Increasing the Miniaturization Limit of Wireless Implantable Devices Through a Multimode Wireless Power Transfer Approach

Implantable electronic devices are constantly evolving at an astonishing pace, supported by the technological breakthroughs of fields such as microelectronics, packaging, and integration techniques. The reduction of the implants' size is of paramount importance for their usefulness and development of new applications and therapies. However, state of the art biomedical devices often have their minimum volume limited by their power modules, i.e., battery and/or antenna. This paper presents a solution to significantly reduce the volume of an implantable device featuring wireless power transfer. This is achieved by resorting to a WPT method that allows implantable antennas to become considerably smaller. Simulated and experimental results determine that a three-fold decrease in antenna length is made possible resorting to multimode wireless power transmission technology. Such solution allows to deliver the same power to a smaller device while maintaining the same SAR level considered for standard WPT solutions.