Publications

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2019
Cristovão, A. F., D. Sousa, F. Silvestre, I. Ropio, A. Gaspar, C. Henriques, A. Velhinho, A. C. Baptista, M. Faustino, and I. Ferreira, "Customized tracheal design using 3D printing of a polymer hydrogel: influence of UV laser cross-linking on mechanical properties", 3D Print Med, vol. 5, pp. 12, 2019.
Coroa, J., B. M. Morais Faustino, A. C. Marques, C. Bianchi, T. Koskinen, T. Juntunen, I. Tittonen, and I. Ferreira, "Highly transparent copper iodide thin film thermoelectric generator on a flexible substrate", RSC Advances, vol. 9, pp. 35384, 2019.
Esperança Garcia, D. M., A. S. Taborda Martins Pereira, A. C. Almeida, U. Santana Roma, A. Ben Aissa Soler, P. D. Lacharmoise, I. M. M. das Ferreira, and C. C. D. Simao, "Large-Area Paper Batteries with Ag and Zn/Ag Screen-Printed Electrodes", ACS Omega, vol. 4, pp. 16781−16788, 2019. acsomega.9b01545.pdf
2018
Ropio, I., A. C. Baptista, J. P. Nobre, J. Correia, F. Belo, S. Taborda, M. B. M. Faustino, J. P. Borges, A. Kovalenko, and I. Ferreira, "Cellulose paper functionalised with polypyrrole and poly(3,4-ethylenedioxythiophene) for paper battery electrodes", Org Electron, 2018. AbstractDOI

A simple process of commercial paper functionalisation via in situ polymerisation of conductive polymers onto cellulose fibres was investigated and applied as electrodes in paper-based batteries. The functionalisation involved polypyrrole (PPy) and Poly (3,4-ethylenedioxythiophene) (PEDOT) as conductive polymers with the process of functionalisation optimised for each polymer individually with respect to oxidant-to-monomer ratios and polymerisation times and temperature. Paper with conductivity values of 44 mS/cm was obtained by exposing the samples to pyrrole vapour for a period of 30 min at room temperature; however, polymerisation at temperatures of 40 °C lead to higher conductivity values to up 141 mS/cm. Consequently, functionalised PPy and PEDOT papers were applied as cathodes in batteries with Al foil anodes and commercial paper soaked in an electrolyte solution of NaCl.

Baptista, A. C., I. Ropio, B. Romba, J. P. Nobre, C. Henriques, J. C. Silva, J. I. Martins, J. P. Borges, and I. Ferreira, "Cellulose-based electrospun fibers functionalized with polypyrrole and polyaniline for fully organic batteries", J Mater Chem A, vol. 6, issue 1, pp. 256-265, 2018. AbstractDOI

A novel cellulose-based bio-battery made of electrospun fibers activated by biological fluids has been developed. This work reports a new concept for a fully organic bio-battery that takes advantage of the high surface to volume ratio achieved by an electrospun matrix composed of sub-micrometric fibers that acts simultaneously as the separator and the support of the electrodes. Polymer composites of polypyrrole (PPy) and polyaniline (PANI) with cellulose acetate (CA) electrospun matrix were produced by in situ chemical oxidation of pyrrole and aniline on the CA fibers. The structure (CA/PPy|CA|CA/PANI) generated a power density of 1.7 mW g−1 in the presence of simulated biological fluids, which is a new and significant contribution to the domain of medical batteries and fully organic devices for biomedical applications.

Faustino, B. M. M., D. Gomes, J. Faria, T. Juntunen, G. Gaspar, C. Bianchi, A. Almeida, A. C. Marques, I. Tittonen, and I. Ferreira, "CuI p-type thin films for highly transparent thermoelectric pn modules", Sci Rep, vol. 8, issue 1, pp. 6867-6867, 2018. AbstractDOI

Developments in thermoelectric (TE) transparent p-type materials are scarce and do not follow the trend of the corresponding n-type materials – a limitation of the current transparent thermoelectric devices. P-type thermoelectric thin films of CuI have been developed by three different methods in order to maximise optical transparency (>70% in the visible range), electrical (σ = 1.1 × 104 Sm−1) and thermoelectric properties (ZT = 0.22 at 300 K). These have been applied in the first planar fully transparent p-n type TE modules where gallium-doped zinc oxide (GZO) thin films were used as the n-type element and indium thin oxide (ITO) thin films as electrodes. A thorough study of power output in single elements and p-n modules electrically connected in series and thermally connected in parallel is inclosed. This configuration allows for a whole range of highly transparent thermoelectric applications.

