Study of RF power attenuation with MEMS coils

Wireless power delivery to implantable biomedical devices by means of inductive coupling has been proved to be feasible. While RF power attenuation in bio-body is not studied very well. In this paper, an experiment was setup to measure the effect of the situation and angle misalignment between the transmitter and receiver coils both in air and HBSS (Hanks´ balanced salt solutions). High Q MEMS coils are utilized as the transmitter and receiver separately. The measuring frequency is from 10 MHz to 200 MHz. It can be observed that the received power peak appears at 80 MHz in air, whereas, there exists two peaks at 30 MHz and 60 MHz in HBSS. In addition, the power attenuation decays exponentially when the transmission distance increases at lower frequencies.