This document provides an overview of magnetic field sensing and different types of magnetic sensors. It begins with definitions of sensors and detectable phenomena. It then discusses various physical principles that magnetic sensors utilize, like Ampere's law and Faraday's law of induction. The document reviews the need for sensors and factors in choosing a sensor. It provides a market analysis of the magnetic sensor industry and examples of applications. Finally, it describes various types of magnetic sensors in more detail, including vector magnetometers, total field magnetometers, search-coil magnetometers, fluxgate magnetometers, and superconducting quantum interference device (SQUID) magnetometers.
Dielectric and Magnetic Properties of materials,Polarizability,Dielectic loss...A K Mishra
In this PPT contains ,Dia,Para,Ferromagnetism,Clausius-Mossoti equation,Dielectric Loss ,Hysteresis,Hysteresis loss and its Applications,Determination of susceptibility,types of polarisation in mateials,relative permability
Dielectric and Magnetic Properties of materials,Polarizability,Dielectic loss...A K Mishra
In this PPT contains ,Dia,Para,Ferromagnetism,Clausius-Mossoti equation,Dielectric Loss ,Hysteresis,Hysteresis loss and its Applications,Determination of susceptibility,types of polarisation in mateials,relative permability
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Basically i have tried giving every details about the phenomenon Superconductivity in the simplest way. This is my first upload.I'll be very glad if u all give your valuable feedback. Thank u.
The following presentation consists of introduction to dielectrics, and includes following topics - Basic terms, Polarization of Dielectric, Polarization method, Internal Field, Clausius-Mossotti Equation, Types of dielectric, Properties of good Dielectric, and Application of Dielectric.
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Basically i have tried giving every details about the phenomenon Superconductivity in the simplest way. This is my first upload.I'll be very glad if u all give your valuable feedback. Thank u.
The following presentation consists of introduction to dielectrics, and includes following topics - Basic terms, Polarization of Dielectric, Polarization method, Internal Field, Clausius-Mossotti Equation, Types of dielectric, Properties of good Dielectric, and Application of Dielectric.
THE NATURE OF MAGNETIC MATERIAL FORCE & TORQUE ON CLOSED CIRCUITvishalgohel12195
Magnetic Forces, Materials and Inductance
Force On A Moving Charge
Force on a Differential Current
Force And Torque On A Closed Circuit
Force And Torque On A Closed Circuit
The Nature of Magnetic Materials
1. contents - NMR SPECTROMETER
INTRUMENTATION OF NMR
COMPONENTS OF NMR SPECTROMETER
REFERENCES
2. NMR Spectrometer is an instrument which is used to obtain NMR Spectra.
A high resolution spectrometer contains a complex collection of electronic equipments.
NMR spectrometers are referred to as 300 MHz instruments (or) 500 MHz instruments, depending upon the frequency of the RF radiation used for resonance.
These spectrometers use very powerful magnets to create a small but measurable energy difference between two possible spin states.
3. COMPONENTS OF NMR SPECTROMETER
Magnet
Field Lock
Shim Coils
Probe Unit
- Sample Holder
- RF Oscillator
- Sweep Generator
- RF Receiver
Detector
Read out Device
4. magnets ;-
The heart of both continuous-wave and Fourier form NMR instruments is the magnet.
Magnets produces the magnetic field, which determines the frequency of any nucleus.
Sensitivity and resolution are critically dependent on quality of magnet.
It should give homogenous magnetic field, i.e. the strength of the magnetic field should not change from point to point.
The magnet must be capable of producing a very strong magnetic field with strength at least 10,000 gauss
5. Types of Magnets
Permanent Magnet:
Permanent magnets with field strengths of 0.7, 1.4, and 2.1 T are mostly used.
Permanent magnets are highly temperature-sensitive and require extensive thermostating and shielding as a consequence.
It is inexpensive and simple to operate.
They are operated up to 30 – 60 MHz
They provide field of good homogeneity.
Disadvantage:- Field variation is not possible, as required, because different nuclei resonate at different magnetic field.
6. Electro Magnets:
They require power supply to produce magnetic field
Cooling system is required to counter the heat generated from the electric power.
They are more effective than the permanent magnet because of possibility of field variation
They are operated up to 60 - 90 MHz
7. 3. Super conducting magnet:
A super conducting magnet has an electromagnet made up of superconducting wire.
These magnets attain fields large as 21 T.
Superconducting wire has a resistance approximately equal to zero by immersing it in liquid helium (at 0° c).
Superconducting magnet systems be filled with liquid nitrogen every 10 days
The length of superconducting wire in the magnet is typically several miles.
