Spintronic Sensors Freitas, Paulo P.; Ferreira, Ricardo; Cardoso, Susana
Proceedings of the IEEE,
2016-Oct., 2016-10-00, Letnik:
104, Številka:
10
Journal Article
Recenzirano
This paper describes how magnetoresistive materials can be optimized and integrated in magnetic field sensor devices. Giant magnetoresistive (GMR) and tunnel magnetoresistive (TMR) can provide ...advantageous solutions for a wide range of applications, of which some are described here. Considerations on field sensitivities, intrinsic noise mechanisms, biasing, and integration schemes are presented.
The research and development in the field of magnetoresistive sensors has played an important role in the last few decades. Here, the authors give an introduction to the fundamentals of the ...anisotropic magnetoresistive (AMR) and the giant magnetoresistive (GMR) effect as well as an overview of various types of sensors in industrial applications. In addition, the authors present their recent work in this field, ranging from sensor systems fabricated on traditional substrate materials like silicon (Si), over new fabrication techniques for magnetoresistive sensors on flexible substrates for special applications, e.g., a flexible write head for component integrated data storage, micro-stamping of sensors on arbitrary surfaces or three dimensional sensing under extreme conditions (restricted mounting space in motor air gap, high temperatures during geothermal drilling).
•Magnetic Sensors (MSs) are versatile & cost-effective for NDE and corrosion monitoring, enabling faster processes.•MSs offer low power consumption, high sensitivity, small size, driving IoT and ...smart structures.•MSs can be easily automated to identify inner damages and corrosions penetration over large areas.•Combining different types of MSs can enhance accuracy and reliability for NDE.•Future prospects: Address challenges like magnetic shock, crossfield effect, calibration, loading history, feature selection, and high-speed scanning sensors.
The growing demand towards life cycle sustainability has created a tremendous interest in non-destructive evaluation (NDE) to minimize manufacturing defects and waste, and to improve maintenance and extend service life. Applications of Magnetic Sensors (MSs) in NDE of civil Construction Materials to detect damage and deficiencies have become of great interest in recent years. This is due to their low cost, non-contact data collection, and high sensitivity under the influence of external stimuli such as strain, temperature and humidity. There have been several advancements in MSs over the years for strain evaluation, corrosion monitoring, etc. based on the magnetic property changes. However, these MSs are at their nascent stages of development, and thus, there are several challenges that exist. This paper summarizes the recent advancements in MSs and their applications in civil engineering. Principle functions of different types of MSs are discussed, and their comparative characteristics are presented. The research challenges are highlighted and the main applications and advantages of different MSs are critically reviewed.
Encoding information in patterns printed with magnetic ink can extend the usability of barcode and QR code technologies to applications that do not require a line of sight between the sensor and the ...code. Such an implementation garners an interest in security, track-and-trace, and recyclable packaging applications. Previous work has demonstrated a device that can read a barcode obscured by a layer of opaque and 1 mm thick material. However, given that the most widespread magnetic toners are soft magnetic, a permanent magnet (PM) is needed in the system alongside the sensor to magnetically bias the barcode, which affects the sensor sensitivity. Here, we describe a protocol to evaluate the impact of different PM geometries on the performance of the sensor and validate it with experimental results, enabling active feedback for integration in the scanner system. As a result, we have reached an improved geometry that increases the reading distance of the device to at least 2 mm. This study is also useful for other applications that require optimization of the interaction between a PM and a magnetic sensor (e.g., nanoparticle tracking in magnetoresistive biosensors).
Magnetorheological elastomers (MREs) are a category of smart materials composed of a magnetic powder dispersed in an elastomeric matrix. They are characterized by the ability to change their ...mechanical properties when an external magnetic field is applied, called magnetorheological (MR) effect. When a conductive filler is added to a magnetorheological elastomer, the resulting hybrid filler composite showcases both MR and piezoresistive effects. For such a reason, these composites are referred to as self‐sensing magnetorheological elastomers. In this case, the synthesized self‐sensing magnetorheological elastomers are based on styrene‐based thermoplastic elastomers (TPS), carbonyl iron particles (CIP), and carbon black (CB). The hybrid filler concept using various coated CIP and constant CB content showed that above 25 vol.% CIP the resistivity increased rapidly. This work proposes the first case of a 3D printable self‐sensing magnetorheological elastomer and cyclic mechanical compression and tensile mode analysis at high deformation (up to 20% and 10%, respectively). The results showcase a magnetoresistive change of up to 68% and a piezoresistive change of up to 42% and 98% in compression and tension, respectively. In addition, the magnetostriction of the self‐sensing samples has been characterized to be 3.6% and 5.6% in the case of CIP 15 and 30 vol.%, respectively.
Self‐sensing magnetorheological elastomers (MREs) showcase resistive changes induced both by magnetic fields and mechanical loads, on top of magnetic‐dependant stiffening. In this work, it is reported the first case of 3D printable self‐sensing magnetorheological elastomers. The proposed materials are characterized both as a function of a varying magnetic field and mechanical cyclic load, both in compression and tension.
