Designs and Characterizations of Soft Magnetic Flux Guides in a 3-D Magnetic Field Sensor

Less than thirty years after the giant magnetoresistance (GMR) effect was described, GMR sensors are the preferred choice in many applications demanding the measurement of low magnetic fields in small volumes. This rapid deployment from theoretical basis to market and state-of-the-art applications can be explained by the combination of excellent inherent properties with the feasibility of fabrication, allowing the real integration with many other standard technologies. In this paper, we present a review focusing on how this capability of integration has allowed the improvement of the inherent capabilities and, therefore, the range of application of GMR sensors. After briefly describing the phenomenological basis, we deal on the benefits of low temperature deposition techniques regarding the integration of GMR sensors with flexible (plastic) substrates and pre-processed CMOS chips. In this way, the limit of detection can be improved by means of bettering the sensitivity or reducing the noise. We also report on novel fields of application of GMR sensors by the recapitulation of a number of cases of success of their integration with different heterogeneous complementary elements. We finally describe three fully functional systems, two of them in the bio-technology world, as the proof of how the integrability has been instrumental in the meteoric development of GMR sensors and their applications.

“…This gain is determined by the overall geometry, the separation between poles and the corresponding

[ 36 ]. For a proper optimized design, numerical simulations are often used [ 37 ]. As an example, in Figure 7 we show the simulated gain as a function of the gap between MFC.…”

Section: Spreading the Performancementioning

confidence: 99%

Integration of GMR Sensors with Different Technologies

Cubells-Beltrán

Reig

Madrenas

et al. 2016

“…The sensor described here is based on GMR spin valves due to their high sensitivity and linearity. Soft magnetic flux guides are used to attenuate and redirect the (external) magnetic flux in the air gap [ 76 , 77 , 78 , 79 , 80 , 81 , 82 ].…”

Section: Current Developmentsmentioning

confidence: 99%

Recent Developments of Magnetoresistive Sensors for Industrial Applications

Jogschies

Klaas

Kruppe

et al. 2015

Self Cite

233

113

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).

“…However, this type of sensor requires cryogenic refrigeration to operate, and the sensitivity is proportional to the superconducting flux area [10,11]. Magnetic flux concentrators (MFC) are another competitive method to improve the properties of MTJ sensors [12,13,14,15,16]. Firstly, it is easy to realize industrial production with low cost and low power consumption by using the mature integrated circuit technology, which benefits the miniaturization of the sensor system.…”

Section: Introductionmentioning

confidence: 99%

Double-Gap Magnetic Flux Concentrator Design for High-Sensitivity Magnetic Tunnel Junction Sensors

Qiu

et al. 2019

To improve the sensitivity of the magnetic tunnel junction(MTJ)sensor, a novel architecture for a double-gap magnetic flux concentrator (MFC) was studied theoretically and experimentally in this paper. The three-dimensional finite element model of magnetic flux was established to optimize the magnetic field amplification factor, with different gaps. The simulation results indicate that the sensitivity of an MTJ sensor with a double-gap MFC can be significantly better than that of a sensor with a traditional single-gap MFC, due to the fact that the magnetic magnification sharply increases with the decrease in effective gap width. Besides this, the half-bridge MTJ sensors with the double-gap MFC were fabricated using photolithography, ion milling, evaporation, and electroplating processes. Experimental results show that the sensitivity of the MTJ sensor increased by ten times compared to the sensor without the double-gap MFC, which underlines the theoretical predictions. Furthermore, there is no significant increase in the sensor noise. The work in this paper contributes to the development of high-performance MTJ sensors.