93913 - Bioelectromagnetism

Learning outcomes

The students, will first learn the main phenomena related to the propagation of RF electromagnetic waves in free space, in real channels and in guided structures and will learn how they interact with materials. The budget in terms of exchanged electromagnetic energy is deeply analyzed and related with different fields of interest for biomedical applications such as energy and data transmission, for telemetry purposes and heat conversion for therapy applications. These competences will allow the students to be instructed on: - the main phenomena of the propagation electromagnetic fields. - mechanisms of interaction of electromagnetic fields with different material means for different working frequencies. - mechanisms of interaction between electromagnetic fields and biological systems: dispersive behavior. - design and characterization of simple antenna elements. - elementary principles of the dosimetry of electromagnetic fields.

Course contents

The course aims to provide students with the knowledge to understand the interaction between electromagnetic fields and material media, in particular biological tissues, and how these are the basic mechanisms for different applications of bioengineering.

The first part will introduce the fundamental laws of electromagnetism, the concept of uniform plane waves and the laws of propagation in homogeneous and non-homogeneous materials and their characterization through EM propagation.

The dispersive media will then be introduced and the polarization mechanisms of the media and the relative frequencies at which these phenomena occur will be explained.

In the second part of the course the study of Nuclear Magnetic Resonance techniques and apparatuses will be deepened. Students will thus be able to see an exemplary application of different concepts of electromagnetism, starting from static fields up to frequencies in the VHF band.

Then we will deal with the notions of far field, antenna and characteristic quantities of radiation to provide students with the fundamental concepts of radiofrequency and microwave dosimetry and telemetry techniques.

Finally, the concepts of lumped constants and distributed constants circuits will be compared, at the basis of the modeling of bioelectricity phenomena and the transmission of electrical signals in the human body.

Some software laboratory activities are planned in which students will practice electromagnetic simulation and build simple models to characterize the interaction between electromagnetic fields and biological tissues. The topics covered in groups and the expected times for each group are described in detail below.

INTRODUCTION (2)
Bioelectromagnetism, bioelectricity, bioelectromagnetics.
Classification of EM fields and mechanisms of interaction with different media.

BASIC ELECTROMAGNETISM (24)
Electromagnetic fields in the time domain:
- Maxwell's equations.
- Material means and constitutive relations.
- Discontinuity.
- Conservation laws.

Sinusoidal electromagnetic fields:
- Maxwell's equations.
- Poynting's theorem and other fundamental theorems.
- Polarization of the electromagnetic field.
- Dielectric means.
- Conducting means.

Uniform plane waves:
- Equations and general characteristics.
- Propagation in the media.
- Reflection and transmission.
- Propagation of plane waves through one layer and several layers.

NUCLEAR MAGNETIC RESONANCE (16)

Principles of operation
Fundamental equations of the NMI
Structure of an apparatus for NMR
Static field B0 and main magnet.
Gradient field and design methods for low frequency fields. Radio frequency
field B1: circuit analysis and by means of the moment method.

ANTENNAS and DOSIMETRY (12)
Elementary sources.
Extensive sources.
Characteristic quantities of radiation.
Antenna arrays.
Elements of dosimetry.

CIRCUITS and SIGNAL TRANSMISSION (6)
Circuits with lumped constants.
Circuits with distributed constants.
Transmission lines and modeling of biological phenomena.

Readings/Bibliography

1) Perregrini, Conciauro Fundamentals of electromagnetic waves - Mc Graw Ill

2) Electromagnetic analysis and design in magnetic resonance imaging / Jianming Jin

Teaching methods

power point presentations; sessions to verify the understanding of the topics through group work; lectures by students with teach back methods.

Assessment methods

Verification of learning takes place through an oral test preceded by a written test in which the student is invited to prepare a pattern of answers to three questions relating to the program. During this test the use of books, notes, calculators, electronic media is not allowed.

The written test aims to ascertain the skills acquired in highlighting the fundamental aspects of the topics covered and to solve problems in the context of the issues addressed. The oral exam follows the written exam and aims to deepen the verification of the acquisition of the knowledge required by the course program. The final grade is expressed out of thirty and takes into account the results obtained in both tests.

Teaching tools

Personal computer, Cadence AWR, CST Microwave studio

Office hours

See the website of Alessandra Costanzo

See the website of Giacomo Paolini