They are operated up to 470 MHz
8. field lock
In order to produce a high resolution NMR spectrum of a sample there is need of homogeneous magnetic field.
The field strength might vary due to aging of the magnet, movement of metal object near the magnet, and temperature fluctuations.
9. shim coils
Shim coils are pairs of wire loops.
By using these coils Current is adjusted until the magnetic field has required homogeneity.
Magnetic field produced by the Shim coils cancels the small residual inhomogeneities in the magnetic field.
MAGNETOMETER
Outline
• Pinciples of operation of magnetometer.
• How Magnetometer works…???
• Cordinate Systems
• Types
• SQUID Magnetometer
• Applications
MAGNETOMETER – PRINCIPLES OF OPERATION
Hall Effect Magnetometer
Lorentz Force -
Benefits-
Solid-state
Low Temperature
Sensitivity
Highly Linear
Small
Cheap
Drawbacks-
Saturation limit
Calibration Issues
How Magnetometers Work..???
Coordinate Systems
TYPES OF MAGNETOMETER
SQUID MAGNETOMETER
APPLICATIONS OF MAGNETOMETER
1. They are used for navigational purposes.
2. They are used in anti-lock braking systems in vehicles.
3. Fluxgate magnetometers have been used in space missions for magnetic field measurements.
4. Magnetometers are used for mineral exploration; it is used to search world-class deposits of gold,silver, iron copper, etc.
5. They are used in many defence applications; UAVs, submarines, etc.
6. Magnetometers have found usages in smartphones which have applications that serve as compasses.
7. And many more..
THANK YOU.
In our conventional electronic devices we use semi conducting materials for logical operation and magnetic materials for storage, but spintronics uses magnetic materials for both purposes. These spintronic devices are more versatile and faster than the present one. One such device is Spin Valve Transistors (SVT).
Spin valve transistor is different from conventional transistor. In this for conduction we use spin polarization of electrons. Only electrons with correct spin polarization can travel successfully through the device. These transistors are used in data storage, signal processing, automation and robotics with less power consumption and results in less heat. This also finds its application in Quantum computing, in which we use Qubits instead of bits.
Builder.ai Founder Sachin Dev Duggal's Strategic Approach to Create an Innova...Ramesh Iyer
In today's fast-changing business world, Companies that adapt and embrace new ideas often need help to keep up with the competition. However, fostering a culture of innovation takes much work. It takes vision, leadership and willingness to take risks in the right proportion. Sachin Dev Duggal, co-founder of Builder.ai, has perfected the art of this balance, creating a company culture where creativity and growth are nurtured at each stage.
DevOps and Testing slides at DASA ConnectKari Kakkonen
My and Rik Marselis slides at 30.5.2024 DASA Connect conference. We discuss about what is testing, then what is agile testing and finally what is Testing in DevOps. Finally we had lovely workshop with the participants trying to find out different ways to think about quality and testing in different parts of the DevOps infinity loop.
Essentials of Automations: Optimizing FME Workflows with ParametersSafe Software
Are you looking to streamline your workflows and boost your projects’ efficiency? Do you find yourself searching for ways to add flexibility and control over your FME workflows? If so, you’re in the right place.
Join us for an insightful dive into the world of FME parameters, a critical element in optimizing workflow efficiency. This webinar marks the beginning of our three-part “Essentials of Automation” series. This first webinar is designed to equip you with the knowledge and skills to utilize parameters effectively: enhancing the flexibility, maintainability, and user control of your FME projects.
Here’s what you’ll gain:
- Essentials of FME Parameters: Understand the pivotal role of parameters, including Reader/Writer, Transformer, User, and FME Flow categories. Discover how they are the key to unlocking automation and optimization within your workflows.
- Practical Applications in FME Form: Delve into key user parameter types including choice, connections, and file URLs. Allow users to control how a workflow runs, making your workflows more reusable. Learn to import values and deliver the best user experience for your workflows while enhancing accuracy.
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We’ll wrap up with a glimpse into future webinars, followed by a Q&A session to address your specific questions surrounding this topic.
Don’t miss this opportunity to elevate your FME expertise and drive your projects to new heights of efficiency.
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In this insightful webinar, Inflectra explores how artificial intelligence (AI) is transforming software development and testing. Discover how AI-powered tools are revolutionizing every stage of the software development lifecycle (SDLC), from design and prototyping to testing, deployment, and monitoring.
