Low EMF Design of Cochlear Implant Wireless Power Transfer System using A Shielding Coil

Wireless power transfer (WPT) technology is widely used for various applications because of convenience and safety. Especially, medical implant devices such as a cochlear implant are one of the typical application of the WPT technology. However, WPT systems have problems with electromagnetic field (EMF) leakage, which can cause electro-magnetic interference (EMI) issues in the human body. In this paper, we propose an additional shielding coil for the effective suppression of EMF radiation of a WPT system. The proposed method reduces the EMF leakage in operating frequency range. We verified that the proposed shielding coil reduced the EMF leakage by 5.1 dB using 3D EM simulation. Also, the power transfer efficiency (PTE) and link gain stability of the proposed cochlear implant WPT system are designed to work well with proposed shielding coil.