SWEAT - Sleeping Wireless Energy-transfer And Trickle charging: Building a coupled inductor system for powering biomedical implants

In a world of improving health care, some diseases are still very hard to diagnose. The most common reasons for this problem is the fact that those diseases are non-symptomatic. To gain better diagnoses of such illnesses long term ExG by using bio-medical implants is a good option. These implants have to be powered by a wireless power link. This thesis analyses the possibilities for the development of a wireless transfer system that can transfer at least 360 µWh of energy within six hours through the air and into tissue tissue. After analysis of the influence of the environment on the wave efficiency it is proven that resonant magnetic transfer is the best option for the given scenario. 13.56 MHz is chosen as operating frequency. Energy for the implant is needed at DC level, therefore a rectifier layout is analysed, designed and built out of discrete parts. With the use of discrete components and hand-made inductors, the final operating frequency became 17.50 MHz. The laboratory equipment used restricted the maximum input voltage amplitude to 4.56 V. The final result of this thesis is a prototype wireless energy transfer system that generates a maximum of 75.9 µW of power continuously at a power efficiency of 10.1 percent at a distance of 15 mm.At a distance of 75 mm, the maximum output power was still equal to 2 µW. The power efficiency at 75 mm distance is equal to 0.29 percent, which means that to generate 360 µWh within six hours the input power must be at least 25.9 mW, a value that can easily be reached without causing flicting damage to human tissue or the system itself. This proves that magnetically coupled inductor systems can be used for the future development of autonomous ExG implants.

Subject

wireless energy transfer
magnetic field
ExG implants
RFID

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Student theses

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master thesis

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MSc_Thesis_Sander_Fondse.pdf

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