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Publications

Publications by PHT

2017

2D computational modeling of optical trapping effects on malaria-infected red blood cells

Authors
Paiva, JS; Ribeiro, RSR; Jorge, PAS; Rosa, CC; Guerreiro, A; Cunha, JPS;

Publication
Optics InfoBase Conference Papers

Abstract
A computational method for optical fiber trapping of healthy and Malariainfected blood cells characterization is proposed. A trapping force relation with the infection stage was found, which could trigger the development of a diagnostic sensor. © OSA 2017.

2017

Optical Fiber Sensor for Early Warning of Corrosion of Metal Structures

Authors
Coelho, L; Santos, JL; Jorge, PAS; de Almeida, JMMM;

Publication
OCEANS 2017 - ABERDEEN

Abstract
Long period fiber gratings (LPFGs) were over coated with iron (Fe) and subjected to oxidation in air and in solutions of water containing different sodium chloride (NaCl) concentrations. The formation of iron oxides and hydroxides was monitored in real time by following the features of the gratings attenuation band. Preliminary results show that Fe coated LPFGs can be used as sensors for early warning of corrosion in offshore and in coastal projects where metal structures made of iron alloys are in contact with sea or brackish water.

2017

Fabrication of Microfluidic Channels by Femtosecond Laser Micromachining and Application in Optofluidics

Authors
Maia, JM; Amorim, VA; Alexandre, D; Marques, PVS;

Publication
PROCEEDINGS OF THE 5TH INTERNATIONAL CONFERENCE ON PHOTONICS, OPTICS AND LASER TECHNOLOGY (PHOTOPTICS)

Abstract
Micromachining with femtosecond laser can be exploited to fabricate optical components and microfluidic channels in fused silica, due to internal modification of the glass properties that is induced by the laser beam. In this paper, we refer to the formation of microfluidic channels, where an optimization of the fabrication procedure was conducted by examining etch rate and surface roughness as a function of the irradiation conditions. Microfluidic channels with high and uniform aspect ratio and with smooth sidewalls were obtained, and such structures were successfully integrated with optical components. The obtained results set the foundations towards the development of new optofluidic devices.

2017

Fabry-Perot Sensor based on Two Coupled Microspheres for Strain Measurement

Authors
Monteiro, CS; Kobelke, J; Schuster, K; Bierlich, J; Frazao, O;

Publication
2017 25TH INTERNATIONAL CONFERENCE ON OPTICAL FIBER SENSORS (OFS)

Abstract
A Fabry-Perot based sensor with two coupled hollow microspheres is presented. The sensor was fabricated using fusion splicing techniques, enabling a low-cost, highly reproducible, production. The coupling of the two microspheres gives rise to a highly sensitive strain sensor, reaching a sensitivity of 4.07 pm/mu epsilon. The allsilica composition leads to a low thermal sensitivity, making the proposed structure suitable applications in environments with varying external conditions.

2017

Fiber Bragg grating sensor based on cantilever structure embedded in polymer 3D printed material

Authors
Lima, R; Tavares, R; Silva, SO; Abreu, P; Restivo, MT; Frazao, O;

Publication
2017 25TH INTERNATIONAL CONFERENCE ON OPTICAL FIBER SENSORS (OFS)

Abstract
A cantilever structure in 3D printed based on a fiber Bragg grating (FBG) sensor embedded in polymer material is proposed. The FBG sensor was embedded in 3D printed coating and was tested under three physical parameters: displacement, temperature and vibration. The sensor was tested in displacement in two different regions of the cantilever, namely, on its midpoint and end point. The maximum displacement sensitivity achieved was (3 +/- 0.1) pm/mm for end point displacement, and a temperature sensitivity of (30 +/- 1) pm/degrees C was also attained. In the case of vibration measurements it was possible to obtain a 10.23Hz-low frequency oscillation.

2017

Comparative study of the optical properties of colon mucosa and colon precancerous polyps between 400 and 1000 nm

Authors
Carvalho, S; Gueiral, N; Nogueira, E; Henrique, R; Oliveira, L; Tuchin, VV;

Publication
DYNAMICS AND FLUCTUATIONS IN BIOMEDICAL PHOTONICS XIV

Abstract
Optical properties of biological tissues are unique and may be used for tissue identification, tissue discrimination or even to identify pathologies. Early stage colorectal cancer evolves from adenomatous polyps that arise in the inner layer of the colorectal tube - the mucosa. The identification of different optical properties between healthy and pathological colorectal tissues might be used to identify different tissue components and to develop an early stage diagnosis method using optical technologies. Since most of the biomedical optics techniques use light within the visible and near infrared wavelength ranges, we used the inverse adding-doubling method to make a fast estimation of the optical properties of colorectal mucosa and early stage adenocarcinoma between 400 and 1000 nm. The estimated wavelength dependencies have provided information about higher lipid content in healthy mucosa and higher blood content in pathological tissue. Such data has also indicated that the wavelength dependence of the scattering coefficient for healthy mucosa is dominated by Rayleigh scattering and for pathological mucosa it is dominated by Mie scattering. Such difference indicates smaller scatterer size in healthy mucosa tissue. Such information can now be used to develop new diagnosis or treatment methods for early cancer detection or removal. One possibility is to use optical clearing technique to improve tissue transparency and create localized and temporary tissue dehydration for image contrast improvement during diagnosis or polyp laser removal. Such techniques can now be developed based on the different results that we have found for healthy and pathological colorectal mucosa.

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