Effects of Conductive Tissue on Capacitive Wireless Power Transfer

Biomedical devices are one of the most successful applications of Inductive Power Transfer (IPT) where it provides a lifetime of power without the risk of infection associated with percutaneous leads. However, the preference in the industry for metallic packages to meet the biocompatibility and hermeticity requirements is a barrier to applying IPT technologies. Capacitive power transfer (CPT) is introduced as an alternative solution to these applications where metal barriers exist. With the aim of understanding how capacitive power can be applied in conductive media such as body tissue, we developed a finite element model of a capacitive power transfer system and validated it by comparison with a laboratory tissue phantom. It was found that the impedance, electric field and current in the phantom closely matched the simulation predictions with a worst case discrepancy of 20%. In the future, we will apply this model and the test phantom to understand the implementation and safety challenges in applying the capacitive power technology for powering implantable devices.