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Miniaturization of Implantable Antennas for Medical Applications (Σμίκρυνση Εμφυτεύσιμων Κεραιών Για Ιατρικές Εφαρμογές)

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Miniaturization of Implantable Antennas for Medical Applications (Σμίκρυνση Εμφυτεύσιμων Κεραιών Για Ιατρικές Εφαρμογές) European Postgraduate Programme on Biomedical Engineering Miniaturization of Implantable Antennas for Medical Applications (Σμίκρυνση Εμφυτεύσιμων Κεραιών για Ιατρικές Εφαρμογές) A Dissertation submitted in partial fulfilment of the requirements for the degree of Master of Science in Biomedical Engineering Supervised by Prof. Nikolaos Uzunoglou UNIVERSITY OF PATRAS NATIONAL TECHNICAL UNIVERISTY OF ATHENS FACULTY OF MEDICINE SCHOOL OF ELECTRICAL & COMPUTER ENGINEERING Panagiotis Blanos June 2013 Panagiotis Blanos - Miniaturization Of Implantable Antennas For Medical Applications Acknowledgements I would like to thank Professor Nikolaos Uzunoglou and Senior Researcher Irene Karanasiou for their supervision, help and encouragement throughout the research and project work. I would also like to thank MediWise Ltd, in particular George Palikaras and Themos Kallos, for their support, guidance and their technical expertise, as well as for giving me the chance through this project suggestion to further my knowledge and expertise. Last but not least, I would like to thank my respective friends and family for their love and for believing in me. 1 Panagiotis Blanos - Miniaturization Of Implantable Antennas For Medical Applications Abstract The use of advanced technology to deliver healthcare from a distance has the potential to be one of the defining medical revolutions of the 21st century. It is commonly recognized that modern wireless technology will play an important role in making advanced telemedicine possible. The development of implantable medical devices (IMDs) is one of the most important aspects towards establishing such an advanced healthcare system. Essential element of implantable devices are antennas embedded in such systems, which enable the exchange of data between implantable devices and external environment. The underlying project was ran in collaboration with MediWise Ltd. The solution proposed in this dissertation is an optimised implantable antenna, for wireless radiation dosimetry for usage within external-beam radiotherapy, which aims to be further developed in the future in order to produce a commercially viable product. The dissertation presents the design of two types of implantable antenna structures that are suitable for miniaturisation, and focuses on the development of an implantable antenna design that is smaller than 5 x 5 mm in size which operates at 402 - 405 MHz MICS band and on the optimization of the chosen implantable antenna for bandwidth, return loss, radiation, etc. and aim to miniaturise further the antenna at 1 x 1 mm in size. 2 Panagiotis Blanos - Miniaturization Of Implantable Antennas For Medical Applications Περίληψη Η χρήση της προηγμένης τεχνολογίας για την παροχή υγειονομικής περίθαλψης από απόσταση έχει τη δυνατότητα να είναι μία από τις πιο καθοριστικές ιατρικές επαναστάσεις του 21ου αιώνα. Είναι κοινώς αποδεκτό ότι η σύγχρονη ασύρματη τεχνολογία θα διαδραματίσει σημαντικό ρόλο στην εξέλιξη της προηγμένης τηλεϊατρικής. Η ανάπτυξη των εμφυτεύσιμων ιατρικών συσκευών (IMDs) είναι μία από τις πιο σημαντικές πτυχές για την εγκαθίδρυση ενός τέτοιου προηγμένου συστήματος υγειονομικής περίθαλψης. Σημαντικό στοιχείο των εμφυτεύσιμων συσκευών είναι κεραίες που ενσωματώνονται σε τέτοια συστήματα και επιτρέπουν την ανταλλαγή δεδομένων μεταξύ των εμφυτεύσιμων συσκευών με το εξωτερικό περιβάλλον. Η εν λόγω εργασία έγινε σε συνεργασία με την ερευνητική ομάδα της MediWise Ltd. Η λύση που προτείνεται στην παρούσα εργασία είναι μια βελτιστοποιημένη εμφυτεύσιμη κεραία για ασύρματη δοσιμετρία ακτινοβολίας για χρήση σε ακτινοθεραπεία εξωτερικής δέσμης, που έχει ως στόχο να αναπτυχθεί περαιτέρω στο μέλλον, προκειμένου να παραχθεί ένα εμπορικά βιώσιμο προϊόν. Η διατριβή παρουσιάζει το σχεδιασμό των δύο τύπων των εμφυτεύσιμων δομών κεραίας που είναι πιο κατάλληλα για την ελαχιστοποίηση των διαστάσεων, και επικεντρώνεται στην ανάπτυξη ενός εμφυτεύσιμου σχεδιασμού της κεραίας που είναι μικρότερο από 5 x 5 χιλιοστά σε μέγεθος το οποίο λειτουργεί στα 402 - 405 MHz MICS μπάντα και στην βελτιστοποίηση της επιλεγμένης εμφυτεύσιμης κεραία για εύρος ζώνης, απώλεια επιστροφής, ακτινοβολία, κλπ. και αποσκοπεί στην περαιτέρω σμίκρυνση της κεραίας σε μέγεθος 1 x 1 χιλιοστά. 3 Panagiotis Blanos - Miniaturization Of Implantable Antennas For Medical Applications Table of Contents Acknowledgements .............................................................................................................................. 0 Abstract ................................................................................................................................................. 