The document discusses the interaction of electromagnetic fields (EMFs) with biological systems. It notes that the topic is studied to assess potential health hazards, enable applications in biology and medicine, and optimize the design of EM devices. The document outlines various effects of EMF exposure at different frequencies, therapeutic and diagnostic EMF applications, and the need to model human exposure and effects through governing equations and human body models. Key areas covered include dosimetry, various human body models, RF applications like keyless entry and MRI, hyperthermia modeling, and diagnostic applications such as endoscopic capsules.

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The Interaction of EMFs
with Biological Systems
Why Study EMF?
 Interaction of EMFs with biological systems.
 Health hazard prevention
 Applications in biology and medicine
 Design of EM devices and optimization
What do you think???
Cell phone usage (the more the better)
Living under base stations or in front of them
Exposure effects of low frequencies versus high
frequencies (are they the same)

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Assingment # 1
 List as many applications of magnetic biosensors
in the BME field (figures and theory of operation
should be listed)
 There will be a prize for the largest number
found.
 Please bring TO CLASS next time
Interaction of EMF with Biological
Systems
Interest was motivated by:
1. Possible Human health hazards: Adverse effects
at low frequencies as well as high frequencies.
2. The successful applications of EMFs in therapy
and diagnostics.
 Low frequency fields (0-3kHz)
 High frequency fields (RF and microwaves)
3. Wireless applications (Telemetry)

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 Onset of childhood Leukemia
 Cardiac fibrillation
 Vision of phosphenes
 Nerve and muscle stimulation
 Interference with implanted medical devices:
- Pacemakers (time varying fields)
- Orthopedic prosthesis like metal bars or screws
in bones (static fields)(Like can occur in ? device)
Adverse Effects:
due to the exposure at power line frequencies (50/60 Hz)
or in the industrial environment (power transformers, electric
appliances, welding equipment, etc.)
Mobile Phone Exposure (0.9- 2.2 GHz):
EMF risk assessment:
Different approaches for assessment of EMF emitted by devices
performed under well defined and controlled lab conditions.
(WHY Lab?)

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Cellular Phones – Human Interaction
SAR TEMP
Therapeutic and diagnostic applications
 Postponed to the end of the lecture (slide 21)

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Interaction of EMF with biological systems either to
assess health risks or for therapeutic/diagnostic
applications:
We need to:
1. The type of the electromagnetic field formulations used
to solve the electromagnetic problem: Maxwell’s eqns.
2. The source of electric, magnetic or EM field that may
induce the biological effect.
3. The use of a human body model (realistic or simplified)
with electric and thermal characteristics of biological tissues
(WHY?).
4. The computation of field quantities in different tissues
(E, J, SAR, T).
To assess human exposure or therapeutic
effects we need to evaluate:
 Magnetic flux density, B [T]
 Induced current density, J [Am-2]
 Magnetic field, H [Am-1]
 Electric field, E [Vm-1]
 Specific Absorption Rate (SAR) [Wkg-1] and
tissue temperature (K) (Bioheat Eqn)
 Power density, S [Wm-2]

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Governing Equations
Maxwell’s equations
12

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hQJETk
t
T
c 



Bioheat Equation
)( blb TTh
T
k 


n
Heat transfer coefficient Blood temperature
Density
Specific
heat
Thermal
conductivity
Time
Temperature
Current
density
Electric field
intensity
heat loss
to blood
perfusion
VARIABLES
Heat
Change
MATERIAL PROPERTIES
EJ 
Electrical
conductivity
Density
Specific
heat
Thermal
conductivity
Time
Temperature
Current
density
Electric field
intensity
heat loss
to blood
perfusion
heat loss
to blood
perfusion
Heat
Conduction
Joule Heat
Various Human Body models
Norman Zuabl Brooks Hugo
Human Head Model

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Low Frequency Dosimetry
Acquisition Segmentation
Reconstruction Ella head model

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Electromagnetic Modelling of
the Human Body
Phantom Development –
NORMAN
NORmalised MAN
Height: 1.76 m
Weight: 73 kg
Developed from MRI scans
8.3 million voxels (2 mm)3
37 different tissue types
Frequency dependent conductivity and
permittivity
Also scaled to represent children at ages 1, 5 and
10 years
Example: Power Absorption from
Radiofrequency Fields
Relative contributions of the body parts to whole-body SAR
Individual SAR values expressed as a rainbow spectrum:
violet = lowest, red = highest
absorption gradually moves awayincreasesAs frequency
from knees and ankles to the upper torso

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Keyless Entry: A wireless device for remotely locking and unlocking the
vehicle
Never Underestimate the Power of the Chin
315 MHz ,a simple radiating loop antenna
EM Field Exposure from a monopole antenna placed above the
trunk of the car (SAR in an axial slice of the head)

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Magnetic Resonance Imaging
Imaging Devices (???)

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Full 3D simulation model including human
model and RF shield of gradient coil
The problem with
7T MRI...
(High power…. SAR
limits reached)
-Advanced multi-
channel coils are
required.
(Biomedical
Engineers)
Assignment 2
Visit this site:
https://www.itis.ethz.ch/virtual-
population/virtual-population/overview/
What did you find?
https://www.itis.ethz.ch/customized-research/
List the research topics you found? Be prepared to
discuss in class

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Applications of EMF at 100 MHz – 30 GHz
Examples of some HT applicators

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BSD Deep Heating
Hyperthermia Modeling

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3D Treatment Plan
1. Segmentation of images
2. Stacking of MR/CT images
3. Positioning of Antennas
4. SAR calculation
5. Temperature Distribution
SAR

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Hyperthermia Results
Electric Field Temp
Brain Tumor Hyperthermia
Geometry
Tissue parameters
Boundary conditions
Numerical modeling
Prototype
Head
Model
Antenna
Chamber

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Temperature distribution in head tissues

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C.
Coil 1
Coil 2
Induced E field

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Cardiac ablation
RF Cardiac Ablation
J

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RF Hepatic Ablation
Liver
Stainless steel
trocar
Insulated
trocar
4 tines of
electrode Blood vessel
(10 mm)
A
B
Temperature Distribution
Highest
temerature

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Electro-Osteo-Stimulation
Magnetic nanoparticlesDrug targeting of magnetic
nanoparticles to treat
intramedullary spinal tumors)
:To be discussed in class
http://uicscience.tumblr.com/post/176482290873/
video-created-by-adriana-orland-a-student-in-the

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Biological Effects of Diathermy
1-Increased metabolism.
2-Relief of pain.
3-Stimulated wound healing.
4-Relaxed muscle spasm.
5-Accelerated wound healing.
6-Decreased haematoma formation

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Diagnostic Applications: Endoscopic Capsule

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Course Outline
 Electrostatic fields
 Magnetostatic fields
 Time-varying fields
 Electromagnetic waves (antennas and propagation in
different media)
 Antennas: therapy, diagnosis, telemetry
 Electrical and thermal properties of biological tissues
 Therapeutic applications in biology and medicine
(challenges)
 Numerical modeling

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References
 Elements of Electromagnetics (Sadiku)
 Basic Introduction to Bioelectromagnetics
(Cynthia Furse)