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Sobre

Sobre

Investigador Auxiliar do CRAS, doutorado em Engenharia Eletrotécnica e de Computadores, no Departamento de Eletrónica Industrial da Universidade do Minho, em Dezembro de 2013. Desenvolvo transdutores de ultrassons piezoelétricos aplicados a comunicações sem fios em ambientes subaquáticos e desenvolvo diferentes sensores de baixo custo e tamanho reduzido. Participo e/ou lidero a execução de um total de 14 Projetos de P&D com financiamento competitivo, dos quais 2 como IP e 4 como Co-PI.

Tópicos
de interesse
Detalhes

Detalhes

  • Nome

    Marcos Martins
  • Cargo

    Investigador Auxiliar
  • Desde

    01 junho 2022
003
Publicações

2025

DBD plasma-treated polyester fabric coated with doped PEDOT:PSS for thermoregulation

Autores
Magalhaes, C; Ribeiro, AI; Rodrigues, R; Meireles, A; Alves, AC; Rocha, J; de Lima, FP; Martins, M; Mitu, B; Satulu, V; Dinescu, G; Padrao, J; Zille, A;

Publicação
APPLIED SURFACE SCIENCE

Abstract
The manufacturing process of thermoregulation products with polyester (PES) fabric and conductive polymers such as poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate) (PEDOT:PSS) with proper wearability, comfort, and high performance is still a challenge due to low adhesion, environment instability and nonuniform coatings. This study presents a simple and effective method for producing thermoregulatory PES fabrics using the Joule heating effect. Textiles treated with dielectric barrier discharge (DBD) plasma were functionalized with PEDOT:PSS incorporating secondary dopants, such as dimethyl sulfoxide (DMSO) and glycerol (GLY). PEDOT:PSS was used because it does not compromise the mechanical properties of base materials. DBD plasma treatment was applied to PES to improve the substrate's functional groups and consequently increase adhesion and homogeneity of the PEDOT:PSS on the substrate. The polymer were applied to the textiles by dip-pad-drycure method ensuring uniform distribution and homogeneous heating of the materials. The samples' conductivity, impedance, potential and Joule effect, and their morphological, chemical and thermal properties were studied. Control samples without plasma treatment and secondary dopants were also prepared. The results showed that the DBD-treated samples, coated with 5 layers of PEDOT:PSS, doped with DMSO 7 % (w/v), displayed the best conductivity and Joule effect performance reaching 44.3 degrees C after 1 h.

2025

Enhancing Sea Wave Monitoring Through Integrated Pressure Sensors in Smart Marine Cables

Autores
Matos, T; Rocha, JL; Martins, MS; Goncalves, LM;

Publicação
JOURNAL OF MARINE SCIENCE AND ENGINEERING

Abstract
The need for real-time and scalable oceanographic monitoring has become crucial for coastal management, marine traffic control and environmental sustainability. This study investigates the integration of sensor technology into marine cables to enable real-time monitoring, focusing on tidal cycles and wave characteristics. A 2000 m cable demonstrator was deployed off the coast of Portugal, featuring three active repeater nodes equipped with pressure sensors at varying depths. The goal was to estimate hourly wave periods using fast Fourier transform and calculate significant wave height via a custom peak detection algorithm. The results showed strong coherence with tidal depth variations, with wave period estimates closely aligning with forecasts. The wave height estimations exhibited a clear relationship with tidal cycles, which demonstrates the system's sensitivity to coastal hydrodynamics, a factor that numerical models designed for open waters often fail to capture. The study also highlights challenges in deep-water monitoring, such as signal attenuation and the need for high sampling rates. Overall, this research emphasises the scalability of sensor-integrated smart marine cables, offering a transformative opportunity to expand oceanographic monitoring capabilities. The findings open the door for future real-time ocean monitoring systems that can deliver valuable insights for coastal management, environmental monitoring and scientific research.

2025

Protection of custom satellite antennas for deep-sea monitoring probes: Insights from the SONDA project

Autores
Matos, T; Dinis, H; Faria, CL; Martins, MS;

