Repositório Comunidade: DEI
https://hdl.handle.net/1822/1273
DEI2024-03-28T14:48:43Z3 mm deep microelectrode needle array based on aluminum for neural applications
https://hdl.handle.net/1822/89990
Título: 3 mm deep microelectrode needle array based on aluminum for neural applications
Autor: Peixoto, Alexandre Coumiotis Moreira; Gonçalves, Sandra Beatriz Tomé; Ferreira da Silva, Alexandre; Correia, J. H.; Mota, P.; Dias, N. S.
Resumo: This paper presents a simple and cost-effective fabrication method of invasive neural microelectrode arrays based on aluminum, which is a viable alternative to other state-of-the-art technologies that rely primarily on silicon. A 10 x 10 array with 3.0 mm deep reaching pillars were fabricated, each having a pyramidal tip profile. Each aluminum pillar is insulated with a biocompatible layer of aluminum oxide. The electrode tip was covered by an iridium oxide thin-film layer via pulsed sputtering, providing a stable and a reversible behavior for recording/stimulation purposes, each with a 145 Ohm impedance in a wide frequency range of interest (10 Hz - 100 kHz). Each pillar is electrically individualized from the adjacent ones by an insulating layer of epoxy resin. High-aspect-ratio pillars (20:1) are achieved through a combination of dicing, thin-film deposition, anodizing and wet-etching. The described approach allows an array of deeper penetrating electrodes and a simpler fabrication procedure when compared to previous works.
<b>Tipo</b>: conferencePaperLow-cost/high-reproducibility flexible sensor based on photonics for strain measuring
https://hdl.handle.net/1822/89984
Título: Low-cost/high-reproducibility flexible sensor based on photonics for strain measuring
Autor: Rocha, R. P.; Gomes, M. J.; Carmo, João Paulo Pereira; Ferreira da Silva, Alexandre; Correia, J. H.
Resumo: This paper presents a flexible sensor based on photonics for measuring strain, curvatures and vibrations. This flexible sensor is composed by a Fiber Bragg Grating (FBG) embedded into polydimethylsiloxane (PDMS). The selected FBG resonates at the wavelength of 1552.37 nm and is embedded before the curing for enabling a strong adhesion between both components. Few prototypes were fabricated and characterized. The measurements showed a maximum strain sensitivity of approximate to 400 pm per 1% elongation, revealing to be sensitive to strain/bending forces and vibration. The measurements allowed to establish a predictable response for both static and dynamic behavior, corresponding to a resolution of approximate to 88 pm per curvature degree. This flexible sensor also allowed high strain cycles and presented the linear behavior of approximate to 14 pm degrees C-1 over the temperature range 20-110 degrees C. The high-simplicity of the fabrication process results on low-cost with high-degree of reproducibility of their characteristics. (C) 2013 Elsevier Ltd. All rights reserved.
<b>Tipo</b>: articleLong neuroprobes based on silicon dicing and iridium oxide for electrical stimulation/recording
https://hdl.handle.net/1822/89979
Título: Long neuroprobes based on silicon dicing and iridium oxide for electrical stimulation/recording
Autor: Oliveira, Maria J.; Peixoto, Alexandre Coumiotis Moreira; Correia, J. H.; Gonçalves, Sandra Beatriz Tomé; Ferreira da Silva, Alexandre
Resumo: This paper synthesizes the development of a new 3D neuroprobe array, constituted by microelectrodes capable of electrical stimulation and recording. The array's design relies on a bulk silicon substrate dicing technology and it comprises 6 x 6 neuroprobes with three different penetrating lengths (from 3 to 4 mm) and a 180 mu m cross-section. A reproducible fabrication method was demonstrated, capable of producing longer shafts than in previously reported arrays. In addition, sputtered titanium/iridium oxide microelectrodes have shown the required performance, with a consistent reversible electrochemical behavior and an impedance value of 145 Omega in the same frequency range as the stimulation protocols.
<b>Tipo</b>: conferencePaperFabrication and mechanical characterization of long and different penetrating length neural microelectrode arrays
https://hdl.handle.net/1822/89974
Título: Fabrication and mechanical characterization of long and different penetrating length neural microelectrode arrays
Autor: Gonçalves, Sandra Beatriz Tomé; Peixoto, Alexandre Coumiotis Moreira; Ferreira da Silva, Alexandre; Correia, J. H.
Resumo: This paper presents a detailed description of the design, fabrication and mechanical characterization of 3D microelectrode arrays (MEA) that comprise high aspect-ratio shafts and different penetrating lengths of electrodes (from 3 mm to 4 mm). The array's design relies only on a bulk silicon substrate dicing saw technology. The encapsulation process is accomplished by a medical epoxy resin and platinum is used as the transduction layer between the probe and neural tissue. The probe's mechanical behaviour can significantly affect the neural tissue during implantation time. Thus, we measured the MEA maximum insertion force in an agar gel phantom and a porcine cadaver brain. Successful 3D MEA were produced with shafts of 3 mm, 3.5 mm and 4 mm in length. At a speed of 180 mm min(-1), the MEA show maximum penetrating forces per electrode of 2.65 mN and 12.5 mN for agar and brain tissue, respectively. A simple and reproducible fabrication method was demonstrated, capable of producing longer penetrating shafts than previously reported arrays using the same fabrication technology. Furthermore, shafts with sharp tips were achieved in the fabrication process simply by using a V-shaped blade.
<b>Tipo</b>: articleWearable textile elongation sensor
https://hdl.handle.net/1822/89968
Título: Wearable textile elongation sensor
Autor: Goncalves, Carlos; Ferreira da Silva, Alexandre; Simões, Ricardo João Ferreira
Resumo: This work shows a developed wearable elongation sensor based on an optical fiber. The presented approach to sew a fiber optic into a lycra textile enables the modulation of light amplitude in respect to textile strain. This apparatus in combination with small-size instrumentation enables the development of a wearable textile garment capable of monitoring and acquiring strain data, and send it wirelessly to a base station. The light amplitude increases with the increment of textile strain. The output voltage remains stable over time for the resting and maximum textile strain position.
<b>Tipo</b>: conferencePaper2024-03-25T14:25:10Z