Antenna Designs for Wireless Medical Implants

TitleAntenna Designs for Wireless Medical Implants
Publication TypeThesis
Year of Publication2013
AuthorsConran, C
Date Published09/2013
UniversityDublin Institute of Technology
CityDublin, Ireland
Thesis TypeMaster Thesis

Active medical implants are devices that are surgically implanted inside the body. They have been developed to treat a wide range of ailments and many require some form of communications link with the outside world for maintenance and for remote medical diagnostics. Radio links promise a wide range of benefits over the traditional low frequency inductive coupling method.
Body tissue is a challenging environment, both for the device and for the radio signal that it transmits. Innovation in medical technology is creating a demand for high bandwidth links, and this in turn is driving the development of implantable antennas.
Many factors constrain antenna design choices. These include low signal power levels, minimal space availability and the effect that tissue characteristics have on the antenna’s performance. Most body tissues are highly dissipative and antennas must be specifically designed for a high dielectric environment.
A review of spectrum availability indicates that the 401 – 406 MHz and 2.4 GHz bands are suitable for implant links. Multiband antennas were explored in the research, but the design priority focussed on the 401 – 406 MHz band.
Custom antenna designs were simulated in software and prototypes were later produced and tested in a range of different materials that closely imitate body tissue.
Two final designs were developed. The designs are meander-line variants of an inverted-L antenna. Validation tests confirmed a return loss of 10 to 20 dB in a replicated implant environment. The design process, test results and antenna specifications are described in detail.


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