Thickness dependence of elliptical planar Hall effect magnetometers

Nhalil, Hariharan; Das, Proloy T.; Schultz, Moty; Amrusi, Shai; Grosz, Asaf; Klein, Lior

doi:10.1063/5.0033681

Cited by 15 publications

(14 citation statements)

References 25 publications

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“…Our data reveal that it is more desirable to use a bilayer sensor for the larger dynamic range of ~10 mT, but a tri-layer sensor can be used for higher resolution. In order to improve the sensor detection limit further, tri-mPHMR sensors (>5 rings) and an adjustable electronic circuit with some advanced noise reduction technologies [ 15 , 16 , 21 ] can be designed next. PHMR sensors are therefore general-purpose high-performance magnetometers that can potentially satisfy most kinds of requirements for a wide range of applications.…”

Section: Discussionmentioning

confidence: 99%

“…Extremely-low magnetic field sensing in the low-frequency range is an important task for a wide range of application areas such as magnetic random access memory (MRAM) [ 1 ], neuromorphic computing [ 2 ], magnetic communication [ 3 , 4 ], noninvasive biomedical diagnosis [ 5 , 6 , 7 , 8 ], nondestructive materials evaluation [ 9 ], human–machine interaction [ 10 , 11 ], robotics [ 12 ], and automotive or consumer-based industrials [ 13 ]. Most of these applications demand miniaturization, low-cost fabrication, high thermal stability, flexibility in usage, and robustness in a harsh environment with a very high sensor resolution [ 14 , 15 , 16 , 17 ]. In this perspective, many researchers have been involved in the development of an ultra-sensitive magnetic sensor over the past ten years, and it has been found that magnetoresistive (MR) sensor is always one of the best choices due to its high scalability and inherent capability to install ROIC (readout integration circuit) and also due to its excellent integration compatibility with CMOS (complementary metal-oxide-semiconductor) MEMS (micro-electro-mechanical systems) devices [ 18 , 19 , 20 , 21 ].…”

Section: Introductionmentioning

confidence: 99%

“…Temperature dependence of the noise power spectral density and its detailed systematic analysis in MR sensors always provides a promising directive for its application even in harsh environments. In the literature, most of the noise analysis of MR sensors [ 16 , 21 , 32 , 33 , 34 , 35 , 36 ] has been done by comparing the experimental noise spectra with different numerical models, and the analyses deal with sensor noise performance at room temperature only, whereas very few systematic works have been carried out to investigate the total average noise as a function of temperature [ 37 ]. In the temperature dependence of the noise spectrum, an additional noise component appears due to the rise of temperature, generally caused by thermal drift.…”

Section: Introductionmentioning

confidence: 99%

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Operational Parameters for Sub-Nano Tesla Field Resolution of PHMR Sensors in Harsh Environments

Jeon

Das

Kim

et al. 2021

Sensors

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The resolution of planar-Hall magnetoresistive (PHMR) sensors was investigated in the frequency range from 0.5 Hz to 200 Hz in terms of its sensitivity, average noise level, and detectivity. Analysis of the sensor sensitivity and voltage noise response was performed by varying operational parameters such as sensor geometrical architectures, sensor configurations, sensing currents, and temperature. All the measurements of PHMR sensors were carried out under both constant current (CC) and constant voltage (CV) modes. In the present study, Barkhausen noise was revealed in 1/f noise component and found less significant in the PHMR sensor configuration. Under measured noise spectral density at optimized conditions, the best magnetic field detectivity was achieved better than 550 pT/√Hz at 100 Hz and close to 1.1 nT/√Hz at 10 Hz for a tri-layer multi-ring PHMR sensor in an unshielded environment. Furthermore, the promising feasibility and possible routes for further improvement of the sensor resolution are discussed.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Operational Parameters for Sub-Nano Tesla Field Resolution of PHMR Sensors in Harsh Environments