2017
Delgado-Lima, A., J. P. Borges, I. M. Ferreira, and A. V. Machado, "Fluorescent and conductive cellulose acetate-based membranes with porphyrins", Materials Today Communications, vol. 11, pp. 26-37, 2017. AbstractDOI

The unique properties of electrospun nanofibers combined with functional compounds allow the preparation of novelty materials that can be employed in a wide range of applications. Among a vast number of polymers, Cellulose Acetate (CA) it is considered easy to electrospun and it was employed as the polymeric matrix, where free and iridium-porphyrins were incorporated. Two different solvent systems were employed according to the porphyrin used, and the best dispersion level on both the electrospun solution and the membranes, was achieved with the iridium porphyrin. The nanofibers with this porphyrin also exhibited electrical properties, while the fluorescence was quenched by the presence of specific axial ligands.

Faria, P., P. Duarte, D. Barbosa, and I. Ferreira, "New composite of natural hydraulic lime mortar with graphene oxide", Constr Build Mater, vol. 156, pp. 1150-1157, 2017. AbstractDOI

Recent studies show the incorporation of graphene oxide (GO) in cement composites. But these composites are frequently incompatible with original materials for building rehabilitation. To overcome this limitation, natural hydraulic lime mortars were used as matrix, and the influence of GO percentage and type of mixing was investigated. The influence on the microstructure, mechanical and physical properties was assessed. The best results were obtained with dispersed GO at concentrations of 0.05% and 0.1%. A slight improvement of mechanical and physical characteristics was achieved. This could lead to new mortars with improved properties that can be used for building rehabilitation.

Figueira, J., J. Loureiro, J. Marques, C. Bianchi, P. Duarte, M. Ruoho, I. Tittonen, and I. Ferreira, "Optimization of Cuprous Oxides Thin Films to be used as Thermoelectric Touch Detectors", ACS Appl Mater Interfaces, vol. 9, issue 7, pp. 6520-6529, 2017. AbstractDOI

The electronic and optical properties of p-type copper oxides (CO) strongly depend on the production technique as it influences the obtained phases: cuprous oxide (Cu2O) or cupric oxide (CuO), the most common ones. Cu films deposited by thermal evaporation have been annealed in air atmosphere, with temperature between 225 and 375 °C and time between 1 and 4 h. The resultant CO films have been studied to understand the influence of processing parameters in the thermoelectric, electrical, optical, morphological, and structural properties. Films with a Cu2O single phase are formed when annealing at 225 °C, while CuO single phase films can be obtained at 375 °C. In between, both phases are obtained in proportions that depend on the film thickness and annealing time. The positive sign of the Seebeck coefficient (S), measured at room temperature (RT), confirms the p-type behavior of both oxides, showing values up to 1.2 mV·°C–1and conductivity up to 2.9 (Ω·m)−1. A simple detector using Cu2O have been fabricated and tested with fast finger touch events

2016
Bari, M., J. Loureiro, M. Pudas, K. Tappura, K. Jaakola, M. Ruoho, I. Tittonen, S. Volz, C. Pavan, K. Costabello, D. Bollen, M. Haslam, and I. Ferreira, "TransFlexTeg: Large area transparent thin film thermoelectric devices for smart window and flexible applications", 14th European Conference on Thermoelectrics, ECT 2016, 20-23 Sep, 2016. Abstract

The main objective of TransFlexTeg is to develop an innovative large area distributed sensor network integrating transparent thin film thermoelectric devices and sensors for multifunctional smart windows and flexible high impact volume applications. Different breakthrough concepts will be developed: 1) large area high performance transparent thermoelectric thin films deposited on flexible substrates for thermal energy harvesting; 2) low cost high throughput thin film thermal sensors for thermal mapping and gesture sensing; 3) flexible smart windows and walls with energy harvesting, environmental sensing and wireless communication functionalities. This technology aims to demonstrate the functionalities of a smart window able to measure air quality and environmental parameters such as temperature, sun radiation and humidity. The data is automatically collected and can be utilized for controlling heating, cooling and ventilation systems of indoors. Active radio interface enables long range communication and long term data collection with WiFi or a similar base station. The proposed concept of smart windows replaces several conventional sensors with a distributed sensor network that is integrated invisibly into windows. In addition to the power generated from the thermal energy harvesting, the thermoelectric elements (TE) are also used as temperature sensors that, while being distributed over large area, enable thermal mapping of the area instead of just one or a few values measured from particular points. This smart window can be produced on glass. The active layer itself can be flexible glass layer or polymer sheet, which will significantly broaden the field of applications and improve business opportunities. Both can be manufactured in batch, or in Roll to Roll Atomic Layer Deposition (R2R ALD) process. High environmental impact is expected with savings of more than 25% of the electrical usage of residential homes and office buildings.