Volume conduction for powering deeply implanted networks of wireless injectable medical devices: a numerical parametric analysis

Abstract

The use of networks of wireless active implantable medical devices (AIMDs) could revolutionize the way that numerous severe illnesses are treated. However, the development of sub-mm AIMDs is hindered by the bulkiness and the transmission range that consolidated wireless power transfer (WPT) methods exhibit. The aim of this work is to numerically study and illustrate the potential of an innovative WPT technique based on volume conduction at high frequencies for powering AIMDs. In this technique, high frequency currents are coupled into the tissues through external electrodes, producing an electric field that can be partially picked-up by thin, flexible, and elongated implants. In the present study, the system formed by the external electrodes, the tissues and the implants was modeled as a two-port impedance network. The parameters of this model were obtained using a numerical solver based on the finite element method (fem). The model was used to determine the power delivered to the implants’ load (PDL) and the power transmission efficiency (PTE) of the system. The results allow the identification of the main features that influence the PDL and the PTE in a volume conduction scenario and demonstrate that volume conduction at high frequencies can be the basis for a non-focalized WPT method that can transfer powers above milliwatts to multiple mm-sized implants (<10 mm3 ) placed several centimeters (>3 cm) inside the tissues.