Jeon

Das

Kim

et al. 2021

Sensors

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“…A constant current is driven along the ellipse’s long axis, and the transverse voltage is measured across the ellipse’s short axis to detect the magnetic field. The EPHE sensor is attractive compared with other magnetoresistive sensors due to its low-temperature dependence [ 38 ], simple fabrication, and high resolution [ 17 , 21 , 22 , 37 ]. Grosz et al reported PHE sensors with an equivalent magnetic noise or resolution of ~200 pT/√Hz [ 21 ], and the noise can be reduced to ~5 pT/√Hz by adding a magnetic flux concentrator [ 11 , 37 , 39 ].…”

Section: Introductionmentioning

confidence: 99%

Design and Optimisation of Elliptical-Shaped Planar Hall Sensor for Biomedical Applications

et al. 2022

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The magnetic beads detection-based immunoassay, also called magneto-immunoassay, has potential applications in point-of-care testing (POCT) due to its unique advantage of minimal background interference from the biological sample and associated reagents. While magnetic field detection technologies are well established for numerous applications in the military, as well as in geology, archaeology, mining, spacecraft, and mobile phones, adaptation into magneto-immunoassay is yet to be explored. The magnetic field biosensors under development tend to be multilayered and require an expensive fabrication process. A low-cost and affordable biosensing platform is required for an effective point-of-care diagnosis in a resource-limited environment. Therefore, we evaluated a single-layered magnetic biosensor in this study to overcome this limitation. The shape-induced magnetic anisotropy-based planar hall effect sensor was recently developed to detect a low-level magnetic field, but was not explored for medical application. In this study, the elliptical-shaped planar hall effect (EPHE) sensor was designed, fabricated, characterized, and optimized for the magneto-immunoassay, specifically. Nine sensor variants were designed and fabricated. A customized measurement setup incorporating a lock-in amplifier was used to quantify 4.5 µm magnetic beads in a droplet. The result indicated that the single-domain behaviour of the magnetic film and larger sensing area with a thinner magnetic film had the highest sensitivity. The developed sensor was tested with a range of magnetic bead concentrations, demonstrating a limit of detection of 200 beads/μL. The sensor performance encourages employing magneto-immunoassay towards developing a low-cost POCT device in the future.

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“…On the contrary, the Hall effect also exists in metals. The low resistance of metals could increase uniformity of the current density and reduce dependence of linearity on bias current [ 9 , 10 ]. However, the transverse voltage is too small to have any practical application [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

Physical Investigations on Bias-Free, Photo-Induced Hall Sensors Based on Pt/GaAs and Pt/Si Schottky Junctions

Wang

Sun

Cui

et al. 2021

Sensors

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Hall-effect in semiconductors has wide applications for magnetic field sensing. Yet, a standard Hall sensor retains two problems: its linearity is affected by the non-uniformity of the current distribution; the sensitivity is bias-dependent, with linearity decreasing with increasing bias current. In order to improve the performance, we here propose a novel structure which realizes bias-free, photo-induced Hall sensors. The system consists of a semi-transparent metal Pt and a semiconductor Si or GaAs to form a Schottky contact. We systematically compared the photo-induced Schottky behaviors and Hall effects without net current flowing, depending on various magnetic fields, light intensities and wavelengths of Pt/GaAs and Pt/Si junctions. The electrical characteristics of the Schottky photo-diodes were fitted to obtain the barrier height as a function of light intensity. We show that the open-circuit Hall voltage of Pt/GaAs junction is orders of magnitude lower than that of Pt/Si, and the barrier height of GaAs is smaller. It should be attributed to the surface states in GaAs which block the carrier drifting. This work not only realizes the physical investigations of photo-induced Hall effects in Pt/GaAs and Pt/Si Schottky junctions, but also opens a new pathway for bias-free magnetic sensing with high linearity and sensitivity comparing to commercial Hall-sensors.

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Thickness dependence of elliptical planar Hall effect magnetometers

Cited by 15 publications

References 25 publications

Operational Parameters for Sub-Nano Tesla Field Resolution of PHMR Sensors in Harsh Environments

Operational Parameters for Sub-Nano Tesla Field Resolution of PHMR Sensors in Harsh Environments

Design and Optimisation of Elliptical-Shaped Planar Hall Sensor for Biomedical Applications

Physical Investigations on Bias-Free, Photo-Induced Hall Sensors Based on Pt/GaAs and Pt/Si Schottky Junctions

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