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https://alandix.com/academic/papers/synergy2024-epistemic/
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https://arxiv.org/abs/2306.08302
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Speakers:
Bob Boule
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Gopinath Rebala
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Here is something new! In our next Connector Corner webinar, we will demonstrate how you can use a single workflow to:
Create a campaign using Mailchimp with merge tags/fields
Send an interactive Slack channel message (using buttons)
Have the message received by managers and peers along with a test email for review
But there’s more:
In a second workflow supporting the same use case, you’ll see:
Your campaign sent to target colleagues for approval
If the “Approve” button is clicked, a Jira/Zendesk ticket is created for the marketing design team
But—if the “Reject” button is pushed, colleagues will be alerted via Slack message
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And...
Speakers:
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Charlie Greenberg, Host
Connector Corner: Automate dynamic content and events by pushing a button
Magnetic field sensing
1. Magnetic Field Sensing
Course: Nanomagnetic Materials and DevicesNAST 736
Submitted to
Dr.A.Kasi.Vishwanath
Associate Professor
Center for Nanoscience & Technology
Submitted by
Zaahir Salam
2. Contents
•
•
•
•
•
•
•
•
What are Sensors?
Detectable Phenomenon
Physical Principles – How Do Sensors Work?
Need for Sensors
Choosing a Sensor
Market analysis and World wide Revenue
General Applications
Types of Sensors
3. What are Sensors?
• American National Standards Institute (ANSI) Definition
– A device which provides a usable output in response to a
specified measurand.
Input Signal
Output Signal
Sensor
• A sensor acquires a physical parameter and converts it into a
signal suitable for processing (e.g. optical, electrical,
mechanical)
4. Detectable Phenomenon
Stimulus
Acoustic
Biological & Chemical
Electric
Magnetic
Quantity
Wave (amplitude, phase, polarization), Spectrum, Wave
Velocity
Fluid Concentrations (Gas or Liquid)
Charge, Voltage, Current, Electric Field (amplitude,
phase,
polarization), Conductivity, Permittivity
Magnetic Field (amplitude, phase, polarization), Flux,
Permeability
Optical
Refractive Index, Reflectivity, Absorption
Thermal
Temperature, Flux, Specific Heat, Thermal Conductivity
Mechanical
Position, Velocity, Acceleration, Force, Strain, Stress,
Pressure, Torque
5. Physical Principles
• Amperes’s Law
– A current carrying conductor in a magnetic field experiences a force
(e.g. galvanometer)
• Curie-Weiss Law
– There is a transition temperature at which ferromagnetic materials exhibit
paramagnetic behavior
• Faraday’s Law of Induction
– A coil resist a change in magnetic field by generating an opposing
voltage/current (e.g. transformer)
• Photoconductive Effect
– When light strikes certain semiconductor materials, the resistance of the
material decreases (e.g. photoresistor)
6. Need for Sensors
• Sensors are omnipresent. They embedded in our bodies,
automobiles, airplanes, cellular telephones, radios, chemical
plants, industrial plants and countless other applications.
• Without the use of sensors, there would be no automation !!
– Imagine having to manually fill water bottles.
11. Magneto-encephalography
MagnetoCardiography
Mars Global Explorer (1998)
“Biomagnetism using SQUIDs: Status and
Perspectives” Sternickel, Braginski, Supercond.
Sci. Technol. 19 S160–S171 (2006).
Magnetic RAM
North Caroline Department of Cultural
Resources “Queen Anne’s Revenge”
shipwreck site Beufort, NC
12. Introduction
• Magnetic sensors can be classified according to whether they measure the
total magnetic field or the vector components of the magnetic field.
• The techniques used to produce both types of magnetic sensors
encompass many aspects of physics and electronics.
• There are many ways to sense magnetic fields, most of them based on the
intimate connection between magnetic and electric phenomena.
Fig. 1. Estimate of sensitivity of different magnetic sensors. The symbols and GMN are used to
indicate the strength of the Earth’s magnetic field and geomagnetic noise, respectively.
The symbols E and GMN are used to indicate the strength of the Earth’s magnetic field
and geomagnetic noise, respectively.
13. Types of Magnetic Sensors
• Vector Magnetometers.
• Total Field Magnetometers.
– insensitivity to rotational vibrations.
– splitting between some electron or nuclear spin
energy levels is proportional to the magnitude of
the magnetic field over a field range sufficient for
magnetometry.
14. Vector Magnetometers
Measures both the magnitude and the direction.
First, nearly all vector magnetometers suffer from noise,
especially 1/f noise (Geomagnetic Noise).
Solution- MEMS flux concentrator
which will shift the operating frequency above
the range where noise dominates.
