17 documents found, page 1 of 2
Influence of adhesive on optical fiber-based strain measurements on printed cir...
Freitas, C.; Leite, T. M.; Lopes, H.; Gomes, M.; Cruz, Sílvia Manuela Ferreira; Magalhães, R.; Ferreira da Silva, Alexandre; Viana, J. C.; Delgado, I.The use of optical fiber sensing for strain measurements on printed circuit boards is a recent approach, and there is a lack of f reliable methods to obtain valid strain measurements. This work investigates the influence of different adhesives and their application for strain measurements using optical fiber sensors on PCB, considering room and high temperature tests. Strain developed in PCB during production a...
Injection molding of high-precision optical lenses: A review
Peixoto, Carina; Valentim, Pablo T.; Sousa, Patrícia C.; Dias, Diana; Araújo, Cátia; Pereira, Diogo; Machado, Catarina F.; Pontes, A. J.; Santos, HélioInjection molding (IM) is the most efficient mass production technology for manufacturing polymers in complex and detailed geometries with high precision. Although, with the demanding requirements for the optical components, the manufacturing process continues to be a challenge. The majority of optical components require high optical quality with low residual stress, high replication degree, and precisely contr...
Anti-reflective and superamphiphilic coatings on polycarbonate
Valentim, P. T.; Retolaza, A.; Llobet, J.; Araújo, C.; Cruz, Sílvia Manuela Ferreira; Machado, C.; Pontes, A. J.; Santos, H.; Sousa, P. C.In this work, we investigated the transmission enhancement of a polycarbonate substrate (PC) at the beginning of the near-infrared part of the electromagnetic spectrum, by incorporating anti-reflective coatings (ARC) on the surface. Thin film ARC formed by combining layers of SiO2, TiO2, and SiNx were studied, and the influence of the layers thickness on the optical response of the systems was explored, with th...
Thermoelectric response of a screen printed silver-nickel thermocouple
Cruz, Sílvia Manuela Ferreira; Azevedo, Gabriela; Raya, Clara Maria Cano; Manninen, Nora Kristiina Alves Sousa; Viana, J. C.The lack of inks with adequate properties for the development and construction of a fully printed thermocouple requires the adoption of a different approach. Silver and nickel screen printing inks were selected for the sensing materials, considering their low sintering temperature, required for polymer substrates, and its greatest cost-benefit ratio between the existing materials. This work studied the influenc...
Distributed optical fiber sensors for PCB-strain analysis
Gomes, José Miguel Sousa; Cruz, Sílvia Manuela Ferreira; Lopes, Henrique; Arcipreste, Bruno; Magalhães, Roberto; Ferreira da Silva, AlexandrePrinted circuit board (PCB)-strain tests are part of the quality control processes to detect and identify predamages on manufactured products. Such tests are commonly performed by instrumenting a PCB, and subjecting it to the manufacturing conditions. Among the various parameters to evaluate on the production equipment, the induced strain on the PCB is one of them, enabling the assessment of the manufacturing e...
Piezo-resistive behaviour at high strain levels of PEDOT:PSS printed on a flexi...
Cruz, Sílvia Manuela Ferreira; Rocha, Luís Alexandre Machado; Viana, J. C.In this work a conductive poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) thin film was deposited on a treated surface of a flexible substrate using ink-jet printed technique. The novel surface treatment method increased significantly the substrate surface energy (by 45 %) and consequently the thermoplastic polyurethane wettability. SEM and AFM evaluated the thickness uniformity and roughness of the pri...
Analysis of the bonding process and materials optimization for mitigating the Y...
Cruz, Sílvia Manuela Ferreira; Sousa, Andre; Viana, J. C.; Martins, TiagoThe Optical Bonding (OB) technology has become a critical aspect of the performance of displays, and an essential requisite of their supply chain. This paper presents the development and the implementation of a technological solution to the OB of automotive instrument panel displays. The goal is to select and develop the adequate materials and bonding techniques that can meet the rigorous performance, quality, ...
Enhanced printability of thermoplastic polyurethane substrates by silica partic...
Cruz, Sílvia Manuela Ferreira; Rocha, Luís Alexandre Machado; Viana, J. C.A new method development for surface treatment of thermoplastic polyurethane (TPU) substrates.The proposed method increases TPU surface energy (by 45%) and consequently the TPU wettability.Great increase of the TPU surface roughness (by 621%).Inkjet printed conductive ink was applied to the surface treated TPU substrate and significant improvements on the printability were obtained.
Inkjet printed pressure sensing platform for postural imbalance monitoring
Cruz, Sílvia Manuela Ferreira; Dias, Daniel Agostinho Leite Ribeiro; Viana, J. C.; Rocha, Luís Alexandre MachadoIn this paper, a low-cost printed pressure sensing platform is presented. The sensing platform consists of a flexible printed circuit board manufactured using conventional technology (defining the electrical connections and the capacitors dimensions) together with two flexible polymeric membranes made from a thermoplastic elastomer (TPU) printed with conductive ink Poly (3,4-ethylenedioxythiophene)-poly (styren...
Melt blending and characterization of carbon nanoparticles-filled thermoplastic...
Cruz, Sílvia Manuela Ferreira; Viana, J. C.In this work, thermoplastic polyurethane (TPU) elastomers reinforced with carbon nanosized particles were produced by a special melt blending technique. A TPU was melt blended with high-structured carbon black and carbon nanofibres (1 wt%). A miniature asymmetric batch mixer, which applies high shear levels to the melt, ensured good particles dispersion. The TPU material systems were then thoroughly characteriz...