Publicação
APPLIED OCEAN RESEARCH

Abstract
This study presents the development and testing of satellite antennas for the SONDA probe, an innovative deepsea monitoring system designed to be deployed by high-altitude balloons. The probe descends to the deep ocean, resurfaces, and transmits data while functioning as a drifter. The project faced unique design constraints, including the need for low-cost materials and lightweight construction for balloon deployment. These constraints ruled out traditional hermetic housings, necessitating alternative solutions for antenna protection. The work focused on custom ceramic patch antennas and their performance under various protective coatings, which affected the antennas' resonance and gain. Thinner layers effectively protected the antennas from high-pressure conditions and water ingress, maintaining functionality. Experiments on antenna height revealed optimal positioning above the water surface to minimize wave-induced signal interference. Hyperbaric chamber tests validated the mechanical integrity and functionality of the antennas under pressures equivalent to depths of 1500 m Antenna characterization techniques were employed in an anechoic chamber to validate antenna performance with the coating and to assess their correct operation after the hyperbaric tests. Field deployments demonstrated the antennas' capability to transmit data after diving. Challenges included communication delays, corrupted data, and mechanical vulnerabilities in materials. The findings emphasize the importance of rigorous mechanical design, material selection, and system optimization to ensure reliability in marine environments. This work advances the development of low-cost, lightweight, and modular probes for autonomous ocean monitoring, with potential applications in long-term drifter studies, real-time marine monitoring and oceanographic research.

2025

Advancing fatigue life prediction of cortical bone under mode I loading using the DCB test

Autores
Campos, TD; Martins, M; Quyen, N; de Moura, MFSF; Dourado, N;

Publicação
THEORETICAL AND APPLIED FRACTURE MECHANICS

Abstract
A comprehensive understanding of the mechanisms underlying bone fatigue failure is crucial for advancing treatment strategies. In this regard, this study presents a novel approach to quantify crack propagation in cortical bone tissue through fatigue testing under mode I loading. To closely replicate real bone damage mechanisms, pre-cracked bone samples were subjected to cyclic loading. A compliance-based beam method and cubic B-spline interpolation method were employed to accurately extract fatigue coefficients and reduce experimental noise, yielding refined modified Paris law coefficients. A cohesive zone model for high-cycle fatigue was used to simulate crack propagation, capturing the nonlinear material response by means of the cohesive zone length, mimicking the non-negligible fracture process zone. The goal is to validate the followed experimental procedure. This study offers valuable insights into the fatigue and fracture mechanisms in cortical bone, providing a more accurate and realistic framework for characterizing fatigue life compared to previous methodologies. Coefficients produced from the cohesive model may be readily integrated into simulation tools commonly used in many areas of engineering, allowing biomechanical experts to create more robust designs that simulate actual world conditions for application in implants and orthopaedic structures.

2024

The Influence of Hydroxyapatite Crystals on the Viscoelastic Behavior of Poly(vinyl alcohol) Braid Systems

Autores
Quinaz, T; Freire, TF; Olmos, A; Martins, M; Ferreira, FBN; de Moura, MFSM; Zille, A; Nguyen, Q; Xavier, J; Dourado, N;

Publicação
BIOMIMETICS

Abstract
Composites of poly(vinyl alcohol) (PVA) in the shape of braids, in combination with crystals of hydroxyapatite (HAp), were analyzed to perceive the influence of this bioceramic on both the quasi-static and viscoelastic behavior under tensile loading. Analyses involving energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM) allowed us to conclude that the production of a homogeneous layer of HAp on the braiding surface and the calcium/phosphate atomic ratio were comparable to those of natural bone. The maximum degradation temperature established by thermogravimetric analysis (TGA) showed a modest decrease with the addition of HAp. By adding HAp to PVA braids, an increase in the glass transition temperature (Tg) is noticed, as demonstrated by dynamic mechanical analysis (DMA) and differential thermal analysis (DTA). The PVA/HAp composite braids' peaks were validated by Fourier transform infrared (FTIR) spectroscopy to be in good agreement with common PVA and HAp patterns. PVA/HAp braids, a solution often used in the textile industry, showed superior overall mechanical characteristics in monotonic tensile tests. Creep and relaxation testing showed that adding HAp to the eight and six-braided yarn architectures was beneficial. By exhibiting good mechanical performance and most likely increased biological qualities that accompany conventional care for bone applications in the fracture healing field, particularly multifragmentary ones, these arrangements can be applied as a fibrous fixation system.

Teses
supervisionadas

2024

Acoustic Communication System for Underwater Environments

Autor
Diogo José Ferreira Cerqueira

Instituição
UM

2023

Estudo do sistema de portas dos fornos Bur-in

Autor
Nuno Costa

Instituição
UM

2023

Acoustic Communication System for Underwater Environments

Autor
Diogo José Ferreira Cerqueira

Instituição
UM

2022

Deep-Sea Acoustic Transducers development

Autor
João Luis Lopes e Rocha

Instituição
UM

2022

Sediment circulation and accumulation sensors for in-situ continuous monitoring

Autor
Tiago André Rodrigues de Matos

Instituição
UM