Article
Neurosciences
Patrique Fiedler, Carlos Fonseca, Eko Supriyanto, Frank Zanow, Jens Haueisen
Summary: The new dry 256-channel HD-EEG electrode cap overcomes the principal limitations of HD-EEG in terms of preparation complexity, allowing rapid application by non-medically trained individuals, and enabling new use cases for HD-EEG. The dry electrodes make recording with state-of-the-art EEG amplifiers easier, while also demonstrating superior performance and wearing comfort.
HUMAN BRAIN MAPPING
(2022)
Article
Engineering, Biomedical
Surachoke Thanapitak, Wanlop Surakampontorn, Chutham Sawigun
Summary: A current-balance instrumentation amplifier (CBIA) is proposed, which eliminates the need for input stage linearization and achieves low input-referred noise. This design uses two transistors to simultaneously operate as input transconductance stage and dc-servo loop (DSL), achieving sub-Hz high-pass cutoff frequency for dc rejection. The fabricated CBIA demonstrates good performance with an input-referred noise of 0.91 μV-rms over 100 Hz bandwidth.
IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS
(2023)
Article
Engineering, Multidisciplinary
Hui-Ling Peng, Yue-ling Sun, Cheng Bi, Quan-Fu Li
Summary: A flexible dry electrode based on MXene ink and flexible polyimide substrate was developed, which can accurately record biopotential signals such as ECG, EEG, and EOG, and has good flexibility and adaptability.
Article
Chemistry, Analytical
Mohammad Shamim Reza, Lu Jin, You Jeong Jeong, Tong In Oh, Hongdoo Kim, Kap Jin Kim
Summary: This study aims to find suitable base materials for dry electrode fabrication in order to achieve high accuracy and maintain electrode performance for long-term bioelectric potential monitoring after electroless silver plating. Nanoweb-based chlorinated polyisoprene (CPI) and poly(styrene-b-butadiene-b-styrene) (SBS) rubber were selected as promising candidates due to their excellent elastic properties and nanofibril nature. The electroless silver plating technique was used to coat the nanofiber web, resulting in the fabrication of silver nanoweb (AgNW)-based dry electrodes. Thorough investigations were conducted to evaluate the key electrode properties of AgNW dry electrodes, and human testing showed comparable performance to commercial Ag/AgCl gel electrodes, with superior long-term stability.
Article
Chemistry, Analytical
Yiping Huang, Yatong Song, Li Gou, Yuanwen Zou
Summary: Wearable flexible silver electrodes based on cowhide were prepared and tested for their waveform transmission and impedance. The results showed that these electrodes were comparable to standard gel electrodes when the skin is moist enough, and had higher signal-to-noise ratios than the standard electrodes in the standing posture.
Article
Nanoscience & Nanotechnology
Junshi Li, Yundong Ma, Dong Huang, Zhongyan Wang, Zhitong Zhang, Yingjie Ren, Mengyue Hong, Yufeng Chen, Tingyu Li, Xiaoyi Shi, Lu Cao, Jiayan Zhang, Bingli Jiao, Junhua Liu, Hongqiang Sun, Zhihong Li
Summary: The researchers have developed a flexible MNA electrode that can fit a curved body surface, penetrate the skin without fracture, and be mass-produced with a simplified process. The electrode is compatible with wearable wireless systems and has a short preparation time, improving the comfort and convenience of electrophysiological recording.
NANO-MICRO LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Salvatore Andrea Pullano, Venkata Deepa Kota, Karthik Kakaraparty, Antonino S. Fiorillo, Ifana Mahbub
Summary: In this paper, an optically unobtrusive dry electrode based on the iono-electric properties of zeolite is developed and proposed for continuous electrocardiogram (ECG) monitoring. The electrical and bio-electrical characterizations are evaluated for different types of electrodes, and the results show that certain parameters lead to the best performance.
IEEE SENSORS JOURNAL
(2022)
Article
Neurosciences
Beatriz Vasconcelos, Patrique Fiedler, Rene Machts, Jens Haueisen, Carlos Fonseca
Summary: The novel dry arch electrode proposed in this study provides increased comfort for prolonged dry-contact measurement and shows comparable signal characteristics with dry pin-shaped electrodes.
FRONTIERS IN NEUROSCIENCE
(2021)
Article
Chemistry, Analytical
Vignesh Ravichandran, Izabela Ciesielska-Wrobel, Md Abdullah al Rumonl, Dhaval Solanki, Kunal Mankodiya
Summary: This study focuses on the impedance characteristics of dry e-textile electrodes and a laser-cut knit electrode under various contact forces and moisture conditions. The results showed that certain electrodes exhibited a significant decrease in impedance after moisture exposure, indicating the impact of stitch design and moisture. However, after controlled drying, some electrodes experienced an increase in impedance. Overall, the knit electrode and embroidered electrodes demonstrated superior performance in terms of impedance, moisture retention, and ECG signal quality.