2 Chapter 1 ........................................................................................................................................... 8 Introduction ...................................................................................................................................... 8 1.1 Introduction to Implantable Devices ....................................................................................... 8 1.2 Wireless Medicine ................................................................................................................. 11 1.3 Biomedical Telemetry ........................................................................................................... 12 1.4 Frequency Bands [1] ............................................................................................................. 15 1.5 Implantable Antennas ............................................................................................................ 16 1.6 Challenges in the Design of Implantable Antennas .............................................................. 18 1.7 MediWiSe [19] ...................................................................................................................... 19 1.8 Aims, Objectives and Overview of the MSc Thesis ............................................................. 19 Chapter 2 ......................................................................................................................................... 21 Theory and Research Background ............................................................................................... 21 2.1 Biological Tissues Properties ................................................................................................ 21 2.1.1 Biocompatibility and Biomaterials ................................................................................ 21 2.1.2 Electrical Properties of Human Tissue .......................................................................... 22 2.1.3 Electromagnetic Radiation Interaction with biological tissues ..................................... 22 2.2 Operating Principles of Implantable Antennas ..................................................................... 24 2.2.1 Microstrip - Patch Implantable Antenna ....................................................................... 24 2.2.2 Planar Inverted F-Antenna (PIFA) [31] ........................................................................ 24 2.2.3 Loop Antenna ................................................................................................................. 25 2.3 Antenna Performance Parameters ......................................................................................... 26 2.4 Miniaturization Techniques................................................................................................. 29 2.5 Literature Review .................................................................................................................. 30 2.5.1 Microstrip and PIFA Antennas ...................................................................................... 30 2.5.2 Stacked PIFA Antennas.................................................................................................. 33 2.5.3 Loop Antennas ............................................................................................................... 34 2.6 CST Microwave Studio - 3D EM Simulation Software [72] ................................................ 36 2.6.1 Antenna Calculations ..................................................................................................... 36 2.6.2 Meshing (Discretization) ............................................................................................... 37 2.6.3 Simulation ...................................................................................................................... 37 2.6.4 Adaptive Meshing........................................................................................................... 38 Chapter 3 ......................................................................................................................................... 39 Antenna Designs - Simulations - Parametric Studies - Effects .................................................. 39 3.1 Initial Antenna Designs ......................................................................................................... 39 3.1.1 Meandered PIFA ............................................................................................................ 40 3.1.2 Spiral PIFA .................................................................................................................... 42 4 Panagiotis Blanos - Miniaturization Of Implantable Antennas For Medical Applications 3.2 Parametric Studies of Meandered PIFA – Effects ................................................................ 44
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