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LIU, XIAOYU (2013) DESIGN, OPTIMIZATION AND IMPLEMENTATION OF AN ORTHO-TAG RFID SYSTEM. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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There are two major problems with traditional methods of operating an RFID tag embedded on orthopedic implants by wireless transmission: (1) interference with metallic orthopedic implants causes significant signal attenuation around the RFID tag; (2) interference with other medical devices may lead to the failure of their functionality. The creation of a feasible solution to the above two problems is critical to the success of operation of implanted RFID devices embedded on or near metallic implants and in any other situation where wireless interference may occur. The solution proposed in this dissertation is the Ortho-tag RFID system which uses the conductivity of human tissue at radio frequencies for energy and signal transmission. With the viability experiments proving the feasibility of using volume conduction in this research, two present issues have been addressed: (1) the lack of availability of a matching technique between tissue/saline and the RFID device; (2) the lack of an efficiency study on the operation of RFID through tissue/saline with variable thickness. This fundamental work then details the development of a general solution for the above two issues, in a power and communication platform technology for implanted RFID devices. The platform is developed using equipment in the RFID Center of Excellence in which pig skin and saline are used as a medium for in vivo environment as human tissue surrogates. The selection and design of the volume conduction electrodes are discussed and optimized using ANSYS/HFSS. The system optimization focuses on matching the RFID reader and the tag to the tissue/saline based on an equivalent 2-port network model for tissue using Z parameters. Matching networks are designed and optimized so that the tag is matched to the tissue from the internal side, and the tissue is matched to the RFID reader from the external side. For high data rate considerations, two RFID frequencies are utilized for the Ortho-tag RFID system. The frequencies are HF at 13.56 MHz and UHF at 915 MHz. The system is finally prototyped and demonstrated as the proof of concept.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
LIU, XIAOYUxil56@pitt.eduXIL56
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairMickle, Marlinmickle@pitt.eduMICKLE
Committee MemberSun, Minguidrsun@pitt.eduDRSUN
Committee MemberCain, Jamesjtc@pitt.eduJTC
Committee MemberMao, Zhi-hongmaozh@engr.pitt.eduZHM4
Date: 16 March 2013
Date Type: Publication
Defense Date: 7 October 2011
Approval Date: 16 March 2012
Submission Date: 3 November 2011
Access Restriction: 5 year -- Restrict access to University of Pittsburgh for a period of 5 years.
Number of Pages: 123
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Electrical Engineering
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: RFID, volume conduction, Ortho-tag, orthopedic implant, matching
Date Deposited: 11 Sep 2013 05:00
Last Modified: 16 Mar 2017 05:15


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