Magnetic field sensor with voltage-tunable sensing properties

We report on a magnetic field sensor based on CoFeB/MgO/CoFeB magnetic tunnel junctions. By taking advantage of the perpendicular magnetic anisotropy of the CoFeB/MgO interface, the magnetization of the sensing layer is tilted out-of-plane which results in a linear response to in-plane magnetic fields. The application of a bias voltage across the MgO tunnel barrier of the field sensor affects the magnetic anisotropy and thereby its sensing properties. An increase of the maximum sensitivity and simultaneous decrease of the magnetic field operating range by a factor of two is measured. Based on these results, we propose a voltage-tunable sensor design that allows for active control of the sensitivity and the operating filed range with the strength and polarity of the applied bias voltage.Comment: 4 pages, 4 figures, lette

Hybrid GMR Sensor Detecting 950 pT/sqrt(Hz) at 1 Hz and Room Temperature.

Advances in the magnetic sensing technology have been driven by the increasing demand for the capability of measuring ultrasensitive magnetic fields. Among other emerging applications, the detection of magnetic fields in the picotesla range is crucial for biomedical applications. In this work Picosense reports a millimeter-scale, low-power hybrid magnetoresistive-piezoelectric magnetometer with subnanotesla sensitivity at low frequency. Through an innovative noise-cancelation mechanism, the 1/f noise in the MR sensors is surpassed by the mechanical modulation of the external magnetic fields in the high frequency regime. A modulation efficiency of 13% was obtained enabling a final device's sensitivity of ~950 pT/Hz1/2 at 1 Hz. This hybrid device proved to be capable of measuring biomagnetic signals generated in the heart in an unshielded environment. This result paves the way for the development of a portable, contactless, low-cost and low-power magnetocardiography device

Novel molecularly imprinted photonic sensors applied to IBD detection

Sara Resende gratefully acknowledges the financial support from Fundação para a Ciência e a Tecnologia (FCT) through PhD grant SFRH/BD/139634/2018info:eu-repo/semantics/publishedVersio

Study of data variability acquired by multiple profilometers

The accuracy and reliability of road monitoring data constitute a major concern among road designers, contractors and road administrations. These data may have foremost implications on rehabilitation strategies and, therefore, on costs and service life. For this reason, this paper aims to provide the interested bodies referred with useful information in relation to the variability of data acquired by road profilometers that is usually required. Five road profilometers, which belong to consultancy companies and research institutions, were used. Macrotexture and unevenness was measured on three selected road trials. Five runs were performed by each profilometer in both lanes of the road trials. The mean and the standard deviation were used to study the variability of the results. In relation to the macrotexture no significant differences were registered. For the unevenness the ratio between standard deviation and average MRI is higher than 20% and about twice the one found for macrotexture

Planes de acción de reducción del rudio: consideración del coste beneficio de superficies de bajo ruido y del impacto de medidas de gestión de la velocidad

A elaboração de Planos de Ação para gestão do ruído, de acordo com a diretiva Europeia nº 2002/49/CE é uma tarefa com a qual os municípios de elevada densidade populacional têm que lidar e coordenar com outros planos. Neste contexto a Agência Portuguesa para o Ambiente identifica o uso de pavimentos de baixo ruído como a melhor medida custo/benefício para redução do ruído. Não obstante o imenso esforço para desenvolver superfícies rodoviárias de baixo ruído na Europa, este assunto é ainda muitas vezes tratado de forma incorreta e breve, assim como os aspetos relacionados com a incomodidade provocada pelo ruído rodoviário e de algumas medidas de gestão de velocidade. Assim, este trabalho pretende contribuir para o desenvolvimento de Planos de Ação para reduzir o ruído de duas formas. Em primeiro lugar, através da análise custo/benefício de várias superfícies de pavimentos, tais como superfícies delgadas com ou sem betume modificado com borracha, e outros materiais inovadores. Seguidamente, serão discutidos os aspetos relativos incomodidade causada por algumas destas superfícies e o impacto das medidas de gestão da velocidade, tais como a implementação de lombas redutoras de velocidade e bandas sonoras. A seleção da melhor solução para redução do ruído não deve ser somente baseada na análise custo/benefício, que se apoia em indicadores de ruído objetivos, mas deve também integrar a perceção da população, com base em indicadores de ruído subjetivos, e nos efeitos dos elementos das estradas que podem perturbar os indivíduos em locais específicos.La elaboración de los Planos de Acción para la gestión del ruido, de acuerdo con la Directiva Europea N º 2002/49/CE es una tarea con la que los municipios densamente poblados tienen que tratar y coordinar con otros planos o proyectos existentes o en elaboración. En este contexto, la Agencia Portuguesa de Medio Ambiente identifica el uso de pavimentos de bajo ruido como la mejor medida de costo-beneficio para la reducción del ruido. A pesar del enorme esfuerzo para desarrollar superficies de bajo ruido en Europa, este tema, muchas veces ha sido abordado de una forma incorrecta y pequeña, así como los aspectos relacionados con la incomodidad generada por el ruido causado por los vehículos que circulan en la vía pública y de algunas medidas de control de la velocidad. Así, este trabajo tiene como principal objetivo contribuir para el desarrollo de los planes de acción para reducir el ruido de dos maneras. En primer lugar, por análisis del coste / beneficio de las diversas superficies de pavimento, tales como, las superficies delgadas de asfalto con o sin betún modificado y con granulado de caucho, y otros materiales innovadores. A continuación, se discutirá los aspectos relativos a la incomodidad proporcionada por algunas de estas superficies y el impacto de las medidas de control de la velocidad, tales como, la implementación de reductores de velocidad y bandas sonoras o resaltos. Por eso, la escoja de la mejor solución para la reducción del ruido no debe tener en cuenta solamente la análisis costobeneficio, que se apoya en indicadores objetivos de ruido, sino que, también debe integrar la percepción de la población, sobre la base de los indicadores subjetivos del ruido, y los efectos de elementos de caminos que pueden perturbar los individuos en lugares específicos

Analysis of test methods for texture depth evaluation applied in Portugal

Texture is a surface characteristic which has a very wide influence on pavements functional quality. It is currently assessed by a number of test methods. Road Administrations face the problems of dealing with data acquired by different methods and, in addition to that, the repeatability and reproducibility of the results. This paper presents an analysis of test methods used for texture depth evaluation in Portugal: the volumetric patch method and two methods based on surface profiles. Hence, three roads with low (dense asphalt), medium (“open texture asphalt”) and high (porous asphalt) texture depths were selected, where five profilometers made five runs. Two subsections of 150 m length were also selected to carry out the volumetric patch test. The texture indicators analysed were: the mean texture depth, the mean profile depth and the sensor measured texture depth. The average and the standard deviation were the statistical parameters used for the analysis. The results obtained for each method are significantly different and a good correlation between the mean profile depth and the sensor measured texture depth was established

Validation of masonry systems for in-plane lateral loading using truss reinforcement

The paper presents and describes the main issues related to two building systems for modern masonry structures using truss reinforcement, currently under development at University of Minho, one based on lightweight concrete blocks and another based on reinforced concrete block masonry. Details of the experimental and numerical work carried out are addressed, together with conclusions on the performance of the system for in-plane lateral loading