BIO-BIO-MAGNETISMMAGNETISM

Anurag ChandAnurag Chand

1060703210607032

OUTLINEOUTLINE

INTRODUCTIONINTRODUCTION BIOMAGNETIC THERAPYBIOMAGNETIC THERAPY INSTRUMENTATION OF BIO-MAGNETSINSTRUMENTATION OF BIO-MAGNETS TYPES OF SQUIDSTYPES OF SQUIDS WORKINGWORKING APPLICATIONS OF SQUIDSAPPLICATIONS OF SQUIDS ADVANTAGESADVANTAGES DISADVANTAGES OF MAGNETIC DISADVANTAGES OF MAGNETIC

MEASUREMENTMEASUREMENT

IntroductionIntroduction Bio-magnetism is a new field of research Bio-magnetism is a new field of research

dealing with the measurement and dealing with the measurement and interpretation of magnetic fields produced interpretation of magnetic fields produced by organs or by magnetic contaminants of by organs or by magnetic contaminants of the body the body

Some examples are:Some examples are:

The bio-magnetic fields arising from iron-The bio-magnetic fields arising from iron-bearing proteins in human liver.bearing proteins in human liver.

Magnetic contaminants may be found in the Magnetic contaminants may be found in the lungs and stomach lungs and stomach

BIOMAGNETIC THERAPYBIOMAGNETIC THERAPY The healthy tissue produces a distinct negative, The healthy tissue produces a distinct negative,

micro voltage. micro voltage. When trauma, stress or malfunction occurs, the When trauma, stress or malfunction occurs, the

potential changes to a positively charged statepotential changes to a positively charged state. .

TThe nervous relay system immediately transmits the he nervous relay system immediately transmits the relay to the brain, which floods the problem area with relay to the brain, which floods the problem area with healing negative charges to correct the chaotically healing negative charges to correct the chaotically charged areacharged area

The metabolism process in each cell is dependent on The metabolism process in each cell is dependent on biopotential in this cell biopotential in this cell

The negative field of a magnet is used to correctly The negative field of a magnet is used to correctly stimulate & create the healthy cellular charge state stimulate & create the healthy cellular charge state of a strong negative potential. Henceof a strong negative potential. Hence the need for the need for properly designed biomagnetic field.properly designed biomagnetic field.

Current in the body is not like current Current in the body is not like current through a wire. (A)through a wire. (A)

It is expressed as current dipole (mA-m) It is expressed as current dipole (mA-m) A current dipole consists of a source A current dipole consists of a source at the dendrite and a sink at the soma. at the dendrite and a sink at the soma. The distance between source and sink The distance between source and sink determine he impact of current dipole determine he impact of current dipole on the other dipole in the surrounding on the other dipole in the surrounding

tissue.tissue. The total effect produces two current The total effect produces two current

patterns of opposite polarity, one patterns of opposite polarity, one outward outward

and the other inward, hence the and the other inward, hence the

name ‘current dipole’.name ‘current dipole’.

INSTRUMENTATIONINSTRUMENTATION

Super Conductivity Quantum Interference Super Conductivity Quantum Interference Device (SQUID) is a magnetometer used to Device (SQUID) is a magnetometer used to measure extremely weak magnetic field.measure extremely weak magnetic field.

Threshold for SQUID: 10^-14 TThreshold for SQUID: 10^-14 T Magnetic field of brain: 10^-13 TMagnetic field of brain: 10^-13 T Magnetic field of earth: 2.5x10^-8 Magnetic field of earth: 2.5x10^-8

SQUIDSQUID is an assembly of is an assembly of Josephson junctions within a Josephson junctions within a

superconducting ring.superconducting ring.

The Josephson junction is composed of two The Josephson junction is composed of two

superconductors separated by a thinsuperconductors separated by a thin

insulating layer.insulating layer.

Electrons can tunnel through the insulator. Hence Electrons can tunnel through the insulator. Hence

current crosses the junction across current crosses the junction across superconductor despite insulator. This is Josephson superconductor despite insulator. This is Josephson Effect.Effect.

There are two main types of SQUIDThere are two main types of SQUID (1)(1) Direct current (DC) –Two Josephson Junction Direct current (DC) –Two Josephson Junction

usedused

(2) Radio Frequency (RF)- One Josephson Junction (2) Radio Frequency (RF)- One Josephson Junction usedused

DC SQUID DC SQUID Phase changes with Phase changes with

changing magnetic changing magnetic field.field.

So does the super So does the super current around the ring current around the ring and thereby voltage.and thereby voltage.