Article
Computer Science, Information Systems
Kee S. Moon, Sung Q. Lee, John S. Kang, Andrew Hnat, Deepa B. Karen
Summary: This study proposes the use of semi-dry electrodes with low impedance and excellent wearability, as well as a small, portable device with wireless communication capabilities, to monitor eye movements in real-life scenarios. The impedance of the semi-dry electrode produced by the electrospinning technique was 3.5 times lower than that of the existing dry electrode, and it demonstrated low impedance drift even after long-term use. Furthermore, the wearable device was able to classify eye movements at a meaningful level.
Article
Engineering, Electrical & Electronic
Abolfazl Harati, Amir Jahanshahi
Summary: A relatively inexpensive, flexible, and stretchable dry electrode for EEG recording is presented in this study. The electrode demonstrates good mechanical and electrical reliability, with electrical performance similar to standard wet Ag/AgCl electrodes. The mechanical endurance of the electrode is verified through custom-designed stroke tests under relatively severe conditions.
SENSORS AND ACTUATORS A-PHYSICAL
(2021)
Article
Chemistry, Analytical
Claudia Lopes, Patrique Fiedler, Marco Sampaio Rodrigues, Joel Borges, Maurizio Bertollo, Eduardo Alves, Nuno Pessoa Barradas, Silvia Comani, Jens Haueisen, Filipe Vaz
Summary: In this study, a new type of nanostructured titanium-based thin film dry electrode for non-invasive monitoring of body surface biopotentials was proposed. Different Ti-Me metallic binary systems were prepared by magnetron sputtering, showing morphology dependent on chemical composition. In an in-vivo study on volunteers, Ti-Me dry electrodes demonstrated good reusability and reliability, with Ti-Au system performing excellently close to the Ag/AgCl reference electrodes.
Article
Engineering, Biomedical
Xiaolin Yang, Jiawei Xu, Marco Ballini, Hosung Chun, Menglian Zhao, Xiaobo Wu, Chris Van Hoof, Carolina Mora Lopez, Nick Van Helleputte
Summary: This paper presents a front-end architecture for recording biopotential signals that addresses challenges such as noise, electrode DC offset cancellation, and motion artifact tolerance by utilizing a Delta n-ary sumation modulator and an additional n-ary sumation stage. The prototype achieves high performance metrics, demonstrating the capability to acquire biopotential signals in the presence of large motion artifacts.
IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS
(2021)
Article
Engineering, Electrical & Electronic
Granch Berhe Tseghai, Benny Malengier, Kinde Anlay Fante, Lieva Van Langenhove
Summary: The research has developed a washable and flexible textile-based dry EEG electrode that can detect brain activities. The electrode offers clear and reliable EEG signals even after multiple washing and bending cycles, opening up possibilities for long-term EEG monitoring.
IEEE SENSORS JOURNAL
(2021)
Article
Materials Science, Multidisciplinary
Shanshan Yao, Weixin Zhou, Robert Hinson, Penghao Dong, Shuang Wu, Jasmine Ives, Xiaogang Hu, He Huang, Yong Zhu
Summary: This article reports the fabrication and applications of ultrasoft breathable dry electrodes that can address several challenges for their long-term wearable applications. The proposed electrodes rely on porous and conductive silver nanowire-based nanocomposites, eliminating the necessity of conductive gel while establishing a low electrode-skin impedance. These electrodes allow for efficient monitoring of heart, muscle, and brain activities, and they have the potential for prosthesis control, neurorehabilitation, and virtual reality.
ADVANCED MATERIALS TECHNOLOGIES
(2022)
Article
Materials Science, Ceramics
M. A. Correa, A. Ferreira, S. A. N. Franca Jr, W. Acchar, M. Rodrigues, M. Gamino, F. Bohn, F. Vaz
Summary: GnP doped Al2O3 flexible tapes were produced through Tape Casting technique and used as substrates for Co2FeAl/GnP doped Al2O3 heterostructures. The Co2FeAl layers were grown using Magnetron Sputtering. The integration of both techniques allowed exploration of the thermomagnetic properties of the heterostructure through the Anomalous Nernst Effect, and the results showed isotropic magnetic behavior of the Co2FeAl films.
