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Operational Parameters for Sub-Nano Tesla Field Resolution of PHMR Sensors in Harsh Environments. SENSORS 2021; 21:s21206891. [PMID: 34696103 PMCID: PMC8539847 DOI: 10.3390/s21206891] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 10/08/2021] [Accepted: 10/11/2021] [Indexed: 11/17/2022]
Abstract
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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Wei S, Liao X, Zhang H, Pang J, Zhou Y. Recent Progress of Fluxgate Magnetic Sensors: Basic Research and Application. SENSORS 2021; 21:s21041500. [PMID: 33671507 PMCID: PMC7926354 DOI: 10.3390/s21041500] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/30/2021] [Accepted: 02/05/2021] [Indexed: 12/26/2022]
Abstract
Fluxgate magnetic sensors are especially important in detecting weak magnetic fields. The mechanism of a fluxgate magnetic sensor is based on Faraday's law of electromagnetic induction. The structure of a fluxgate magnetic sensor mainly consists of excitation windings, core and sensing windings, similar to the structure of a transformer. To date, they have been applied to many fields such as geophysics and astro-observations, wearable electronic devices and non-destructive testing. In this review, we report the recent progress in both the basic research and applications of fluxgate magnetic sensors, especially in the past two years. Regarding the basic research, we focus on the progress in lowering the noise, better calibration methods and increasing the sensitivity. Concerning applications, we introduce recent work about fluxgate magnetometers on spacecraft, unmanned aerial vehicles, wearable electronic devices and defect detection in coiled tubing. Based on the above work, we hope that we can have a clearer prospect about the future research direction of fluxgate magnetic sensor.
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Affiliation(s)
- Songrui Wei
- Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China; (S.W.); (H.Z.)
| | - Xiaoqi Liao
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China;
- Ångström Laboratory, Department of Engineering Sciences, Uppsala University, 75121 Uppsala, Sweden
| | - Han Zhang
- Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China; (S.W.); (H.Z.)
| | - Jianhua Pang
- Shenzhen Institute of Guangdong Ocean University, International Biological Valley, Dapeng District, Shenzhen 518060, China;
| | - Yan Zhou
- School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen 518172, China
- Correspondence:
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Silva M, Franco F, Leitao DC, Cardoso S, Freitas PP. Two-dimensional arrays of vertically packed spin-valves with picoTesla sensitivity at room temperature. Sci Rep 2021; 11:215. [PMID: 33420189 PMCID: PMC7794481 DOI: 10.1038/s41598-020-79856-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 12/08/2020] [Indexed: 11/09/2022] Open
Abstract
A new device architecture using giant magnetoresistive sensors demonstrates the capability to detect very low magnetic fields on the pT range. A combination of vertically packed spin-valve sensors with two-dimensional in-plane arrays, connected in series and in parallel, delivers a final detection level of 360 pT/[Formula: see text] at 10 Hz at room temperature. The device design is supported by an analytical model developed for a vertically packed spin-valve system, which takes into account all magnetic couplings present. Optimization concerning the spacer thickness and sensor physical dimensions depending on the number of pilled up spin-valves is necessary. To push the limits of detection, arrays of a large number of sensing elements (up to 440,000) are patterned with a geometry that improves sensitivity and in a configuration that reduces the resistance, leading to a lower noise level. The final device performance with pT detectivity is demonstrated in an un-shielded environment suitable for detection of bio-signals.
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Affiliation(s)
- Marilia Silva
- Instituto de Engenharia de Sistemas e Computadores - Microsistemas e Nanotecnologias (INESC-MN), 1000-029, Lisbon, Portugal. .,Instituto Superior Tecnico (IST), Universidade de Lisboa, 1040-001, Lisbon, Portugal.
| | - Fernando Franco
- Instituto de Engenharia de Sistemas e Computadores - Microsistemas e Nanotecnologias (INESC-MN), 1000-029, Lisbon, Portugal.,Instituto Superior Tecnico (IST), Universidade de Lisboa, 1040-001, Lisbon, Portugal.,Analog Devices, Limerick, V94 RT99, Ireland
| | - Diana C Leitao
- Instituto de Engenharia de Sistemas e Computadores - Microsistemas e Nanotecnologias (INESC-MN), 1000-029, Lisbon, Portugal.,Instituto Superior Tecnico (IST), Universidade de Lisboa, 1040-001, Lisbon, Portugal
| | - Susana Cardoso
- Instituto de Engenharia de Sistemas e Computadores - Microsistemas e Nanotecnologias (INESC-MN), 1000-029, Lisbon, Portugal.,Instituto Superior Tecnico (IST), Universidade de Lisboa, 1040-001, Lisbon, Portugal
| | - Paulo P Freitas
- Instituto de Engenharia de Sistemas e Computadores - Microsistemas e Nanotecnologias (INESC-MN), 1000-029, Lisbon, Portugal.,INL - International Iberian Nanotechnology Laboratory, 4715-330, Braga, Portugal
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Novel Magnetic Field Modulation Concept Using Multiferroic Heterostructure for Magnetoresistive Sensors. SENSORS 2020; 20:s20051440. [PMID: 32155770 PMCID: PMC7085550 DOI: 10.3390/s20051440] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 02/29/2020] [Accepted: 03/02/2020] [Indexed: 11/16/2022]
Abstract
The low frequency magnetic field detection ability of magnetoresistive (MR)sensor is seriously affected by 1/f noise. At present, the method to suppress the influence of low frequency noise is mainly to modulate the measured magnetic field by mechanical resonance. In this paper, a novel modulation concept employing a magnetoelectric coupling effect is proposed. A design method of modulation structure based on an equivalent magnetic circuit model (EMCM) and a single domain model of in-plane moment was established. An EMCM was established to examine the relationship between the permeability of flux modulation film (FMF) and modulation efficiency, which was further verified through a finite element simulation model (FESM). Then, the permeability modulated by the voltage of a ferroelectric/ferromagnetic (FE/FM) multiferroic heterostructure was theoretically studied. Combining these studies, the modulation structure and the material were further optimized, and a FeSiBPC/PMN-PT sample was prepared. Experimental results show that the actual magnetic susceptibility modulation ability of FeSiBPC/PMN-PT reached 150 times, and is in good agreement with the theoretical prediction. A theoretical modulation efficiency higher than 73% driven by a voltage of 10 V in FeSiBPC/PMN-PT can be obtained. These studies show a new concept for magnetoelectric coupling application, and establish a new method for magnetic field modulation with a multiferroic heterostructure.
