Wireless power transfer to extremely-miniaturized diagnostic devices

Recent advancements in electronics and microfabrication techniques have increased attention to the use of implantable miniaturized biosensors. In vivo biosensing is going to radically change healthcare by allowing personalized medicine. By continuous monitoring, the basic health of an individual could be well understood, making possible to detect upcoming pathologies. A further option is the continuous monitoring of a therapeutic drug that could eliminate dosage intakes by providing an individualized pharmacokinetic report of a drug. These devices could also be used in vitro to monitor cell cultures that are useful for various purposes, such as understanding and modelling certain biomechanisms, developing novel medicinal products and treatments or in the area of regenerative medicine. These devices need a power supply and must be miniaturized at the same time, so it is necessary to use wireless power transfer. For this purpose, in this work, the wireless power transfer via electromagnetic waves is examined. This thesis focus on analysing the physical limits of this technique when the receiving antenna is implanted in the human body and try to quantitatively provide values of maximum transferable power in relation to the size of the implanted antenna, depth in tissue and working frequency. Finally, through Ansys HFSS, a commercial finite element method solver, extremely miniaturized antennas (with a size of 1x1x1 mm3 and 2x2x2 mm3) are designed and simulated implanted in the human body and inserted in a petri dish, in order to provide practical examples in vivo and in vitro, to demonstrate that a sufficient amount of power to power a small biosensor can be transferred in both scenarios without exceeding the legal limits of transmitted power.