Nosocomial or hospital‐acquired infections (HAIs) have a major impact on mortality worldwide. Enterococcus and Staphylococcus are among the leading causes of HAIs and thus are important pathogens to ...control mainly due to their increased antibiotic resistance. The gold‐standard diagnostic methods for HAIs are time‐consuming, which hinders timely and adequate treatment. Therefore, the development of fast and accurate diagnostic tools is an urgent demand. In this study, we combined the sensitivity of magnetoresistive (MR) sensors, the portability of a lab‐on‐chip platform, and the specificity of phage receptor binding proteins (RBPs) as probes for the rapid and multiplex detection of Enterococcus and Staphylococcus. For this, bacterial cells were firstly labelled with magnetic nanoparticles (MNPs) functionalized with RBPs and then measured on the MR sensors. The results indicate that the RBP‐MNPS provided a specific individual and simultaneous capture of more than 70% of Enterococcus and Staphylococcus cells. Moreover, high signals from the MR sensors were obtained for these samples, providing the detection of both pathogens at low concentrations (10 CFU/ml) in less than 2 h. Overall, the lab‐on‐chip MR platform herein presented holds great potential to be used as a point‐of‐care for the rapid, sensitive and specific multiplex diagnosis of bacterial infections.
A rapid and multiplex detection of nosocomial pathogens on a magnetoresistive (MR) lab‐on‐chip platform is described. For this, we combined the sensitivity of MR sensors, the portability of a lab‐on‐chip platform and the specificity of two phage receptor binding proteins (RBPs) as probes for Enterococcus and Staphylococcus. The cells were firstly labelled with magnetic nanoparticles functionalized with RBPs and, subsequently, recognized by RBPs immobilized on the chip where sensors detected simultaneously both pathogens from 10 CFU/mL in less than 2 h.
A novel fabrication method for stretchable magnetoresistive sensors is introduced, which allows the transfer of a complex microsensor systems prepared on common rigid donor substrates to prestretched ...elastomeric membranes in a single step. This direct transfer printing method boosts the fabrication potential of stretchable magnetoelectronics in terms of miniaturization and level of complexity, and provides strain‐invariant sensors up to 30% tensile deformation.
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•Size of locally magnetized area of CoFeB heterostructures exceed Fe/Fe3O4 cluster size.•Particle-film interaction causes an additional magnetic anisotropy.•Dipole field of cluster ...affects critical field of switching of film magnetization.•Diameter of magnetized area of thin film depends on particle diameter.•Identification of type of locally magnetized areas by micromagnetic modeling.
Fe/Fe3O4 nanoparticles have been deposited on the surfaces of ultrathin CoFeB film and CoFeB/Ta/CoFeB hetero-structure to be detected due to the stray field generated by one particle or a cluster of particles. Exchange biased Fe/Fe3O4 core-shell nanoparticles have been used to stabilize the particles magnetization. Comparison between the Atomic Force and Magnetic Force Microscope images and subtraction of corresponding phase contrasts allows visualization of the film magnetization affected by the particles. Spectra of Ferromagnetic Resonance of the ultrathin films with deposited particles allow one to estimate particle/film dipolar interaction. The results will be useful for the development of lab-on-chip sensors of magnetically labeled cells. Estimation of particles number by magnetic response of the CoFeB heterostructure is demonstrated.
A new nondestructive inspection method, the magnetic hammer test (MHT), which uses a compact and highly sensitive tunnel magnetoresistance (TMR) sensor, is proposed. This method complements the ...magnetic flux leakage method and eliminates the issues of the hammer test. It can therefore detect weak magnetic fields generated by the natural vibration of a pipe with a high signal-to-noise ratio. In this study, several steel pipes with different wall thicknesses were measured using a TMR sensor to demonstrate the superiority of MHT. The results of the measurement show that wall thickness can be evaluated with the accuracy of several tens of microns from the change in the natural vibration frequency of the specimen pipe. The pipes were also inspected underwater using a waterproofed TMR sensor, which demonstrated an accuracy of less than 100 μm. The validity of these results was by simulating the shielding of magnetic fields and vibration of the pipes with the finite element method (FEM) analysis. The proposed noncontact, fast, and accurate method for thickness testing of long-distance pipes will contribute to unmanned, manpower-saving nondestructive testing (NDT) in the future.
In this study, we developed a signal detection unit composed of a magnetoresistive sensor and magnetic flux transformer circuit for ultra-low field magnetic resonance imaging (ULF-MRI). The ...equivalent noise level of the detection unit was reduced to approximately 1/20 using the flux transformer compared to the original magnetoresistive sensor. Additionally, the flux transformer made of copper wires and plastic bobbins contributed to prevent the distortion of the magnetic field for MRI measurements. Spin-echo magnetic resonance signal measurements and ULF-MRI measurements were demonstrated using a phantom at a static magnetic field of 1 mT. The spin-echo signal and the MR image were successfully obtained by the developed signal detection unit. These results show the effectiveness of using the flux transformer to realize the ULF-MRI measurement using magnetoresistive sensors.
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