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Kim SN, Choi JW, Lim SH. Tailoring of magnetic properties of giant magnetoresistance spin valves via insertion of ultrathin non-magnetic spacers between pinned and pinning layers. Sci Rep 2019; 9:1617. [PMID: 30733523 PMCID: PMC6367389 DOI: 10.1038/s41598-018-38269-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 12/21/2018] [Indexed: 11/09/2022] Open
Abstract
The low-field sensitivity of a giant magnetoresistance (GMR) spin valve can be enhanced by tailoring the bias field of the free layer because this sensitivity and bias field are known to show a strong correlation. In this study, the free-layer bias field is reduced considerably to almost zero via the insertion of an ultrathin nonmagnetic spacer between the pinned layer and the pinning layer. The spacer promotes an increase in the density of Néel walls in the pinned layer. This increase, in turn, induces domain-wall-induced magnetostatic interactions of the free poles formed on the Néel walls inside the free and pinned layers. The magnetostatic interactions result in the formation of flux closures that act as pinning sites during the magnetization reversal process and stabilize the antiparallel magnetization state between the free layer and the pinned layer by suppressing the switching of the free layer from the antiparallel state to the parallel state. Furthermore, the spacer offers an additional advantage of increasing the GMR ratio by inducing a specular scattering effect at its top and bottom interfaces. A highly improved low-field sensitivity of 12.01 mV/mA·Oe is achieved in the sample with a Cu/Pt dual spacer.
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Affiliation(s)
- Si Nyeon Kim
- Department of Materials Science and Engineering, Korea University, Seoul, 02841, Korea
| | - Jun Woo Choi
- Center for Spintronics Research, Korea Institute of Science and Technology, Seoul, 02792, Korea
| | - Sang Ho Lim
- Department of Materials Science and Engineering, Korea University, Seoul, 02841, Korea.
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Lin YN, Dai CL. Micro Magnetic Field Sensors Manufactured Using a Standard 0.18-μm CMOS Process. MICROMACHINES 2018; 9:E393. [PMID: 30424326 PMCID: PMC6187693 DOI: 10.3390/mi9080393] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 08/01/2018] [Accepted: 08/06/2018] [Indexed: 11/23/2022]
Abstract
Micro magnetic field (MMF) sensors developed employing complementary metal oxide semiconductor (CMOS) technology are investigated. The MMF sensors, which are a three-axis sensing type, include a magnetotransistor and four Hall elements. The magnetotransistor is utilized to detect the magnetic field (MF) in the x-axis and y-axis, and four Hall elements are used to sense MF in the z-axis. In addition to emitter, bases and collectors, additional collectors are added to the magnetotransistor. The additional collectors enhance bias current and carrier number, so that the sensor sensitivity is enlarged. The MMF sensor fabrication is easy because it does not require post-CMOS processing. Experiments depict that the MMF sensor sensitivity is 0.69 V/T in the x-axis MF and its sensitivity is 0.55 V/T in the y-axis MF.
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Affiliation(s)
- Yen-Nan Lin
- Department of Mechanical Engineering, National Chung Hsing University, Taichung 402, Taiwan.
| | - Ching-Liang Dai
- Department of Mechanical Engineering, National Chung Hsing University, Taichung 402, Taiwan.
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Guedes A, Macedo R, Jaramillo G, Cardoso S, Freitas PP, Horsley DA. Hybrid GMR Sensor Detecting 950 pT/sqrt(Hz) at 1 Hz and Room Temperature. SENSORS (BASEL, SWITZERLAND) 2018; 18:E790. [PMID: 29509677 PMCID: PMC5876515 DOI: 10.3390/s18030790] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 02/24/2018] [Accepted: 02/26/2018] [Indexed: 11/26/2022]
Abstract
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.
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Affiliation(s)
| | | | | | - Susana Cardoso
- INESC Microsystems and Nanotechnologies and IN-Institute of Nanoscience and Nanotechnology, 1000-029 Lisbon, Portugal.
- Instituto Superior Tecnico, Universidade de Lisboa, Av. Rovisco Pais, 1000 Lisbon, Portugal.
| | - Paulo P Freitas
- INESC Microsystems and Nanotechnologies and IN-Institute of Nanoscience and Nanotechnology, 1000-029 Lisbon, Portugal.
| | - David A Horsley
- Picosense Inc., Berkeley, CA 94704, USA.
- Berkeley Sensor and Actuator Center, University of California, Davis, CA 95616, USA.
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