The change in flux The change in flux crossing across the crossing across the ring is quantized.ring is quantized.

The quanta of flux is The quanta of flux is given bygiven by

RF SQUIDS RF SQUIDS Uses only one Josephson junction .Uses only one Josephson junction . Less sensitive compared to DC SQUIDS Less sensitive compared to DC SQUIDS Widely used due to less costWidely used due to less cost The RF SQUID is coupled to a resonant tank The RF SQUID is coupled to a resonant tank

circuit . As the SQUID operates the effective circuit . As the SQUID operates the effective inductance of the tank circuit changes and inductance of the tank circuit changes and thereby resonant frequency changes.thereby resonant frequency changes.

Output voltage is sinusoidal with linear variation Output voltage is sinusoidal with linear variation in flux.in flux.

Structure of SQUIDsStructure of SQUIDs

APPLICATIONS OF APPLICATIONS OF SQUIDS SQUIDS

MEASUREMENT OF IRON IN LIVERMEASUREMENT OF IRON IN LIVER

The liver is a major site for iron The liver is a major site for iron which is in the form of ferrinite which is in the form of ferrinite and hemosiderin protein which are and hemosiderin protein which are paramagneticparamagnetic

PARTICLES IN LUNGS PARTICLES IN LUNGS

Well-known examples of such particlesWell-known examples of such particles

are asbestos fibers, coal dust are asbestos fibers, coal dust

and metal aerosols. and metal aerosols.

MEDICAL IMAGINGMEDICAL IMAGING

Computerized Tomography (CT) Computerized Tomography (CT) Magnetic Resonance Imaging Magnetic Resonance Imaging

(MRI) (MRI) Positron Emission Tomography Positron Emission Tomography

(PET)(PET)

MAGNETOENCEPHALOGRAPHY MAGNETOENCEPHALOGRAPHY (MEG)(MEG)

Measures the magnetic fields produced in the Measures the magnetic fields produced in the brain by ionic current flow arising from neural brain by ionic current flow arising from neural

activity.activity.

COMPARISION OF MEG, MRI & COMPARISION OF MEG, MRI & PETPET

MAGNETOCARDIOGRAPH (MCG) MAGNETOCARDIOGRAPH (MCG)

Used for heart monitoring.Used for heart monitoring.

Heart produces a rhythmically synchronized signal. This signal is described by means of a current dipole.

SQUIDS pick up the magnetic signal. Signal is then amplified and sampled and then fed to processor

ADVANTAGES OF ADVANTAGES OF MAGNETIC MAGNETIC

MEASUREMENTMEASUREMENT Non- invasiveness Non- invasiveness Quick measurement Quick measurement Good spatial resolution.Good spatial resolution. MCG exceeds the diagnostic value of MCG exceeds the diagnostic value of

ECG. ECG. Magnetic field is less than distorted Magnetic field is less than distorted

by tissues than the electric potential. by tissues than the electric potential.

DISADVANTAGES OF DISADVANTAGES OF MAGNETIC MAGNETIC

MEASUREMENT MEASUREMENT Environmental noiseEnvironmental noise Most effective solution is a magnetically Most effective solution is a magnetically

shielding room (MSR).shielding room (MSR). Magnetic shielding: Mu metal Magnetic shielding: Mu metal

(high permeability alloy) (high permeability alloy) Eddy current and RF shielding: Eddy current and RF shielding:

aluminum (high conductivity)aluminum (high conductivity)

FUTURE SCOPEFUTURE SCOPE

A new program to image cancer and A new program to image cancer and tumors with SQUID sensor arrays tumors with SQUID sensor arrays and super paramagnetic nano and super paramagnetic nano particles is currently under particles is currently under development.development.

Biomagnetism also have a good Biomagnetism also have a good diagnostic value. diagnostic value.

REFERENCESREFERENCES I.P.Wiksow, Jr; “SQUID magnetometers for I.P.Wiksow, Jr; “SQUID magnetometers for

Biomagnetism and Nondestructive Testing”: Biomagnetism and Nondestructive Testing”: Important Questions and Intial Answers. –IEEE Important Questions and Intial Answers. –IEEE Transactions on Applied Super Conductivity Vol Transactions on Applied Super Conductivity Vol 5, No:2,June19985, No:2,June1998

Handbook of Biomedical Instrumentation, Handbook of Biomedical Instrumentation, R.S.KhandpurR.S.Khandpur

www.biomagnetism.com www.biomagnetism.com

THANK YOUTHANK YOU