CERAMICS INTERNATIONAL
(2023)
Article
Chemistry, Analytical
Marcio A. Correa, Armando Ferreira, Arthur L. R. Souza, Joao. M. Dantas Neto, Felipe Bohn, Filipe Vaz, Galina V. Kurlyandskaya
Summary: Fe3Co67Cr3Si15B12 ribbons with high flexibility and excellent corrosion stability were produced using rapid quenching technique. Their structural characteristics were verified by X-ray diffraction, and their static magnetic properties were explored using inductive technique and vibrating sample magnetometry. The thermomagnetic response of the ribbons, investigated through the Anomalous Nernst Effect, showed a linear behavior and demonstrated potential for sensor applications on curved surfaces.
Article
Computer Science, Information Systems
Julio Barros, Francisco Cunha, Candido Martins, Paulo Pedrosa, Paulo Cortez
Summary: The emergence of Industry 4.0 and digital transformation have significantly improved supply chain performance and competitive advantage. This study focuses on enhancing the order fulfilment process and specifically the cement loading process by using machine learning to predict weighing deviations. The random forest model provides the best predictive performance, and the Shapley additive explanations method helps understand the influence of input data attributes.
Article
Chemistry, Analytical
Ricardo Spyrides Boabaid Pimentel Goncalves, Jens Haueisen
Summary: Three-dimensional scanning using rotation and immersion in a water-based fluid was developed as a low-cost alternative to traditional CT scanners. By utilizing a container filled with water and Xanthan gum, objects were submerged and scanned at various rotation angles. The results showed that this technique was feasible for producing reconstructed images of objects with irregular shapes or openings at a significantly lower cost.
Article
Nanoscience & Nanotechnology
Claiudia Lopes, Armando Ferreira, Marcio Correa, Andre Machado Rodrigues, Paulo Mendes, Filipe Vaz
Summary: This study investigates the potential of thin-film technology in the development of new electromagnetic interference shielding and conductive materials for textiles and wearables. The study used three different thin films (pure Ti, pure Cu, and Ti-doped Cu) to enhance textile knits made of cotton and lyocell fibers. The films exhibited varying structures, morphologies, and topographies based on their chemical compositions. The effectiveness of these functionalized knits in shielding against EMI was evaluated, as well as their electrical response under stress.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Materials Science, Ceramics
S. A. N. Franca Junior, W. Acchar, S. L. A. Dantas, P. H. Chiberio, H. P. A. Alves, M. R. D. Bomio, F. V. Motta, F. Bohn, A. Ferreira, F. Vaz, M. A. Correa
Summary: We conducted a comprehensive investigation on the high-frequency dielectric properties of (ZrO2)100-x(BaTiO3)x heterostructures. By adjusting the content of BaTiO3, we could modify the dielectric constant of the resulting ceramic sheets. Our results demonstrated successful fabrication of heterostructured ceramic sheets and the ability to tailor the electric, structural, and dielectric properties of both ZrO2 and BaTiO3 materials. Furthermore, the evolution of the dielectric constant could be manipulated according to specific technological applications.
CERAMICS INTERNATIONAL
(2023)
Article
Chemistry, Physical
Armando Ferreira, Carlos M. Costa, Marcio A. Correa, Rafael S. Pinto, Renato Gonsalves, Luana C. Benetti, Senentxu Lanceros-Mendez, Filipe Vaz
Summary: The necessity for energy conversion solutions has increased in recent years, particularly for powering small and flexible IoT devices. This study explores the use of thermoelectric effects, specifically the anomalous Nernst effect, by producing Co2FeAl/P(VDF-TrFE-CFE) heterostructures on flexible poly (vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)) substrates. The results demonstrate that the flexible polymer substrate does not affect the thermomagnetic effect, opening new possibilities for integrating flexible high-dielectric polymers with thermomagnetic phenomena for energy harvesting applications.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Materials Science, Multidisciplinary
Claudia Lopes, Marco S. Rodrigues, Armando Ferreira, Francisco Macedo, Ioana Borsan, Camelia Gabor, Mihai-Alin Pop, Eduardo Alves, Nuno P. Barradas, Daniel Munteanu, Filipe Vaz
Summary: This study investigated the impact of nanostructure design on the optical, electrical, and thermal properties of titanium nitride (TiNx) thin films. Results showed that modifying the nanostructure design rather than changing the composition can alter the properties of thin films. Thin films prepared by GLancing Angle Deposition (GLAD) exhibited wider and more significant variations in optical and electrical properties, while thermal properties were more affected by structural changes induced by the N content in the films. GLAD geometries resulted in a reduction in film reflectivity and color coordinates, as well as an increase in electrical resistivity. The thermal parameters of effusivity ratio and diffusivity decreased with an increase in the N/Ti ratio.