Another major problem with vector magnetometers is that
they are affected by rotational vibrations.
15. Search-Coil Magnetometer
• The principle of working Faraday’s law of induction.
• The search coil (also known as Inductive Sensor) is a sensor which
measures the variation of the magnetic flux.
• It is just coils wound around a core of high magnetic permeability.
• They measure alternating magnetic field and so can resolve changes in
magnetic fields quickly, many times per second.
Photograph of the search coil magnetometers used
on the THEMIS and Cluster/Staff mission
16. • The signal detected by a search-coil magnetometer depends
on the permeability of the core material, the area of the coil,
the number of turns, and the rate of change of the magnetic
flux through the coil.
• The frequency response of the sensor may be limited by the
ratio of the coil’s inductance to its resistance, which
determines the time it takes the induced current to dissipate
when the external magnetic field is removed. The higher the
inductance, the more slowly the current dissipates, and the
lower the resistance, the more quickly it dissipates.
• Detect fields as weak as 20 fT , and there is no upper limit to
their sensitivity range.
• Their useful frequency range is typically from 1 Hz to 1 MHz,
the upper limit being that set by the ratio of the coil’s
inductance to its resistance.
• They require between 1 and 10 mW of power.
17. In addition to this passive use, one can also operate a search coil in an
active mode to construct a proximity sensor.
A proximity sensor is a sensor able to detect the presence of
nearby objects without any physical contact.
A proximity sensor often emits an electromagnetic field or a beam
of electromagnetic radiation (infrared, for instance), and looks for
changes in the field or return signal.
Magnetic proximity fuze
It is a type of proximity fuze that initiates a detonator in a piece
of ordnance such as a land mine, naval mine, depth charge, or
shell when the fuse's magnetic equilibrium is upset by a
magnetic object such as a tank or a submarine.
18. Fig 2(a), a balanced inductive bridge
where an inductance change in one
leg of the bridge produces an out-ofbalance voltage in the circuit.
Fig. 2(b), incorporates a resonant
circuit where a change in inductance
results in a change in the circuit’s
resonant frequency.
Called eddy-killed oscillator, since
conductive materials near the active
coil will have eddy currents induced,
which will produce a mutual
inductance change in the circuit.
Ferrite cores are often used in this
approach because they can be
designed with the coil to offer a
temperature insensitive impedance.
Fig. 2(c) uses a single coil in the sensor
and the remainder of the electronics
is connected remotely.
19. Fluxgate Magnetometer
• The fluxgate magnetometer consists of a ferromagnetic material wound
with two coils, a drive and a sense coil.
It exploits magnetic induction together with the fact that all ferromagnetic
material becomes saturated at high fields. This saturation can be seen in the
hysteresis loops shown on the right side of Fig. 4.
20. • When a sufficiently large sinusoidal current is applied to the
drive coil, the core reaches its saturation magnetization once
each half-cycle.
• As the core is driven into saturation, the reluctance of the
core to the external magnetic field being measured increases,
thus making it less attractive for any additional magnetic field
to pass through the core.
• This change is detected by the sense coil. When the core
comes out of saturation by reducing the current in the drive
coil, the external magnetic field is again attracted to the core,
which is again detected by the sense second coil.
• Thus, alternate attraction and lack of attraction causes the
magnetic lines of flux to cut the sense coil. The voltage output
from the sense coil consists of even-numbered harmonics of
the excitation frequency.
21. • The sensitivity of this sensor depends on the shape of the hysteresis curve.
For maximum sensitivity, the magnetic field magnetic induction (B-H)
curve should be square, because this produces the highest induced
electromotive force (emf) for a given value of the magnetic field. For
minimum power consumption, the core material should have low
coercivity and saturation values.
22. But they consume roughly five times more
power than proximity sensors.
Most of these achieve lower power
consumption by operating the sensor on a
minor hysteresis loop, thus not driving the
core from saturation to saturation.
23.
24. Superconductor Magnetometers
• SQUID sensors
The most sensitive of all instruments for measuring a magnetic field at
low frequencies ( 1 Hz) is the superconducting quantum interference
device (SQUID) illustrated in Fig. 6.
It is based on the remarkable interactions of electric currents and
magnetic fields observed when certain materials are cooled below a
superconducting transition temperature. At this temperature, the
materials become superconductors and they lose all resistance to the flow
of electricity.
25. • For a large number of applications extremely small magnetic signals have to
be detected and accurately measured.
