessed by agar diffusion assays) against sensitive (ATCC 25923) and clinically isolated (MRSA) S. aureus strains.
Desenvolvimento de fios condutores para aplicações em têxteis inteligentes utilizando a técnica de Electrofiação
Publication . Rodrigues, Frederico Ferreira; Baptista, Ana; Canejo, João
Nas últimas duas décadas, a investigação sobre a aplicação de nanofibras poliméricas nas áreas dos têxteis inteligentes tem ganho cada vez mais interesse nomeadamente em sensores, engenharia de tecidos, comunicação e medicina. As nanofibras possuem características notáveis e com grande potencial, como a sua elevada área superficial, baixa porosidade, e excelentes propriedades mecânicas.
A Electrofiação é um método simples, versátil e de baixo custo de produção, que tem sido amplamente utilizado por vários investigadores no fabrico de nanofibras para têxteis inteligentes.
Esta dissertação tem como objetivo o desenvolvimento de fibras condutoras à base de Acetato de Celulose e Policaprolactona produzidas por Electrofiação, dispostas sob a forma de membranas e fios. O Polipirrole foi o polímero condutor utilizado para conferir condutividade elétrica às fibras. Foi utilizada a polimerização in situ do pirrol de modo a revestir as membranas e fios produzidos e estes adquirirem propriedades condutoras. Assim, foi realizado um estudo detalhado dos melhores parâmetros de polimerização (vários tempos de imersão de agente oxidante (FeCl3) e de tempo de polimerização) de modo a maximizar a condutividade das membranas/fios sem afetar as suas propriedades mecânicas.
Foram realizados ensaios de tração, para comparar as propriedades mecânicas (módulo de Young, resistência à fratura e percentagem de elongação) das membranas e fios com e sem revestimento.
As membranas atingiram condutividades elétricas planares e transversais, de 2,3x10-2 S.cm-1 e 7,9x10-4 S.cm-1, respetivamente, enquanto os fios exibiram condutividades planares de 4,0x10-2 S.cm-1.
Understanding the Capacitive and Diffusion-Controlled Behavior of Electrophoretically Deposited V2CTx on Carbon Yarn as a Potential Anode for Asymmetric Devices
Publication . Rafique, Amjid; Naeem, Usman; Marques, Ana; Ferreira, Isabel; Rizwan, Syed; Baptista, Ana Catarina; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; ACS - American Chemical Society
Recently, a novel class of emerging 2D materials identified as MXene have been revolutionizing the fabrication and development of flexible energy storage systems, i.e., batteries and supercapacitors. Herein, the focus is on the remarkable capacitive performance of V2CTx MXene-based flexible electrodes so far poorly explored. However, research was focused on Ti3C2Tx and its applications in the energy field, although more than 100 other members of this group have already been reported. Some of these MXenes are emerging as potential candidates for energy applications with promising results such as Ti2C and Mo2C in aqueous electrolytes, but many others remain to be explored. The paper detailed a comprehensive study of the electrophoretic deposition of V2CTx on carbon yarn wires and the evaluation of their electrochemical behavior (capacitive and diffusive) in three electrolytes at different pH values: acidic, basic, and neutral pH to investigate the correct potential window for this material in energy applications. The devices exhibited specific capacitances of 248, 177, and 89 F g-1 for EPD10, EPD20, and EPD30, respectively. The synthesized and deposited MXene nanoparticles were analyzed by XRD, Raman, and SEM for phase identification, chemical structure identification, and morphological analysis, respectively. The synthesized material showed good electrochemical performance in terms of cyclic stability after 3000 cycles with >90% capacitance retention.
Fabric based supercapacitors towards wearable applications
Publication . Oliveira, Eduardo Varandas; Baptista, Ana; Ferreira, Isabel
Nowadays, the constant need to obtain energy from renewable energies demands a
high range of devices capable of storing energy. Comparing renewable energy to non-renew-
able energy, the ability to store energy is very important due to the lack of continuity of en-
ergy generation. The use of supercapacitors is a great opportunity to obtain a storage device
capable of supplying small electronic devices with properties such as high flexibility and per-
meability, which allow these components to be integrated in wearable technologies.
Some supercapacitors were already developed, showing the potential to be used as en-
ergy storage devices, using carbon yarns as electrodes and SSS as electrolyte, providing the
desired properties for these devices to be used in wearable technologies. In this thesis re-
search was conducted to study the potential of using commercial carbon yarns as a substrate
to obtain electrodes with different active materials, for instance copper and copper iodide, to
use in fiber-based supercapacitors. These materials were analyzed trough optical microscopy
to understand the material's adhesion, Raman spectroscopy for elemental characterization,
Cyclic voltammetry to obtain the electrochemical information needed to seek the potential of
these samples, from both 3-electrode analysis (isolated electrode behavior) and 2-electrode
setup to evaluate a fully constructed supercapacitor when subjected to different potential
windows and scan-rates.
The result of this thesis provides alternatives to the prepare electrodes for fiber-shaped
supercapacitors towards wearable technologies, expanding the range of characteristic prop-
erties and therefore, make these devices more desirable to use in this mean. Supercapacitor
behavior was found using devices with both electrodes, even with some problems regarding
electrode stability due to the irreversible reactions occurring during the potential sweep, hav-
ing the electrode coating react with the electrolyte.
1D Fiber-shaped supercapacitors
Publication . Henriques, João Tiago Soares; Baptista, Ana; Ferreira, Isabel
Nowadays, exponential technological advances, allied with contemporary mass globalization, drove humankind to a whole new world of possibilities and specialized solutions, able to answer our daily challenges of all life aspects. An example of these new technological solutions is the emerging intelligent textiles, best known as wearables or e-clothes, capable of enhancing daily garments, by adding new revolutionary functionalities.
In this work, it will be presented three new configurations of energy storage devices (supercapacitors) based on already studied textile materials [1], especially suitable for wearable electronics applications. The presented configurations, namely, the braid-like, the woven, and the mesh-like configuration, have commercial carbon threads as electrodes and share a simulated sweat solution electrolyte since these devices were designed to work with user sweat. For the separation layer, electrospun cellulose acetate nanofibers were used in the braid-like and the mesh-like configurations, and a hydrophilic felt for the woven one. Moreover, electrode functionalization with polypyrrole (PPy) was carried out, showing considerable results in the device performance enhancement. Regarding the electrical study, cyclic voltammetry and cyclic charge-discharge experiments were the primary characterization technics. Additionally, washability and cyclic charge-discharge endurance (for 1000 cycles) were addressed for the two most successful configuration (the brain-like and internally woven configurations). The electrical characterization showed promising results, estimating 0.62 F.g-1 for the most successful device (replica 3 from internally woven configuration) and one order of magnitude enhancement with electrodes functionalization step. Moreover, the washability study proven the supercapacitors (the brain-like and internally woven configurations) ability to maintain most of its electrical performance after 5 washing cycles, with special highlights for the internally woven configuration that maintain more than 80% of its initial specific capacitance for both studied replicas. Additionally, electrodes PPy functionalization’s quality and assembling processes proven to be the key points for devices success.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
3599-PPCDT
Número da atribuição
PTDC/CTM-CTM/1571/2020