MATERIALS CHEMISTRY AND PHYSICS
(2023)
Article
Chemistry, Analytical
Daniel Carvalho, Sandra Marques, Giorgia Siqueira, Armando Ferreira, Joao Santos, Dulce Geraldo, Cidalia R. Castro, Ana V. Machado, Filipe Vaz, Claudia Lopes
Summary: This study evaluates the lifespan of Ti-Ag dry electrodes prepared using flexible polytetrafluoroethylene (PTFE) substrates. The research finds that higher Ag content results in increased corrosion and reduced lifespan of the electrodes. The long-term performance of electrodes is critical for reliable and sustained monitoring and stimulation in remote biomedical applications like smart wearables.
Article
Chemistry, Analytical
Marcio A. Correa, Andrey V. Svalov, Armando Ferreira, Matheus Gamino, Edimilson F. da Silva, Felipe Bohn, Filipe Vaz, Danniel F. de Oliveira, Galina V. Kurlyandskaya
Summary: Thermoelectric phenomena are promising for sensor applications in renewable energy. This study reveals the mechanism of how Pt enhances the thermoelectric response in flexible electronic materials and designs a flexible thermopile without the lithography process.
Review
Chemistry, Multidisciplinary
Ines Ferreira, Claudia Lopes, Armando Ferreira, Filipe Vaz, Irene Pina-Vaz, Benjamin Martin-Biedma
Summary: This study conducted a systematic review to evaluate the effect of non-thermal plasma treatments on the adhesion of root canal sealers to dentin. Four studies were included in the analysis, with three using the push-out test in human extracted teeth and one using bovine dentin samples to measure the contact angle. The results suggested that non-thermal plasma might positively influence the adhesion ability of BioRoot RCS and Endosequence BC, but there was no consensus for AH Plus sealer. However, the scarcity of studies on this topic warrants caution in interpreting the findings.
APPLIED SCIENCES-BASEL
(2023)
Proceedings Paper
Computer Science, Artificial Intelligence
R. Conselheiro, C. Lopes, N. Azevedo, P. Leitao, C. Agulhari, H. Veloso, F. Vaz, J. Goncalves, T. Franco, L. Sestrem
Summary: Wet electrodes, which rely on conductive electrolyte gel, have issues such as long setup time, disposability or time-consuming cleaning, skin irritation, and signal quality deterioration. To overcome these drawbacks, 3D printed bases with polymers and functionalized with thin films of titanium and titanium-nitride, doped with copper, were developed. The results show that these dry electrodes have similar performance to wet AgCl/Ag electrodes for data acquisition, but improvements are needed for muscle stimulation and the durability and adhesion of the thin films.
19TH INTERNATIONAL SYMPOSIUM ON DISTRIBUTED COMPUTING AND ARTIFICIAL INTELLIGENCE
(2023)
Article
Chemistry, Physical
Diogo Costa, Marco S. Rodrigues, Eduardo Alves, Nuno P. Barradas, Joel Borges, Filipe Vaz
Summary: This work describes the development of nanoplasmonic thin films with Au, Ag, or Au-Ag nanoparticles dispersed in a TiO2 matrix, and the optimization of deposition parameters to adjust their optical response. The study found that using Au-Ag nanoparticles can increase the refractive index sensitivity of the thin films and reduce the cost of fabrication.
Article
Chemistry, Analytical
Diana I. Meira, Marco S. Rodrigues, Joel Borges, Filipe Vaz
Summary: The extinction efficiency of noble metal nanoparticles, such as gold and silver, depends on their size and the dielectric surrounding them. By exploiting the Localized Surface Plasmon Resonance (LSPR) phenomenon, the composition and structure of these nanoparticles can be tailored to optimize their sensitivity to environmental changes. Incorporating these nanoparticles into solid support in the form of nanocomposite thin films enhances the robustness of LSPR sensing. In this study, bimetallic films composed of gold, silver, and their mixture in a titanium dioxide matrix were grown using reactive DC magnetron sputtering. The LSPR response and sensitivity of the films were tunable by thermal treatment at different temperatures. The bimetallic film with an Au/Ag atomic ratio of 1 exhibited the highest refractive index sensitivity, showcasing the potential of bimetallic film systems in enhancing LSPR sensing.
Article
Engineering, Electrical & Electronic
Giorgia Siqueira, David Baptista, Claudia Lopes, Marcio A. Correa, Filipe Vaz, Armando Ferreira
Summary: This study explores the influence of non-magnetic cap layer thickness on the thermoelectric properties of Co2FeAl/NM heterostructures and analyzes their potential applications in the Anomalous Nernst Effect and Longitudinal Spin Seebeck Effect. The experimental results demonstrate that Co2FeAl/W and Co2FeAl/Ti heterostructures exhibit enhanced ANE voltages, providing valuable insights into Co2FeAl-based materials and spintronic devices.
SENSORS AND ACTUATORS A-PHYSICAL
(2023)