Specific absorption rate of inductively powered brain implanted circuits

This paper discusses the simulated exposure to a 5 MHz electromagnetic field powering implanted electronic devices using an inductive link. A high efficiency class-E transmitter circuit operating at 5 MHz has been designed. The circuit generates a 1 W to 5 W transmitted power by means of two possible planar primary coil designs, and powers 5 identical implants which are individually equipped with a secondary inductor. Simulations illustrate that a maximum localized SAR level (averaged over 10 g) of 1.16 W/kg is obtained in a rectangular bone structure with a thickness of 10 mm, when the power transmission is equal to 5 W.