– Sensitivities of magnetic sensors:
Hall probes ~ mT
Flux gate sensors ~ nT
SQUIDs ~ fT
• SQUIDs allow to detect and characterize the magnetic signals which are so
small as to be virtually immeasurable by any other sensors.
• How sensitive? Allows to measure magnetic fields produced by the nerve
currents associated with the physiological activity of the human heart
(magneto cardiogram – MCG) or the human brain (magnetoencephalogram –
MEG); these signals have a typical strength ~ pT.
• Best of the SQUID sensors have energy sensitivity approaching Planck’s
constant.
• SQUIDs are the most sensitive detectors
of extremely small changes in magnetic flux.
Fluxes can be created by currents – therefore the most sensitive current sensors
as well
26. SQUIDs - basic facts
•
•
•
•
SQUIDs combine the physical phenomena
of flux quantization in superconducting
loops and Josephson tunneling.
The Josephson effect refers to the ability of
two weakly coupled superconductors to
sustain at zero voltage a supercurrent
associated with transport of Cooper pairs,
whose magnitude depends on the phase
difference
between
the
two
superconductors.
The maximum current which a Josephson
weak link can support without developing
any voltage across it is known as its critical
current Ic. When the current passed
through a Josephson weak link exceeds Ic, a
voltage appears across it
If a closed loop made of superconductor
magnetic field cannot enter the loop
(“ideal diamagnetism”). But if there is a
weak link flux enters the loop in quanta!
Flux quantum
h
0
2.07 1015T m 2
2e
28. Hall Sensor
•
Utilizes the Lorentz force on charge
carriers
•
predominantly use n-type silicon when
cost is of primary importance and
GaAs for higher temperature capability
due to its larger band gap.
29.
30. Temperature Dependence of Hall Resistance and Hall Voltage
Different materials and different doping levels result in tradeoffs between sensitivity
and temperature dependence.
31.
32. Applications of Hall Field Sensors
Response to South or North Polarity
Motor-Tachometer application
where each rotation of the
motor shaft is to be detected
When ring magnet rotates w/
motor, South Pole passes the
sensing face of the Hall sensor
after each revolution.
Sensor
Actuated when the South Pole
approaches sensor
Deactuated when South Pole
moves away from sensor
Single digital pulse produced for
each revolution.
33. application continued…..
Gear Tooth Sensing
• Sense movement of
ferrous metal targets
(magnetically biased)
• Sensor
detects change in
flux level
• Translates it into a
change in the sensor
output (high to low)
42. Typical application of AMR Sensors
•
•
•
•
Cylinder position sensing in pneumatic cylinders
Elevator sensor
Lid sensor for laptop computers
Position sensor for materials handling equipment (lift
trucks)
• Blood analyzer
• Magnetic encoders
43. GMR is achieved by using a four layer structure that consists of two thin
ferromagnets separated by a conductor. The fourth layer is an
antiferromagnet that is used to pin (inhibit the rotation) the
magnetization of one of the ferromagnetic layers. The ferromagnet layer
that is being pinned is between the conductor and the antiferromagnet.
The pinned ferromagnet is called the hard ferromagnet and the unpinned
ferromagnet is called the soft ferromagnet. This structure is called a spin
valve.
44. • The difference in resistivity between the case when the
magnetizations are parallel to when they are antiparallel can
be as large as 12.8% at room temperature.
• To optimize the effect the layers must be a very thin, i.e.
about a nanometer thick.
• For the low field response of the sensor to be a linear function
of the field, it is necessary that the soft ferromagnetic have its
easy axis of magnetization in zero field perpendicular to the
magnetization of the pinned ferromagnet.
• The zero field orientation of the two magnetizations is
depicted in Fig. 11(a). The resistance is measured either in the
plane of the ferromagnetics or perpendicular to this plane.
45.
46. • This multilayer geometry increases the percentage resistance
change because it increases the probability of spin flip
scattering by increasing the number of interfaces where spin
flip scattering occurs.
47.
48.
49.
50. Total Field Magnetometers
• Total field magnetometers have the important advantage of
insensitivity
to
rotational
vibrations.
Total
field
magnetometers use the fact that the splitting between some
electron or nuclear spin energy levels is proportional to the
magnitude of the magnetic field over a field range sufficient
for magnetometry.
Optically Pumped Magnetometer:
Based on the Zeeman effect. In 1896, the
Dutch physicist Zeeman showed that some
of the characteristic spectral lines of atoms
are split when the atoms are placed in a
magnetic field; one spectral line becomes a
group of lines with slightly different
wavelengths. The splitting is particularly
pronounced in alkali elements such as
cesium and rubidium.